D STATES went of ERCE

NATION

NBS TECHNICAL NOTE 542

Activities of the

NBS Spectrochemical

Analysis Section

July 1969 to June 1970

ITTOWAL BUREAU OF STMBlffln

UNITED STATES DEPARTMENT OF COMMERCE

Maurice H. Stans, Secretary

i NATIONAL BUREAU OF STANDARDS • Lewis M. Branscomb, Director

+

NBS TECHNICAL NOTE 542

ISSUED NOVEMBER 1970

Nat. Bur. Stand. (U.S.), Tech. Note 542, 114 pages (Nov. 1970)

CODEN: NBTNA

Activities of the

NBS Spectrochemical Analysis Section

July 1969 to June 1970

Bourdon F. Scribner, Editor

Spectrochemical Analysis Section

Analytical Chemistry Division

Institute for Materials Research

National Bureau of Standards

Washington, D.C. 20234

""»<*» of *

NBS Technical Notes are designed to supplement the Bureau's regular publications program. They provide a means for making available scientific data that are of transient or limited interest. Technical Notes may be

listed or referred to in the open literature.

For sale by the Superintendent of Documents, U.S. Government Printing Office, Washington, D.C, 20402.

(Order by SD Catalog No. C 13.46:542). Price $1.25.

FOREWORD

The Analytical Chemistry Division was established as a separate division at the National Bureau of Standards on

September l s 1963* and became part of the Institute for

Materials Research in the February 1, 1964, reorganization.

It consists at present of nine Sections and about 100 technical personnel encompassing some 45 different analytical

competences from activation analysis and atomic absorption to

vacuum fusion and x-ray spectroscopy. These competences, and

in turn the Sections which they comprise, are charged with

research at the forefront of analysis as well as awareness of

the practical sample, be it standard reference material or

service analysis. In addition it Is their responsibility to

inform others of their efforts.

Formal publication in scientific periodicals is a highly

important output of our laboratories. In addition, however,

it has been our experience that informal, annual summaries of

progress describing efforts of the past year can be very valuable in disseminating information about our programs. A word

is perhaps in order about the philosophy of these yearly

progress reports. In any research program a large amount of

information is obtained and techniques developed which never

find their way into the literature. This includes the

"negative results" which are so disappointing and unspectacular but which can often save others considerable work. Of

importance also are the numerous small items which are often

explored in a few days and which are not important enough to

warrant publication -- yet can be of great interest and use to

specialists in a given area. Finally there are the experimental techniques and procedures, the designs and modifications

of equipment, etc., which often require months to perfect and

yet all too often must be covered in only a line or two of a journal article.

in
Thus our progress reports endeavor to present this information which we have struggled to obtain and which we

feel might be of some help to others . Certain areas which

it appears will not be treated fully in regular publications

are considered in some detail here. Other results which are

being written up for publication in the journal literature

are covered in a much more abbreviated form.

At the National Bureau of Standards publications such

as these fit logically into the category of a Technical

Note. In 1970 we plan to issue these summaries for all of

our Sections. The following is the sixth annual report

on progress of the Spectrochemical Analysis Section.

W. Wayne Meinke 3 Chief

Analytical Chemistry Division

IV
PREFACE

This is the sixth in a series of annual progress reports of the Spectrochemical Analysis Section of the Analytical Chemistry Division. The Section is concerned with

instrumental elemental analysis, especially for those

spectroscopic techniques that are capable of multi-element

determinations, including optical and x-ray spectroscopy.

Chemical elements are uniquely identified by the

characteristic frequency of emitted spectra, and amounts

present can be determined by measurement of the intensity of

emitted radiation. However, many factors enter into

successful spectral analysis and must be carefully controlled.

These include, in optical and x-ray spectrometry, the

production of radiant energy by excitation, the dispersion of

radiant energy into a spectrum, and the measurement of

spectral wavelengths and intensities. In general these are

methods of comparative analysis in which calibration by

synthesized or analyzed standards is required.

The research program of the Section is directed largely

toward a better understanding of the phenomena involved in

producing and measuring optical and x-ray emitted energy

and the improvement of spectrochemical methods, instruments,

and calibration procedures. Included in the work of the

Section are the development of appropriate standard reference

materials, analyses of materials to assist other research

projects, and literature surveys such as bibliographies and

critical reviews

.

The purpose of this report is to review the program,

facilities, and accomplishments of the Section for the

past year.
In order to specify procedures adequately, it has been

necessary occasionally to identify commercial materials and

equipment in this report. In no case does such identification imply recommendation or endorsement by the National

Bureau of Standards, nor does it imply that the material

or equipment identified is necessarily the best available

for the purpose.

Bourdon F. Scribner, Chief

Spectrochemi cal Analysis Section

vl
TABLE OF CONTENTS

PAGE

ABSTRACT 1

1. INTRODUCTION 2

A. Facilities 2

B. Activities 3

C. Computerized Data Acquisition System 7

2. ELECTRON PROBE MICROANALYSIS 9

A. Instrumental Improvements 9

B. Qualitative Analysis 11

C. Scanning Electron Probe Analysis 11

D. Quantitative Analysis 16

1. Emission of Continuous Radiation 18

2. Further Measurements on Standard Reference

Materials 19

3. Quantitative Analysis of Minerals and

Ceramics 21

4. Quantitative Applications of Energy Dispersion Detector Systems 22

E. Computer Program COR for the Correction of

Quantitative Microprobe Measurements 25

1. Theories Used in the Correction Procedure 25

2. Internal Structure of the Program COR . . 26

3. Input to the Program 2 8

4. Output of the Program 29

5. Documentation of the Program 29

F. Service Analyses 31

G. Literature Research 36

3. X-RAY FLUORESCENCE SPECTROMETRY .... 37

A. Research Activities 39

B. Applications ^3

1. Zinc Diecast Gears ^3

2. Thickness Determination of Fe-Be

Layers ^3

3. Homogeneity Analysis of a Research Ingot of

Cu-Ni-Fe

^

4. Replacement for 1100 Series Steel

SRM's ^6

C. Contributions of NBS Personnel ^9

vii
PAGE

4. OPTICAL SPECTROMETRY 50

A. Air Pollution Studies 50

B. Analysis of Clinical Materials 52

C. Literature Research 55

D. Applications to Analysis 55

1. Analyses of Standard Reference

Materials 55

2. Other Analyses 58

5. PRECONCENTRATION TECHNIQUES 6l

A. Optical Emission 6l

1. Ingot Iron 6l

2. Botanical Materials 64

3. Miscellaneous 64

B. Isotope Dilution 65

1. Ingot Iron 65

2. High-Purity Reagents 70

3. Botanical Materials 71

6. PERSONNEL AND ACTIVITIES 72

A. Personnel Listing 72

B. Publications 73

C. Talks Given 75

D. Committee Activities 78

7. ACKNOWLEDGMENTS 79

8. LIST OF REFERENCES 8l

APPENDIX A: CERTIFICATES FOR NBS STANDARD REFERENCE

MATERIALS RECENTLY ISSUED 84

1. SRM 1155 Stainless Steel Crl8-Nil2-Mo2

(AISI 316) °5

2. SRM 97a Flint Clay °7

3. SRM 98a Plastic Clay ° 8

4. SRM 59a Ferrosilicon 8 9

5. SRM 1143, 1144, 1147, 1148, and 1149 Blast

Furnace and White Iron Standards 91

viii
PAGE

6. SRM 1132 Lead-Base Bearing Metal

84Pb-10Sb-6Sn 93

7. SRM 1140, 1141, 1142 Ductile Iron

Standards 95

APPENDIX B: INPUT DATA FOR THE PROGRAM COR FOR CORRECTION OF QUANTITATIVE ELECTRON PROBE

MEASUREMENTS 97

LIST OF FIGURES

FIGURE NO.

1. Front view of the electron probe tank, with

recent modifications 10

2. Improvement of energy resolution with silicon

detector 12

3. Energy dispersion spectra of rhenium at various

voltages 13

4. Circuit diagram of the target current

amplifier 14

5. Copying camera for color composites 15

6. Specimen mount for minerals 1°

7. Measurements at 2 kV on copper-gold standard

reference materials 20

8. Superimposed contamination marks from a matrix

run of 15 hours duration on pure nickel . . 24

9. Diagram of the subprograms in the program

COR 27

10. Typical output of program COR for the analysis

of a mineral, using compound standards ... 30

11. Scanning electron micrograph of a breccia from

flight Apollo 11 31

12. Target current and x-ray scanning images of a

rock fragment in breccia from Apollo 11 . . 32

IX
PAGE

13- Target current and x-ray scanning images of a

rock fragment from flight Apollo 12 .... 34

14. Single-channel , vacuum x-ray fluorescence

spectrometer 38

15. Calibration curves for Fe and Ni in the Fe-Ni

binary system 40

16. Graphs of C/R as a function of C 4l

17. Ni calibration in austenite/ferrite matrix and

Ni calibration in low alloy steels 42

18. Photomicrograph of a section of a zinc die-cast

gear 44

19. Thickness calibration for thin, supported layers

of Fe-Be ^5

20. Correlation of x-ray fluorescence and optical

emission results in the analysis of proposed

SRM 1262 ^7

21. Correlation of x-ray fluorescence results and

provisionally accepted values for proposed

SRM 1262 48

22. Arc-spark stand mounted on photoelectric spectrometer 52

23. Sketch showing sampling of steel slab for

homogeneity studies 57

24. Apparatus for laser-probe analysis 59

25- Clean environment evaporator 62

26. Electrolysis cells in enclosure 69

LIST OF TABLES

TABLE NO.

1. Standard reference materials of interest for

spectrometric applications 6

2. Summary of spectrometric analyses 6

x
PAGE

3. Analysis of Cu-Ni-Fe specimens 46

4. Spectrometer conditions for beryllium determinations 53

5. Determinations of impurities in glucose ... 54

6. Spectrographic details for determination of

impurities in iron 63

7. Analysis of ingot iron SRM 1265 by optical

emission spectrography 64

8. Analysis of ingot iron SRM 1265 by isotope

dilution - spark source mass spectrography 67

9. Analysis of high-purity perchloric acid by

isotope dilution - spark source mass

spectrography 71

xi

ACTIVITIES OP THE NBS SPECTRO CHEMICAL

ANALYSIS SECTION

July 1969 to June 1970

Edited by Bourdon F. Scribner

Spectrochemical research activities., Improvements in

equipment, and applications, especially to the certification

of NBS Standard Reference Materials, are summarized. In

electron probe microanalysis, a comprehensive computer correction program for accurate analysis of materials relative

to single elements or simple compounds was developed, an

improved lithium-doped silicon detector was found to provide

increased resolution, and improvements in microprobe instrumentation produced a high level of stability. Studies of

procedures for correction of x-ray fluorescence measurements

were made, instrumental changes resulted in marked improvement

in performance reliability, and new applications were made.

In optical emission spectrometry, studies were made of beryllium determination in an air pollution investigation and trace

analyses were made of organic materials to parts per billion

_q

(10 ) limits. Methods of pre-concent ration of impurities

are described for optical emission and isotope dilution spark

source mass spectrometric analysis of ingot iron, botanical

materials, and high purity reagents. Work on Standard Reference Materials resulted in certification of stainless steel,

clays, ferrosilicon, blast furnace irons, white irons, lead

bearing metal, and ductile irons. Listings are given of 18

publications and 28 talks by members of the Section during

the year.

Key words

:

Analysis; computer program; electron probe; microanalysis;

optical spectrometry; pre-concentration techniques; spectrochemical analysis; standard reference materials; x-ray

fluorescence analysis.

1
1. INTRODUCTION

In the earlier reports in this series [1-5] we described

the facilities and programs of the Section, and references to

the past reports will be found in the current report. Copies

of the earlier reports are available on request. In each

report, the research activities and the output in terms of

publications, talks given, and analytical work have been recorded. This report follows the same general format although

the order of the main topics has been changed. In the introduction we will summarize the major activities of the Section

and briefly describe a new and promising Division-wide computing system now being developed.

A . Facilities

No additions of major equipment were made this year;

however, the equipment for the electron probe and x-ray

fluorescence have been considerably upgraded for improved

performance. The spark source mass spectrometer has been

trans fere d to the Analytical Mass Spectrometry Section, but

cooperative work continues in the area of isotope dilution

spark source mass spectrometry.

The major equipment of the Section includes the following.

3-meter Eagle mounting grating spectrograph

3.4-meter Ebert mounting grating spectrograph

21-foot Wadsworth mounting grating spectrograph

2-meter multi-channel optical spectrometer

3-meter multi-channel optical spectrometer

1.5-meter multi-channel vacuum optical spectrometer

0.75-meter Ebert mounting, scanning spectrometer

0.75-meter Czerny-Turner mounting spectrograph/spectrometer

Multi -channel x-ray fluorescence spectrometer

Single-channel vacuum x-ray fluorescence spectrometer

Electron probe microanalyzer with 3 x-ray spectrometers

2
B. Activities

The laboratory is organized into four major groups with

personnel as listed in section 6 of this report . The groups

are electron probe microanalysis , x-ray fluorescence spectrometry, optical emission spectrometry, and enrichment techniques.

At the end of the fiscal year, there were 10 full time and 4

part time employees with 2 summer assistants. During the year,

several guest workers contributed to the work of the Section.

The guest workers included Dr. Jean Henoc, from the Centre

National d'Etudes des Telecommunications, France; Barry L.

Hammond, research associate, from the Naval Ship Research and

Development Center, Annapolis, Md . ; and Dr. Ellas Belkas,

Greek Atomic Energy Commission, Athens. Other guests, on a

part-time basis, were Dr. Toshiaki Kuroha, Harvey Yakowitz,

and Fielding Ogburn from NBS groups.

The activity of the Section continued to be divided

approximately equally between (1) general research and development and (2) service activities involving spectrometric

analyses for certification of standard reference materials,

analyses for other projects at NBS, and development of methods

and analyses for other Government laboratories. Research

activities are directed toward empirical and theoretical

studies of sources of error in optical and x-ray spectrometry,

the development of models and devices for correction of measurements to obtain more accurate results, and the improvement

of instruments to attain improved performance.

In electron probe microanalysis, work was nearly completed on the development of a comprehensive correction procedure for the accurate analysis of materials relative to

standards of single elements or simple compounds. This procedure, now involving correction for fluorescence by the continuum, will be made available with a documented computer

program. Experimental measurements on metallic alloys are
underway to test the procedure and the measurements will be

extended to studies of minerals in the near future. Improvement in the lithium-doped silicon detector provides much

better resolution, so that energy dispersion spectrometry is

becoming an important tool for quantitative as well as qualitative analysis. Stability of the microprobe has been

extended to the point where continuous automatic runs for

several hours are practicable , for example, in studies of

homogeneity of materials by matrix scanning of up to 100

positions on the sample. The use of the microprobe as an

electron scanning microscope as well as a means of determining

composition is an important development, especially with the

production of color prints showing composite images of topography and composition for selected elements

.

Activity in x-ray fluorescence spectrometry continues on

correction techniques for interelement interferences and an

improved correction procedure has been developed. Modifications

of the x-ray fluorescence spectrometer and associated electronics as described in this report have resulted in a large

gain in stability and reliability, so that down time is practically eliminated. Applications of x-ray fluorescence

analysis continue to be made to homogeneity studies of materials

and to a wide variety of analytical problems, including measurements of thickness of thin layers of metallic coatings,

measurement of austenite in steel standards, and correlation

studies comparing results of x-ray and other methods of

analysis of standard reference materials.

Work in optical emission spectrometry is being directed

toward pollution studies where this method can provide extremely fast and economical analyses. The spectrometric

determination of beryllium in paper swipes for surveillance

of possible contamination areas now provides determintions

down to as low as 0.1 ng Be. Analyses of 100 samples per

day for beryllium is considered feasible on a routine basis
by one operator. The study of standard reference materials

for homogeneity also represents a relatively high speed and

economical method and is applied to the analysis of a variety

of materials. The optical emission method is particularly

useful for trace analyses when impurities can be concentrated

by simple methods. An example is shown of the analysis of

glucose where detection limits attained were as low as 1 ng/g

(1x10 %) for several elements.

Chemical preconcentration procedures are being developed

to obtain improved limits of detection or to provide analytes

in a form more suitable for analysis by either optical emission spectrometry or isotope dilution spark source mass spectrometry. Methods have been devised for the analysis of ingot

iron, botanical materials, and high purity reagents. The

procedures are especially designed to employ isolation systems

and minimum handling thus keeping contamination to a controllable low level.

Studies of standard reference materials for homogeneity

and determination of composition have continued as a large

effort this year. The Section contributed effectively to the

analysis of 53 standards including low alloy steels, blast

furnace iron, white cast iron, stainless steel, silicon steel,

clays, glucose, metallo-organic compounds, orchard leaves, and

micro-bead standards. Standards of interest for spectrometric

analysis, that were issued during the year, are listed in

Table 1. These are available with final analysis except for

SRM 1155 which is provisional. Certificates for most of these

standards have been reproduced in appendices to this report.

A set of low alloy steels, SRM 1261-1265, prepared to

replace the earlier group of spectrometric steel standards,

will be available soon with provisional certificates of

analysis

.
Table 1. Standard reference materials of interest

for spectrometric applications

SRM No

1155

97a

98a

5 9a

Title

Stainless Steel

Crl8-Nil2-Mo2 (AISI 316)

Flint Clay

Plastic Clay

Ferrosilicon

1143,1144,1147 Blast Furnace and White

1148,1149 Iron Standards

1132 Lead-Base Bearing Metal

(84Pb-10Sb-6Sn)

1053a Cadmium Cyclohexanebutyrate

Il40,ll4l,ll42 Ductile Iron Standards

Date Issued

August 1969

October 1969

October 1969

November 1969

December 1969

January 1970

January 1970

February 1970

Analyses made by the groups in the Section during the

12-month period June 1, 1969 through May 31, 1970 are summarized in Table 2.

Table 2. Summary of spectrometric analyses

Method

Optical emission

Electron microprobe

X-ray fluorescence

Total

Sample s Determinations Report s

566 14,714 113

61 2,910 20

88 1,486 17

715 19,110 150
In addition to the analyses, the x-ray spectrometer is

employed for rapid determination of compositions to check

the labeling of spectrome trie standard reference samples

where there may be a question of identity. This work Involved

2,551 samples, 7*570 determinations, and 4 reports.

C. Computerized Data Acquisition System

During the past year, we contributed considerable effort

to the planning and procurement of a Division-wide computerized data acquisition system. This system will have great

potential for rapid and efficient data handling for our Section

in view of our digital recording systems already in use

[3s P- 1] • A five-member evaluation committee, under the

chairmanship of Dr. James DeVoe, drew up a request for proposals and an evaluation procedure that would make possible

objective rating of the proposals received. The other members

of this committee were Roy Saltman, Ronald Shideler, Pillmer

Ruegg, and Stanley Rasberry.

Eight manufacturers submitted proposals. These were

carefully reviewed by the evaluation committee, with technical

ratings being completed on April 28, 1970. The evaluation

was made only on the basis of technical specifications ; the

committee had no access to cost data until after reporting

its ratings. Following that report, cost data were released

to the committee and price/performance was completed to

permit logical choice of the supplier. Subject to contract

negotiations, the computer will be delivered in early 1971-

The primary application for this computer system will

be real-time, multi-instrument data acquisition, and supervisory instrument control. A disc, with one-million words

storage capacity, will give the system great flexibility in

acquiring, sorting, and managing experiment data files. As

a background function, the computer will process data for

those jobs which do not exceed the capability of the computer.

7
For jobs exceeding those limits, completed data files will

be transferred to magnetic tape for processing on the Univac

1108 at the NBS Computation Center.

Interfacing the experiments to the computer system is in

the design phase. The plan, for digital data, is to buffer

the data from the laboratory experiments onto a common digital

data bus. The data bus will enter an interface device located

at the computer site ahead of the computer to buffer the lines

and sort the data according to rate; i.e., high speed for

direct memory access entry, and low speed for priority-interrupt

entry. Within the computer, the data will be sorted, by a single acquisition program, into the file of the appropriate

experiment

.

An executive program will schedule jobs and allocate

memory space according to user demand and job priority, with

data acquisition being given high priority.

In our Section, there are seven devices that have data

output buffered on either scalers or multi-channel pulse-height

analyzers. Included are the electron microprobe, x-ray

fluorescence spectrometers, optical emission spectrometers,

and a microphotometer . Presently, these instruments log data

on paper tape for later processing by either time-shared

computer or batch loading. Because they already contain some

interfacing electronics, the instruments should be easily

interfaced to the digital data bus.

One of our first projects will be to get the electron

microprobe on-line to the computer. Some of the experiments

now running on the microprobe have high data volume. Furthermore, the automatic control equipment (matrix scanner) now

in use gives us less flexibility in experiment design than

we require and the computer can supply.

B. F. Scribner and S. D. Rasberry
2. ELECTRON PROBE MICROANALYSIS

With other laboratories in our Section, the electron

probe microanalysis laboratory performs both service and

research. The aim of the research program is to improve the

efficiency of the use of the electron probe by increasing

the accuracy, sensitivity, speed, and scope of application of

electron probe microanalysis. The research activities cover

aspects of theory, technique, computation methods, and instrumental development. The experience acquired in the performance of service work, and the problems which arise in the

execution of such tasks, are a valuable guidance for establishing priorities in the research program.

The present report covers the progress achieved in the

fiscal year 1969-70. References to the activities prior to

this period will serve to connect our present work to the

overall plan of research.

A. Instrumental Improvements

To ease the task of the operator, we have relocated, close

to the front of the instrument, the most important controls

and monitoring devices and we have removed devices previously

occupying space upon the microprobe bench (see Figure 1).

The illuminator control, meters indicating the ratemeter output from the three crystal spectrometers, and the flowmeter

for the detector gas are now mounted on the front of the

instrument. Meters for target current and monitor current,

the controls for magnetic lenses, and a power line monitor,

are relocated on a panel within reach of the operator. The

target current amplifier (to be described later in more detail),

and the oscilloscope used to observe area scans are also very

close to the operator.
Figure 1. Front view of the electron probe tank, with

recent modifications. 1: illuminator control;

2: x-ray countrate meters; 3: flowmeter for

flow proportional detectors; 4: meters for

monitor- and target current; 5: lens controls;

6: line voltage monitor; 7: first stage of

target current amplifier; 8: lithium-drifted

silicon detector.

Three new solid-state ratemeters were constructed. One

is a periodic integrator, the other two are conventional. We

also built two highly stable supplies for the electronic

lenses with remote output control; these have no observable

drift for periods of several hours.

The vacuum system was also changed. The mechanical pump

for the specimen chamber was replaced by a larger pump. Both

mechanical pumps were mounted in a cabinet removed from the

main body of the microprobe, in order to reduce vibrations.

All valves are now manually operated. The specimen chamber

can be pumped down in less than half the time needed previously,

10
and the main instrument tank can be evacuated with both pumps

operating in tandem. The pumping period needed to bring the

main tank from atmospheric pressure to operating conditions

is only 20 - 30 minutes.

We are at present constructing a new power supply for the

beam voltage which will operate over a continuous range from

zero to fifty kilovolts . It is hoped that this supply will

combine stability and freedom from noise with ease of repair

and adjustment.

B. Qualitative Analysis

Replacement of the Li-doped silicon detector by one of

higher energy resolution reduced the width at 50% of peak

height from 500 eV to 250 eV (see Figure 2). This improvement

substantially reduces the overlap of adjacent peaks. For

instance, Cu Ka and Cu K3 peaks are now fully separated.

Furthermore, the peak-to-background ratio is increased by a factor of two.

The availability of the non-diffractive (energy dispersion) spectral read-out [6] has substantially reduced the

time spent in qualitative tests. Thus, the silicon detector

has proven to be a most valuable addition to the electron probe

The solid-state detector has good sensitivity and resolution at high energies (20-50 keV) . Its usefulness for qualitative purposes can be extended to these energies by working

at operating voltages above 2 kV whenever the deterioration

of spacial resolution is unimportant (Figure 3)-

C

.

Scanning Electron Probe Analysis

Work on scanning techniques was mainly a continuation of

projects started before this fiscal year. A non-linear amplification stage was incorporated in the differential target

current amplifier described previously [5*7] • This stage

permits the compressing of extremes in current in the input

11
CuKc Cu SPECTRUM

20 kV

Figure 2. Improvement of energy resolution with silicon

detector. Left, new detector. Right, old detector.

signal which would otherwise produce areas of extreme brightness on the scanning images. The non-linear stage can be

bypassed if compression is not desired.

The target current amplifier was also used with the

secondary electron output signal of a scanning electron microscope (Metallurgy Division, NBS). It could be shown that the

principles on which this device is based apply equally to

secondary electron signals, and that the use of such an amplifier in scanning electron microscopes can considerably improve

the quality of the scanning images based on secondary electron

signals [7]- The complete circuit diagram of the amplifier

is shown in Figure 4.

12
Ma + M/3

Figure 3- Energy dispersion spectra of rhenium at

vari ous vo It age s

.

The experiments with the scanning electron microscope

were performed in cooperation with H. Yakowitz (Metallurgy

Division, NBS ) . We have described [4,7] a method of color representation

of x-ray area scans. This method has been perfected this

year by adding information from target scans. In the new

technique, up to three area scans are represented in primary

colors, and a target current scan is added in neutral gray

tones. The target current scan adds topographical information

to the composite, which is helpful in recognizing the

scanned area. It also sharply outlines the contours of

the phases which are characterized by the x-ray scan. This

procedure overcomes, to a large degree, the lack of sharpness

of the x-ray scans caused by statistical factors as well as

to the production of secondary x-ray emission.

13
•Pauuop

(D50u

cti -p

<u .c

-poS

bOd

•H

-PHo

?H •HO

0)u

50

•H

14
The proportions of the representation of topography and

of composition can be changed at will by varying the lengths

of the corresponding photographic exposures. One obtains , as

a result, a true microscopic picture of the scanned area, with

the display of the distribution of up to three elements. This

technique constitutes a novel kind of microscopy which has

already been shown to be very useful for a wide variety of

specimens, including alloys and minerals such as lunar specimens . The first experiments in this technique antedate this

fiscal year [5]. We have now established the best exposure

conditions. We have also provided the copy camera with a filter holder, and a stage with x-y translation to which the

original scanning images are affixed by suction. The stage

translation is used for correcting shifts in registration between scanning images (Figure 5)- In the course of our work

Figure 5. Copying camera for color composites.

A: filter holder, B: stage with x-y trans^

1 at ion

15
, in scanning target current images, we discovered two unexpected

sources of noise. We found that, after all sources of amplifier noise and noise induction within the instrument were

reduced or eliminated, a moire pattern persisted on the scanning images of uniform surfaces. We found that the oscillations which cause these patterns were caused by ripple in the

high voltage power supply; this could be observed even though

the supply was within specifications (0.1% ripple).

When the electron beam was cut off, a slight pattern

could still be observed, which was traced back to the oscilloscope . Although these effects do not detract from the accuracy

of quantitative analysis, they are undesirable in scanning

electron microscopy by means of target current signals. A

power supply now under construction should contribute to the

improvement of the scanning images. A good case can also be

made for the use of cathode-ray tube oscilloscopes of high

quality. At moderate magnifications, the sharpness of the

scanning electron images is limited by the resolution of the

cathode-ray tubes commonly used in microprobes. We hope to

explore the advantages which should accrue from the use of

high-resolution oscilloscopes having high stability and low

noise

.

D . Quantitative Analysis

Research in quantitative electron probe analysis includes

instrumental and theoretical aspects. We have previously reported on our investigations of spectrometer alignment [3]

and of pulse coincidence losses [9]- In this fiscal year,

we started a study of the background corrections, which become

particularly important when energy dispersion spectrometers

are used in quantitative analysis [10]

.

16
The theoretical study of the corrections for absorption

of primary emission [11], for primary generation of x-rays

[12], and for fluorescence due to characteristic lines [13] , is now complemented by an investigation of fluorescence caused

by continuous radiation. The theoretical treatment is greatly

aided by measurements of x-ray intensities obtained under

varying conditions from the standard reference materials of

Au-Ag and Au-Cu alloys which had been developed and tested

for this purpose at NBS [5]-

In order to increase the speed and accuracy of the tests

for homogeneity of these and other alloys, we had developed

an automatic device for analysis of many points on a specimen

- the matrix scanner -. This device is described in a previous annual report [3]» A computer program written by

S. Rasberry (TOPO) now provides a topographic and statistical

characterization of the degree of homogeneity of the tested

material. During the present fiscal year, we continued the

study of the application of the matrix scanner. The aim of

this study is to develop a technique of completely automated

and unattended matrix analysis, which could be performed

during overnight periods.

The analysis of lunar specimens has greatly stimulated

the interest in the quantitative analysis of minerals. We

have initiated a systematic study of the application of the

theoretical principles of microprobe analysis - which were

primarily developed for alloys - to mineral specimens. For

this purpose we have assembled a large number of wellcharacterized mineral specimens (Figure 6) which were obtained

through the kindness of several investigators.

The need for techniques for the analysis of small particles and of biological specimens is even more pressing due to

the social significance of the studies of pollution and of

biological and medical problems. Unfortunately, this is the

most difficult area within the realm of quantitative electron

17
ML ••/ V . \

•^V-— !3 V | •&-& Lv v^*v rSr)

' ^• ' i

1

Figure 6. Specimen mount for minerals. The small circles

in center contain elements. The larger circles

at the periphery contain 45 minerals, mostly

in groups of four, which are mounted on removable and exchangeable cylinders. The entire

assembly measures 25 mm in diameter.

probe microanalysis. In view of the urgency of progress in

this field, we hope soon to broadly attack this important

subject, to which we have already given much attention in

the past years

.

We will now comment, in more detail, on some aspects of

the research on quantitative analysis which we have outlined

above

.

1. Emission of Continuous Radiation

The study of the continuous emission is the basis for

the development of a technique of background correction.

Moreover, the correction for fluorescence due to the continuum

requires the quantitative knowledge of the continuum emission.

18
A study of the correction for fluorescence by the continuum

[14] indicates that the uncertainty in the emission of continuous radiation is the largest potential source of error

in this correction. Existing experimental evidence [15,16]

is contradictory. Our preliminary experimental data on the

atomic number dependence of the intensity of the continuum

disagree with those published by Green [15] and tend to

support the results obtained by Rao-Sahib and Wittry [16].

Further extensive experimental studies of this subject are

under way

.

We have not found any reference in literature to the

intensity of continuous radiation of targets containing more

than one element. Measurements on the gold-copper Standard

Reference Materials indicate that the intensity varies (at

least at short wavelengths) linearly with the weight-fraction

of the components (Figure 7), in agreement with Henoc's

prediction. Further measurements will be made. Experiments

on the x-ray emission of undiffused metal couples [17] are

also being performed. We are confident that these measurements

will provide the necessary basis for an accurate correction

of the fluorescent contribution from the continuum.

2 . Further Measurements on Standard Reference Materials

The Standard Reference Materials of gold-silver and goldcopper alloys mentioned in previous reports [4,5], are being

used to obtain experimental intensity ratios under varying

excitation conditions. The results, and comments on the fit

of the theoretical models to these results, will be published

shortly. This is intended primarily to illustrate the variety

of tests that can be performed with the aid of the Standard

Reference Materials. At the same time, it is hoped that the

results obtained at the NBS laboratory will further the studies

of the theory of quantitative electron probe microanalysis.

19
.20 .40 .60

WEIGHT FRACTION OF GOLD

.80

Figure 7. Measurements at 20 kV on copper-gold standard

reference materials. The signal intensities

are on an arbitrary scale. Both target current and continuous radiation (background at

2.29 A) vary linearly with weight fraction.

20
It should be noted that the intensity ratios obtainable on

the Standard Reference Materials provide tests on all existing

corrections. The measurements of the Au Ma line in both

series, and of the Ag La lines in the Au-Ag series, provide

a test of the absorption correction; fluorescence by the Au

L lines affects the intensity of Cu K emission in the Au-Cu

series; fluorescence by the continuum also occurs in the Cu

K emission; and the atomic number effect influences the intensities of all elements in these series.

3 . Quantitative Analysis of Minerals and Ceramics

Over 40 specimens of well-characterized mineral specimens,

mostly, but not exclusively, silicates, were obtained from

several laboratories which are listed in the acknowledgments

.

These specimens - some of which are exceedingly small - were

skillfully mounted and polished by C. Fiori, of this Section

(see Figure 6). Some of these specimens were used in the

standardization of analyses of lunar specimens. Systematic

measurements and analysis of all of them are presently under

way. The purposes of this study are as follows;

a. To estimate the accuracy achievable by theoretical and empirical correction procedures.

b. To estimate the reliability and homogeneity of

chemically analyzed minerals as standards.

c. To attempt to establish a simple system for the

analysis by means of a limited number of natural or synthetic

standards which are easy to prepare or obtain, and which

could be issued by the National Bureau of Standards.

The results obtained at present indicate that the theoretical calculations can be applied to mineral and ceramic

specimens, and that a system of calibration using a limited

number of standards is feasible. This work will be continued

in the coming fiscal year.

The work on minerals is partially sponsored by NASA.

21
4. Quantitative Applications of Energy Dispersion

Detector Systems

In view of the success obtained in the qualitative use

of energy dispersion spectrometry (particularly with the

lithium-doped silicon detector), we began investigating the

possibilities of using this technique for quantitative purposes.,

The following advantages can be obtained:

1. Since deflection of the electron beam does not produce optical defocusing when such systems are used, the matrix

analysis can be applied over larger areas than those which can

be investigated quantitatively with the use of focusing spectrometers . 2. The combined use of energy dispersion and x-ray

dispersion spectrometry permits the simultaneous measurement

of a large number of elements. This possibility was successfully exploited in the analysis of lunar specimens.

Since the line-to-background ratios in non-diffractive

analysis are less favorable than with diffractive devices,

more attention must be given to the background correction.

In particular, the concentration limits of detection and determination are lowered. Detailed studies of the background

correction are presently under way, as mentioned previously.

The combined use of the solid-state energy -dispersion

spectrometer and the crystal x-ray spectrometers proved to

be particularly useful in the analysis of mineral specimens,

where the simultaneous determination of many elements is a

significant advantage. It is difficult to relocate areas of

interest on a complex inhomogeneous mineral. Since many

minerals (particularly silicates) contain a considerable

number of constituents, the complete quantitative evaluation

of small grains is, thus, very tedious and sometimes inaccurate

when only crystal spectrometers are used. In the analysis of

lunar silicates and other minerals, we were able to determine,

22
with sufficient accuracy., the elements Si, Ca, and Pe by means

of energy-dispersion spectrometry, even in the presence of

Al and Mg, using a single-channel pulse height analyzer for

each element. The interference of the Al line with the Si

line could be reduced to negligible proportions by judicious

setting of a single-channel analyzer across the part of the

energy distribution of the Si signal which does not overlap

with the distribution of the Al signal. The crystal spectrometers were used simultaneously for the determination of

other elements present, such as Na, K, Mg, Al, Ti, and Cr.

A maximum of six elements was determined simultaneously.

Comparison with the results of analysis of Si, Ca, and Pe

,

using crystal spectrometers, showed satisfactory agreement.

The energy distributions were very stable, so that, even in

the case of the determination of Si, no drift was observed.

Another area in which the application of energy dispersion analysis is very promising is the analysis of points

distributed in a two-dimensional matrix of locations for the

study of homogeneity of materials to be used as standard

references. In our instrument, the matrix is generated by

electromagnetic deflection of the beam. If this deflection

is large, defocusing of the crystal-spectrometer optics is

observed [2, p. 52]. The largest matrix we can presently

generate at 20 kV is 500 X 500 urn. Measurements using energydispersion techniques on a matrix of this size showed the

absence of defocusing effects.

We have started a study of the factors which affect the

accuracy of measurements performed in matrix scans of long

duration. Preliminary experiments indicate that the ratio of

monitor current to beam current may be subject to slow drift;

therefore, there is some doubt concerning the efficiency of

using monitor current as a means of drift correction. The

output of the silicon detector appears to be quite stable

provided that the specimen current does not drift

.

23
The stability and reproducibility of the beam positions

on the specimen are excellent, as can be observed in Figure 8.

This figure shows the superimposed contamination marks on a specimen which was scanned for three consecutive times. The

total time of scan was 15 hours.

The programming of automated overnight runs of matrices

will be greatly aided by connecting the electron probe to the

on-line computer facilities which we expect to acquire during

the next fiscal year (see Section 1 C )

.

The experiments on stability during overnight runs were

performed in cooperation with H. Yakowitz (Metallurgy Division,

NBS).

Figure 8. Superimposed contamination marks from a matrix

run of 15 hours duration on pure nickel. Size

of the matrix: 575 x 667 ym.

24
E . Computer Program COR for the Correction of Quantitative

Microprobe Measurement s

This program was written in order to include in the

correction procedure all known refinements of the quantitative theory of electron probe microanalysis, avoiding all

unnecessary simplifications. The original version of the

program is due to Jean Henoc, who was a guest worker in our

electron probe laboratory from October 1969 to October 1970.

Further work after Dr. Henoc's departure was performed by

Henoc in Paris, and by R. L. Myklebust , in our Section.

The purpose of the program is not limited to obtaining

the best possible corrections for analytical data. Rather,

it is a starting point for studying the effects of uncertainties arising from the theories, from parameters, and constants, and from the approximations frequently used in other

programs. The following comments briefly outline the structure of the program.

1 . Theories Used in the Correction Procedure

The generation equation (atomic number correction) follows the procedures of Philibert and Tixier [18] for integrating the stopping power of the target for electrons over the

range of deceleration. Although several expressions for the

mean ionization potential can be used, we usually employ the

values proposed by Berger and Seltzer [19] • We follow a

procedure advocated by Duncumb and Reed [20] for the calculation of backscatter losses.

The calculation of the absorption of primary x-rays uses

the modification by Heinrich [21] of the procedure of Philibert and Duncumb [22]. The mass attenuation coefficients are

those proposed by Heinrich [23]. If desired, other values

can be substituted.

25
The correction procedure for fluorescence produced by

characteristic lines is that of Henoc, Maurice, and Zemskoff

[17]. The primary intensities of the exciting lines are calculated rigorously, using the full generation calculations.

Hence, the approximations for primary intensities used by

other authors are avoided. The fluorescence due to each

exciting line (Ka, K3, Lo^, LB

1

, etc.) is calculated separately.

In the calculation of the attenuation of emergent fluorescent

radiation, a refinement by Criss [24] is employed. We usually

apply the data of Fink et al. [25] for fluorescent yield.

The treatment of fluorescence by the continuum is based

on previous work by Henoc. As in earlier versions by Henoc,

the calculation of the intensity of the continuous radiation

is based on Green's modifications to Kramer's law [15]. However, this aspect may subsequently be modified. Contrary to

previous procedures by Henoc, COR performs a numerical integration of the fluorescent intensity with respect to wavelength.

This not only eliminates the need for the assumption that the

variation of attenuation coefficients with wavelength follows

a cubic law; it also permits a physically more meaningful

interpretation of the factors affecting the magnitude of the

fluorescent emission.

2 • Internal Structure of the Program COR

A schematic diagram of the structure of COR is shown in

Figure 9. Besides the main program, COR contains several subroutines which provide partial steps of calculation to be used

in the main program. Thus, the mass absorption coefficients,

primary intensities, fluorescent contributions, etc., are

calculated in sub-units which can easily be studied. We are

at present writing extensive comments to the program and

subprograms so as to enable the user to understand them and,

if desired, make modifications.

26
INPUT Z=|> MAIN

PROGRAM

CALI

reorders sequence

of data

OUTPUT

COCA

constants for

fluorescence correction

PRA

primary emission

FQI

primary absorption

FCA

char, fluorescence

CO

fluorescence contin- uum

Figure 9- Diagram of the subprograms in the program COR.

The subprogram FT is only needed if the printout of the absorption factor for fluorescence

from the continuum is desired.

The decision-making processes in the program are an important feature. The program decides by itself which fluorescent correctures must be applied. If operating conditions are

chosen improperly, or if relevant parameters (e.g., mass attenuation coefficients) are not known, warning messages are transmitted to the output. These decision-making processes are

designed to minimize the possibility of operator errors in the

choice of experimental conditions or input.

The iteration procedure is a modification of that proposed

by Criss and Birks [26]. The modified Criss iteration has

been tested extensively prior to its inclusion in the program

27
MULTI7. It is rapid and always converges. We strongly feel

that this iteration procedure is by far better than other

proposed techniques.

3 . Input to the Program

The constants for each element contained in the analyzed

specimens (name, atomic number, atomic weight, absorption

parameters, fluorescent yield) are entered by means of a set

of cards. The card file can be completed as the necessity

arises. (See examples in Appendix B to this report).

The analytical information for the input can consist of

background- and deadtime -corrected intensity ratios, or of

the uncorrected photon counts obtained by the instrument.

In the second case, the background and deadtime corrections

are performed by a sub-program written by R. L. Myklebust.

Elements which were not included in the x-ray intensity measurement can be determined by difference (one element only)

or on the basis of stoichiometric relations - e.g., oxygen

in oxidic materials - or their concentration can be assumed

to be known. (e.g., the main constituents when analyzing for

impurities). The program- can also be used to calculate theoretical intensity ratios for specimens of known composition.

Standards composed of several elements (e.g., for the

analysis of minerals) can be employed. Their characteristics

are entered via a few cards . The program permits the use of

a different excitation voltage or x-ray emergence angle for

each element. We believe that we have covered all contingencies which may arise in the analysis of a flat, semi -infinite

specimen of homogeneous (within the excited area) composition

There are no provisions, however, for the analysis of data

obtained by using an electron beam of non-normal incidence

upon the specimen. This case requires further studies of

the backscatter losses for oblique beam incidence.

28
4 . Output of the Program

Since Henoc's departure, R. L. Myklebust has written a new output program for COR, which provides the following

information: a label (name or number of specimen, date, etc.),

number of sample (when several points or specimens within a system were analyzed), characterization of standards, symbols

and atomic numbers of elements included in the calculations,

atomic fractions obtained, weight fractions obtained, standard

deviations (if several measurements were made on the same

point or specimen), absorption losses (f(x)) for primary and

fluorescent emission (by characteristic and continuum excitation), absolute primary intensities for specimens and standards,

ratio of fluorescence by characteristic lines to primary

intensity, ratio of fluorescence by continuum to primary intensity, sum of computed mass fractions, and number of iterations. Warning labels may also appear in the output. When

elements are calculated by stoichiometry , molar weight fractions (e.g., SiOp, CaCO~, etc.) are also printed.

An example of the program output is shown in Figure 10.

- 5 . Documentation of the Program

Since requirements and preferences for input and output , as well as for certain variables and constants to be used in

the program, change from laboratory to laboratory, it is

important to thoroughly document programs intended to be used

widely. This also reduces the possibility that errors in

the program remain indefinitely undiscovered. We are at

present adding extensive commentaries to the program which

identify each step of the procedure. These will be complemented by a general discussion, which will be included with

copies of the program.

29
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30
The program is at present used routinely for data reduction. Certain minor features are still being tested. Copies

will be available after the documentation and testing are

completed.

F. Service Analyses

Besides the homogeneity characterization on the gold-silver

and gold-copper Standard Reference Materials, we have performed

a large number of service analyses, including the following:

1. Analysis of lunar material from flights Apollo 11

and Apollo 12 (Figures 11-13).

Figure 11. Scanning electron micrograph of a breccia

from flight Apollo 11. Magnification: 1200X

31
Figure 12. Target current and x-ray scanning images of a rock

fragment in breccia from Apollo 11. Magnification: 40 ym/cm.

(A) Target current. (B) Si Ka . (C) Fe Ka. (D) Ti Ka. The

major phases observable in this series are orthoclase (low

iron level), pyroxene (medium iron level, silicon present),

and ilmenite (high iron and titanium, silicon absent).

32
The work was performed both on basalt -like rock fragments

and on breccia. On all of these specimens, the analyses

started with a general survey, performed by target current

scanning, x-ray scanning, and qualitative or semi -quantitative

local analysis by means of crystal spectrometers or energy

dispersion detectors. By these means, we established which

phases were present in each specimen and the approximate composition of each phase. Color composites were also prepared

to illustrate the element distribution in several areas of

interest

.

The following phases were observed in rock specimens:

a. Major phases: pyroxene, feldspar, ilmenite,

and (only in Apollo 12 sample) olivine

b. Minor phases: apatite (containing rare earths),

cristobalite, troilite, metallic iron, mesostasis (feldspar

with high level of potassium) , and ulvospinel

In breccia, besides the aforementioned phases, glassy

spherules of composition approximating the average composition

of the crystalline rocks were also analyzed.

The compositional variations within grains and from grain

to grain were quantitatively investigated, by means of the

simultaneous determination of six elements over hundreds of

points. Some of the results of this work, performed in cooperation with I. Adler, L. Walter, and B. French (Goddard Space

Flight Center, NASA), were reported in references [27-28],

2. Failure analysis: Analyses were performed on various

materials affected by corrosion or other failure processes.

These include:

a. Sections of an eye-bar and of a hanger-strap

from the collapsed Point Pleasant bridge

b. A specimen from a helicopter

c. Corrosion products on Cu-Pd alloys and on

aluminum

33
Figure 13- Target current and x-ray scanning images of a rock

fragment from flight Apollo 12. Magnification: 25 ym/cm.

(A) Inverted target current. The numbers indicate the phases

present in the specimen: 1-olivine, 2-pyroxene, 3-plagioclase,

4-mesostasis (a silicate with high contents of potassium, and

some aluminum), 5-ilmenite, 6-ulvospinel, 7-troilite, and

34
8-metallic iron. (B) Derivative target current image, showing

grain boundaries and other topographic features. (C) Ka.

(D) Mg Ka. (E) Al Ka. (F) Si Ka. (G) S Ka. (H) K Ka.

(I) Ca Ka. (J) Ti Ka. (K) Cr Ka . (L) Fe Ka

35
3. Diffusion couples: Hundreds of measurements were

performed on Cu-Zn and Al-V diffusion couples.

4. Binary two-phase alloys: Very accurate measurements

were performed on the systems Pt-V and Cr-Ir, as part of a

program to investigate the respective equilibrium phase

diagrams

5. Five single crystals of a Cu-Au alloy were analyzed

for local variations in composition. A zinc oxide specimen

and sapphire crystals were investigated for distribution and

composition of localized impurities.

6. A large number of specimens obtained in the research

concerning "polywater" were investigated for the distribution

of impurities.

7. Extensive work was performed on microbeads of ionexchange resins loaded with various cations.

8. Other miscellaneous work included the quantitative

analysis of evaporated thin films of various alloys, and the

investigation of counterfeit documents

G. Literature Research

We have updated our literature card files to the end of

1969. The classifying of these cards into categories is

almost finished. However, due to reduction in personnel,

work on the issuance of a bibliography had to be postponed.

K. P. J. Heinrich

36
3. X-RAY FLUORESCENCE SPECTROMETRY

The program and instrumentation for x-ray fluorescence

spectrometry have been reviewed in prior technical notes of

this series [1-5] • Continued research in the field of calibration, especially the area of correction techniques for

interelement interferences, has given us new insight into

this problem. We have produced an improvement to the state

of the art on interelement interference correction methodology.

Again, as in the past few years, about one-half of the

work of the x-ray fluorescence project has been in the area

of support to SRM production and service analyses for a wide

variety of projects from both inside and outside NBS . The

types of support that have been provided to the Office of

Standard Reference Materials include analysis of chemical

composition, homogeneity testing, specimen sorting, and rapid

verification of composition of labeled specimens. Through

consulting, cooperative work, and instrument sharing, this

project has assisted in the certification of a number of

different SRM's for plating thickness. Our x-ray fluorescence

instrumentation was first described and illustrated in 1965

[1]. Since that time, the equipment has been up-graded through

gradual replacement of components. Seven of the ten modules

shown in 1965 have been replaced and an oscilloscope for pulse

monitoring and a system for automatic data acquisition have

been added [2-4]. The current instrumentation, Figure 14,

includes the following devices:

1. A 50-kV full-wave rectified x-ray generator, consisting of a power supply and a properly shielded and cooled

x-ray tube. Two tubes, of a "quick change" design, are currently available, one with a tungsten target, the other with

a chromium target.

37
Figure 14. Single-channel, vacuum x-ray fluorescence

spectrometer. The power supply for the x-ray

generator and the teletypewriter are to the

left. The x-ray spectrometer is in the center

and, on the right, are the signal processing

electronics and oscilloscope.

2. A vacuum specimen chamber with provisions for introducing, positioning, and exchanging specimens to be measured.

3. A vacuum x-ray spectrometer, including a flat-crystal

monochromator , with a choice of two crystals and two detectors (flow proportional and scintillation), and a wide-range

goniometer with motor drive.

4. An electronic assembly for processing x-ray signals,

including power supplies, preamplifiers, linear amplifier,

single-channel pulse-height analyzer, scaler, timer, linear

38
ratemeter, chart recorder, data scanner for interface to

teletypewriter, and a teletypewriter.

5. An oscilloscope for pulse monitoring.

The performance of the new electronics, all solid-state,

has been very satisfactory. During the past two years, the

equipment has been used almost continuously. Maintenance and

down-time (principally related to the x-ray generator) consumed about five days during that period.

A. Research Activities

In seeking improvements in methods for data correction

for interelement effects, it is helpful to begin with the binary

alloys; with these, interaction relationships are easier to

consider and a prerequisite of any valid model is that it will

apply to binary cases. A classical set of binary interelement

effect curves of relative intensity (R) is given in Figure 15

•

These curves have been approximated as hyperbolae in the past;

but, if one plots C/R versus C, for the same data, (Figure 16)

straight lines are not obtained, especially for the fluoresced

element, Fe . A hyperbola in Figure 15 would be represented

by a straight line in Figure 16 . Earlier models were based

on equations of the sort:

(C/R)

A

= aMC

A

+ aAB C

B

where the R's and C's are as defined before, a's are interaction coefficients, and the subscripts A and B are labels

denoting the two elements of a binary. This does not reasonably fit the curvature apparent in Figure 16 , consequently we

have introduced the calibration equation:

(C/R)

A

= 1 + a M (CA

-R

A

) + aAB C

B

with the symbols defined as before.

39
Figure 15

.

Calibration curves for Fe and Ni in the Fe-Ni

binary system. Close examination will show

that the interelement effects of fluorescence

for Fe and absorption for Ni are not exactly

hyperbolic

.

Our testing, to date, indicates that this model very

accurately calibrates the analysis of binary systems. Current effort is directed toward extending these ideas to

multi-element systems

.

40
Figure 16

.

Graphs of C/R as a function of C. The same

data as in Figure 15 are used to construct

graphs to demonstrate more clearly the

departure from a hyperbolic function. Here

true hyperbolae would be represented by

straight lines

.

Frequently, ideas for new extensions of our technique

are prompted by requests for service analyses. A recent

request for assistance, by the Metallurgy Division, is typical

of such cooperative developments. The problem, from the

metallurgists' point of view, was to accurately, nondestructively, and economically determine the austenite in discs

prepared by powder metallurgy as SRM's for the measurement

of retained austenite. The measurement process sought also

had an important requirement that the determination be specific

to the surface. These SRM's are intended only for surface

techniques (optical methods and x-ray diffraction) and differences between surface and bulk determinations have been

observed. The requirements for economy and nondestructiveness

are present because of the necessity of certifying individual

discs

.

41
While austenite cannot be directly determined by x-ray

fluorescence, we still had an approach to this problem. The

two powders mixed in preparation of the discs were ferrite

(which contained no nickel) and austenite (which contained

a constant proportion of nickel); therefore, a determination

of Ni is directly proportional to the amount of retained

austenite present.

Over ranges of a few percent, x-ray fluorescence calibration curves can be generally approximated as linear.

In Figure 17 we see a curve for Ni in austenite/ferrite contrasted with a curve for Ni in low alloy steels. The greater

slope in the low Ni region in austenite/ferrite is due to

15 X I03

5 10 15 20 25 30 35% AUSTENITE

1 2 3 4 5 6 7 % Ni

Figure 17. Top curve, Ni calibration in austenite/ferrite

matrix. Bottom curve, Ni calibration in low

alloy steels.

42
the localization of Ni in small particles. The Ni x-rays

from the particles are relatively less absorbed by the adjacent iron than when both are more finely mixed.

During this year a joint paper with Dr. Marvin Margoshes

entitled, "Fitting of Analytical Functions with Digital

Computers" was published [29].

B. Applications

Nearly 700 man-hours have gone into performing 9056

separate quantitative determinations. Four of these projects

seem especially interesting and worthwhile describing:

1. Zinc Diecast Gears

An outside agency submitted four small zinc diecast

gears for analysis and comparison with specification AG40A,

ASTM B-86. Figure 18 illustrates the sort of fractures occuring in some gears of this type. Quantitative determinations

for six elements in each of the four specimens revealed that

one gear was within specification and three gears differed

1 from specification in only one element, lead.

Although Pb was present in these three gears at a concentration of only 0.02%, this exceeds the specification by fourfold. Consultation with a metallurgist revealed that the lead,

being insoluble, migrates to the grain boundaries and lubricates them, propagating any cracks along these boundaries.

2 . Thickness Determination of Fe-Be Layers

Within our Division, the Mossbauer spectroscopy group

provided us with an interesting problem. In the construction

57 of a resonant detector for 14.4 keV Fe gamma rays, they

needed to measure the thickness (in the region of 1000 A to

2000 A) of supported layers of Fe-Be which was to become a

43
Figure 18. Photomicrograph (magnification, 60X) of a

section of a zinc die-cast gear. Note the

fracture between two of the gear teeth.

part of the detector. They were able to provide standards

for this region of thickness and the calibration curve obtained

is illustrated in Figure 19-

For this application, the x-ray fluorescence technique

requires no specimen preparation and is quite rapid, thus

specimens could be measured immediately after production,

simplifying quality control. The set-up and measurement times

for three unknown specimens was approximately 20 minutes.

3 . Homogeneity Analysis of a Research Ingot of Cu-Ni-Fe

In materials research, experimenters should take care

not to invest time and money in employing new specimens

prior to verification of composition and homogeneity. Even

on a non-routine basis, test pieces of experimental ingots can

be economically examined by x-ray fluorescence.

44
20,000

<0Q.O

o 10,000 -

500 1,000 1,500 2,000

THICKNESS OF Fe-Be LAYER IN A"

2,500

Figure 19. Thickness calibration for thin, supported

layers of Fe-Be.

A request, recently received, was fulfilled in one-half

man-day, including preparation, measurement, analysis, and

report generation. The problem was to analyze the end pieces

of two six-inch ingots of Cu-Ni-Fe alloy prior to their use

in a research project of another Division. Table 3 shows the

results of this analysis.

Limitations in the available calibration standards for

these compositions prevented determination of the Cu and Ni

with accuracy of better than +2%, relative. However, the

discrepancy apparent between the top and bottom of specimen

B represents a real difference and alerts the user of the

material that it should not be considered homogeneous.

45
Table 3- Analysis of Cu-Ni-Fe specimens

Specimen Element

(Concentration in Weight Percent)

Cu Ni Fe_ Total

A - Top 81.8 18.2 0.04 100.0

A - Bottom 81.6 19-0 <0.02 100.6

B - Top 81.0 17.6 0.25 98.9

B - Bottom 74.3 23.7 0.15 98.2

4. Replacements for 1100 Series Steel SRM T s

During this fiscal year, a large portion of our service

to the Office of Standard Reference Materials has centered

around evaluation of proposed SRM's 1261-1265, the replacements for the 1100 series low alloy steels and ingot irons.

Our contribution to this program has been along three lines;

preliminary analysis, homogeneity testing, and analysis for

certification. The preliminary analysis is made on a ladle

specimen obtained at the time of pouring the steel; the test

is made to insure that the material is nominally the composition desired prior to further treatment. Using x-ray

fluorescence techniques, we typically determine, quantitatively, 14 elements and report the results within one to

two days after receipt of specimen.

Homogeneity studies begin after the material has been

processed to slab form and properly sampled for the test.

To date, all the preliminary analyses are complete and homogeneity testing remains to be done on only one of the standards, 1264.

46
1

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Figure 20. Correlation of x-ray fluorescence and optical

emission results in the analysis of proposed

SRM 1262.

Analysis for initial certification is accomplished by

several methods, including x-ray fluorescence. These tests,

which are now underway, are made on the material in its final

state; that is, after it has been processed to 1 1/4-inch

diameter rods. The x-ray analyses of the new SRM's are made

relative to standards previously prepared which were analyzed

by general chemical methods. The procedure permits the intercomparison of standards to insure that all are on a consistent basis. If irregularities are observed in plotting the

47
, x-ray data, the possibilities of line interferences in spectra

or of errors in chemical analyses of the material are examined.

The results of two different methods may be compared to

detect errors. As an example, the agreement obtained between

x-ray fluorescence and optical emission spectroscopy is demonstrated in Figure 20, for the case of proposed SRM 1262. A

similar correlation graph for x-ray fluorescence results and

the values (mean of determinations by several methods) which

will be published on the provisional certificate are given

in Figure 21.

.4 .6 .8 CONCENTRATION, IN %- PROVISIONALLY ACCEPTED1.0

Figure 21. Correlation of x-ray fluorescence results

and provisionally accepted values for

proposed SRM 1262.

48
C . Contributions of NBS Personnel

Jerry McKay has assisted in performing quantitative

analyses and tests of homogeneity. Jeremy Winick began researching quantitative x-ray fluorescence analysis by the

approach of fundamental parameters (absolute methods). We

gratefully acknowledge the assistance of Doward Bouchette in

supplying data for several intercomparisons between x-ray

fluorescence and optical emission. He and James Izlar, of

OSRM, assisted in specimen identification and label checking

by x-ray methods.

Fielding Ogburn, Jacob Smit, Virginia Pennington, and

Carole Shriner (from the Metallurgy Division) have been parttime guest workers carrying out a project of thickness measure'

ments on electroplated metal coatings.

S. D. Rasberry, K. P. J. Heinrich

49
li . OPTICAL SPECTROMETRY

During the past year, emphasis has been placed on the

investigation of optical emission spectroscopic methods for

the analysis of air-borne pollutants and of impurities in

clinical and botanical materials. These analytical problems

are vitally important in view of the increasing environmental

hazards that have been recognized. Optical emission spectrometry is especially useful for this type of analysis because of its high speed and relatively simple preparation of

samples

.

The sensitivity of emission spectroscopic methods can

often be extended by preconcentration techniques; these are

discussed in Section 5 of this report.

Literature studies have been continued and an extensive

reference file on emission spectrometry has been maintained.

Homogeneity testing and analysis of Standard Reference

Materials continues to be a major effort in optical spectrometry along with qualitative and quantitative analysis of

a diversity of other samples. The effort is due in part to

the increasing number and variety of Standard Reference

Materials being prepared. Section 4B of this report describes

some of the emission spectrochemical analyses performed this

year and will give an indication of the variety of problems

encountered in this work.

A. Air Pollution Studies

The Spectrochemical Analysis Section has been especially

active in the analysis of dusts, deposits, precipitates and

similar samples by optical emission. The early spectroscopic

work was reported by B. F. Scribner at the United States

Technical Conference on Air Pollution, May 1950 [30]. Applications of this work have continued in our laboratory.

50
The last report in this series [5] briefly described an

application of a semi -quantitative analysis of beryllium

smears as part of a safety surveillance program. During the

past year, we have continued the investigation to extend the

sensitivity of the determination of Be in dust deposits and

dust collected from the air to the subnanogram range. The

samples are collected on 25 mm square or 12 mm diameter filter

papers, placed in cupped electrodes, and charred for approximately 15 minutes in a muffle furnace heated at 450° C. Landis

and Coons [31] have pointed out the advantages of using alkaline earths as a buffer in arcing small amounts of Be and

accordingly, 5 mg of BaCl

?

in a 1:1 BaCl

? + graphite mixture

is added to the cupped electrode after charring. Standards

are prepared by adding aliquots of a beryllium sulfate solution to filter paper, drying, and then handling in the same

manner as the samples.

The samples and reference standards are excited in a controlled atmosphere direct current arc and the Be 3130.4 A

line is recorded photoelectrically . The controlled atmosphere

device that we use is one developed in this Section [32]. A

photograph of the gas sheath device mounted in a multi-purpose

arc-spark stand on a photoelectric spectrometer is shown in

Figure 22. This device makes it possible to excite samples

as rapidly and conveniently in controlled atmospheres, as

in air, does not require modification of the arc stand, and

can be put in place or removed easily. Two advantages of the

controlled atmosphere excitation as opposed to excitation

in air are improved stability of the discharge, resulting in

more uniform burning of the sample, and elimination of CN

bands which obscure the most sensitive lines of several elements. This latter advantage will be particularly useful as

the method is expanded to include other elements. Conditions

for the spectrometric determination of Be are given in Table 4.

51
Figure 22. Arc-spark stand mounted on photoelectric

spectrometer.

Following the readout of the Be 3130.4 A line, calibration

curves relating intensity vs weight of Be contained in the

standards are constructed. This method has enabled us to

detect differences in Be content at the . 1 ng level.

We plan to continue this investigation and to extend

the method to include lead, mercury, and other elements of

concern in air pollution studies.

B . Analysis of Clinical Materials

The analysis of organic materials, such as plastics,

foods, and clinical materials is preceded by careful low

temperature ashing of the sample with collection of the ash

in a suitable high purity material.

52
Table 4. Spectrometer conditions for beryllium determinations

Spectrometer

Slit width

Electrodes

Electrode gap

Atmosphere

Excitation

Recording

3.0 meter grating spectrometer with a

reciprocal linear dispersion of 5.2 A/mm

20 ym entrance slit, 75 ym exit slit

Lower, anode, sample. Undercut thin wall

ASTM type S-12 . Upper, cathode, ASTM type

C-5

H mm - adjusted during burn

70$ argon. 30$ oxygen, 15 cu ft/h

3 lbs/in. 2 r at

Direct current arc. Start at 5 amp for

5 sec then at 2 amp for complete burn

(approximately 90 sec)

Digital print-out of photoelectric integration

An example of this type of analysis is the analysis of

glucose. Three lots of glucose were obtained by the Office

of Standard Reference Materials as potential SRM's. The

materials were submitted to our Section with the request that

they be analyzed for impurity elements. Weighed portions of

each lot were ashed with high purity gallium oxide, which was

used as a collector, and were analyzed by an emission spectrochemical method using a gas sheath around an 1/8-inch

diameter electrode. A short duration 15-amp dc arc burn gave

good line-to-background ratios with complete consumption of

the samples. Synthetic standards of gallium oxide doped with

elements in the ranges desired were arced in the same manner

to provide for standardization. Quantitative data for the

elements Al, B, Cu, Fe , Mg , Si, and Ca, and limits of detection

by this method for 18 elements specifically looked for, but

not detected, are shown in Table 5 •

53
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parts per billion are attained for 14 chemical elements.

C

Literature Research

A systematic survey of the literature has been continued

largely through scanning of Chemical Abstracts for papers on

spectrochemical analysis. References are machine copied and

pasted on cards. A periodic check of original journals is

made to ensure full coverage of the literature. References

are indexed by subject and are employed for publication of

bibliographies or review articles. During this year, the

bibliography on optical emission spectrometry for the years

1956-60 was prepared for publication. A comprehensive twoyear review of Emission Spectrometry was prepared by Margoshes

and Scribner and was published in the April 1970 issue of

Analytical Chemistry.

D. Applications to Analysis

During the past year, as in previous years, the facilities

of this Section for spectrochemical analysis were employed

for analytical work as well as for research activities. For

the period July 1969 through June 1970, analyses were performed by optical emission spectroscopy involving 566 samples,

14,714 determinations, and 113 reports. Some high points of

the analyses will be described.

1. Analyses of Standard Reference Materials

The program of Standard Reference Materials continues

to be an important activity of the Spectrochemical Analysis

Section. The output of this program consists of standard

reference samples of certified composition produced in cooperation with the Office of Standard Reference Materials and

other sections of the Analytical Chemistry Division. Starting

with the preliminary evaluation of the material and carrying

55
through to the final quantitative analyses, this Section contributes to the certification of many reference materials.

Most of the materials are submitted for a qualitative

or semi -quantitative analysis as a step in the preliminary

evaluation. This procedure will show whether or not the

material is pure enough for the intended purpose or, in the

case of alloyed materials, whether it has approximately the

desired composition. It will also provide information to

permit proper planning of subsequent analytical procedures

for certification of composition. Samples carried through

this procedure in the past year include glucose, fructose,

bilirubin, orchard leaves, potassium dichromate, metalloorganic compounds, irons, and steels.

The next step in the production of Standard Reference

Materials is to procure a large quantity of the material and

determine its homogeneity. Homogeneity of the intended

standard is essential to its use, since each user should receive a specimen corresponding in analysis to the certificate

provided for the bulk material. A common procedure is to

select samples from chosen points, which represent the extremes

in the bulk of the material, and to make analyses at each of

these points for elements of interest. An illustration of

the sampling procedure for a 5-ton steel ingot is shown in

Figure 23.

A cylindrical ingot, the cross section of which is shown

in the upper left corner, is forged or rolled to a slab

5 in. thick by 17 in. wide. Previous experience has shown

that areas of heterogeneity are most likely to exist in the

portions corresponding to the top, bottom, and middle of the

ingot; therefore, these portions are cut from the slab and

discarded prior to homogeneity tests. Slices are then cut

from the remaining slab pieces at the top, middle, and bottom

and appropriate samples are taken from the slices to test for

56
TOP

BOTTOM

Figure 23. Sketch showing sampling of steel slab for

homogeneity studies

.

homogeneity. A cross section of one of the slices is shown

in the lower right corner with the positions for sampling

also shown. The twelve samples, so chosen, are representative of the extremes of the trimmed slab] i.e., top, middle,

bottom, inside, and outside.

Emission spectrochemetric methods are generally employed

for the homogeneity testing. Data from the emission spectrometer are recorded directly in digital form and entered

into a computer for statistical treatment. Analysis of

variance serves appropriately for determining that part of

variation in concentration attributable to segregation in

the sample. Materials analyzed for homogeneity in this

manner in the past year include four special low alloy steels

three stainless steels, two tin-lead solders, and two cast

irons.

57
In addition to acceptance testing and homogeneity testing,

we also participate in the quantitative analysis necessary

for certification of Standard Reference Materials. Analyses

by at least two independent methods relative to standards

synthesized from pure materials, along with other analyses

made at NBS, and by cooperators, provide for the provisional

and final certification.

A final check on the analyses and the performance of

the standards in optical emission analysis is made by intercomparison of the SRM's in a group and comparison with other

standard materials. The results are studied by correlation

methods to observe discrepancies that might point to errors

in assigned concentration values or to interferences in the

spectroscopic method. The correlation studies are similar

to those described in Section 3 of this report.

Examples of certificates for Standard Reference Materials

issued in the past year, to which this Section contributed,

are given in the Appendix.

2 . Other Analyses

Spectrochemical analyses are performed by this Section

for other NBS laboratories and other Government agencies as

part of a general service work program. The majority of

analyses made are rapid surveys by optical spectroscopy in

which 51 chemical elements are sought. An occasional request

is made for rare earths and the alkalies to extend the list

of elements to 70. This type of analyses is semi -quantitative

with the concentration of elements found reported in ranges

of factors of 10, e.g., 0.001 to 0.01$, 0.01 to 0.1$, etc.

The information provided will quite often be sufficient for

the problem; if not, it will provide the basis for planning

of additional quantitative analysis by spectrochemical or

other means. Typical samples analyzed in the past year by

this method were dust, boiler scale, metallic oxides, paint

pigment, solder flux, gold plate, and ceramic tubes.

58
Qualitative analysis may also be made on extremely small

and single particles of material by use of the laser probe

and a high aperture spectrograph. A recent application of

this type of analysis involved an investigation by T. Kuroha

of inclusions in high purity Teflon containers. The inclusions,

which were in the order of 100 microns in diameter, were

analyzed directly in the Teflon substrate and the qualitative

information derived was sufficient to identify the particles

as plain steel, stainless steel, and aluminum alloys. A

photograph of the laser head mounted on the optical bar of

the high aperture spectrograph is shown in Figure 24. A more

detailed description of this equipment was given in the last

publication of this series [5].

Figure 24

.

Apparatus for laser-probe analysis. Left,

high-speed spectrograph. Right, laser probe

mounting.

59
In addition to the qualitative and semi -quantitative

survey type analyses, we are frequently called upon to perform quantitative analyses for compliance to chemical composition specifications. These analyses are usually part of

a detailed failure study made at NBS or by other agencies

such as the Transportation Safety Board. An example of this

is an investigation of the cause of an aircraft disk brake

assembly failure. As a first step in the investigation, the

samples identified as stationary disk and rotating disk were

submitted for analysis to verify compliance to alloy specifications. In this case, both parts were found to be the

alloys specified and the investigation has been continued

to find other possible causes of failure. Similarly, other

analyses were made in the past year on bridge steel members,

railroad tank car plate, aluminum sheet and castings, stainless steel tubing, and steel construction rod.

J. L. Weber, Jr., M. M. Darr,

V. C. Stewart, D. M. Bouchette

60
5. PRECONCENTRATI ON TECHNIQUES

This part of the report outlines procedures by which

analytes are separated or preconcentrated from the matrix

material for instrumental determination by optical emission

or spark source mass spectrography. These procedures are

developed to obtain Improved limits of detection or to provide the analytes in a form more suitable for the spectrochemical excitation or ionization step. For instance, in

optical emission spectrochemical methods, the matrix may be

removed and replaced by a smaller amount of material having

a simpler spectrum when excited in a dc arc; or a group of

trace elements may be separated and transferred onto electrodes

for excitation by a high-voltage spark discharge. In both

cases, the analysis is accomplished by comparison with synthesized standards. For spark source mass spectrography,

the analytes are usually isotopically diluted before being

placed on a wire substrate for sparking.

Most of the applications are to a variety of materials

that are issued as NBS Standard Reference Materials after

comparing the results of various analytical methods . When

results obtained, using such fundamentally different procedures

as optical emission and spark source mass spectrography, are

in agreement, the validity of the results and of the methods

that produced them are reinforced. Moreover, because of the

desirability of completely characterizing a composition SRM,

these methods which yield results for a number of analytes

simultaneously are particularly valuable and efficient.

A. Optical Emission

1. Ingot Iron

An optical emission method was developed for determining

cobalt, chromium, copper, and manganese in an ingot iron

material, subsequently issued as SRM 1265- "Less than" values

61
were reported for the aluminum and titanium contents, which

were less than the lowest concentrations in the synthesized

standards. In the procedure, sample weights of 100 mg were

dissolved in 6 M HC1 and a few drops of HNO^ were added to

++ +++ . oxidize Fe to Fe . The iron was then extracted with

methyl isobutyl ketone that had been equilibrated by shaking

with an equal volume of 6M HC1. After making up the aqueous

phase to 25 ml, 5 ml aliquots were pipetted into 100-ml

Teflon evaporating dishes. To each dish were added 400 yl

of gallium nitrate solution, containing 5 mg of gallium per

ml, and 250 ul of indium nitrate solution containing 1 ug of

indium per ml. The indium solution was added to serve as an

internal standard. The solutions were evaporated to approximately 1 ml in a clean environment evaporator, which is

shown in Figure 25 • After adding one drop of HNCU and 0.5 ml

of 12M HCIOk to each solution, they were evaporated to dryness

and the residues ignited at 250°C for 30 minutes.

Figure 25. Clean environment evaporator

62
Synthesized standards were prepared by adding known

amounts of the impurity elements to the same quantities of

gallium and indium solutions used for the samples. Following

the procedure used for the samples, the solutions were dried

and ignited at 250°C for 30 minutes.

The powders from the sample treatment and from the

preparation of the reference standards were transferred to

graphite electrodes and excited in a dc arc. The spectra

produced were photographically recorded and the intensity

ratios of selected pairs of analytical lines and indium

internal standard lines were determined photometrically.

Concentrations of the elements were read from analytical

curves relating log intensity ratio to concentration. Table

6 shows details of the spectrographic procedure.

Table 6. Spectrographic details for determination

of impurities in iron

Spectrograph Ebert, 3.4 meter grating spectrograph with

a reciprocal linear dispersion of 5 8 per mm

Slit width 30 micrometers

Electrodes Lower, anode, sample. Undercut thin wall

ASTM type S-13- Upper, cathode, ASTM

type S-l

Electrode gap 4 mm - adjusted during burn

Atmosphere 70% argon, 30$ oxygen

Excitation Direct current arc. Start at 5 A for

10 seconds then at 15 A for complete burn

plus 5 seconds

Recording Photographic using SA1 emulsion

Developing Routine D-19

63
The results obtained by this method are shown in Table 7.

Table 7. Analysis of ingot iron SRM 1265 by

optical emission spectrography

Average concentration 95% Confidence Number of

Element P ercent by wei ght limits de terminations

Cr 0.0073 +0.0006 6

Co .0070 + .0006 6

Mn . 0069 + .001 6

Cu .0066 + .0006 6

Al <. 001 6

Ti <.002 6

2Botanical Materials

A spectrochemical method for analyzing samples of ground

orchard leaves is being developed. The samples are mixed with

gallium oxide and weighed into graphite electrodes. They are

then ashed, covered with high-purity graphite powder, and

excited with a dc arc. Better burns and lower background is

achieved with a gas sheath [32]. When the ash content is very

low, several ashed portions can be combined in one electrode.

3

Miscellaneous

The copper spark method [33] is a spectrochemical technique for determining trace elements in a solution that has

been evaporated on the ends of a pair of electrodes. The

analytes are subsequently excited by a high-voltage spark

discharge. High-purity graphite has also been used in the

general method instead of copper [3*0. In applying this technique to analytical problems, the procedures for separating

the trace analytes from the matrix often produce a considerable

64
amount of residue. Under these conditions, the residue on

the electrode surfaces can be dislodged by the high-voltage

spark before excitation.

In separating the trace elements from the matrix, they

are usually present as extremely dilute solutions and are

therefore susceptible to "sorption" losses. Moreover, the

manipulations required for preconcentrating the analytes and

evaporating the solution on the electrodes increases the possibility of contamination. Electrodeposition of certain trace

elements from a solution of the matrix directly on the electrode surface would be less subject to such errors. Previous

work from our laboratory describing the electrodeposition of

trace amounts of silver on graphite electrodes was reported

at an NBS Symposium for Trace Characterization [35]. At that

time, initial experimentation was performed on electrodepositing trace amounts of cadmium on mercury -plated copper

electrodes - During this period, additional experiments were performed

to establish conditions for quantitatively electrodepositing

bismuth, cobalt, tin and zinc by using Bi, Co, Sn

65 and Zn as tracers. In addition, a number of other cathodeactive elements present at concentrations of 0.1 ug/ml in

5 ml of solution appeared to be quantitatively deposited.

This investigation will be continued and results made available at a later date.

R. Alvarez, M. Darr, E. Belkas

B. Isotope Dilution

1 . Ingot Iron

In last year's annual report [5] 3 we outlined a stable

isotope dilution - spark source mass spectrographic method

(ID-SSMS) for analyzing ingot iron. Silver, copper, molybdenum and nickel were simultaneously determined in the 100-mg

65
samples of NBS-SRM 1165 using a chemical preconcentration

step to separate the spiked analytes from the matrix. The

concentrations ranged from 0.0005$ for Ag to 0.025$ for Ni

.

Cobalt, a mononuclidic element, was also determined at the

same time by adding known amounts of Co to half of the

samples used for the isotope dilution determinations and

59 60 59 58 measuring the Co/ Ni and ^Co/ Ni ratios. Details of

the method, including a comparison of the results obtained

with the certified values, were published recently in Analytical Chemistry [36].

Applying this method to the analysis of an ingot iron

material intended as a renewal NBS Standard Reference Material,

the basic procedure was altered to investigate whether other

elements could be separated and thus determined. Titanium

was of particular interest. After extracting the iron into

the organic phase, the aqueous phase was evaporated to a

few tenths of an ml instead of being electrolyzed as in the

published procedure. The residue was transferred to highpurity gold wires and ignited at 450°C for 20 minutes in

a tube furnace equipped with a quartz tube liner. The wires

were then sparked in the mass spectrograph and the spectrum

was phototraphically recorded. A line corresponding to SO , which has a mass/charge ratio of 48, was found. This species,

which is an ion fragment from the sulfate in the residue,

interfered with an intensity measurement of the line on the

48 emulsion produced by the Ti . The sulfate in combination

with alkali cations is not removed by ignition. Some of

47 the sulfate came from the Ti spike solution since HpS(X

had been used to dissolve the enriched isotope material.

Moreover, during the subsequent dilutions of the 1 mg/ml

47Ti stock solution, the acid strength had been maintained

with HpSCv to prevent hydrolysis. Had we anticipated the pro-

+ duct ion of SO with this procedure, these dilutions could

have been performed with HClOh. Because of interferences of

66
this type and those from combinations of anions and cations,

we have preferred to incorporate an electrodeposition step

in the previous analytical procedures that we have developed.

This has the advantage of providing the isotopically altered

analytes relatively free of other anions and extraneous

cations, thus greatly simplifying the photographically

recorded spectrum.

Although Ti was not determined, other spiked analytes

yielded interference-free lines on the emulsion. The results

given in Table 8 were calculated from the general isotope

dilution equation:

W K (A - B R)

r = sp sp

M (BR - A)

where C is the concentration in ug/g, W is the weight of

isotopically enriched material ("spike") added in ug, M is

the weight of sample in g, A and B are the natural abundances

of the analyte isotopes a and b, A and B are the abunsp sp

dances of isotopes a and b in the spike, R is the measured

altered ratio of isotope a to isotope b, and K is the ratio

of the natural atomic weight to the atomic weight of the

spike

Table 8. Analysis of ingot iron SRM 1265 by isotope

dilution - spark source mass spectrography

Average cone. No . of

Eleme nt percent by weight 95$ Conf. limi ts Deter'

Cu 0.0058 0.0003 8

Cr .0075 . 0002 9

Ni .040 .001 9

Mo .0041 .0005 6

67
In the analytical procedure, most of the iron and some of

the molybdenum are extracted with MIBK, and if the molybdenum

present In the sample and the molybdenum spike were not in

equilibrium, erroneous results would be obtained. This

attainment of equilibrium, a sine qua non of the method, is

usually ensured by cycling analytes and spikes through

oxidation-reduction states. However, in attempting to determine several trace elements simultaneously, indiscriminate

use of reagents, other than those of highest purity, would

prohibitively increase the method blank for common elements

thus precluding their determinations. We were interested

in determining silver, which, unfortunately, proved to be

less than 0.1 ppm in the samples.

Because of the several stable valence states that molybdenum possesses, there is even more concern regarding the

attainment of equilibrium between that analyte and its spike.

Consequently, two additional experiments were run in which

the spiked samples were dissolved as before but then evaporated

to dryness and treated with concentrated nitric acid. Individual results of 0.0039$ and 0.0042$ were obtained, which

agree with the average value of 0.0041% reported in Table 8.

In another series of experiments designed to determine

titanium, the isotopically altered trace elements were electrodeposited at an increased current density compared to

that usually employed. Although under these conditions

titanium was electrodeposited, as was evident from the mass

spectrum, it could not be determined because of interference

96 48 from the doubly charged ' Mo on the singly charged Ti

.

The relative amount of molybdenum compared to titanium on the

gold wires was greater in this case than in the evaporation

96 procedure. This interference from the doubly charged Mo

was eliminated by extracting the solution with methyl isobutyl

ketone before electrolysis. But obviously, with this extraction

step, we would be substituting molybdenum for titanium as an

analyte

.

68
A secondary problem was the appearance of titanium as a

contaminant, possibly from the porous Vycor plug of the

electrolysis cell. Two of the cells in a clean environment

enclosure are shown in Figure 26. In this cell design, a porous Vycor glass plug separates the anode compartment from

the cell proper containing the sample solution and gold wire

cathodes. The plug is of small diameter, 3-5 mm, to minimize

contaminating the sample solution from the porous glass itself

and also from the electrolyte in the anode compartment. However, because of the increased current used In these experiments and the large resistance of the porous glass plug, the

liquid in the anode compartment was heated to perhaps 80°C.

Under these conditions, the sample solution may have become

contaminated. A change in cell design using a salt bridge

having a greater surface area should remedy this problem.

Figure 26. Electrolysis cells in enclosure

69
An ID-SSMS method was developed for determining a number

of chemically diverse elements in low-alloy steel. Copper,

silver, cerium, neodymium, selenium, tellurium and zirconium

ranging from 0.040$ for Cu to 0.00031$ for Nd were determined

in a steel material subsequently issued by NBS as SRM 1261.

The procedure will be detailed in a manuscript being prepared

for publication.

2 . High-Purity Reagents

The purity of reagents is fundamental to reliable trace

element determinations by most analytical methods. Samples

of high-purity perchloric acid were analyzed by an ID-SSMS

procedure to determine their suitability as reagents for

high-purity materials. Approximately 50 ml of each sample

was spiked with enriched isotope solutions of fourteen elements of interest.

An aliquot of the spiked solution was evaporated to a small volume and transferred to a pair of high-purity gold

wires. The wires were then ignited in a tube furnace to

remove hydrocarbons and residual perchloric acid. The mass

spectra were photographically recorded and the results were

calculated from the measured isotope ratios and the other

experimental data. The results for two lots of HClOj, are

listed in Table 9

.

All fourteen impurity elements were determined simultaneously. In this method, if the enriched isotope spikes

and impurity elements are in physical and chemical equilibrium,

possible losses that may occur during the preconcentration

and handling steps do not affect the final results. This

should be true for these elements under these experimental

conditions. Moreover, providing that enough material is

recovered to detect the "spiking" isotope, either an actual

concentration or upper limit can be reported.

70
Table 9- Analysis of high-purity perchloric acid

by isotope dilution - spark source mass spectrography

Concentrations in parts per billion (ng/g)

Lot "A" Lot "B"

Ag < 0.5 < 0.5

Ca 40 7

Cd 2 4

Cr 22 18

Cu 2 3

Fe 15 10

< 0.5

40

2

22

2

15

14

7

4

14

< 2

22

<10

3

Mg 14 4

K 7 9

Ni 4 < 0.5

Pb 14 16

Sn < 2 < 1

Zn 2 2 17

Ba <10 10

Ti 3 2

3 . Botanical Materials

Orchard Leaves is the first of a series of plant Standard

Reference Materials being issued by NBS to calibrate analytical

procedures. A number of trace elements, essential to plants,

are being determined by ID-SSMS . In addition, the method

yields upper concentration limits for a number of elements

Of particular significance is the presence of an abnormally

high concentration of lead. The relative contributions from

lead arsenate, fallout from internal combustion engine emissions, or possible contamination from the comminuting operation is not known at this time.

R. Alvarez, P. J. Paulsen*, C. W. Mueller*

*Analytical Mass Spectrometry Section

71
6. PERSONNEL AND ACTIVITIES

A . Personnel Listing

Spectrochemical Analysis Section

Bourdon F. Scribner, Section Chief

Karen L. Loraski, Section Secretary

Barbara W. Pastine, Chemist (part time)

Charlotte P. Fleming (part time clerical)

Group I. Electron Probe Microanalysis

Kurt F. J. Heinrich, Chemist

Donald L. Vieth, Metallurgist (On extended leave)

Robert L. Myklebust, Chemist

Jean R. Henoc, Physicist, C.N.E.T., France (Guest

Worker)

Barry L. Hammond, Chemist, U.S. Navy (Research

Associate

)

Charles E. Fiori, Electronic Technician

Katherine C. Burress (Summer Assistant, 1969)

Harvey Yakowitz, NBS Metallurgy Division (Guest

Worker, part time)

Group II. X-Ray Fluorescence Spectrometry

Stanley D. Rasberry, Physicist

Jerome S. McKay, Jr. (Laboratory Assistant, part

time

)

Jeremy R. Winick (Summer Assistant, 196 9)

Fielding Ogburn, NBS Metallurgy Division (Guest

Worker, part time)

Group III. Optical Spectrometry

Joseph L. Weber, Jr., Physicist

Virginia C. Stewart, Chemist

Doward M. Bouchette, Physical Science Technician

Kimberly V. Koppe (Summer Assistant, 1969)

Toshiaki Kuroha, Section 310.09 (Guest Worker,

p art t ime ) Group IV. Enrichment Techniques - Optical and Mass

Spectrometry

Robert Alvarez, Chemist

Martha M. Darr, Chemist

Eli as Belkas, Chemist, Greek Atomic Energy Commission (Guest Worker)

72
B. Publications

Margoshes, M. and Rasberry, S. D.

Application of Digital Computers in Spectrochemical

Analysis — Computational Methods in Photographic

Microphotometry j Spectrochim. Acta 24B , 497-513, (Jan.

1969).

Paulsen, P. J., Alvarez, R., and Kelleher, D. E.

Determination of Trace Elements in Zinc by Isotope

Dilution Spark Source Mass Spectrometry, Spectrochim.

Acta 24B, 535-544 (April 1969)

.

Margoshes, M.

Remarks on Linearization of Characteristic Curves in

Photographic Photometry, Appl. Optics _8, p. 8l8 (April

1969).

Margoshes, M. and Rasberry, S. D.

Fitting of Analytical Functions with Digital Computers

in Spectrochemical Anlaysis, Anal. Chem. 4_1, p. 1163

(Aug. 1969).

Heinrich, K. F. J. and Yakowitz, H.

Propagation of Errors in Correction Models for Quantitative Electron Probe Microanalysis in Proceedings V

International Congress on X-ray Optics and Microanalysis, Tuebingen, West Germany, Sept. 1968, 151-159

( Springer-Ver lag, Berlin, Heidelberg, New York, Dec.

1969)

•

Heinrich, K. F. J.

Advances in the Metallurgical Application of Electron

Probe Microanalysis, Ibid., 415-523.

Scribner, B. F. (Editor)

Activities of the NBS Spectrochemical Analysis Section

July 1968 through June 1969, NBS Tech. Note 502

(Dec. 1969).

Heinrich, K. F. J.

Electron and Ion Microprobe Analysis, in Record of the

10th Symposium on Electron, Ion, and Laser Beam

Technology, Gaithersburg, Md. , 21-23 May 1969, L.

Marton, Ed., San Francisco Press, 353-360 (1969).

Adler, I., Walter, L. S., Lowman, P. D., Glass, B. P.,

French, B. M. , Philpotts, J. A., Heinrich, K. F. J.,

and Goldstein, J. I.

Electron Microprobe Analysis of Lunar Samples, Science

167 , No. 3918, 590-2 (Jan. 1970).

73
10. Heinrich, K. F. J., Fiori, C. E., and Yakowitz, H.

Image Formation Technique for Scanning Electron

Microscopy and Electron Probe Microanalysis, Science

167 , No. 3921, 1129-31 (Feb. 1970).

11. Margoshes, M. and Scribner, B. F.

Emission Spectrometry, Anal. Chem. 42_(5) (1970).

12. Heinrich, K. F. J. and Yakowitz, H.

Uncertainty in the Atomic Number Correction, Mikrochim.

Acta 1970 , 123-134.

13. Margoshes, M.

The Future of Data Acquisition and Computation in

Spectrochemical Analysis, Spectrochim. Acta, 2J5B_( 3

)

(113-122 (March 1970).

14. Ahearn, A. J.

Quantitative Analysis of Solids by Spark Source Mass

Spectrometry in Proceedings of International Conference on Mass Spectroscopy, Kyoto, Japan, Sept. 8-13,

1969 (In press)

.

15. Paulsen, P. J., Alvarez, R. , and Mueller, C. W.

Spark Source Mass Spectrographic Analysis of Ingot

Iron for Ag, Cu, Mo, and Ni by Isotope Dilution and

for Co by an Internal Standard Technique, Anal. Chem.

42, 673 (1970).

16. Heinrich, K. F. J.

Present State of the Classical Theory of Quantitative

Electron Probe Microanalysis, NBS Tech. Note 521 (in

English) and Mikrochim. Acta (in German) (In press).

17. French, B. M. , Walter, L. S., and Heinrich, K. F. J.

Quantitative Mineralogy of an Apollo 11 Lunar Sample,

Geochim. Cosmochim. Acta (In press).

18. Myklebust, R. L. and Heinrich, K. F. J.

Rapid Quantitative Electron Probe Microanalysis with

a Non-Diffractive Detector System, ASTM Special Tech.

Publication (In press).

74
Talks Given

1. Henoc, J. R. , "Quantitative Microanalysis," Fourth

National Conference on Electron Microprobe Analysis,

Pasadena, Calif., July 16, 1969

.

2. Heinrich, K. P. J., "Standard Reference Materials for

Quantitative Electron Probe Microanalysis," Fourth

National Conference on Electron Microprobe Analysis,

Pasadena, Calif., July 16, 1969.

3. Myklebust , R. L., "Qualitative and Semi-Quantitative

Analysis with Non-Dispersive X-ray Detectors," Fourth

National Conference on Electron Microprobe Analysis,

Pasadena, Calif., July 18, 1969.

4. Ahearn, A. J., "Quantitative Analysis of Solids by Spark

Source Mass Spectrometry," International Conference on

Mass Spectroscopy, Kyoto, Japan, Sept. 9, 1969.

5. Scribner, B. F., "Literature Search and Information

Retrieval in Atomic Spectrometric Analysis," Eighth

National Meeting of the Society for Applied Spectroscopy, Anaheim, Calif., Oct. 7, 1969.

6. Paulsen, P. J., "Determination of Trace Elements in Iron

Using Isotope Dilution Spark Source Mass Spectrometry,"

Eighth National Meeting of the Society for Applied

Spectroscopy, Anaheim, Calif., Oct. 9, 1969

•

7. Alvarez, R., "The Analysis of Ultrapure Liquid Reagents

by Isotope Dilution and Spark Source Mass Spectrometry,"

Eighth National Meeting of the Society for Applied

Spectroscopy, Anaheim, Calif., Oct. 9, 1969.

8. Rasberry, S. D., "Improvements in Empirical Interelement

Corrections in X-ray Fluorescence Analysis," Eighth

National Meeting of the Society for Applied Spectroscopy, Anaheim, Calif., Oct. 10, 1969.

9. Heinrich, K. F. J., "Electron Probe Microanalysis," First

Georgetown Conference on Surface Analysis," Washington,

D. C, Oct. 10, 1969.

10. Heinrich, K. F. J., "Present State of Quantitative Electron Probe Microanalysis," Institute for Analytical

Chemistry and Microchemistry , Techn. Hochschule, Vienna,

Oct. 22, 1969.

75
11. Heinrich, K. P. J., "Present State and Perspective of

Mlcroprobe Analysis in the USA," "Microsonde" working

group of France, Saint Germain-en-Laye , Prance, Oct. 31,

1969.

12. Alvarez, R., "Analysis of NBS Standard Reference Materials

by Isotope Dilution Procedures and Spark Source Mass

Spectrometry," American Chemical Society (Southeastern

Regional Meeting), Richmond, Va., Nov. 7, 1969.

13. Myklebust, R. L., "Standards and Calibration in Microprobe Analysis," 1969 Eastern Analytical Symposium,

New York, N. Y., Nov. 21, 1969.

14. Scribner, B. F., "The Role of NBS Standard Reference

Materials in Modern Science and Technology," American

Chemical Society, Upper Montclair, N. J., Dec. 11, 1969.

15. Rasberry, S. D., "The Application of Computers in Spectrochemical Analysis," Society for Applied Spectroscopy, Allentown, Pa., Jan. 9, 1970.

16. Weber, J. L. , Jr., "Current Work of the Spectrochemical

Analysis Section on NBS Standard Reference Materials,"

Society for Applied Spectroscopy, Clarksville, Md.,

Jan. 27, 1970.

17. Scribner, B. P., "Advances in Microanalysis by Optical

and X-ray Spectrometry," University of Florida, Gainesville, Fla., Jan. 28, 1970.

18. Alvarez, R., "Spark Source Mass Spectrographic Analysis

of Ingot Iron for Ag, Cu , Mo, and Ni by Isotope Dilution and for Co by an Internal Standard Technique,"

159th National Meeting of the American Chemical Society,

Houston, Texas, Feb. 23, 1970.

19. Rasberry, S. D., "Reduced-Regression Interelement Corrections in X-ray Fluorescence Analysis," Pittsburgh

Conference on Analytical Chemistry and Applied Spectroscopy, Cleveland, Ohio, March 2, 1970.

20. Alvarez, R. , "Chemical Techniques for Spark Source Mass

Spectrometry," Pittsburgh Conference on Analytical

Chemistry and Applied Spectroscopy, Cleveland, Ohio,

March 5, 1970.

21. Heinrich, K. F. J., "Applications of Electron Probe

Microanalysis to Lunar Specimens," Argentine Atomic

Energy Commission, Buenos Aires, March 9, 1970.

76
Heinrich, K. F. J., "Progress in Quantitative Electron

Probe Microanalysis," Fifth Middle Atlantic Regional

Meeting Program of the American Chemical Society,

Newark, Del., April 1, 1970.

Myklebust, R. L., "A Non-Diffractive Detector System

for Rapid Qualitative or Quantitative Electron Probe

Microanalysis," Fifth Middle Atlantic Regional Meeting

of the American Chemical Society, Newark, Del., April

1, 1970.

Heinrich, K. F. J., "Electron Probe Microanalysis,"

Society for Applied Spectroscopy and the American

Chemical Society, Cleveland, Ohio, April 8, 1970.

Heinrich, K. F. J., "Topographic and Chemical Scanning

Microprobe Analysis," Washington Society for Electron

Microscopy, Catholic University, Washington, D. C.,

May 7, 1970.

Heinrich, K. F. J., "Application of Energy Dispersion

Spectrometry to Electron Probe Microanalysis," Murray

Hill Laboratories, Bell Telephone Co., Murray Hill,

N. J. , May 26, 1970.

Alvarez, R. , "Simultaneous Trace Element Determination

in High-Purity Liquid Reagents by Isotope Dilution

and Spark Source Mass Spectrometry," American Chemical

Society and The Chemical Institute of Canada, Toronto,

Canada, May 27, 1970.

Myklebust, R. L., "Rapid Quantitative Electron Probe

Microanalysis with a Non-Diffractive Detector System,"

73rd Annual Meeting, American Society for Testing and

Materials, Toronto, Canada, June 24, 1970.

77
D. Committee Activities

B. F. Scribner

Member, ASTM Committee E-2 on Emission Spectroscopy

Member, ASTM Committee E-13 on Absorption Spectroscopy

Chairman, Student Awards Committee, Eastern Analytical

Symposium, 1969

Member, Advisory Board, Spect rochimica Acta, Atomic

Section

Member, Committee on Honorary Members, SAS , 1969

Member, Nominating Committee, National Capital Section,

Optical Society of America, 1969

Member, Analytical Services Committee, NBS Analytical

Chemistry Division

K. F. J. Heinrich

Past-President, Electron Probe Analysis Society of

America, 1970

Assistant Editor, Mikrochimica Acta

Secretary, Organizing Committee, 10th Symposium on

Electron, Ion, and Laser Beam Technology, NBS, 1969

R. Alvarez

Member, ASTM Committee E-2 on Emission Spectroscopy

Member, Awards Committee, Baltimore-Washington Section,

SAS, 1970

J . L . Weber, Jr.

Member, ASTM Committee E-2 on Emission Spectroscopy,

Subcommittees IV, VII, and IX

Member, ASTM Committee B-7 on Light Metals and Alloys,

Cast and Wrought

Secretary, Baltimore-Washington Section, SAS, 1969-70

Column Editor, Applied Spectroscopy

S. D. Ras berry

Member, Laser Task Group, ASTM Committee E-2

Delegate, Baltimore-Washington Section, SAS, 1970-72

Member, Membership Education Committee, SAS, 1970

Member, Computer Evaluation Committee, NBS Analytical

Chemistry Division

M. M. Parr

Member, ASTM Committee E-2 on Emission Spectroscopy,

Subcommittee XII

78
7. ACKNOWLEDGMENTS

We have benefited greatly by the cooperation and assistance of persons from other groups and it is a pleasure to

acknowledge these contributions to our work.

Dr. J. Henoc, guest worker from the Centre National

d'Etudes des Telecommunications, France was the main author

of the computer program COR and contributed extensive discussions on various aspects of the theory of quantitative

electron probe analysis.

Barry Hammond, research associate from the U. S. Naval

Ship Research and Development Center, Annapolis, Md. contributed effectively to the electron probe measurements.

Mineral specimens were supplied for electron probe

studies by K. Frederiksson and J. White, Smithsonian Institution, Washington, D. C; by A. L. Albee, California Institute of Technology; by T. R. Boyd, Geophysical Laboratory,

Washington, D. C; and by C. Kieft, Institut voor Aardwetenschappen, Vrije Universiteit , Amsterdam, Netherlands.

Valuable contributions were made to our research program

in optical emission spectrometry by Dr. Elias Belkas , International Atomic Energy Agency Fellow, from the Greek Atomic

Energy Commission, "Democritos" , Athens, Greece.

From our own organization, L. A. Marzetta, Measurement

Engineering Division, provided valuable assistance in the

design of electronic instrumentation, and Morris Schwartzmann

of the same group contributed to the repair of electronic

equipment

Alex Fussinger of the Chemistry Division Contact Shop

has been especially cooperative in the fabrication of small

parts without detailed designs.

The Technical Services Section of our Division, and

especially T. M. McLeod, have provided much helpful assistance

on instrument problems.

79
Mrs. Rosemary Maddock and her group have continued to

give much assistance to us in the planning of illustrations

and slides for publications. In our bibliographic work,

Virginia Stewart, Barbara Pastine, and Charlotte Fleming have

been most helpful.

Finally, Karen Loraski, our Section Secretary, has provided invaluable assistance to members of the Section in a variety of activities, especially in the preparation and

the typing of complex manuscripts and reports.

80
8. LIST OF REFERENCES

[1] Scribner, B. F., ed. , "Spectro chemical Analysis:

Optical Spectrometry j X-Ray Fluorescence Spectrometry _, and Electron Probe Microanalysis Techniques

July 1964 to June 1965," NBS Technical Note 272,

Oct., 1965.

[2] Scribner, B. F., ed., "Activities of the NBS Spectrochemical Analysis Section, July 1965 through June

1966," NBS Technical Note 401, Sept., 1966.

[3] Scribner, B. F., ed. , "Activities of the NBS Spectrochemical Analysis Section, July 1966 through June

1967," NBS Technical Note 422, Jan., 1968.

[4] Scribner, B. F., ed., "Spectrochemical Analysis Section:

Summary of Activities July 1967 to June 1968," NBS

Technical Note 452, Sept., 1968.

[5] Scribner, B. F., ed., "Activities of the NBS Spectrochemical Analysis Section, July 1968 to June 1969,"

NBS Technical Note 502, Dec, 1969

[6] Fitzgerald, R., Keil, K., and Heinrich, K. F. J.,

Science 159., 528 (1968).

[7] Heinrich, K. F. J., Fiori, C, and Yakowitz, H.,

Science 167 , 1129 (1970).

[8] Yakowitz, H., and Heinrich, K. F. J., J. Res., NBS

73A(2), 113 (1969).

[9] Heinrich, K. F. J., Vieth, D., and Yakowitz, H., Adv.

in X-ray Analysis 9_, 208 (1966).

[10] Myklebust, R. L., and Heinrich, K. F. J., "Rapid Quantitative Electron Probe Microanalysis with a Nondiffractive Detector System," (to be published in an

ASTM Special Technical Publication).

Yakowitz, H., and Heinrich, K. F. J., Mikrochim. Acta

1968 , 182.

Heinrich, K. F. J., and Yakowitz, H. , Mikrochim. Acta

1970, 123.

81
[13] Heinrich, K. F. J., and Yakowitz, H., Mikrochim. Acta

1968 , 905.

[ 14 ] Henoc, J., "Fluorescence Excited by the Continuum," in

NBS Special Publication 298 , p. 197 (1968).

[15] Green, M. , "The Efficiency of Production of Characteristic X-Radiation, " Doctoral Thesis, U. Cambridge,

U.K., 1962.

[16] Rao-Sahib, T. S., and Wittry, D. B., "Measurement of the

X-ray Continuum from Thick Targets," 4th National

Conference on Electron Microprobe Analysis, EPASA,

Pasadena, 1969-

[17] Henoc, M. J., Maurice, F., and Zemskoff, A., "Phenomenes

de Fluorescence aux Limites des Phases," Proc. 5th

Internat . Congress on X-ray Optics and Microanalysis,

Tubingen, 1968, Springer-Verlag, Berlin, p. 187,

1969.

[18] Philibert, V., and Tixier, R., "Some Problems with

Quantitative Probe Microanalysis," in NBS Special Publication 298 , p. 13 (1968).

[19] Berger, M. J., and Seltzer, S. M., "Tables of Energy

Losses and Ranges of Electrons and Positrons," Natl.

Acad. Sci., Nat. Res. Council Publ. 1133 , 205 (1964).

[20] Duncumb, P., and Reed, S. J. B. , "The Calculation of

Stopping Power and Backscatter Effects in Electron

Probe Microanalysis," in NBS Special Publication 298,

p. 133 (1968).

v

[21] Heinrich, K. F. J., Adv. in X-ray Analysis 11, 40 (1968).

[22] Duncumb, P., and Shields, P. K., "Effect of Critical

Excitation Potential on the Absorption Correction,"

in The Electron Microprobe , J. Wiley, N. Y., 1966

,

p. 2W.

[23] Heinrich, K. F. J., "X-ray Absorption Uncertainty," in

The Electron Microprobe , J. Wiley, N. Y., 1966,

p. 296.

[24] Criss, J., "On the Structure of Formulas for Quantitative Analysis," in NBS Special Publication 298 , p. 53 (1968).

82
[25] Fink, R. W. , Jopson, R. C, Mark, H., and Swift, C. D.,

Rev. Mod. Physics 38, 513 (1966).

[26] Criss, J. W. , and Birks, L. S., "Intensity Formulae for

Computer Solution of Mu It i -component Electron Probe

Specimens," in The Electron Microprobe , J. Wiley,

N. Y., 217 (196FT

Adler, I., et al. , Science 1967 , No. 3918, 590 (Jan.

1970).

French, B. M. , Walter, L. S., and Heinrich, K. F. J.,

"Quantitative Mineralogy of an Apollo 11 Lunar

Sample," Geochim. Cosmochim. Acta (in press).

[29] Margoshes, M. , and Rasberry, S. D., Anal. Chem. 4l

,

1163 (1969).

[30] Scribner, B. F., "Spectrographic Analysis in Air

Pollution Studies," in Air Pollution - Proceedings

of the United States Technical Conference on Air

Pollution, Louis C. McCabe, Chairman, McGraw-Hill,

New York 1952, pp. 231-5.

[31] Landis, F. P., and Coons, M. C, Appl . Spectry . 8,

71-74 (1954).

[32] Margoshes, M., and Scribner, B. F., Appl. Spectry. 1_8_,

154-5 (1964)

.

[33] Fred, M. , Nachtrieb, N. H., and Tomkins, F. S., J. Opt.

Soc. Am 37_, 279 (1947).

[34] Morris, J. M., and Pink, F. X., Symposium on Spectrochemical Analysis for Trace Elements, ASTM Special

Technical Publication 221, 39 (1958).

[35] Alvarez, R., "Electrodeposition of Trace Constituents

as a Preconcentration Technique for Optical Emission

Spectroscopy," Symposium on Trace Characterization,

Natl. Bur. of Standards, Oct. 3-7,(1966).

[36] Paulsen, P. J., Alvarez, R., and Mueller, C. W. , Anal.

Chem. 42, 673 (1970).

83
APPENDIX A

CERTIFICATES FOR NBS STANDARD REFERENCE

MATERIALS RECENTLY ISSUED

84
S. Depart

Mauric

National A. V

of Commerce

Stans

gEtf Standards

irector

APPENDIX A-1

deritftrat? nf Analgma

STANDARD REFERENCE MATERIAL 1155

Stainless Steel

Cr 18-Ni 12 -Mo 2 (AISI 316)

(This material also is available in chip form as SRM 160b, primarily for application in

chemical methods of analysis)

Element Percent by Weight

Carbon 0.046

Manganese 1.63

Phosphorus 0.020

Sulfur .018

Chromium

Vanadium

Molybdenum

Cobalt

Lead

SIZE AND METALLURGICAL C

and % in (1.9 cm) thick, and

45

0.047

2.38

0.10i

.001

mples are iy± in (3.2 cm) in diameter

e annealed condition.

PROVISIONAL CERTIFICATION -^The provisional value listed for an element is the

present best estim^STwf >rogj5rue value based on the use of methods at NBS of high

reliability. To-tfft^k<n>i5>possible systematic errors, other SRM's were chemically

analyzed concurWmtlyV»The provisional value is not expected to deviate from the true

value by more tnpn ± 1 in the last significant figure reported ; for values having subscripted numbers the deviation is not expected to be more than ± 5 in the subscripted

numbers. Based on the results of homogeneity testing, maximum variations within and

among samples are less than the estimated accuracy figures given above.

Washington, D. C. 20234

August 4, 1969

J. Paul Cali, Acting Chief

Office of Standard Reference Materials

(over)

85
PLANNING, PREPARATION, TESTING, ANALYSIS: For many metal SRM's it is desirable to make the material available both in the form of chips primarily for chemical

analysis and solids primarily for optical emission and x-ray spectrochemical methods of

analysis. Prior to the preparation of the renewal SRM 160b (chip form) plans were made

to also provide this material as SRM 1155 (solid form).

The material for this standard was prepared at Duquesne Works, U. S. Steel Corporation, Pittsburgh, Pennsylvania.

Homogeneity testing was performed at NBS by D. M. Bouchette and J. L. Weber, Jr. and was found to be satisfactory for the elements certified.

Analyses for certification were performed in the laboratories of the Analytical Chemistry

Division of the National Bureau of Standards by J. R. Baldwin, C. E. Champion, T. D.

Gills, E. J. Maienthal, T. J. Murphy, R. A. Paulson, W. R. Shields, B. A. Thompson, and

S. A. Wicks.

The overall direction and coordination of the technical measurement leading to certification were performed by J. K. Taylor.

The technical and support aspects involved in the procurement, preparation and issuance

of this SRM were coordinated through the Office of Standard Reference Materials by R. E.

Michaelis.

86
APPENDIX A-2

U. S. Dei

Mauri

of Commerce

Stans

Standards

', Director Certificate of &nalpafe

STANDARD REFERENCE MATERIAL 97 a

Flint Clay

(Results baaed on sample dried for two hours at 140 °C)

Analyst SiO, A1.0, Fe.O, TiO. PtO. K,0 Na,0 Li,0 ZrOi BaO MgO CaO SrO CrjO, Loss on

Igni- tion

U'l 43.74 38.65 /0.45*\

\ .46"/ fl.88'\ U.89«/

0.34 0.53' 0.033' 0.12' 0.063' 0.078' 0.16« 0.11« 0.17» 0.028h 13.32

21*1 43.68 38.95 .45 1.95 .35 .51- .041' .10« .07 .14« .11« .18« .03 13.31

3 43.60 38.79 .43' 1.87" .38' .46' Arerafe-- 43.67 38.79 0.45 1.90 0.36 0.50 0.037 0.11 0.075

0.15 0.11 0.18 0.03 13.32

References: [1] G.E.F. Lundell and J.I. Hoffman, NBS J. Res. 1, 91 (1928) RP5.

[2] L. C. Peck, Geological Survey Bulletin 1170, (1964). •o-phenanthro line photometric method.

bIron reduced with SnCl = and titrated with standard potas- sium dichromate solution. 'Cupferron gravimetric method.

'HiO: photometric method.

'Flame emission spectrometric method.

'Pyrocatechol violet photometric method. •Atomic absorption method.

h Diphenylcarbazide photometric method. 'Molybdenum-blue photometric method.

List of Analysts

1. R. K. Bell, B. B. Bendigo, T. C. Rains, T. A. Rush,

E. R. DeardorfF, J. R. Baldwin, R. A. Paulson,

W. P. Schmidt, and S. D. Rasberry, Analytical

Chemistry Division, Institute for Materials Research, National Bureau of Standards.

2. L. C. Peck, United States Geological Survey, Denver, Colorado.

3. L. M. Melnick, J. D. Selvaggio, and D. G. Cunningham, Applied Research Laboratory, United

States Steel Corporation, Pittsburgh, Pennsylvania.

The material for the preparation of this standard was proyided by the A. P. Green Fire Brick Company,

Mexico, Missouri. The overall direction and coordination of the technical measurements leading to certification were performed

under the chairmanships of O. Menis and J. I. Shultz. The technical and support aspects involved in the preparation, certification and issuance of this Standard Reference Material were coordinated through the Office of Standard Reference Materials by J. L. Hague.

Washington, D. C. 20234

October 8, 1969

J. Paul Cali, Acting Chief

Office of Standard Reference Materials

87
APPENDIX A-3

U. S. Departi^Boj^of Commerce

iiM. St

ofj Standards

Director Certificate of BLmtyxi*

STANDARD REFERENCE MATERIAL 98 a

Plastic Clay

(Results based on sample dried for two hours at 140 °C)

Analyst SiO, Al.O, Fe,0, TiO, PiO. K,0 Na,0 Li,0 ZrO, BaO MgO CaO SrO Cr.O, Loss on

Igni- tion

H'l 48.98 33.13 fl.34'\ \1.37»;

fl.56'\ \1.63"/ 0.11 1.07' 0.080' 0.075' 0.042' 0.031' 0.42< 0.31« 0.041" 0.030h 12.40

21*1 48.91 33.31 1.35 1.64 .10 1.08' .083" .064« .03 .43' .31« .037« .04 12.49

3 33.12 1.28* 1.61d .11' 0.98' Average.. 48.94 33.19 1.34 1.61 0.11 1.04 0.082 0.070 0.03 0.42 0.31 0.039 0.03 12.44

References: [1] G.E.F. LundeU and J.I. Hoffman, NBS J. Res. 1, 91 (1928) RP5.

[2] L.C. Peck, Geological Survey Bulletin 1170, (1964). *o-phenanthroline photometric method.

bIron reduced with SnCh and titrated with standard potas- sium dichromate solution. 'Cupferron gravimetric method.

d HjOj photometric method.

'Flame emission spectrometry method.

'Pyrocatechol violet photometric method. Atomic absorption method.

b Diphenylcarbazide photometric method. 'Molybdenum-blue photometric method.

List of Analysts

R. K. Bell, B. B. Bendigo, T. C. Rains, T. A. Rush,

E. R. Deardorff, J. R. Baldwin, R. A. Paulson,

W. P. Schmidt, and S. D. Rasberry, Analytical

Chemistry Division, Institute for Materials Research, National Bureau of Standards.

2. L. C. Peck, United States Geological Survey, Denver, Colorado.

3. L. M. Melnick, J. D. Selvaggio, and D. G. Cunningham, Applied Research Laboratory, United

States Steel Corporation, Pittsburgh, Pennsylvania.

The material for the preparation of this standard was provided by the A. P. Green Fire Brick Company,

Mexico, Missouri. The overall direction and coordination of the technical measurements leading to certification were performed

under the chairmenship of O. Menis and J. I. Shultz. The technical and support aspects involved in the preparation, certification and issuance of this Standard Reference Material were coordinated through the Office of Standard Reference Materials by J. L. Hague.

Washington, D. C. 20234

October 8, 1969

J. Paul Cali, Acting Chief

Office of Standard Reference Materials

88
APPENDIX A-4

U. S. Depa;

Maurici

of Commerce

Stans

(Utrtxixtntt nf Analysts

STANDARD REFERENCE MATERIAL 59a

Ferrosilicon

Si Fe C Mn P S Cu Ni Cr Al B Ca w

Hw

i»<

<

i.i IB

Cm

c

eis

3 a ISoO

£3o

.e

1 48.12» 50.00" 0.044c 0.75<< 0.015 0.001"- 0.052" 0.032 0.084' 0.35hl 0.059J 0.039" 2 48.12' 50.06m .044" .76" .016 .001" .051p .032 .0791 .35' .063' .048'

3 48.13 1 50.09 .050 .76 .017 .002 — .039 .079 .35 .05 —

4 48.08* 50.08" .045'' .74" .015 — .056* — .076* .37* .060' .038"

5 48.07 50.00 .046' .76 .016 .003 .049" .028' f.080

12

) (.085" ( .35 .057 .042'

Average 48.10 50.05 0.046 0.75 0.016 0.002 0.052 0.033 0.080 0.35 0.058 0.042

1 0.5g sample fused with Na»Oj, double dehydration with HC1.

b 1-g sample dissolved in nitrohydrofluoric acids and fumed with H2 SO,. Iron precipitated with NH.OH,

acidified with HC1, reduced with SnCU and titrated with standard solution of K:Cr2 07.

f Iron accelerator.

d Persulfate-arsenite titration method. Atomic absorption method.

' Same value by isotope dilution.

* Chromium oxidized with ammonium persulfate and

titrated potentiometrically with ferrous ammonium

sulfate solution.

h Polarographic method.

1 Same value by atomic absorption.

' Isotope dilution.

k Flame emission spectrophotometric method.

1 Double dehydration with HClCv

m Iron reduced with SnCU and titrated with standard

solution of KiCrjCv.

Iron and tin-coated copper accelerators. Sodium pyrophosphate method.

Diethyldithiocarbamate photometric method.

Diphenylcarbazide photometric method. Sodium hydroxide separation of aluminum, followed by titration with 1,2-diaminocyclohexanetetraacetic

acid. Azure C photometric method. EDTA titration. Iron titrated with standard solution of KMnO( . Combustion-conductometric method. KIO» photometric method. Neocuproine photometric method. Cupferron-NH.OH-AljOj gravimetric method.

Spectrographic method. Calcium precipitated as oxalate and titrated with

standard solution of KMnO,.

Spectrometric method.

Washington, D. C. 20234

November 6, 1969

J. Paul Cali, Acting Chief

Office of Standard Reference Materials

(OVER)

89
list of Analysts

1. R. K. Bell, J. R. Baldwin, T. C. Rains, T. A. Rush, S. A. Wicks, E. R. Deardorff, W. R. Shields, E.J. Maienthal, T.J. Murphy, K. M. Sappenfield and L.Moore, Analytical Chemistry Division,

Institute for Materials Research, National Bureau of Standards.

2. J. C. Cline and R. A. Pontello, Interlake Steel Corporation, Beverly, Ohio.

3. L. Risi, Shieldalloy Corporation, Newfield, New Jersey.

4. G. Porter, H. H. Hall and J. T. Waller, Ferroalloys Division, Union Carbide Corporation,

Marietta, Ohio.

5. H. R. Grady, Vanadium Chemical Research, Foote Mineral Company, Exton, Pennsylvania.

Homogeneity testing was performed at NBS by S. D. Rasberry and C. Gifford and was

found to be satisfactory for the elements certified. The overall direction and coordination of the technical measurements leading to certifica- tion were performed under the chairmenship of 0. Menis and J. I. Shultz. The technical and support aspects involved in the preparation, certification, and issuance of

this Standard Reference Material were coordinated through the Office of Standard Reference

Materials by R. E. Michaelis. The material for this standard was furnished by the Interlake Steel Corporation, Beverly,

Ohio.

90
APPENDIX A-5

U. S. DepartraMf' of Commerce

Maurice. H S tans

National Bi L. M Bra:

t>f Standards - Director (Certificate of ^ttalgsi*

STANDARD REFERENCE MATERIALS

1143, 1144, 1147, 1148, and 1149

Blast Furnace and White Iron Standards

1143 1144 1147 1148 1149

Blast Blast White White White

SRM No. Furnace Furnace Iron Iron Iron

Iron 1 Iron 2 <4j) (5L) (6g)

Element Peicent by Weij ;ht

Carbon 3.91 4.27 3.60 2.89 3.28 Manganese 0.41 4 1.33 0.78, 0.66 1.05 Phosphorus • 158 0.11 2 • 16 •30 0.564 Sulfur .028 .021 .059 [l] b •127 Silicon 1.68 •276 1.31 1.82 1.04

Copper 0.144 .090 0.23 0.99 0.49

Nickel •Us .021 .070 .091 138 Chromium • 145 .019 .093 • 146 •363 Vanadium .008 .004 .032 •036 •055 Molybdenum (.005)* .007 •078 •022 •036 Titanium .17 .44 .049 •05 .062 Arsenic (.004) (.004) .022 (.002) •036 Tellurium •02 .02 •01 6 •01 5 •01 3

'Values in parentheses are not certified but are provided for additional information on the composition. "This element exhibits excessive segregation and is not certified.

SIZE AND METALLURGICAL CONDITION: Samples are approximately 1V4 in (3.2 cm) square and V2 in (1.3 cm) thick; they were chill-cast by a rapid unidirectional solidification technique.

CERTIFIED PORTION: The certified portion for each sample is that extending upward 5/16 in (0.8 cm) from the chill-cast or test surface (the largest surface opposite the numbered surface). This

portion only was analyzed in the cooperative program f certification.

FINAL CERTIFICATION: The value listed for an element is the best estimate of the true value based on the results of the cooperative analytical program. The value listed is not expected to deviate from the true value by more than ± 1 in the last significant figure reported; for a subscript

figure, the deviation is not expected to be more than ± 5 in the subscript figure. Based on the results of homogeneity testing, maximum variations within and among samples are estimated to be less than the accuracy figures given above.

Washington, D. C. 20234

December 22, 1969

J. Paul Cali, Acting Chief

Office of Standard Reference Materials

91
PLANNING, PREPARATION, TESTING, ANALYSIS: These standards are made available as a

result of the cooperative program among the National Bureau of Standards, the American Cast Iron

Pipe Company, the Ductile Iron Society, and the General Motors Corporation.

The material for the standards was melted and cast at the American Cast Iron Pipe Company,

Birmingham, Alabama, with use of the NBS chill-cast mold assembly. The preparation and homogeneity testing plan was similar to that described in NBS Misc. Publ. 260-1, Standard Reference

Materials: Preparation of NBS White Cast Iron Spectrochemical Standards, Robert E. Michaelis and

LeRoy L. Wyman, June 19, 1964.

Homogeneity testing was performed at the Research Laboratories, General Motors Corporation,

Warren, Michigan, by A. C. Ottolini under the direction of M. D. Cooper.

Cooperative analyses for certification were performed by members of the Ductile Iron Society

under the direction and coordination of W. R. Kennedy, American Cast Iron Pipe Company, Bir- mingham, Alabama. Cooperating in the program were R. E. Deas and R. N. Smith, American Cast Iron Pipe Company, Birmingham, Alabama; F. R. Bryan, Ford Motor Company, Detroit, Michigan;

C. M. Davis and C. H. Albright, International Nickel Company, Inc., Suffern, N. Y.; and C. P. Gaskill, U. S. Pipe and Foundry Company, Burlington, New Jersey.

Analyses for final certification at the National Bureau of Standards were performed in the

laboratories of the Analytical Chemistry Division by D. A. Becker, B. B. Bendigo, D. M. Bouchette,

E. L. Garner, T.D.Gills, W. D. Kinard, P. D. LaFleur, E. June Maienthal, J. S. McKay, Jr., T.J. Murphy, S. D. Rasberry, W. R. Shields, and J. L. Weber Jr.

Technical measurements at NBS for final certification were coordinated by J. I. Shultz and

J. L. Weber, Jr., under the chairmanship of B. F. Scribner.

The technical and support aspects involved in the preparation, certification, and issuance of

these Standard Reference Materials were coordinated through the Office of Standard Reference

Materials by R. E. Michaelis.

CAUTIONS:

1. Determinations made on other than the chill-cast or test surface are not recommended because of the unidirectional solidification structure.

2. These chill-cast standards are designed for calibration in the analysis of samples prepared in the same manner; samples prepared by other casting techniques or having other than a white struc- ture may result in considerable bias.

3. Because the samples exhibit a change with respect to the columnar structure, both among

standards and from bottom to top of the certified portion of the samples, the surface preparation for x-ray spectroscopic analysis may be critical. (A metallographic polishing technique is recommended.)

4. Because of the poor heat conductivity of the white irons, difference in volatility rates for certain elements in emission spectroscopic analysis may occur depending on the location of the burn

and the source parameters. Sample and standard should be handled in the same way with respect to location of the burn.

92
APPENDIX A-6

U. S. Department' of Commerce

Mauricen. Stana SecMtary

National B#«aj? tffl Standards

L. M. BraAaetMf. Director Certificate td (Attalgsi*

STANDARD REFERENCE MATERIAL 1132

Lead-Base Bearing Metal

(84Pb-10Sb-6Sn)

This material also is available in chip form as SRM 53e, primarily for application in chemical

methods of analysis.

Element Percent by Weight

Antimony 10.26 Tin 5.84 Copper 0.054

Bismuth 052

Arsenic 057

Nickel 003

Iron <001

SIZE: Samples are VA inches (31.4 mm) in diameter and % inch (19.0 mm) thick.

CERTIFICATION: The value listed for an element is the best estimate of the true value based on methods at NBS of high reliability and on the results of outside cooperating laboratories. The value

listed is not expected to deviate from the true value by ± 1 in the last significant figure reported. For values having a subscribed number, the deviation is not expected to be more than ± 5 in the subscribed number. Based on the results of homogeneity testing, maximum variations within and

among samples are less than the estimated accuracy figures given above.

The technical and support aspects involved in the procurement preparation and issuance of this Standard Reference Material were coordinated through the Office of Standard Reference Materials by R. E. Michaelis.

Washington, D. C. 20234 J. Paul Cali, Acting Chief

January 30, 1970 Office of Standard Reference Materials

(over)

93
PLANNING, PREPARATION, TESTING, ANALYSIS: For many metal SRMs it is desirable to make the material available both in the form of chips or powder primarily for chemical analysis, and

solids primarily for optical emission and x-ray speotrometric methods of analysis. Prior to the preparation of the renewal SRM 53e, plans were made to provide this material as SRM 1132, solid form.

Material for this standard was prepared by Alcan Metal Powders, Inc., Elizabeth, New Jersey, to

specifications for lead-base bearing alloy SAE 13. About 1500 pounds was atomized to powder of minus 140 mesh size. At NBS the material was sized between 170 and 325 mesh sieves and

thoroughly blended. Some 1000 pounds was reserved as SRM 53e. About 500 pounds of the powder material was converted to 100% dense rods for this standard at Whitaker Metals Corporation, West Concord, Massachusetts, first by cold compaction at 13 tons psi to billets, then followed

by cold extrusion to size without use of a lubricant.

Homogeneity testing of this material and SRM 53e was performed at NBS by R. K. Bell and

S. D. Rasberry and was found to be satisfactory for the elements certified.

Analyses for certification were performed in the laboratories of the Analytical Chemistry Divi- sion of the National Bureau of Standards by R. K. Bell and E. June Maienthal. Since this SRM 1132

was found to be identical to SRM 53e for all practical purposes, the same values are used for both

standards. Cooperating in the analyses of the 53e material was J. H. Kanzelmeyer and J. J. Aldrich,

St. Joseph Lead Company, Zinc Smelting Division, Monaca, Pennsylvania; and L. W. Anderson and

D. J. Henrie, American Smelting and Refining Company, South Plainfield, New Jersey.

94
APPENDIX A-7

U. S. Departnltnt'of Commerce

Maurice.;*. Stan* Certificate of (Anal^si*

STANDARD REFERENCE MATERIALS

1140, 1141, 1142

Ductile Iron Standards

SRM No. 1140 1141 1142

Ductile Iron 1 Ductile Iron 2 Ductile Iron 3

Element Percent

Carbon 3.18 3.64 2.94 Manganese

Phosphorous

Sulfur

0.725 .007 .010

0.48

.073 .020

0.183 •21 .015

Silicon 1.92 1.11 3.33 Copper

Nickel 0.096

.028

0.204 •548

1.02

1.63 Chromium .030 .138 •055 Vanadium .030 .009 .006 Molybdenum

Titanium

.095 •096

.051 .013

.023 .008 Aluminum (.01) (.005) .089

Arsenic .072 •036 •oi Magnesium

Cerium

Yttrium

.019

(.09) (<.002)

.044

(.05) •04

.097 (.015)

.01 Lead

Bismuth

.0052 •001 5

(.0009)

(.00008)

(.0005)

(.00002)

'Values in parenthesis are not certified but are provided for additional information on the composition.

SIZE AND METALLURGICAL CONDITION: Samples are approximately 1 1/4 inches (3.2 cm)

square and 1/2 inch (1.3 cm) thick; they were chill-cast by a rapid unidirectional solidification technique.

CERTIFIED PORTION: The certified portion for each sample is that extending upward 5/16 inch

(0.8 cm) from the chill-cast or test surface (the largest surface opposite the numbered surface). This

portion only was analyzed in the cooperative program for certification.

FINAL CERTIFICATION: The value listed for an element is the best estimate of the true value based on the results of the cooperative analytical program. The value listed is not expected to

deviate from the true value- by more than ± 1 in the last significant figure reported; for a subscript

figure, the deviation is not expected to be more than ± 5 in the subscript figure. Based on the results of homogeneity testing, maximum variations within and among samples are estimated less than the accuracy figures given above.

Washington, D. C. 20234

February 24, 1970

J. Paul Cali, Acting Chief

Office of Standard Reference Materials

(over)

95
PLANNING, PREPARATION, TESTING, ANALYSIS: The three ductile iron standards are made

available as a result of the cooperative program between the National Bureau of Standards and the American Cast Iron Pipe Company. The standards were developed at the request of the Ductile Iron Society and the American Foundrymen's Society.

The material for the standards was melted and cast at the American Cast Iron Pipe Company,

Birmingham, Alabama, with use of the NBS chill-cast mold assembly. The preparation and homogeneity testing was similar to that described in NBS Misc. Publ. 260-1, Standard Reference

Materials: Preparation of NBS White Cast Iron Spectrochemical Standards, Robert E. Michaelis and

LeRoy L. Wyman, June 19, 1964.

Homogeneity testing was performed at NBS by D. M. Bouchette and was found to be satisfactory for the elements certified.

Cooperative analyses for certification were performed at the American Cast Iron Pipe Company,

Birmingham, Alabama by I. Glaze, J. B. Hobby, W. R. Kennedy, and R. N. Smith.

Analyses for final certification at the National Bureau of Standards were performed in the laboratories of the Analytical Chemistry Division by J. R. Baldwin, D. M. Bouchette, M. M. Darr, E. L. Garner, P. D. LaFleur, G. J. Lutz, E. J. Maienthal, M. Margoshes, L. I. McClendon, T. J. Murphy, T.

C. Rains, S. D. Rasberry, T. A. Rush, B. A. Thompson, and J. L. Weber, Jr.

Technical measurements performed at NBS for final certification were coordinated by J. I. Shultz and J. L. Weber, Jr. under the chairmanship of B. F. Scribner.

The technical and support aspects involved in the preparation, certification, and issuance of these Standard Reference Materials were coordinated through the Office of Standard Reference Materials by R. E. Michaelis.

CAUTIONS:

1. Determinations made on other than the chill-cast or test surface are not recommended because

of the unidirectional solidification structure.

2. These chill-cast standards are designed for calibration in the analysis of samples prepared in the same manner; samples prepared by other casting techniques or having other than a white struc- ture may result in considerable bias.

3. Because the samples exhibit a change with respect to the columnar structure, both among

standards and from bottom to top of the certified portion of the samples, the surface preparation for x-ray spectroscopic analysis may be critical. (A metallographic polishing technique is recommended).

4. Because of the poor heat conductivity of the ductile irons, difference in volatility rates for certain elements in emission spectroscopic analysis may occur depending on the location of the burn and the source parameters.

96
APPENDIX B

INPUT DATA FOR THE PROGRAM COR FOR CORRECTION OF

QUANTITATIVE ELECTRON PROBE MEASUREMENTS

In its present form, COR requires two groups of cards

for input, which will be called, respectively, Permanent

Table and Run Input.

The Permanent Table contains all necessary constants

for the elements contained in the specimen and the standards.

These constants are invariant with respect to operating

conditions, and are not changed after they have been established for an element, unless mistakes were made in punching

the cards. Eventually, this information will be incorporated

permanently in the memory of the program and will no longer

be considered input. At present, the Permanent Table is

entered with every run for two reasons: a. Elements are

added to the Table as required for our analysis. We now have

4l elements in it. However, since the main program is stored

on a magnetic drum, it would not be convenient to make piecemeal additions for each new element to the contents of the

drum; b. The table is systematically checked for mistakes

and will be made part of the memory after this check. In

summary, the fact that the Table is part of the input is

temporary, and in no way related to the structure of the

program.

The Run Input contains all the necessary information which

may change from run to run. This includes operating conditions

(voltage, x-ray emergence angle, choice of line), dimension

statements (numbers of specimens, points on each specimen,

etc.) and commands for decision-making switches (choice of

input, stoichiometry , difference, etc.), as well as a label

for each case.

97
In the present configuration, the Run Input also contains

Kramer's constant for continuous x-ray production, which

logically should be in the Permanent Table or even in the

main program. This anomaly is justified by the uncertainty

in the values for this constant as a function of atomic number.

Since we are presently working on the determination of this

constant (or constants, if there is indeed an atomic number

dependence), its inclusion in the Run Input facilitates its

change for experimental calculations.

A . Examples of Permanent Table Input

I. Element of low atomic number (e.g., Na)

:

Card Input

1 Atomic number, number of absorption edges listed

in table, atomic weight, constants for absorption

coefficients C v and n„, n VT

2 Wavelength of K- absorption edge, K jump ratio, K

fluorescence yield, number of lines related to

this edge

3 Wavelength of K3, weight of line K3

4 Wavelength of Ka, weight of line Ka

5 Wavelength of L

T absorption edge (if larger than

99 S, use "99")

98
II. Element of high atomic number (e.g., Au) :

Card Input

1 Atomic number, number of absorption edges listed

in table, atomic weight, Coster-Kronig coefficients

f

?

, f _ , f

? ., constants for absorption coefficients

CKL (if Z >50), nKL

2 Wave length of K absorption edge, K jump ratio, K

fluorescence yield

3 Wavelength, jump ratio, and fluorescence yield of

L T edge, number of lines generated by L

T (2)

4 Wavelength and weight of Lg„

5 Wavelength and weight of LBk

6 Wavelength, jump ratio, and fluorescence yield of

L-j-j edge, number of lines generated by L

TT (2)

7 Wavelength and weight of Ly -,

8 Wavelength and weight of L8-,

9 Wavelength, jump ratio, and fluorescence yield of

L TTT edge, number of lines generated by L TTT (3)

10 Wavelength and weight of L3

?

11 Wavelength and weight of La,

12 Wavelength and weight of Lou

99
13 Wavelength, jump ratio, and fluorescence yield of

M-j- edge

lH Wavelength, jump ratio, and fluorescence yield of

M

TT edge

15 Wavelength, jump ratio, and fluorescence yield of

MTTT edge, number of lines generated by M TTT edge (I)

16 Wavelength and weight of My

17 Wavelength, jump ratio, and fluorescence yield of

MTV edge, number of lines (1)

18 Wavelength and weight (=1) of MB

19 Wavelength, jump ratio, and fluorescence yield of

Mvedge, number of lines (1)

20 Wavelength and weight (=1) of Ma

21 Wavelength of the N T absorption edge

The Permanent Table is preceded by a card indicating the number

of elements contained in the Table.

B . Input for a Run

The sequence of cards varies depending on the following

alternatives

:

1. We may either calculate intensity ratios for known

compositions or vice versa.

100
2. In the second case, for measured elements, we may

either input the uncorrected experimental data, or intensity

ratios corrected for background and dead-time. If uncorrected

data are entered, the dead-times of the spectrometers must be

entered for use in the subprogram which performs the corrections .

3. If one phase (or point) is measured more than once,

we may either obtain the individual results or the averages

for each element, with the standard deviation of the signal.

4. Elements which were not measured can be calculated

either by difference or on the basis of known stoichiometric

relations. In case stoichiometric relations are used, the

valences of the appropriate elements must be entered.

5. Two output formats are available: a short format

(see Figure 10) or a test output format which contains detailed

information concerning intermediate steps.

For all elements present, the atomic number and Kramer's

constant must be entered. For the measured elements we need,

besides the experimental data (or intensity ratio), the

operating voltage, the choice of line, and the x-ray emergence

angle

6. If composite standards are used, we must enter the

atomic number, the concentration, and Kramer's constant for

each element.

7. All elements present in specimens and standards

must be listed in the Permanent Table.

Although the total input requirements seem impressively

large, they are necessary for any complete procedure which

includes the aforementioned options, without making use of

approximation which this program seeks to avoid. Once the

101
Permanent Table is completed and the problem of Kramer's

constant is resolved, the input requirements will be similar

to those of simpler programs in current use.

Users who always work under the same operational conditions (such as x-ray emergence angle) will be able to further

simplify the input, particularly if they do not intend to use

stoichiometric relations and multi-element standards.

102
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