II <k


NBSIR 75-759 (R)

Standard Reference Materials and

Data For Raman Spectroscopy,

Electron Paramagnetic Resonance,

and Magnetic Moment Measurements

H. S. Bennett, G. A. Candela, T. Chang, R. E, Mundy, and G, J. Rosasco

National Bureau of Standards

institute for Materials Research

Solid State Materials Section

Washington, D.C. 20234

July 1975

u s. DEPARTMENT OF COMMERCE

NATIONAL BUREAU OF STANDARDS
1
NBSIR 75-759

STANDARD REFERENCE MATERIALS AND

DATA FOR RAMAN SPECTROSCOPY,

ELECTRON PARAMAGNETIC RESONANCE,

AND MAGNETIC MOMENT MEASUREMENTS

H. S. Bennett, G. A. Candela, T. Chang, R. E. Mundy, and G. J. Rosasco

National Bureau of Standards

Institute for Materials Research

Solid State Materials Section

Washington, D.C. 20234

July 1975

U.S. DEPARTMENT OF COMMERCE, Rogers C.B. Morton, Secretary

James A. Baker, III, Under Secretary

Dr. Betsy Ancker-Johnson. Assistant Secretary for Science and Technoiogy

NATIONAL BUREAU OF STANDARDS, Ernest Ambler, Acting Director

STANDARD REFERENCE MATERIALS AND DATA FOR RAMAN SPECTROSCOPY,

ELECTRON PARAMAGNETIC RESONANCE, AND MAGNETIC MOMENT MEASUREMENTS

ABSTRACT

This publication contains the analyses of three surveyquestionnaires to assess the needs and markets for standards in

Raman spectroscopy, electron paramagnetic resonance, and magnetic

moment measurements. These analyses give the requirements and

suggest the strategies to be followed for making each of the above

three measurement methods more quantitative than they are at

present. Some of the requirements are data cataloging, standards

for data presentation, standard reference materials, and standard

reference data.

Keywords: Electron paramagnetic resonance; magnetic moment; Raman

spectroscopy; standard reference data; standard reference materials.

Table of Contents

1.0 Introduction 1

2.0 Summary of Findings and Highlights 1

2.1 Raman Spectroscopy 1

2.2 Electron Paramagnetic Resonance 2

2.3 Magnetic "oment Measurements 2

3.0 Survey Report on Standards for Raman Spectroscopy . 3

3 . 1 Summary 3

3.2 Domestic and Foreign Responders 6

3.3 Fields and Areas of Application 7

3.4 Data Base Problems 11

3.5 Standard Reference Materials 11

3.6 Reference Data 12

3.7 Formats for Raman Data Presentations 13

3.8 Problem Definition and Research Strategy 13

4.0 Survey Report on Standards for Electron Paramagnetic Resonance .... 16

4.1 Introduction 16

4.2 Findings and Discussion 18

4.3 Additional Comments 25

5.0 Survey Report on Standards for Magnetic Moment Measurements 25

5.1 Introduction 25

5.2 Data Base and Findings 28

5.3 Possible Users 33

5.4 Summary 33

5.5 Technical References 34

6.0 Acknowledgments. . 34

1.0 INTRODUCTION

The Solid State Materials Section at the National Bureau of Standards conducts research

on solid state materials with emphasis on their technologically important behavior which

results from their optical, electrical, and magnetic properties. It interprets the mechanisms for such properties in terms of physical, structural, and chemical factors and

develops measurement methods, data, and standards required to support selected technologies.

To continue our efforts on the provision of standard reference materials and data, we have used three survey-questionnaires to assess the needs and markets for standards

in Raman spectroscopy, electron paramagnetic resonance (EPR) , and magnetic moment measurements. In addition, we have used these surveys to determine the requirements for making

such measurements more quantitative than they are at present. The detailed analyses

of these three surveys are given, respectively, in parts 3.0, 4.0, and 5.0 of this

publication

.

Our general approach for these three surveys was to obtain mailing lists of workers

who had a reasonable probability of using one or more of the above three measurement

techniques. After the mailings were completed, we analyzed those questionnaires which

were voluntarily returned to us. Because of limitations on the resources available

to us, we did not seek responses from those who had not returned the questionnaires.

Hence, our analyses were based upon volunteer responders and as such represented a lower bound on the size and needs of the potential beneficiaries of our standards

services

.

2.0 SUMMARY OF FINDINGS AND HIGHLIGHTS

We mention briefly in the next several paragraphs some highlights from these three

surveys

.

2.1 RAMAN SPECTROSCOPY

The magnitude of the response was 111 out of 285, or 39%. Some of our findings

are listed below:

(1) Many respondents encounter problems because the Raman frequency

shifts, relative band intensities, and depolarization ratios are not reported

accurately.

(2) A definite interest in data compiling efforts exists among the

respondents

.

(3) Raman standard reference materials elicit strong, positive comments. Our

analysis reveals two problems: namely, how do we measure the standard

spectrum of a standard reference material? and, how do we transfer the neces- sary measurement technology to the user of the SRM? Standard reference

materials will make Raman spectroscopy a more quantitative measurement science

than it is at present.

(4) The setting of standards for data presentation is essential for the success of any SRM effort.

- 1 -
This survey is a first step for the National Bureau of Standards in its efforts to help promote standardization in the important measurement science of Raman spectroscopy.

Please direct inquiries on standards in Raman spectroscopy to Gregory J. Rosasco

(telephone: 301-921-2780).

2.2 ELECTRON PARAMAGNETIC RESONANCE

Our EPR survey assesses the need for a standard reference material (SRM) by which

to improve intensity measurements in electron paramagnetic resonance (EPR) . As in Raman

spectroscopy, such an EPR SRM will make EPR a more quantitative technique. The number of

answered questionnaires is 175 out of 503 or 35%.

From our analysis, about one quarter of the EPR users is in physics, one quarter

is in biomedicine, and the remaining half is in chemistry. By references to journals in

which researchers in physics and in biomedicine publish we discern a trend for the number

of EPR users in physics to decrease and the number of EPR users in biomedicine to increase.

We cite here highlights of the survey:

(1) The EPR respondents need and want an intensity EPR SRM (93% say yes)

.

Everyone who has attempted quantitative EPR measurements stated that the

lack of standards presents great handicaps and difficulties.

(2) A standard reference material which results in EPR line intensity measurements

accurate and precise to within 10% will satisfy the present needs of over half

of the respondents.

(3) The purchasers of EPR SRM's will require technical help and advice, and

particularly, detailed and extensive instructions on how to use the EPR SRM's;

i.e., a challenge exists to transfer our technology in EPR to the EPR user

community.

Please direct inquiries on standards for electron paramagnetic resonance to

Te-Tse Chang (telephone: 301-921-2820).

2.3 MAGNETIC MOMENT MEASUREMENTS

The number of answered questionnaires is 297 out of 781 or 38%. The magnetic

moment survey reveals that 87% of the 124 workers who returned questionnaires, and who

stated that they need a magnetic moment SRM, already use some type of reference materials.

Nickel is the most frequently used calibrant by this subset of workers. None of the

workers who used a reference material state the accuracy of their own calibrant.

The value of the saturation magnetization for nickel given in the literatvire

varies by 8% among reliable sources. Workers do not know which value is the correct one

to use.

And finally, this survey shows that if NBS were to issue a magnetic moment SRM,

then it should have the following properties:

(a) an accioracy within ±1%,

(b) more than one size (perhaps a 1-mm and a 3-mm sphere)

,

(c) nickel will most likely be one of the calibrants,

(d) the price should be less than $150.00.

Please direct inquiries on standards for magnetic moment measurements to George A. Candela (telephone: 301-921-2780).

- 2 -
1

3.0 SURVEY REPORT ON STANDARDS FOR RAMAN SPECTROSCOPY

3.1 SUMMARY

The survey "Standards for Raman Spectroscopy" was distributed in January 1973,

The numerical results, the analysis of these results, and conclusions derived from

the survey are presented here.

To summarize the results, the five major subject areas are presented in a graphical format below. Each subject area is briefly described in a paragraph following

the graph. In the graphs, the n\mber of respondents or the number of responses of a given type are plotted by the horizontal bars. Percentages (indicated by %) of relevant

response totals are often provided; however, only numbers of respondents or responses

are plotted. Categories in which a single respondent could give more than one reply

are indicated by an asterisk (*)

.

1. Kcspoasa

O.SJl.

M

OriJir.al .".ail jr.;

100

. I 120 140

I 160

I 180

I 200

Rgspcns 40%

CisAda. Europe

,

Seipoases 35 i 33 %

Iknu of Scientific tsdeavor

al«C3l«r Physics

tad CTieaistry of all phases of utter

Asalytical

Chratstry

riiTSical Oacsistxy aoUd fiMtt

fbfsics

Orfaale Oaaistzy

locheoistry/

Blo^ysies

Zaer^anic Ocmittry

Iislyeer Physics

•ad Oieaistry

jBatnsent Kanutactuze and 9ata

eatalo<3inq

The magnitude of the response is 39%. The breakdovm of the areas of scientific endeavour

is based on the descriptive titles most used by the respondents.

- 3 -
3. to you tncountor probltms In con- pArlion of spectra froB other

•ourees?

*tvp«» of Problemi

Kelatlve/Absolute

Intensity frequency Shift/ Linewldth rolarlzatlnn Character of a Band

Inoonplate Specif, of Relevant Exp. VaiaDatari

J! I

10 40 SO •0 70 •0 10 100

Beplleii 90»r«plled qoo/lll)

Of the s e 100 who replied

Tea 84 9,

There are significant problems encountered in the comparison of Raman data from "other

sources." Interestingly, a large number of respondents have encountered problems because

the Raman frequency shifts are not accurately reported. Since accurate frequency calibration is generally a routine matter, this observation suggests that improvements in the

data base can be achieved by spectroscopists being a little more conscientious.

1. Oata Catalog*

Xitportant to

your work

Taa oBewhat o

Z«portant to h^tm

Spaetroteopists

in Cemral

y«a

looawhat Mo

Kaaa catalogs you know

Rone Ona

Two

Three or Bora

Should •efforts" in this area b* •spanded

y«t

10 J_

30 40 50

B3* replied (9:/lll)

Of these 92

J21_

"I

76 gjreplied (87/111)

Of these 87 76%

0%

83 ^replied (92/111)

7S% replied (83/111)

Of these 83 95^

" 5%

BO _I_

100

There is definite interest in data cataloging efforts. In replying to the question of

increased "efforts" in this area, many respondents cited "efforts" such as "systematization"

and "standardization." There were warnings to avoid a repetition of the history of IR

data cataloging ventures. The nature and importance of this problem are generally understood. These concerns have been communicated to a variety of groups whose activities

involve "reference data."

.- 4 -
4. Keeoisner.datloni for Presentation of

«*nan Spectra for Cataloging a.-.d Doc- cscntatlon in Farranent Data Collections

Additional

iu73esti':ns 7

ao

>e«

Il<jcb«r of types of suggestions

Specific eca- B«nt of coa- patUble RanantH foraat

Yas Bo

10 20 30 40 SO 60 70 60 90 100

5B% replied [65/111)

Of these 65

5:%

This subject area was included in the questionnaire in order to assess the reaction to the "Recommendations" and, further, to assess the need for simultaneous presentation

of Raman and infrared data in data collections. The number of positive replies (34 of

111) is not large enough to allow a resolution of these questions.

S. standard Reference ~ Materials

Important/Useful to your work?

tea Secevhat Ho

Important/Useful to

Jtasan Spectroscopists In General

Tes

Sooe-what Ho

toggast Materials for Ose as SKM ^General Categories:

"Coraon" Solvents Aqueous Solutions

•Polyoers" Other Orgvdc ''.iquids and Solids

Inorganic Solids a.-id tlqulds

Gasas

*Sp<elfic Substances: CCiu

CtHg C9B7

"2•AIR" Single crystal a-5i02

rW|

, 02

CjoHa

Single crystal XF2 X Ca,Ba,Mn

COj Internal Standard: Fluorescent or Resonant Baaan Scattering

10 50 £0 90 100

83% replied (92/111)

Of these 92 74%9^

8:% replied (91/111)

Of these 91

8-! %

2 %

77 Responses

94 rifferer.t Materials

I gualified 'Yes" .iS %

*Rainan Newsletter, No. 29, 1971. - 5 -
The area of standard reference materials elicited strong, positive comment overall. A very important consideration which is not easily quantified "emerged" from the

analysis of the survey. This consideration involves two problems! (1) How do we measure

the standard spectrum of a standard reference material, and (2) how do we transfer the

necessary measurement technology to the user of the SRM? The definition and/or development

of this technology involves (1) accurate laser power measurement (at the sample) , (2) selection of reproducible scattering geometry and laser focusing parameters, (3) accurate

determination of collection and transfer efficiency of the fore optical system, (4) measure- ment of the spectrometer transfer efficiency, (5) measurement of the absolute detector

response function, (6) measurement of the polarization character of the incident and

scattered light, and (7) measurement and deconvolution of the- spectral effects of the

instrument function.

The use of standard reference materials will, hopefully, allow laboratories to measure

a spectrum truly representative of the material without the need of performing all the

calibrations listed above. The development and implementation of simple, accurate techniques for calibrations such as the above items are first priorities for establishing

a useful standard reference material.

The information gained in this survey has been communicated to a number of organizations involved in standards for Raman spectroscopy. These activities are detailed in

Section 3.8. Positive steps pursuant to the promulgation of useful standards for

data presentation are being taken in cooperation with the Joint Committee on Atomic

and Molecular Physical Data. Developments relevant to the measurement of the absolute

detector response function (item 5 above) have been communicated to Raman spectroscopists.

Progress in this area will follow the level of the developments described above. A round-robin test designed to establish the magnitude of the errors encountered in data

comparisons is also recommended.

This survey is a first step for the National Bureau of Standards in its efforts

to help promote standardization in Raman spectroscopy* It is important

to continue interacting with the scientific community in the area of standardization

for Raman spectroscopy.

3.2 DOMESTIC AND FOREIGN RESPONDERS

The questionnaire was sent to 285 people, 192 of these in the U.S.A., and 93

in Canada, Europe, and Japan. The list for mailing was assembled from:

1. Mailing list of the RAMAN NEWSLETTER obtained from the Optical Society of

America,

2. "Users" lists from Raman instrviment manufacturers:

Spex Industries, Inc. Jarrel-Ash Division, Fisher Scientific

Gary Instruments Division, Varian Associates

Beckman Instruments

3. Lists of participants: The International Conference on Light Scattering

in Solids, 1968 (New York) ; 1971 (Paris).

The U.S. mailing can be broken down into two categories:

A. national laboratories

commercial/industrial research laboratories

instrument manufacturers

government agencies and laboratories

B. universities.

- 6

-
57% (110/192) of the surveys were sent to those in category A. We note also that there are 69 organizations represented in category A.

The total number of responders was 111 or 39%; 4C% (76/192) of the U.S, mailing

and 38% (35/93) of the rem.ainder. Various estim^ates by the Raman Technical Group of

the Optical Society of America concluded that there are from 50C to 800 Ranan facilities

in the world and from 250 to 400 Raman facilities in the U.S.A. Her.ce we have sampled

roughly one-c'uarter to one-half of the domestic Raman facilities.

Under category A (governr.ent, industry, etc.) of the U.S. mailing, 37% (41/110)

responded, whereas 43% (35/82) of those in the -universities responded. The response

by number of organization in category A was 48% (33/69) . There was a significant response

from those involved in the comir.erciai design and manufacture of R.aran instrum.entation

.

The magnitude of the response (39%) is quite good, but even more important was the detail

and quality of the completed questionnaires. The survey covered a broad range of topics.

Being somewhat "free-form," it also attempted to elicit a great deal of individual response.

The efforts of the responders to relate valuable information in many areas of their

expertise and their eagerness in many cases to assist in standards efforts are very

encouraging indications to the significance of a "standards" effort.

V7e enclose a copy of the questionnaire as figure 1 for the convenience of the

reader

.

3.3 FIELDS AND AREAS OF APPLICATION

Questions II. 1. A and II.l.C assess the areas of scientific interest

responders. These areas are best described by the set of descriptive titles

named by the responders. (In many cases, one person mentioned more than one The breakdown is as follows:

Molecular physics and chemistry of gases.

liquids and solids 31 Analytical chemistry 29 Physical chemistry 29

Solid state physics 25 Organic chemistry 15

Biochemistry/biophysics 14 Inorganic chemistry 12 Polymer physics and chemistry 10

InstruTient manufacture/data cataloging 8

The scientists involved in these areas of research utilize data from, a great

variety of experimental disciplines (Question II.l.B). Infrared spectra and structural

data (x-ray, neutron, and electron diffraction) naturally predominate among those mentioned. NI-'J^ spectra are also widely er.ployed.

The wide variety of physical, chem.ical and biological disciplines enccuntered

in the responses to this question suggests:

1. The survey results should reflect the needs and interests of a great many

scientists

.

2 . The inter-disciplinary nature of light scattering research and its wide

application to problems in diverse areas.

3. The importance of a useful and m.eaningful data base for Raman spectroscopy.

of the

most regularly

area .

)

- 7 -
0MB No. 41-S72080 Figure 1. approval expires JUNE 30, 1973 NBS-732 U. 8. DEPARTMENT OF COMMERCE

(1.73) NATIONAL BUREAU OF STANOAnOS

STANDARDS FOR RAMAN SPECTROSCOPY QUESTIONNAIRE

PART I Please complete identification material below

Name (Last, first. Middle! Organization/Affi liation

Address tStroel. Cilv. Slate, ZIPI

PART II Please answer the following questions

1 A. To what areas of science and technology do you apply the techniques of Raman spectroscopy?

B. What other types of data do you utilize in conjunction with Raman spectroscopy?

C. What type of problem do you attempt to solve by means of Ramrn spectroscopy?

2. Do you encounter problems in comparison of spectra from other sources that you would trace to lack of proper standardization procedures? (e.g., inaccuracies in frequency calibration, depolarization ratios and relative intensities.)

3. Standard Reference Materials. These materials could be used in Raman instruments for frequency and intensity calibration, and possibly will allow determination of instrument functions.

A. How would you assess the importance of standard reference materials?

(1 ) to your specific efforts?

(2) for the users of Raman spectroscopy?

B. What type of standard materials would be most useful? Please suggest specific candidates (useful to you or useful in leral) in each category.

(1 ) Gas

(2) Liquid

(3) Solid

- 8 - CONTINMD
Figure 1 (continued)

C. Woj'd you prefef an internal (trace additivel standard (e.g., a species which shows sharp ime fluorescence or resonar.; Raman scanenngi'

Arty Suggestions''

D. What types of sampling geometries and cells would you recommend' (Please be as specific as possible.)

E. In what form would the companion Standard spectrum be most useful to you: graphical/digital/tabular?

4. Catalog of reference Raman spectra.

A. How would you assess the impo<rtance of a catalog of Randan spectra?

(1 1 to your specific efforts'

(2) to the efforts of scientists as a whole?

(3) what Raman spectral catalogs are you pfesently aware of?

B. Should efforts in this area be expanded?

C. What types of materials would be important' Please specify some important rraterials in each category.

(1 ) Solvents (laboratory and/or commercial)?

(2) Substrate, window and cell materials?

(3) Conmon gases (pollutants)?

(4) Important solids'

5. lUPAC has approved a set of "Recom.T>endat,ons for Presentation of Rarnan Spectra for Cataloging and Documentation ,n Permanent Data Collections" (Raman Newslener, No. 29, .Way 1971),

A. Do you have additional suggestions for the format in which the data is presented, such as presentation of Raman and infra- red data simultaneously?

B. Do you have a preference for graphical, tabular, or digital presentation of standard spectra?

- 9 - CONTINUED
Fiyure 1 (cont:iniiPri^ Du you have siiggostioiis coiiccniiny tho need to ycnerate Ramon standard referon(;e materials which can be used as

standards in other fields of spectroscopy, chemical analysis, and physical measurements' IPIoJSC be siiccilic)

Does this need for compatibility affect all types of Raman Standards?

7A. What specific problems must be overcome in order to

|1 ) define a standard spectrum?

(2) make it practically useful?

B. What suggestions can you offer to meet these difficulties?

8. In what capacity can the National Bureau of Standards be most useful to spectroscopists in an effort to establish standards

for Raman spectra?

PART III We would appreciate any comments you may wish to add

- 10 - USCOHM-NBS-OC
3.4 DATA BASE PROBLEMS

Question II. 2 examines the magnitude of the problems encountered in comparison

of Raman data from various sources. One hundred (90%) of the responders replied to

this question and of these only 16% experienced "no" problems. In some of these cases, there were no problems because very little literature data was available with which

to compare their data. The 84% who experienced problems cited a variety of types of

inaccuracies. The following lists the problems and the number of times cited (more

than one area was typically mentioned in a response)

Accuracy (relative and absolute) of

measurement of intensity of scattered 64

light

Accuracy of frequency (shift) measurements

(and in some cases also linewidth 58

measurements)

Accuracy of determination of polarization

properties 51

Incomplete specification of relevant

experimental parameters and sample 18

characteristics

The responses to this question indicate that serious problems are encountered

in the measurement and reporting of all the vital parameters of Raman spectrum. Some

of these inaccuracies are primarily rooted in the difficult nature of certain measurements

and calibration, e.g., intensity measurements and linewidth deconvolutions . It is somewhat

surprising that frequency inaccuracies are encountered so often. This may stem from

the fact that in many experiments accurate frequency values are not particularly important.

An important inference is that the problem areas cited by the responders may in many

cases be remedied by selecting standard techniques and reference materials.

3.5 STANDARD REFERENCE MATERIALS

Question II. 3 addresses the use of Standard Reference Materials, described in

the questionnaire by: "These materials could be used in Raman instruments for frequency

and intensity calibration, and possibly will allow determination of instrument functions."

The question of the importance of SRM's to "your specific efforts" (Question II.3.A.1)

and "for the users of Raman specrroscopy" (Question II. 3. A. 2) was answered as follows

To Question II.3.A.1, 83% (92/111) replied, and of these 74% (68/92) thought

that an SRM would be important or very important to their work, 17% (16/92) saw some importance, and 9% (8/92) said not important.

To Question II. 3. A. 2, 82% (91/111) replied, and of these 84% (76/91) thought

that an SRM would be important or very important to users in general, 14% (23/91) saw

some importance, and 2% (2/91) said not important.

Many responders used the word "useful" and the word "important" should be understood in this context.

Question II. 3. B asks for specific candidates for reference materials. A number

of responders emphasized that frequency calibration is "best" accomplished by means

of "known" atomic standards, i.e., Ne, Ar, Kr lamps, or possibly the non-lasing emission

lines from the laser plasma. The important characteristics (spectral properties and

- 11 -
material properties) of a standard reference material were outlined by others (20-30

responders) . Such characteristics were also mentioned in response to Questions II.7.A&B.

For example, the Raman spectrum of the material should exhibit strong, sharp lines, cover a wide frequency range, and be insensitive to temperature and excitation wavelength.

The material itself should be non-toxic, non-hygroscopic, easy to purify and easy to measure

.

Seventy-seven (77) of the responses included some specific recommendations

for a reference material. In the remaining portion of this paragraph the numbers in

parentheses represent the number of times a material was cited. Eighty-four different

substances were named in the categories of common solvents (12) , aqueous solutions (10)

,

polymers (5), "other" organic liquids and solids (12), inorganic liquids and solids

(30), and gases (15). Some frequently mentioned compounds were: CCli^ (28), C5H5 (20),

C9H7 (Indene) (16), N2 (15), "Air" (8), single-crystal a-Si02 (8), CHi+ (7), O2 (7),

CeHi2 (7), CioHe (Napthalene) (7), single-crystal XF2 (X = Ca, Mn, Da) (6), and CO2 (6). In many cases the "popular" materials do not display some of the important characteristics

of a "reference" material. A set of "best" candidates has not emerged from the evaluation

of the survey.

Question II. 6 addresses the need for compatibility of reference materials among

the various physical and chemical disciplines. Only 20% (22/111) of the responders

commented on the need for compatibility. From these answers there was no strong indication

of the necessity to design strictly compatible standards although such efforts "might

be helpful."

Question II.S.CfiD explored two further areas with regard to reference materials.

The possibility of using a "trace" additive internal standard was the subject of Question

II. 3. C. The trace additive standard, which was suggested in the question, might display

either sharp-line fluorescence or resonant-Raman scattering. There were several objections

to the use of fluorescent or resonant standards; namely, the strong wavelength dependence,

unknown solvent effects, and some basic uncertainties with regard to the nature of the

effect in the case of resonant scattering. Objections were also raised because of possible

chemical interferences. Over-all, then, 52% of the 83 responses were against the idea

of an "internal" standard. The remaining 48% gave a qualified yes.

Part D of Question II. 3 addressed the problems of sample cells and scattering

geometry. There were 69 responses to this question. 90° geometry was suggested 50

times vs. 13 suggestions of 180" scattering. Capillary tubes (melting point type) were

suggested 23 times as sample cells for liquids. Cylindrical cells illuminated along

their axes (8 responses) and rectangular cells (7 responses) were mentioned among the

other "popular" cells. Single pass was explicitly mentioned ten times and multi-pass

in five responses.

3.6 REFERENCE DATA

In Question II. 4 the survey attempted to assess the present level of interest

in data cataloging efforts in the field of Raman spectroscopy. The results of these

inquiries are as follows:

Question II.4.A.1 Are data catalogs important to your specific efforts?

83% (92/111) indicated that the catalogs were important or very important;

17% (16/92) said "some importance"; and 23% (21/92) indicated "not important .

Question II. 4, A. 2 Are the data catalogs important to users of Raman spectroscopy

in general?

- 12 -
78% (67/111) conzer.red; 78% (cS/37) of rhcse who zo—.er.zed said ir.pcrtar.t or very inportant; ar.d 22% (19/87; said "sorse ir^crtar.ce .

This question — I". 4. A. 3 — also asked -r.e respor.der zo r.ar.e z'r.e caralcgs cf

Ranar. spectra of which he was aware. 83% 02/111; cc—.er.ted. The resul-s v/ere as follows:

25%, none; 3"%, one; 21%, frfo; 17%, three or -ere. Zr. z'r.Ls quesricn zr.e responders

mentioned the veri-- lir^ced editions of certain instr-— er.- rar.uf ac^ jrers

.

The svibject of Question II. 4. 3 was need for further efforts in this ar&a.

73% (83/111) contoented; and of these 95% (79/S3) felt that these "efforts" should be

expanded. However, the nature of these "efforts" was, in nany cases, suggestions to "organize," "syster^tize , " and "evaluate" the speczral catalogs. A significar.i r.u.-her cf

coments concerned z'r.e need to avoid proliferaiion , duplication, and incc-pa -:Jcili-y of

the cataloging efforts in^Ranan spectroscopy.

Question II. 4. C. asked for specific candidate materials for spectral cataloging.

The response to trJ.s question was not as large as for the siriilar q'jes-ion wLzs. regard to SSM's (II. 3. 3). There was a large '/ariety in the responses -.".zs. no trends.

3.7 FCR:-L-.rs TZ?. ?j-2c-.:: ^ata ppzsenta.ioks

Question II. 5 ccncernsd the recently p'jhlished 'IVPAC approved) "RecoEssenda-ions

for Presentation of ?^-an Spectra for Cataloging and Ioc'^.entaticn in r£rr.anent -ata

Collections." We asksd for additional suggestions for the fcrrat of the data and, in

particular, q'aestioned if the ?.ar=.n and infrared fort::at3 should he identical and if the

"Permanent Data Collections" should present both -he Ranan and infrared spectra of a

coi^pc^jnd. 53% ;£5/lll) restcnded to the question and of these 48% (31/65) had no additional suggestions. Fifteen Z'/zes of suggestions were -ade; the most significant cf

these was: 17 people wanted co-patihle I?.-?.ar.an forra.ts whereas 5 were against this

position (or at least wanted sor.e :h=r.r5E ir. the cm"- region z people wanted the

spectra presented after correction ftr ir.str _-er.t5.1 effects. Cur irtression is that r.any of those who ref.i2med the ~^estionnaire vrere not aware either of the "P-etc—.endations" or of their intent.

Z'r.e 00—ents associated vrith Question II. £ are included in the disc-ussicn of

Question II . 3

.

3.8 PSDBLE2'i czji^.:iric:; a:- pzsza-P.c:-: siraizsy

Question 11." is extreoely vital to the evaluation cf any efforts to provide

a standard reference spectr-JE of a standard reference material . Z'r.e conr-jents on the nature

of the material chosen as a standard have been included -jinder the discussion of Question

11.3. The important conclusion to be dravm from the ans-rfers to Question II. 7 and th^cughou

relevant sections of the q-jesticrj-.aire is that there are f-undar-ental probler.s involved in

the measurement of a "standard" spe:tr-^-. , i.e., a spectr-jr, tr'ily representative only cf the

material, not of the instr-~.ent used tc r.ai^e the -eas-urer.ents . Tnis latter req-uirer.ent is

essential to the definition of a standard reference material. rh_i= problem area v,-ill be

dealt with in the s-m— ary of options discussed below.

Question II. S asked "In what capacity can the National Bureau of Standards be

most useful to spectroscopists in an effort to establish standards for Raman spectra?"

The responses to this question and many coments from other parts of the que3tior.naire

are relevant tc the choice cf directions to be p-ursued by the ::atitn=l Bureau of Standards

and others concerned with standards efforts. These responses oar. 'ze = z be discussed -under two headings: I. Assuring efficient production cf (oc—.eroial) spectral catalogs, and

II. Proceeding toward the generation of standard reference spectra.
Under heading I, there were a wide variety of recommendations. Some of

these have been discussed in question II. 4. B. It is suggested that a classification of

Raman spectra along the same lines as the Coblentz designations IR - I, II, III would

be appropriate for spectral catalogs and standard reference spectra. The production and

distribution of commercial spectral catalogs is seen as important by the responders.

However, these catalogs must be extensive to be useful and at the same time inexpensive

to produce if they are to be practical for both the producer and purchaser. Thus, they

would generally fall into a category similar to Coblentz IR-III. The responders were generally in agreement that, within the limits of this class, efforts should be directed

toward assuring the maximum, practical quality of the data (sample quality and spectral

quality) . Relevant spectral parameters must be specified (see discussion below) , and

the format of presentation should be uniform both within a data compilation and for

different compilations. The specification of relevant spectral parameters and questions

of format for data presentation have been addressed in the "Recommendations" of the Raman

subcommittee of the Joint Commission on Atomic and Molecular Physical Data (NSRDS) and

approved by lUPAC. At least a minimal subset of these recommendations should be adopted

as a uniform requirement for Class III collections. As mentioned above, there is a need

to "organize," "systematize," and "standardize" data catalogs. The Bureau is seen by

the responders as having varying degrees of responsibility towards realization of these

goals. The concerns of the responders have been communicated to the Raman Technical Group

of the Optical Society of America (Spring Meeting, Denver, Colorado, March 1973) and have

been discussed with the chairman of the Raman Technical Group; Dr. Ted Becker,

National Institutes of Health, Chairman of the Raman Committee of the Coblentz

Society; and Dr. Stephen Rossmassler, National Bureau of Standards, Office of Standard

Reference Data.

Recently, at the September 12, 1974, meeting of the Executive Committee of

the Joint Committee on Atomic and Molecular Physical Data, the topic of standards for

Raman data presentation was addressed. The results of this survey were presented as part of the meeting agenda. As a result of this interaction, G. Rosasco, with the consultation of the JCAMPD and a panel of Raman experts, will be preparing a manuscript which

will serve to establish a preferred set of specifications for Raman data presentation.

Concerning heading II, the results of the survey generally are positive on

the usefulness of determining standard reference spectra (of standard reference materials)

,

and indicate a definite role for NBS in such an effort. The areas of effort are:

(1) Specification of standards and techniques for calibration of frequency,

intensity and instrument response functions.

(2) Development, evaluation, and recommendation of standard methods for obtaining

reference quality (Class II and I) spectra.

(3) Selection, measurement, and distribution of reference spectra of reference

materials.

The order of importance (and frequency) of suggestion is as numbered above.

This order is based on a systematic approach to the standardization problem and thus

constitutes a reasonable framework for structuring a measurement strategy. Within this

strategy provision should be made for multi-lab measurements of "standard" samples;

this point was raised by a number of responders, and, in fact, some volunteered to cooperate

in such an effort.

In the context of a research strategy based essentially on items (1) through

(3), some initial efforts are under way by G. Rosasco in search of spectroscopic standards

and techniques for frequency and intensity calibration. As an example of this effort, we are inquiring into Bureau calibration of radioactively pumped phosphors as intensity

- 14 -
standards. The present intensity standard is a photometric standard whose specific

properties and certain concomitant difficulties in technical procedures (and high cost) cause it to be less than ideal for routine standardization of Raman spectrometers.

The experimental procedures to be addressed in item (2) involve questions as to laser power measurement, determination of polarization properties of incident and

scattered light, and techniques for measurement and deconvolution of the effects of

instrument functions of Raman spectrometers. G. Rosasco visited the MBS Boulder Laboratories in March 1973 specifically to learn more about accurate laser power measurement.

We have informed Raman spectroscopists via the RAMAN NEWSLETTER (August 1973) of the

Bureau's efforts (in conjunction with the ASTM Committee F-1.02) in a Measurement Assurance

Program for laser power measurements. G. Rosasco is attempting to keep abreast of developments at NBS (Boulder) and^ from ASTM F-1.02 in order to inform Raman spectroscopists.

Within the context of item (2) , it appears useful for NBS to communicate significant information from the "experts" in an associated problem area to Raman spectroscopists.

The "experts" in many cases will come from the field of Raman spectroscopy, and in any

selection of a "standard" technique the particular needs of Raman spectroscopists must

be considered. These efforts seem appropriate for NBS and follow from a significant

number of suggestions from the responders.

A natural evolution from significant achievements under items (1) and (2) would

be specific efforts on the part of NBS and other interested parties toward fulfillment

of item (3) . There are a variety of strategies one can apply to the selection of reference

materials. Because of the many interests of Raman spectroscopists, it may he necessary

to select a number of materials. In some cases a "material" may have to be defined,

e.g., a mixture of liquids or gases. A list of minimum requirements for a reference

material should be selected and possible candidates chosen. In this process the experts

in each area (gas phase, aqueous solutions, etc.) should be consulted. Careful evaluation

of the candidates should be made by a group of Raman spectroscopists; for example, the

Advisory Board of the RAMAN NEWSLETTER.

In addition to a role in the communication of important developments towards

the realization of "standards" for Raman spectroscopy as outlined above, another important

contribution could be made at this time. This effort would be a first round of multilab testing of a selected sample for the purposes of evaluation of routine Raman measurements. This idea evolved from a discussion at the Spring 1973 meeting of the Raman

Technical Group. A number of variations to the nature of the test were suggested.

However, a simple, straightforward test specification seems most useful at this point.

The procedure for the multi-lab test seems relatively straightforward and G. Rosasco

is willing to implement the testing, i.e., sample preparation, distribution and compilation

of results. Further details will be specified after the basic concept is approved.

This development sequence is based on the knowledge of problem areas related

to Raman spectroscopy. Solution of each level of problem and an adequate evaluation

of routine test spectra will be invaluable to the design, measurement and successful

implementation of a standard reference material.

- 15 -
4.0 SURVEY REPORT ON STANDARDS FOR

ELECTRON PARAMAGNETIC RESONANCE

4.1 INTRODUCTION

We report here the findings of our survey-questionnaire to assess the need

for a standard reference material (SRM) by which to improve intensity measurements in

electron paramagnetic resonance (EPR) . This report summarizes the requirements of the

potential users of EPR SRM's and reveals possible areas of difficulties where we may

render technical assistance.

Table 1 gives an analysis of the survey sampling. The list for mailing was assembled from the mailing list of an EPR spectrometer manufacturer and from our own

contacts. We enclose a copy of the questionnaire as figure 2, We sent out 518 questionnaires. Of this number 15 either were returned by the Post Office as not deliverable

or were sent to persons who are no longer performing EPR measurements. We therefore

take 503 as the base number. The number of answered questionnaires is 175. This is

35% (175/503) of the base number. We received answers from 24 different companies, 26

different government laboratories, and 90 different universities.

Table 1. Analysis of Sampling

Number

Total number of questionnaires sent out 518

Returned by Post Office as not deliverable 13

No longer in EPR 2 Base nxjmber of questionnaires sent out 503

Answered questionnaires 175 (35%)

We estimate that there are about 1000 EPR groups in the world, and that the

number of domestic EPR groups is between 400 and 500. Most of the foreign EPR groups

listed in Table 1 are from Europe, Canada, and several from Japan, Australia, and South

America. We did not reach east European countries, Russia, China, India, or Arabia.

We know of several groups in these countries.

The background of the responders is given in Table 2. We prepared Table 2 from

our knowledge of the organizations of the responders. We divide the EPR users into three

major disciplines; namely, physics, chemistry, and biomedicine. For this analysis we place biologists, medical researchers, and pharmacists in the biomedical category. We

recognize that some physicists and chemists also work on biological problems. Thus, one quarter of the EPR users is in physics, one quarter is in biomedicine, and the remaining

half is in chemistry. We find by reference to the journals in which researchers in physics

and biomedicine publish that there is a trend for the number of EPR users in biomedicine

- 16 -
FicMre ^ 0MB NC. 41-S72080

IS-721 U. S. DEPARTVEM OF CCV.MERCE

MAT:CNAL BUREAU OF StAVUAKU>

QUESTIONNAIRE FCR ELECTRON PARAMAGNETIC RESONANCE (EPR) STANDARD RErERL\CE VATEF.IALS

TO: r

L J

PLEASE RETURN! THIS QUESTIONNAIRE TO:

Dr. Te—Tse Chang

National Bureau of Staniiards

Bldg. 223, Roon A- 253

Washington, . C. 20234

la Do yOu think National Bureau of Starviards certified EPR stanoard referervce r%ater:ais are needed? YES

b. If rvo, d's^egati t"e 'z ow"-: c.'sst o-s S"' re:j-~. t-e c_5s: c--a -e

NO

2a. Have you ever ar.e-iptec to -r.easare tne njroer cf sdi-s r, YO_r experirrents'

b. If yes, what refererice sarr.pie did you use?

YES NC

c. How accurate f-»d precise v.as tne reference samole you used? Accuracy =reciSior- % .

d. If the experiments are describee - s-r\' p_s cat.o-s, piease ser« a rep'int. pr cite re-ere-ce

3. if yoo v,e'e p-rc-3s -5 a set pf Erfi stancard reference materials, list your preference for the foliowir.g;

a. shape b. size C. concentration range of paramagnetic ions

<!•. Within wtvat Krr.perature range wouid you use the EPR standard reference materiaiS'

e. List frequency DanMs) you:

(1 ) now operate in (2) expect to operate .n, in the future

f. How accurate would you want the EPS stanoard reference materiais to oe'

4, Any additional comrr>ents would be weico<T*ed

- 17 -

USCOMM-NSS -oc
to Increase and for the number of EPR users In physics to decrease.

TaUsle 2. Background of Responders

Physics Chemistry Biomedicine Not determined Total

35 71 29 • 40 175

4.2 FINDINGS AND DISCUSSION

4.2.1 Question 1 — Need

Question 1 assesses the need for EPR standard reference materials.

Table 3 shows that 93% (163/175) of the responders answered "yes." Hence the EPR community

needs and wants a standard reference material.

Table 3. Is a National Bureau of Standards certified SRM for EPR needed?

U.S.A. Foreign Total Percent

Yes 121 . 42 163 93%

No 10 2 12 7%

4.2.2 Question 2 — Present Reference Samples

Question 2 concerns the existing samples by which EPR users measure line

intensities. These samples are not calibrated nor certified. They estimate the spin

concentration by knowing the weight of the sample and its chemical composition.

Table 4 shows that 87% (129/157) of the responders to question 2 tried

some quantitative EPR measurements. Everyone who attempted quantitative EPR measurements

mentioned that the lack of standards presents great handicaps and difficulties. Among

those who had not attempted quantitative EPR line intensity measurements, some stated

that they plan to do so in the near future. Others stated that they cannot make quantitative line intensity measurements because there are no standards. The general assessment

is that a good standard reference material is necessary for EPR intensity measurements.

Table 4 . Quantitative Measurement Attempted

U.S.A. Foreign Total

Yes 96 33 129

No 20 8 28

Table 5 lists the commonly used reference samples in order of the number

of times each sample was cited. In order to shorten this table we have combined some

of the entries. For example, the item "copper salts in various forms" represents

- 18 -
CuSOii, CuCl2» and other Cu bearing salts in single crystal, powder, or solution forms.

The copper content of such samples may also be diluted. This table shows that convenience

and availability are important factors in selecting reference samples.

Tcible 5. Existing Reference Samples

Reference Sample Number of times cited

DPPH 53

Pitch in KCl and Varian samples 37

Cu salt in various forms 37

Mn salt in various forms 16 Various free radials (except DPPH) 16

Spin label, in various forms 14

P-doped Si (Bell Laboratories sample) 8

Charcoal (including radiated carbon, burned

^ sugar, etc.)

vo'''"'" in various forms 4 Ruby or Cr ions in various forms 4 02 2 F-center in KCl 1

Fe'*"'"'^:Al203 1

Table 6 presents the assessments by the responders themselves of the

accuracy and precision of their present reference samples. This table shows that a standard

reference sample which results in EPR line intensity measurements accurate and precise

to within 10% will satisfy the present needs for over half of the responders. In addition,

comments on the answered questionnaires, follow-up conversations with some of the responders, and this Table 6 all indicate that we must educate some of the potential users of

EPR SRM's to understand the difference between accuracy and precision.

Table 6. Quality of Existing Reference Samples

Percent accuracy or precision Number of times cited for

stated by responders . Accuracy Precision

0.1% to 4.9% 14 15

5.0% 17 17

6.0% to 14.9% 25 19

15% to 50% 8 24

greater than 50% 2 11

Responders stated that accuracy and

precision for the number of spins is:

Not known 14 16

Poor 4 4 Known to an order of magnitude 6 6

- 19 -
If the EPR spectrometer has reliable and stable units, and if the experimental conditions are kept the same or are monitored for changes and the data are corrected

accordingly, the reproducibility of the EPR measurements may be precise to within 1%.

This is good precision but the correlation of the experimental results with the true

number of spins is not straightforward, particularly when the correlation is not well

defined. Also, very accurate reference samples may be prepared, but transferring this

accuracy to the EPR measurements may not be achieved readily. For example, the CuSOi|

solution may be prepared with a concentration known to a ±0.01% accuracy; however, the

transfer of this accuracy becomes questionable when the solution is placed in a quartz

tube and inserted into the microwave cavity without additional precautions. The manners

in which the reference sample and the unknown sample perturb the electric and magnetic

fields of the cavity must be determined first. That is, the user must know what quantity

is being measured.

4.2.3 Question 3 — Sample Characteristics

Question 3 considers the shape, size, and concentration range of paramagnetic ions, temperature range, and frequency range. Table 7 summarizes the shapes and

sizes which the responders preferred. The item "cylinder" in this table includes also

rods and tubing. The item "cube" includes cxibes, squares, rectangles, and needles.

Because most users place samples in quartz tiJoes, they would prefer a cylindrical standard

sample. Most responders want sample standards 4 mm in size or smaller, so that placing

the standards near the unknown sample in the cavity does not disturb the measurement.

The second largest number requested cube-shaped samples. We conclude that EPR SRM's

which are small cylinders or cubes will satisfy the needs of most people.

Table 7. Shape or Form

Number of Times Cited

Cylinder 77 Cube 21

Single crystal 9 Powder 17 In solution 7

Size — 4 mm or smaller

Figures 3 to 6 are bar graphs and illustrate the distributions of concen- tration ranges for the paramagnetic ions (spins) expressed by the responders. Each figure

corresponds to one of the several ways in which responders expressed the concentration.

Each vertical bar in these figures represents the range of concentrations requested by

an individual responder. The average value for the concentration in the mole/liter

(figure 3) is about 5 x 10"^ moles/liter. If we use a quartz tube with a 2-mm inside

diameter in a 25-mm length, the volume is about 0.8 x 10"** liters and the number of

paramagnetic ions is in the 1 x 10^^ range. The average number for the paramagnetic

ions in each of the remaining three figures is also about 10^^. Hence, from these data

we conclude that the first EPR SRM to be issued should contain about 10^ ^ spins and that

succeeding EPR SRM's should then possess concentrations both greater and lower than this

value.

- 20 -
Figure 3. Molar concentration of paramagnetic ions

Molar (moles/liter)

10

10-1

10-2

10-3

10"

10 -5

10"

10"

10-&

II

10-

Each vertical line represents the range of concentration

requested by an individual responder.
Figure 4. Number of spina/gm

10^

lOll

10l3

10l9

1020

10^2

1023

Each vertical line represents the range of

number of spins per gram requested by an individual responder.

- 22 -
Figure 5 . Number of spins/cm

10'

10-

10 10

10

10

11

12

10

10

13

lU

10

10

15

16

10

10

17

10

18

19

]020

1021

10 22

II

1023

Each vertical line represents the range of

the number of spins per cubic centimeter

requested by an individual responder.

- 23 -
Figure 6. Total number of spins in sample

108

lolo

10

10

10

11

12

13

lOl**

10l5

10l6

10

10

10

17

18

19

10 20

1021

1022

10 23

Each vertical line represents the range in

the total number of spins requested by an individual responder.

- 24 -
Most responders stated that we should provide the most accurate sample

possible. Our present knowledge and experience suggest that our first goal be an SRM

which is 20% to 50% accurate. In the future we should work towards the 5% to 15% range

indicated by the survey.

4.3 ADDITIONAL COMMENTS

Most of the answered questionnaires contained enthusiastic comments. Some responders

also offered to assist us, and others were pleased that someone finally is engaged to develop an EPR SRM.

The analysis of the answers to this questionnaire establishes that the EPR commu- nity needs standards. The first standard could be a single crystal in the shape of a cylinder or cube which is small enough to fit into 4-mm inside-diameter tubing and which

has about 10^^ spins. We should consider later issuing other concentrations and other

sizes and exploring alternative materials for standards. We should develop continuing

research and calibration efforts. And, finally, the purchasers of EPR SRM's should be

provided with technical help and advice, and, particularly as indicated by Tables 2 and

6, with detailed and extensive instructions on how to use EPR SRM's.

5.0 SURVEY REPORT ON STANDARDS FOR

MAGNETIC MOMENT MEASUREMENTS

5.1 INTRODUCTION

At present, there are no reliable and accurate standard calibrants for magnetic

moment measurements. For this reason, we at NBS are considering the preparation and

certification of a Standard Reference Material (SRM) for magnetic moment. In order to assess the need and to determine the characteristics for such a standard reference material,

we have undertaken a survey-questionnaire. Figure 7 is a copy of the questionnaire.

During October 1974, 781 questionnaires were mailed to addresses in the United

States. These addresses were obtained from the mailing list maintained by the American

Institute of Physics for the annual Conference on Magnetism and Magnetic Materials.

In this report the following classification is used: industry, university, government,

private individual, and unknown. The classification "unknown" is for those questionnaires

which were returned without a name or address on them.

Table 8 shows the mailing distribution of the questionnaire.

Table 8. Mailing Distribution

Classification Number Percentage

Industry 337 43

University 276 35

Government 116 15

Private 52 7 Total 781 100

- 25 -
Figure 7. 0MB i4l-S7'4077

APPROVAL EXPIRES; June. 1975

NBS-79'+

(9-7^4)

U. S. DEPARTMENT OF COMMERCE

National Bureau of Standards

QUESTIONNAIRE FOR MAGNETIC MOMENT

STANDARD REFERENCE MATERIALS

TO: PLEASE RETURN THIS

QUESTIONNAIRE TO: r ~1 Office of Standard Reference

Hater lALS Chemistry Bloc, Room 8311 National Bureau of Standards Washington, 0. C. 2023^^ _l (a pre-aooressed, postage-paid

envelope is enclosed for your convenience.)

The National Bureau of Standards is proposing to prepare ano certify a Standard Reference Material (SRM) for magnetic moment. The proposed SRM is for a 3mm-diameter

nickel sphere certified for saturation ma gn e t i za t i on a t room temperature to within

_+ 5 percent accuracy.

The purpose of this questionnaire is to determine the extent of the need FOp SUCH AN SRM. Because questionnaires may not reach all interested parties, you are encouraged

TO submit the names of colleagues whom you feel would wish to receive the questionnaire

1. Do you need a standard reference material for magnetic moment to calibrate

magnetometers? (a) Yes (b) No (c) Not in my field of interest

IF (b) Or"(c )', D I SREGAR D the FOLLOwTng" QUEST I o'^^Ti^TeTuYn" THE QUEST I ONNA I RE

2. Do you now use a calibrant with your apparatus? (a) Yes (s) No

If "Yes^' please answer the following questions:

(A) What calibrant do you use?

(B) Is your apparatus adaptable to various sizes of samples? (a) Yes (b) No

(C) What is the maximum magnetic field obtained with your magnet?

(D) Please cite the references that describe your experiments, or send reprints.

- 26 -
, FigurR 7 .(cogtinuad] .

3i Please list your preferences for an SRM for magnetic hohent.

(a) Shape (if other than spherical) (e) Magnitude of magnetic moment

(b) Size (f) Temperature (other than room)

(c) Material (g) Other Specifications (list)

(d) Accuracy (if better than + 5%)

If the proposed SRM (3mm-diameter nickel sphere) were available for approximately

$150, would you purchase it? (a) Yes (b) No

5. Please list the names and addresses of any persons you feel would be interested in an SRM FOR magnetic moment.

additional comments

- 27 - USCOMM-NrtS-D,C
Table 9 lists the returns as of December 2, 1974.

Teible 9. Returns

Normalized Returns

Percent of

Number of Number of Number Sent Out Relative

Classification Returns Returns (Table 8) Percent

Industry 69 120 36 40

University 71 124 45 42

Government 22 38 33 13

Private 9 15 33 5 Unknown 126

Total 297 297 100

We have normalized the returns by assuming the 126 unknown returns have the same distribution among classifications as those returns with a name or address on them.

Both in number and percentage, a slightly larger response was obtained from universities.

5,2 DATA BASE AND FINDINGS

In this report, each question will be stated, followed by a summary of tlie response to it, and then analyzed.

Question 1. Do you need a standard reference material for magnetic moment to calibrate magnetometers?

(A) Yes (B) No (C) Not in my field of interest

Table 10. Response to Question 1

Classification Number of Returns

Yes No Not in my field of interest

Industry 35 25 9 Universities 38 is 15

Government 9 5 8 Private 2 .2 5 Unknown 40 43 43

Total 124 93 80

Percent of response 42 (124/297) 31 (93/297) 27 (80/297)

Percent of those

in field 57 (124/217) 43 (93/217)

A majority (57%) of the responses from workers in the field claims that a need for an

SRil exists. The remainder of this report will analyze the 124 questionnaires on which the

response to question 1 was yes.

- 28 -
Question 2. Do you now use a calibrant with your apparatus?

Yes No

Yes - 103 No - 16 Percent Yes - 87

Of the 124 who claimed they need an SRM/ 103 or 83% already are using a calibrant. This

response and that to Question 1 indicate that these workers are not completely satisfied

with their own reference material and would like an SRM certified by a reputable standards

laboratory.

Question 2, continued

If "Yes," please answer the following questions:

2A. What calibrant do you use?

Table 11. Response to Question 2A

Number Percent

Ni 78 60

Area-turns 15a 12

Paramagnetic salts lib 9

Fe 8 6

Ferrites 5 4 Iron oxides 4 3 Superconductors 4 3 Others 4c 3 Total 129

of Total

^Includes reference magnets (5) , reference voltage (1) ^Persons informed of existing SRM' s for paramagnetism

^h, Ge, Ta, Mo

The majority of those who use a calibrant use nickel.

2B. Is your apparatus adaptable to various sizes of samples?

Yes No

Yes - 98 No - 12

Although 89 percent (98/110) answered yes to this question, a size preference is shown

later in question 3B.

- 29 -
2C. What is the maximum field obtained with your magnet?

Table 12. Response to Question 2C

Field (tesla) Number Percent of Total

0-0.1 7 6 0.1 - 0.5 9 7 0.5 - 1.0 25 21

1.0-2.0 34 28

2.0 - 3.0 17 14

..,^3.0 - 5.0 7 . • 6

. . ..^.t** 5.0 - up 22 18 i Total 121

Most of the fields above 3 teslas are produced by superconducting magnets. Approximately 13% of the responses need a moment characterized in a field of less than 0.5 tesla.

2D. Please cite references that describe your experiments, or send reprints.

References cited 51

Reprints sent 22

The responses from questions 2A and 2D show that the majority of the workers (124) are active in the field of magnetism.

Question 3. Please list your preferences for an SRM for magnetic moment.

There are seven parts to this question (A-G) . These are discussed separately.

3A. Shape (if other than spherical)

Table 13. Response to Question 3A

Shape Number Percent

sphere* 96 • 72

cylinder 20 15

film or disc 15 11

ellipsoid 3 2 Total 134

Includes those who wrote in sphere (22) and those who left

3A blank. See questions 2A and 4. The vast majority chose

el sphere which is easy to fabricate and whose demagnetization

factor is well established.

- 30 -

I
3B. Size

Table 14 . Response to Question 3B

Size (diameter mm)* Number Percent

1 9 16

2 15 27

3 20 36

4 4 7

5 4 7 10 4 7 Total 56

*Only the size for a sphere has been tabulated.

More than one size sphere may be needed to satisfy the requests.

3C. Material ^

Table 15. Response to Question 3C

Material Numbsr Percent

Ni 38 75

Fe 6 12

Other* 7 13

Total 51

*Fe203 (2) , nonmetallic (2) , ferrite (1) , Permalloy (1)

,

superconductor (1)

.

There was a low response to this question; however, question 2A showed that most

workers used nickel.

3D. Accuracy (if better than ±5 percent)

Table 16. Response to Question 3D

Accuracy (%) Number Percent

.1 - .5 12)

.6 - 1.0 30> 49

1.1 - 4.0 16)

4.1 - 5.0 _61 51

Total 119

This is a very important question and clearly shows that about one-half of the workers

would like an SRM certified to better than ±5 percent accuracy. One notes that our high

- 31 -
response for a ±5 percent accuracy may have been prejudiced by our phrasing of the question.

However, the responses to question 4 and the additional comments given below indicate that

a ±1 percent SRM is needed.

3E. Magnitude (emu/g)* Number

< .1 10

> .1 12

Only 22 persons answered this question, but it appears froifl other questions about

materials that the majority of the workers need an SRM with amoment > .1 emu. (See

questions 2A, 3C, and 4. Also note that the saturization magnetization for nickel is

approximately 50 emu/g.)

*Most workers who responded to this questionnaire use

(emu/g) for the "cgs" units of magnetic moment. To convert

this td,. SI units, multiply by 47r x l5'* p, where p is the

denisity of the material in g/cm^

.

3F. Temperature (other than room)

Temperature Number

4.2 K 26

77 K 13

4.2 K to 293 K 4 43

Approximately 35% of the workers would like an SRM to check or calibrate their

equipment at low temperatures

.

3G. Other Specifications (list)

Only one person responded, and the response did not pertain to magnetic moment

considerations.

Question Ai If the proposed SRM (3 mm diameter nickel sphere) were available

for approximately $150, would you purchase it?

Yes No

Table 17. Response to Question 4

Yes, if accuracy Percent

Classification No Yes is better than 5% Total Total Yes

(write in)** Yes (normalized)

Industry 5 23 7 30 46

University 11 21 6 27 44

Government 4 6 6 9

Private 2 2 1 Unknown 9 26 4 30

Total 29 78* 17 95

Percent 23 63 (78/124) 14 77

*This includes 19 maybe 's. Seventeen people who answered this question wrote in "Yes, if accuracy is

better than 5%."

- 32 -
The responses to this question show that 63% of the 124 responses would buy the 5% SRM

for $150 even though many prefer a more accurate SRM. Response to question 3D showed that

50% of the workers claimed they needed an SRM to better than 5%. A total of 77% (95/124)

would purchase the SRM if it were certified to better than 5% accuracy. Approximately 46%

of the potential customers are companies, 44% universities, and 9% government. Only 14%

(17/124) would not buy an SRM with an accuracy of 5%.

Question 5. Please list the names and addresses of any persons you feel would be

interested in an SRM for magnetic moment. This question brought 44 responses.

5.3 POSSIBLE USERS

We mention here who the users of these standard reference materials might be

.

5.3.1 Industry

Users of vibrating sample magnetometers in industry require such standard

reference materials for calibration purposes. Vibrating sample magnetometers are commercial instruments and are widely used. In fact, two SRM's with different moments have been

suggested. They would be used to determine the linearity of magnetometers.

Producers and customers of rare earth cobalt magnets need such standard

reference materials to certify field measurements traceable to NBS.

5.3.2 Universities

Researchers at universities also request SRM's for vibrating sample

magnetometers. Others state a requirement for magnetization standards with moments

as small as 10"^ emu/g. The latter standards interest researchers concerned with the

magnetism of rocks (both terrestrial and lunar) . Some investigators suggest standards

to calibrate mutual inductance systems for measuring differential susceptibility at liquid helium temperatures. This latter suggestion involves a non-metallic sample.

Preferably the sample should be an optically transparent, magnetic insulator with a known Faraday rotation.

5.3.3 Government and Others

Additional' potential users mention the need to calibrate sensitive Faraday

magnetometers, Faraday microbalances , torque magnetometers, and hysteresigraphs by

insertion of known samples

.

5.4 SUMMARY

The 124 responses were from workers who are active in the field of magnetism.

Approximately 87% of these 124 workers use a calibrant (mainly nickel) . Approximately

one-half of the workers want a certified SRM. However, some workers have confused

precision and accuracy. Also, none of the workers who have used a reference material

volunteered to state the accuracy of their own calibrant. Some workers thought the price

of $150 was too high.

There is an uncertainty in the value of saturation magnetization for nickel in

the literature. Values given by reliable sources vary by about 8%. Workers do not know

what value to use.

- 33 -
If NBS issues an SRM for magnetic moment, it should probably have the following

properties

1. Accuracy within ±1%.

2. More than one size (perhaps a 1-mm and a 3-mm sphere)

.

3. Material most likely of nickel.

4. A price less than $150.00.

5. The actual magnetic moment determined at known values of magnetic

field (H) greater than 5000 oersteds.

5.5 TECHNICAL REFERENCES

(1) "Calibration of Vibrating-Seunple Magnetometers," J. Res. Natl. Bur. Stand.

(U.S.) C. Engineering and Instrumentation, Vol. 70C, No. 4, October-December

1966. W. E. Case and R. D. Harrington.

(2) "The Magnetization of Pure Iron and Nickel," Proc. Roy. Soc. London A321 , 447-491 (1971). J. Crangle and G. M. Goodman.

(3) "New Determinations of the Saturation Magnetization of Nickel and Iron,"

J. Appl. Phys. 39^, 2 (1968). H. Danan, A. Herr, and A. J. P. Meyer.

6.0 ACKNOWLEDGMENTS

We wish to acknowledge and to thank the many people both at the National Bureau of

Standards and outside the Bureau who have assisted us in these three surveys. We thank

the staffs of the Office of Standard Reference Materials and the Office of Standard

Reference Data. In particular, we acknowledge Mrs. Ruth Meyer for her help with the

over-all design and format of the questionnaires. We gratefully thank Frances Fussinger

for administrative assistance and for typing and preparing this report.

USCOMM-NBS Dt - 34 -
KeS-n4A :f!Ev. 7-73)

U.S. DEP-. CP COMM. BIBLIOGRAPHIC DATA

SHEET

1. PUBLICATION OR REPORT NO. NBSIR 75-759

2. Gov't Accf.ssion No.

3. Rec ipicnt '.s Acccs.sion No.

4. TITLE .AND SLBTlTLii

STANDARD REFERENCE MATERIALS AND DATA FOR RAMAN

SPECTROSCOPY, ELECTRON PARAMAGNETIC RESONANCE, AND

MAGNETIC MOMENT MEASUREMENTS

5. Publication Date- July 1975

6. Performing Organization Code

7. .AUTHOR S- E. S. Bennett, G. A. Candela, T. Chang, R. E. Mundy, and G. J. I8. Performing Organ. Report No. ^osasco NBSIR 75-759

9. PERFOR.MLNG ORGANIZ.ATION NAME AND .ADDRESS

NATIONAL BUREAU OF STANDARDS

DEPARTMENT OF COMMERCE

WASHINGTON, D.C. 20234

10. Project Task '''ork Unit No.

11. Contract /Grant No.

12. Sponsoring Organization Name and Complete Address (Street, City, State, ZIP)

Same as No. 9

13. Type of Report & Period Covered

Final

14. Sponsoring Agency Code

15. SUPPLE.VIENTARY NOTES

16. -ABSTR.ACT fA 200--Aord or less factual summary of most si^ificant information. If document includes a significant

bibliography or literature survey, mention it here.)

This publication contains the analyses of three survey-questionnaires to assess

the needs and markets for standards in Raman spectroscopy, electron paramagnetic

resonance, and magnetic moment measurements. These analyses give the requirements

and suggest the strategies to be followed for making each of the above three

measurement methods more quantitative than they are at present. Some of the

requirements are data cataloging, standards for data presentation, standard

reference materials, and standard reference data.

17. KEY UORDS (six to twelve entries; alphabetical order; capitalize only the first letter of the first key word unless a proper name; separated by semicolons

)

Electron paramagnetic resonance; magnetic moment; Raman spectroscopy;

standard reference data; standard reference materials.

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