Quantitative Analysis Softwarefor X-Ray Fluorescence

XRF-FP

XRF-FP is a full-featured quantitative analysis package for XRF
APPLICATIONS• X-Ray Fluorescence• Thin-film Analysis• RoHS/WEEE Analysis• Teaching and Research• Art and Archaeology• Process Control• X-ray Tube Characterization

Experimenter’s Kit with XR-123SDD performing XRF.

FEATURES• Fundamental parameters (FP)• Analysis with or without standards• General bulk and thin-film analysis• Analyze up to 40 elements• Supports all Amptek detectors (Si-PIN, Super     SDD, CdTe), X-ray tubes, and electronics• Auto-mode for continuous or repeated analysis• CdTe escape peak correction• Non-destructive analysis

Experimenter’s Kit with XR-123 performing XRF.

XRF-FP is a quantitative analysis software package for X-Ray Fluoresence (XRF). XRF analysis with Fundamental Parameters (FP) converts elemental peak intensities to elemental concentrations or film thicknesses. It processes the raw X-ray spectra measured using Amptek’s detectors and signal processors to
obtain (1) the elemental peak intensities (i.e., the intensity of the peaks corresponding to each element)
and then (2) the elemental concentrations or film thicknesses.

Figure 1: XRF-FP Main display window. Shows the element table with the various parameters and chemical concentrations.

AMPTEK INC. 14 DeAngelo Drive, Bedford, MA 01730-2204 U.S.A.

Tel: +1 (781) 275-2242

Fax: +1 (781) 275-3470

email: sales@amptek.com www.amptek.com(Page 1 of 8)XRF-FP SPECIFICATIONSIntroduction and Theory of Operation
XRF-FP is a quantitative analysis software package for XRay Fluoresence (XRF). It processes the raw X-ray spectra
measured using Amptek’s detectors and signal processors to
obtain (1) the elemental peak intensities (i.e., the intensityof the peaks corresponding to each element) and then (2)the elemental concentrations or film thicknesses.
There are three major steps to an XRF analysis, after thesystem has been setup and calibrated and the spectrum
measured:
1. Unravel the detector response to recover the incident
photopeaks. This step corrects for the escape peaks,
sum peaks, background continuum, backgroundpeaks, etc. The output of this step is a processed
spectrum, ideally showing only the incident
photopeaks.

Quantitative analysis, the step in which the element
concentrations or film thicknesses are computed from theintensities, can be performed either standardless or using
standards to calibrate the analytical parameters.
With standardless analysis, all parameters are based upon
theoretical equations, the fundamental parameter database,and precise modeling of the detector, X-ray tube, andgeometry. Standardless mode is possible for simple bulk
or single-layer thin-film samples when the film thickness
is known.
With analysis using standards, the fundamental parameters
are based on the measured response of the system for eachelement. The most accurate analytical results are obtained

3. Account for attenuation and matrix effects todetermine the concentrations of the elements inthe sample. The output of this step is a table ofconcentrations, which is the final result of theanalysis.
Spectrum processing corrects the spectrum for escape peaks,
sum peaks, background continuum, Compton backscatter,and other effects. It also corrects for attenuation in the
Be window and detector dead layers and for the detector
efficiency. It can fit the peaks using theoretical models
or measured responses and can perform either a linear
or a non-linear spectral deconvolution. The wide variety
of processing options permits the software to be tailored
to a particular detector/spectrometer and to particularapplications.

Figure 2. Sketch illustrating the data flow in an XRF analysis.
(Page 2 of 8)

Steel 321

Steel 316

2. Deconvolve the photopeaks to determine theintensity of the X-rays interacting in the detector.
The output of this step is a table of the intensities
in each photopeak to be analyzed.

NIST VALUE

XRS-FP VALUE

CR

18.450 ± 0.05

18.500 ± 0.25

Mn

1.630 ± 0.01

1.670 ± 0.07

Fe

65.190 ± 0.07

65.000 ± 0.52

Ni

12.180 ± 0.05

12.270 ± 0.27

Cu

0.169 ± 0.001

0.167 ± 0.026

Mo

2.380 ± 0.01

2.390 ± 0.03

Cr

17.400 ± 0.10

17.590 ± 0.23

Mn

1.800 ± 0.05

1.800 ± 0.07

Fe

69.310 ± 0.15

68.910 ± 0.53

Ni

11.200 ± 0.10

11.420 ± 0.27

Cu

0.121 ± 0.001

0.119 ± 0.022

Mo

0.165 ± 0.005

0.167 ± 0.009

Table 1. Results obtained using XRS-FP on two stainless steel alloys. These were “standard reference materials” from NIST. The
data were taken using Amptek’s XR100-SDD detector with the
PX4 signal processor, Amptek’s Mini-X X-ray tube, and Amptek’s
MP1 mounting plate.

XRF-FP SPECIFICATIONS (con’t)
using a “type” standard, a standard with composition
similar to the material under measurement. Measured“scatter ratios” can be used to estimate the fraction of thesample which consists of low-Z materials that cannot be
quantified by XRF.
XRF-FP is a full-featured analytical software package which
carries out these three steps. The software includes a large
number of variables which the user can adjust to match theexperiment conditions and to optimize processing.

XRF-FP Features• Up to 40 elements can be analyzed at a time. Analysis
can be performed for all elements from H through Fm,
using K, L or M lines, in the energy range from 0.1 keV
up to 60 keV.
• Supports measurement of bulk composition, composition
and thickness of a single layer, or composition of up to
4 layers (for multi-layer call Amptek).
• Includes full correction for losses due to attenuationin air, detector Be windows, detector dead layers, thedetector’s active volume, and filters inserted between
the tube and sample or between the sample and detector.
These are calculated from the user-input parameters
defining the excitation source, the detector, and thespectrometer geometry.
• Spectrum processing parameters include quantities todefine the background continuum, pile-up and sum peaks,smoothing, a measured background spectrum for peaks• Includes full corrections for absorption and both thickand thin-film secondary fluorescence, i.e., all matrix
effects, enhancement and absorption. All possible lines
are considered for both excitation and fluorescence.
• The photopeak intensity can be modeled as a Gaussianfunction, by integrating the net area of the peak, or using
a measured reference photopeak response.
• Linear or nonlinear deconvolution. In nonlinear
deconvolution, the centroid and resolution of the peaks
is adjusted for the optimum fit.
• Quantitative analysis can be implemented using apure fundamental parameters approach, fundamental
parameters with scatter ratios (for samples containing
large amounts of low-Z materials), or by simple leastsquare fitting.
• Fundamental parameter analysis can be based on
calibation from a single multielement standard, multiple
standards, or no standards. Standardless analysis requires
accurate definition of the tube, detector, environmental
and geometry parameters.
• Fundamental parameter calculations are based upon the

Sherman equation.
• Tube spectra can be supplied by the user or calculated
from built-in models (Ebel, Pella et al.). These tube
spectra can be convolved with experimental transfer
functions to derive the expected tube spectrum passing
through an optic such as a polycapillary bundle.
• Includes both an interactive “expert mode” and a “routinemode”. In expert mode, the user can see each step in theanalysis and adjust parameters. In routine mode, after the
spectrometer is set up and calibrated, one need only clicka single button to acquire the data, process the spectrum,
analyze the intensities, and save the output report.

Sample Definition
Elements/Components
Can analyze up to 40 elements as individual elements
and/or compounds. Unanalyzed elements can be specified
stoichiometrically bound with an analyzed element (e.g.,oxides or carbonates). Elements can be analyzed in one ormore compounds within the same analysis. One compound(or element) can be analyzed by difference. Any numberof compounds (or elements) can be “fixed.” For example,
solutions, binders and/or hydrated crystals can be analyzed
this way.

General Bulk and Thin-Film Analysis
Any bulk or single-layer (unsupported) thin-film sample
can be analyzed by either standardless or a calibration-withstandards FP approach. Optional software is available tohandle multilayer samples up to 6 layers for simultaneous
film thickness and composition analysis using FP withstandards (please contact Amptek).

Quantitative Analysis
Analysis Method
The analysis module includes three options:First, one can choose to use fundamental parameters (FP)for the quantitative analysis. This module solves a setof non-linear equations which relate the intensity of the
X-ray peaks to the concentration of the elements in thesample. These equations include terms due to attenuationand enhancement in the sample, production of secondary
X-rays in the sample, attenuation in windows and air, tube
spectra, scattering, etc.
Second, one can choose FP with scatter ratios. This option
is recommended when the sample contains a significant
amount of low-Z materials, such as plastic. An estimate
is made for the unanalyzed fraction of the sample by comparing the known fraction of analytes with the measured
C/R ratio and ascribing the remainder to a pair of elementsthat bracket the estimated mean atomic number.

(Page 3 of 8)XRF-FP SPECIFICATIONS (con’t)
Third, one can choose simple least squares fitting. This isempirical method, which does not use all the information
about a sample. Instead, it relies on simple calibration
coefficients and presumes that the intensity of a particularline is linearly related to the concentration.
When more than one excitation is used, at least one of theelements for each condition must have been calibrated.
Calibration factors may be generated using any type ofstandard (e.g., pure element or analytical “type” standard).
A single “type” standard may be used, or the calibration
may be done with a different standard for each element, or
any combination of standards may be used. If some elements are calibrated and some are not, the latter can use
calibration coefficients derived from the former group.
The mass thickness of the sample can either be specified
or calculated. If the latter, then the analysis cannot bestandardless. Several units are possible for thickness measurement, and the density can be calculated theoreticallyor specified in the case of linear thickness calculations.
Composition units may be ppm or Wt%, with the additional
output of atomic and mole percent.

Calibration Method
With the FP analysis method, one can choose a “standardless” approach. All of the parameters describing the X-ray
tube spectra, filtering, attenuation in air, attenuation in Be
windows and dead layers, attenuation and enhancement in
the sample, etc. are computed from physical models basedon the data the user has entered into the software. It issimple to use standardless analysis but the parameters are
only approximate. This is due to approximations inherent
in the physical models and in the data the user enters.
With the FP analysis method, one can also choose to calibrate its parameters using either a single standard or multiple standards. Calibration is strongly recommended andwill lead to much more accurate analysis results. A single“type” standard may be used, i.e. one can use a single pieceof material containing all of the elements which will laterbe analyzed. For example, one can use a single “standard
reference material” of stainless steel and then obtain very
accurate analyses of other steel alloys. One can also calibrate with a different standard for each element.

source spectrum for complete polychromatic source modeling. Tube anode, windows and filters may be specified.
The tube window can be of any composition (e.g., BeO or
glass). Any element may be chosen for the tube anode, as
well as the tube (electron) incidence and take-off angles.
The kV may range from 3 to 60 kV. Provision is provided
for including a transmission efficiency file for use with, forexample, polycapillary optics placed between the source
and the sample. Radioisotopes can be used using a source
file describing the relative line ratios. For secondary target
excitation, monochromatic excitation is assumed.
Amptek supplies all parameters for its Mini-X X-ray tube
and filter kit. If a tube from a different vendor is used, thenthe customer must find the critical parameters.
Radioisotopes can be used using a source file describing
the relative line ratios. For secondary target excitation,
monochromatic excitation is assumed.

Detectors
Various detectors (Si-PIN, SDD, CdTe, Si(Li), and Ge)
and windows can be fully modeled. The software has
provision for the user to input all the required parameters(e.g., thickness, are, dead layer, etc.) associated with thesedetectors and their windows. Spectral processing with
CdTe involves some significant changes to the processing
routines. For more information on CdTe detector analysis
please see http://www.amptek.com/epeaks.html.
Amptek supplies all the parameters for its XR100 series ofdetectors, including the XR100-SDD, XR100CR for SiPIN,
and XR100-CdTe. If a detector from a different vendor isused, the customer must find the critical parameters.

Geometry
The complete system geometry can be specified including
the sample incidence and take-off angles, the source-to-optic and/or source-to-sample distances, the sample-to-detector distance, as well as the environmental factors. Amptek
supplies all the parameters for its MP1 mounting plate, foruse with the Mini-X and XR100/X-123.

Alpha Angle

Several types of analysis cannot be standardless, i.e. calibration with standards (reference materials) is required.
Least squares analysis cannot be standardless. If the mass
thickness of the sample (i.e., the mg/cm2) is calculated, theanalysis cannot be standardless.

Fluorescence
Incident Angle
Sample Plane

Excitation Sources
Either X-ray tubes or isotopic sources can be used. For
tubes, XRF-FP can model both reflection and transmission
x-rays using either Pella or Ebel models, or via a supplied

X-Ray Detector

Excitation energy from
x-ray tube or source

Figure 3: Geometry angle definitions.

(Page 4 of 8)

Take-Off Angle
Scatter AngleXRF-FP SPECIFICATIONS (con’t)
Background Removal and Blank Subtraction
The background removal module uses iterative filtering
to distinguish peaks, leaving behind the smoothly varying
spectral background. This background is then removed
from the original spectrum, leaving the peaks.
The blank subtraction module is used to remove peaks due
to environmental interference or contamination. Thesepeaks are not due to material in the sample but in the
spectrometer, for example, Ar in the air or Al in the filters
or Pb in a user’s shielding. This module subtracts a spectrum acquired from a “blank” reference material, i.e., one
without the elements to be analyzed.

Figure 4. When using the MP1 mounting plate, refer to this diagram
and the table below. The distance from the edge of the plate to thesample should be 0.375 inches (1 cm) in order to be at the intersecting
point of the detector and x-ray tube. All dimensions are in centimeters(cm).

XRF-FP Parameter

Value

Incidence Angle

67.5°

Take-Off Angle

67.5°

Alpha Angle

0°

Scatter Angle

135°

Tube-to-sample

339 mmSample-to-detector

159 mmFigure 5: Original spectrum before background removal.

Table 2.  When using the MP1 mounting platewith the XRF-FP software, enter these values
in the Geometry setup dialog.

Elements, Lines, and Interelement Corrections
Includes full corrections for absorption and both thickand thin-film secondary fluorescence. All possible lines
are considered for both excitation and fluorescence. The
analysis can be performed for all elements from H throughFm, using K, L or M lines in the energy range from 0.1
keV up to 60 keV.

Figure 6. Processed spectrum and background. The blue curveis the removed background.

Spectrum Processing
Spectrum Calibration
Using known peaks in the spectrum, the software calculates
the effective gain (eV/channel) and offset (zero shift) for
the spectrometer. These factors are applied to subsequent
spectra prior to other spectrum processing. The calibration
can be specified in the XRF-FP software or in the ADMCA
software. XRF-FP can automatically import the calibrationfrom ADMCA.

Escape Peak and Sum Peak Removal
Removes, at the user’s option, both detector escape and sum(pile-up) peaks. The escape peak module uses an internalfunction to estimate the fraction of x-ray events (above theK edge) that will generate K x-rays that will escape fromthe front or backside of the detector. Includes parameters
for both Si and for CdTe.

(Page 5 of 8)XRF-FP SPECIFICATIONS (con’t)
Please see http://www.amptek.com/epeaks.html for information on Escape Peak Corrections for CdTe detectors.
This is important when characterizing the output X-ray
spectrum of an X-ray tube or performing XRF with a CdTe
detector.

In addition to calculating elemental intensities, the software
automatically calculates the estimated uncertainty andbackground values, which allows uncertainty and Minimum Detection Limit (MDL) calculations to be performed
during the FP analysis.

8,000

Processed Spectrum
Original Spectrum

Counts

6,000

4,000

Absorption Edges

2,000

0

Escape Correction

0

20

40
Energy (keV)

60

80

Figure 7. Plot showing a tungsten (W) X-ray tube output spectrum taken with a CdTe detector after processing to remove escape events. The gray trace shows the original spectrum. The
green trace illustrates the escape events in the original spectrum.
These are subtracted from this original spectrum, then the correctenergies are computed (by adding in the energy which escaped).
The blue trace shows the corrected escape events, which are thensummed with the gray trace. The dark black trace shows the final
result of the processing with the events in their correct channels.

Smoothing

Figure 8. Plot showing spectra from a stainless steel sample. The black
trace is the raw spectrum, the blue trace is the processed spectrum,and the red curves show the result of a Gaussian deconvolution. The
quantitative results are in Table 1.

A specified number of 1:2:1 Gaussian smooths can be applied to a spectrum.

Software Options

Deconvolution: Intensity Extraction

There are two methods of spectrum acquisition. The firstis to acquire with the Amptek ADMCA acquisition application which controls the MCA8000A, DP5 Digital Pulse
Processor, X-123, or PX5 Digital Processor and Power
Supply. Once acquired, the XRF-FP can import the file anduse the ADMCA display for spectrum processing. This iscalled “Expert Mode.”This module operates on the processed spectrum to extract
the net peak intensities for the selected elements. It includes
several options:First, the peak areas are computed using one of threemethods: (1) simple peak integration across a fixed Region-Of-Interest, (2) fitting Gaussians to the peaks, using
a known database of line ratios and peak energies, etc.,
and (3) a reference deconvolution, which uses stored
profiles for each element to fit the peaks.
Second, the spectrum fitting can be done using either alinear or nonlinear approach. Both utilize a least-squares
method. In linear fitting, the peak ratios, energies andwidths are fixed. This method is usually very fast. In
nonlinear fitting, these parameters are allowed to vary
within certain constraints. This method is much morecomputationally intensive.
All required line energies and resolutions are calculated
automatically from the specified analyte line. The Gaussian
peak fitting can be done with a linear or non-linear leastsquares approach. The latter allows constrained changes in
the peak positions, intra-series line ratios, and peak widths,
from their nominal starting points.

Spectrum Acquisition

Once the system is set up and calibrated in “Expert Mode”,
it can be used in “Routine Mode.” The user places the
sample in the spectrometer, then in the screen in Figure
9 clicks “Analyze” and XRF-FP acquires the spectrum,saves it, analyzes it, and then saves the report. “RoutineMode” acquires the spectrum directly into the XRF-FP
software which can then be automatically processed. A
repeat measurement capability is provided.

Automatic Peak/Element ID
Using the Amptek ADMCA application, the user can
automatically mark peaks (ROIs) for analysis. If theappropriate element library is loaded into ADMCA thesoftware will associate the marked peaks with elements.
The corresponding elements can then be automaticallyimported into XRF-FP element table.

(Page 6 of 8)XRF-FP SPECIFICATIONS (con’t)
The layer thicknesses must be fixed for standardless analysis. Results can be normalized to any value, and MUST
be normalized for standardless analysis or when the layer
thicknesses are calculated.
Elements (or compounds) can be calculated, fixed, or determined by difference. Elements can also be determinedby stoichiometry from the compound formulae. Composition results can be calculated in units of Wt% or ppm,
and for thin films, units such as ug/cm2 and mg/cm2 areused for mass thickness. The latter can be converted tothickness (microns, microinches, nm, etc.) if the density is
known. The density may be input or optionally calculated
theoretically.
Figure 9. Auto and Repeat Mode.

Advanced Description
There are only two steps in XRF analysis whether or not
the fundamental parameter (FP) method is used. The firststep is to calibrate the response function for each elementfrom one or many standards (called the “Calibration”step). The second step is to produce the sample analysis
of a given material, using the previously stored calibration
coefficients, and the FP algorithms given a definition of thesample (i.e., number of layers, and which elements are inwhich layers).
The software will support single layer or bulk composition
and thickness analysis of up to 40 elements, calculated
as either elements and/or compounds. Up to 4 or more
excitation “conditions” are allowed per analysis. Eachcondition describes a separate analysis, and can be freely
defined with any combination of experimental conditions,such as kV, tube anode, filter, detector filter, environment(air, vacuum, He) and acquisition time. This allows theanalyst to measure some elements with one condition, andothers completely differently, such that each analysis canbe optimized for the specific element, or group of elements.
Likewise, the spectrum processing steps can also be freely
defined, and are all part of the condition code setup.
The FP analysis software will support a single or multiple
standard calibration scheme, or completely standardlessanalysis if the tube, detector, environmental and geometry
parameters are known. Calibration standards should be
passed one at a time and the merging of the calibration
standard information is handled internally. After each calibration step, a set of calibration coefficients and associatedinformation for each of the defined elements is returned,
which can immediately be used if only one standard is
employed. When using multiple calibration standards, all
the coefficients are merged into one set, and then this final
set is available for subsequent quantitative analysis.

All the appropriate FP calculations are made both duringcalibration and for Quantitation, using calculations based
upon the Sherman equation. Tube spectra, required forthe direct fluorescence calculations, can be supplied by theuser or calculated from built-in models (Ebel, Pella et al.).
These tube spectra can be convolved with experimental
transfer functions to derive the expected tube spectrum
passing through an optic such as a polycapillary bundle.
The presence of air paths will also be calculated from the
input geometry parameters for both the source and detector
paths. Single-element filters can also be inserted between
the tube and the sample or between the sample and thedetector, and the software can accommodate both.
The detector parameters (window, thickness, area, etc.)
will also be used to calculate the various absorption andefficiency effects when X-rays pass through the window
and get deposited in the detector material. This is only
strictly necessary when doing standardless analysis, but
the calculations are always done this way for consistency,
and to make it easier to compare calibration coefficients
between elements.
If the theory were perfect all the calibration coefficientswould have the same value. In practice, differences
should be relatively small, especially in comparison withcoefficients that did not fully compensate for the detector
efficiencies. Usually when calibrating elements that all
use the same line series (e.g., K), the coefficient variationis small (<30%), but is often larger when calibrating frommixed lines (e.g., K and L) because it is difficult to makeabsolute calculations that include the line series information (e.g., fluorescence yields).
It is not necessary to collect pure-element spectra for FP
analysis as no direct ratioing is necessary for the elemental
intensities. The calculations are done this way to make iteasier to do standardless analysis. Of course, it is possible
to use pure-element standards if desired, and the complete
FP calibration may be done this way without any “type”(Page 7 of 8)XRF-FP SPECIFICATIONS (con’t)
standards being used at all. This is useful if the analyst
does not have type standards readily available.
Both direct and secondary fluorescence effects are considered in the FP calculations. Included in the FP database are
all the required parameters to calculate or recall absorption
coefficients, fluorescence yields, jump factors, CosterKronig transitions, line energies, line ratios, transition
probabilities, etc.

The software consists of a main program window that provides the user interface. It runs on standard PCs (Windows
XP and later) with at least 256MB RAM of memory. The
XRF-FP software is completely compatible and integrated
with the Amptek ADMCA display and acquisition software.
It can also directly control all Amptek electronics to provide
an auto/repeat/continuous mode of operations.

EXPERIMENTER’S XRF KITS

Experimenter’s XRF Kit with Si-PIN Includes:

Experimenter’s XRF Kit with SDD Includes:• X-123 Complete Spectrometer with Si-PIN
Detector (6 mm2/500 µm, 1 mil Be window)• Mini-X USB Controlled X-Ray Tube
• XRF-FP Quantitative Analysis Software• MP1 XRF Mounting Plate• Stainless Steel 316 (SS316) test sample• Complete documentation with step-by-step
instructions• XRF Kit wizard for quick software setup• X-123 Complete Spectrometer with Super
SDD (25 mm2/500 µm, 0.5 mil Be window)• Mini-X USB Controlled X-Ray Tube
• XRF-FP Quantitative Analysis Software• MP1 XRF Mounting Plate• Stainless Steel 316 (SS316) test sample• Complete documentation with step-by-step
instructions• XRF Kit wizard for quick software setup

See the Experimenter’s XRF Kit: http://www.amptek.com/xrfkit.html

AMPTEK INC. 14 DeAngelo Drive, Bedford, MA 01730-2204 U.S.A.

Tel: +1 (781) 275-2242

Fax: +1 (781) 275-3470(Page 8 of 8)

email: sales@amptek.com www.amptek.com