SNRLXRF Installation and Users Guide

(S. Sutton, Dec. 2000)


Introduction

Installation

Launching the IDL user interface

Overview of the SNRLXRF Interface

Mode and Incident Energy

Beam Filtering Conditions

Major Element Composition and Thickness

Element Contents Summary

Composition Editing Fields

Defining A New Material

Peak Fits Input Control

Peak Selection Control

Output Location Control

Execution Button

Save and Restore Feature

Example of SNRLXRF Output


Introduction

    NRLXRF (Criss 1977) is a Fortran program written for conventional XRF analyses where one has a standard for every element of interest.  Trace element standards with micrometer scale homogeneity are rare.  The modified version of NRLXRF used here is designed for “standard-less” analysis of XRF spectra obtained with monochromatic radiation.  The standard-less approach is to use an internal reference element, i.e., concentration of one element in the spectrum is known independently (stoichiometry, EMP analysis, etc.), and compute relative sensitivities using the prediction capabilities of NRLXRF.  An IDL interface called snrlxrf.pro has been written to provide an easy user interface to the NRLXRF program.  This document describes the use of the Windows version of this software.

Installation

The package consists of the following files:

nrlxrf.exe

executable version of NRLXRF

snrlxrf.pro

IDL user interface to NRLXRF

nrl_init.pro

structure definitions

run_nrl.inp

command file used during NRLXRF execution

run_nrl.bat

batch file used in executing NRLXRF

mono.dat

input file with incident energy data generated by snrlxrf.pro

comp_file.dat

list of user defined major element compositions 

xrdat2.dat

input file containing NRLXRF commands generated by snrlxrf.pro

xrdat3.dat

additional input file (typically not used)

xrdat4.dat

additional input file (typically not used)

xrdatc.dat

list of compositions of frequently used compounds

xrdatp.dat

data file containing fundamental x-ray data (not to be user modified)

  1. Place all the above files in a single folder.

  2. Define a new system environment variable NRLXRF_DIR to be the folder containing these files (access environment variable definitions through the system control panel)

  3. Give all users write permission to this folder.

Launching the IDL user interface

  1. Add the NRLXRF folder to the IDL path through the IDL preferences

  2. At the IDL prompt, type "snrlxrf"

Overview of the SNRLXRF Interface

                    (Click on a particular widget to go directly to its description.)

 

Mode and Incident Energy 

NRLXRF has two modes: Analyze and Predict.  Use the former to compute concentrations based on peak areas.  Use the latter to predict the relative sensitivities for specific fluorescence lines.  Type in the relevant incident beam energy (monochromatic).  In this and all editable fields, the ENTER key on your keyboard must be struck for the change to take effect.  A 45 degree in/ 45 degree out analysis geometry is hardwired into the program but other geometries are possible (consult your local SNRLXRF expert). Return to Graphic

 

 


Beam Filtering Conditions

NRLXRF allows use of an incident beam filter but such filters are irrelevant for the monochromatic/relative sensitivity approach used here.  The detector filtering is important because relative sensitivities can be affected by absorption through these materials.  Three filters can be defined.  For each of the 3, the user can select one of the built-in choices, or, by selecting "Other", enter an element of choice in the adjacent editable field.  Also enter the density and thickness of each filter.  Zero, 1, 2 or 3 detector filters may be used. Return to Graphic


Major Element Composition and Thickness

The user must define the major element composition and thickness of the sample to allow NRLXRF to make absorption, secondary fluorescence, etc. corrections. As for filters, the user can chose one of the built-in materials from the droplist or define a completely new material through the "Composition Editing Fields" (see below).  When a built-in material is selected, the density and major element composition are displayed (the former in the adjacent editable field; the latter in the "Element List" field).   Three "types" of samples are available via the droplist: Homogeneous, Separate and Particulate.  Homogeneous, the typical selection, assumes the sample is a homogeneous parallel-plate.  Separate assumes the sample consists of separated particles (implementation not fully tested).  Particulate assumes the sample consists of densely-packed particles such that shadowing is significant (not implemented in current release). Return to Graphic


Element Contents Summary

Shows the current composition defined for the sample.  Elements listed as "Fixed" are unaltered during the analysis whereas those listed as "Unknown" are optimized.   All "unknown" elements are given an initial (seed) concentration of 0.1 wt % but these can be changed through the "Composition Editing Fields" (see below).  Self-explanatory buttons to the left also allow these entries to be modified.  Return to Graphic


Composition Editing Fields

Allows modification of the compositions shown in the "Element List" field.  Element symbol, concentration and optimization parameter can be modified by selecting the appropriate entry in the Element List.  Remember to use the Enter key on your keyboard after making changes.  Return to Graphic


Defining A New Material

Press the "Clear all elements" button then make new definitions using the "Add new element" button.  Use the "Edit COMP. NAME >" button to give the material a name then press the "NAME and SAVE this composition" button.  The new material will now appear in the Major Element Composition droplist in this and subsequent sessions.  Return to Graphic


Peak Fits Input Control

This routine is designed to be used on fluorescence peak area files generated by M. Rivers EPICS MCA program or his VMS routine called fit_spect.pro. Choose the appropriate Peak File Type through the droplist. To read in one of these files, press the "READ A PEAK FITS FILE" button.  A dialog box will appear to allow you to navigate to the file of interest.  Such files typically contain multiple spectra fits and these will appear in the adjacent field.  The process of selecting a particular fit causes the net peak areas of ALL fitted peaks in that fit to appear in the "Peak List" field.  Return to Graphic


Peak Selection Control

Select the specific peaks which will be used for the concentration calculations (typically the K alpha and L alpha peaks).  Use the Windows mouse features, shift left button and ctrl left button to make multiple selections.  All element selected in this way will be added to the Element List unless they already exist there. Also, "Unknown" is the default but again this can be changed via the modification fields above.  Return to Graphic



Reference Peak Selection

You must select one fluorescence peak which will be treated as the internal reference element.  Type this peak name (Ca Ka, Fe Ka, Pb La1, etc.) in the editable field (hit Enter).  Important Note: This peak must occur in the Peak List and that element must appear as a Fixed entry in the Element List!!  Return to Graphic


Output Location Control

These widgets allow you to control where the composition results are written.  The file name is sequenced but this can be manually overwritten via the editable field.  Return to Graphic


Execution Button

Once you're happy with all the settings, hit the "Run SNRLXRF" button.  A text window will appear containing the results.  One of the nice features of this interface is the ease of repeating the calculations - simply make any desired changes and hit the run button again. Return to Graphic


Save and Restore Feature

Each time an event occurs in the interface screen (e.g., button push, droplist selection), the procedure structures are written to a file called snrlxrf.sav in the user's default directory.  Each time SNRLXRF is launched it will restore values from this file if it exists.  This makes it easy to begin a new session with the previous settings intact.  Return to Graphic

Example of SNRLXRF Output

Click here to view a sample output from SNRLXRF.  The computed concentrations (wt %) are at the end of these files.  Element concentrations fixed during the optimization are so indicated.

COMPONENT         AMOUNT    IMPREC.       BIAS        ADJUSTED

 

     SI       70.00000 (FIXED)                       70.00000

     C        30.00000 (FIXED)                       30.00000

     TI        0.1101385 +/-0.0011014  +0.0000000     0.110    

     V         0.0113847 +/-0.0001138  +0.0000000     0.0113847   

     CR        0.0235369 +/-0.0002354  +0.0000000     0.0235369   

     MN        0.0102146 +/-0.0001021  +0.0000000     0.0102146   

     FE        0.0096415 +/-0.0000964  -0.0000000     0.0096415   

     W         0.0568666 +/-0.0005687  -0.0000000     0.0568666   

     SR        0.0002410 +/-0.0000024  -0.0000000     0.0002410   

     Y         0.0036567 +/-0.0000366  +0.0000000     0.0036567   

     ZR        0.0065216 +/-0.0000652  -0.0000000     0.0065216   

   (TOTAL)   100.2322006 +/-0.0012768  +0.0000000   100.232    

Return to Graphic

 

End of document......

This page was last updated on December 11, 2000