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picture1_Jeol Quantification 1


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File: Jeol Quantification 1
copyright 2008 casa software ltd www casaxps com exponent of 0 2 numerically equivalent rsf values are quantification of jeol xps spectra reproduced in casaxps table 1 is a quantification ...

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                                Copyright © 2008 Casa Software Ltd. www.casaxps.com 
                                                                                        exponent of -0.2, numerically equivalent RSF values are 
                Quantification of JEOL XPS Spectra                                      reproduced in CasaXPS. Table 1 is a quantification table 
                from SpecSurf                                                           calculated in CasaXPS for the same data for which the JEOL 
                                                                                        system reports RSFs shown in Figure 1. The small differences 
                The quantification procedure used by the JEOL SpecSurf                  between the total RSFs reported by CasaXPS and those in 
                software involves modifying the Scofield cross-sections to              Figure 1 are due to different peak positions between the two 
                account for both an energy dependency and also angular                  systems, probably due to slight differences in the background 
                distribution corrections. However, to reproduce the                     definition. 
                quantification tables in CasaXPS produced by the JEOL                    
                                                                                                              Library     Total     Raw       %At 
                SpecSurf software, it is sufficient to use an energy exponent of            Name Position RSF             RSF       Area      Conc 
                -0.2, entered on the Regions Property Page, and the unaltered               C 1s      284.7     1.01548   4.19415   6367.69     58.1
                Scofield cross-sections for the RSF values. While the reported              N 1s      401.2     1.82786   7.39709   78.6979      0.4
                RSFs will not match in absolute terms, the relative RSFs are                O 1s      532.4     2.97535   11.7345   2740.05      8.9
                the same between the two systems and therefore the                          F 1s      688.6     4.49857   17.1189   3212.83      7.2
                quantification tables will be identical (assuming the same                  Si 2p     100.4    0.829645    3.5258   2337.71     25.4
                calculated peak areas and positions for the peaks).                              Table 1: Quantification table generated in CasaXPS 
                                                                                         
                While the infrastructure for adjusting the RSFs for angular 
                distribution is in place for the JEOL software, the current JEOL 
                system sets the asymmetry β parameter to unity and therefore 
                the angular distribution function returns the same value for all 
                transitions, hence the Scofield cross-sections are all scaled by 
                the same factor. The only significant adjustment to the                                                                     
                quantification values derive from the energy dependency. The                  Figure 1: JEOL RSF values for the transitions in Table 1. 
                actual modifications to the Scofield cross-sections applied by 
                the JEOL system can be fully reproduced in CasaXPS version               
                2.3.15, where a set of configuration parameters defined in the          In order to obtain the quantification table in Table 1, it is 
                ParameterFile.txt file in the CasaXPS.DEF directory control             necessary to add lines to the ParameterFile.txt file in the 
                the calculated RSFs. When initialised using an angle of 56º             CasaXPS.DEF directory as shown in Figure 2.  
                between the x-ray source and the analyser, and an energy 
                                                                                                                                                       1
                                   Copyright © 2008 Casa Software Ltd. www.casaxps.com 
                                                                                                 The default CasaXPS library is populated with Scofield cross-
                                                                                                 sections. These Scofield cross-sections are computed from 
                                                                                                 Hartree-Slater wave-functions and therefore are appropriate for 
                                                                                                 an XPS instrument designed with the, so called, magic angle 
                                                                                                 between the x-ray source and the analyser axis. Given the angle 
                                                                                                 between the x-ray source and the analyser, a correction can be 
                                                                                                 made to these magic angle RSFs appropriate for the given 
                                                                                                 instrument. The configuration file in Figure 2 shows the 
                                                                                                 method for specifying the require angle for the JEOL 
                                                                                                 instrument, which is 56º. Each time one or more files are 
                                                                                                 opened in CasaXPS for which the angle has yet to be set, a 
                                                                                                 dialog window prompts the user for the missing angle and 
                                                                                                 offers the configured angle as the default. 
                                                                                                  
                                                                                                 Once a file is updated with an entry in the VAMAS file 
                  Figure 2: ParameterFile.txt file in the CasaXPS.DEF directory used in          comment of the form “SourceAnalyserAngle: 56.000000 d”, 
                                       version 2.3.15 of CasaXPS.                                the source to analyser angle is defined for that file. When 
                                                                                                 coupled with the configuration entry, “jeol angular 
                 The JEOL element library includes the asymmetry parameters                      distribution”, the magic angle Scofield cross-sections from the 
                 and therefore, should these be implemented in future releases                   element library will be adjusted each time an RSF is extracted 
                 of the JEOL software the line in the ParameterFile.txt file “jeol               from the element library for use with a Region or Component. 
                 angular distribution” would need to be changed to “correct for                  The column in Table 1 headed Total RSF is calculated from 
                 angular distribution”. With this adjustment, CasaXPS would                      the RSF in the Region or Component multiplied by the energy 
                 extract RSFs from a Scofield library to include the full angular                dependence defined by the value in the text-field on the 
                 distribution correction.                                                        Regions property page. 
                                                                                                                                     
                 The theory behind the use of angular distribution correction is 
                 discussed in detail elsewhere in the CasaXPS manual. An 
                 outline of the procedure will be given below. 
                  
                                                                                                                                                                      2
                         Copyright © 2008 Casa Software Ltd. www.casaxps.com 
            Quantification Examples 
             
            The follow examples illustrate how to quantify data from the JEOL JPS-9200 instruments at University of Wageningen, The 
            Netherlands. 
                                                                                                                         
                                       
                                                                                                                       3
                           Copyright © 2008 Casa Software Ltd. www.casaxps.com 
                                                                         spectrum displaying element marks for oxygen, carbon and 
                                                                         silicon in preparation for creating regions using the Create 
             Quantification of a Survey Spectrum                         Region button. 
                                                                          
             Survey spectra are typically used to measure elemental       
             concentrations and therefore quantification regions are usually 
             the tool of choice to measure the peak areas. A low resolution 
             acquisition mode enhances the signal-to-noise in a survey 
             spectrum, but broadens the peaks in the data making these 
             peaks less appropriate for chemical state analysis by peak 
             modelling, hence the use of regions only.  The first example 
             describes how to quantify a survey spectrum using 
             quantification regions. 
              
             The Quantification Parameters dialog window is available from 
             the Options menu on the CasaXPS main window or via the top 
             toolbar button  . Quantification Regions are edited on the 
             Regions property page on the Quantification Parameters dialog 
             window, where the limits of integration, background type and 
             RSF parameters are set.  For successful quantification of a 
             sample using a survey spectrum, a set of Regions must be 
             created with the appropriate RSFs for the transitions identified. 
             To ensure the correct RSF is extracted from the element 
             library, the best means of creating regions for survey spectra is 
             to use the Element Library dialog window   to create the 
             regions. Buttons labelled Create Regions are on both the 
             Element Table property page (Figure 3) and the Periodic Table                                                   
             property page. These Create Regions buttons use the set of             Figure 3: Element Library Dialog Window 
             element marks currently defined on the survey spectrum to    
             initialise a set of regions on the data. Figure 4 shows a survey 
                                                                                                                              4
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