Quick Overview #
CasaXPS is a powerful tool for the quantification of photoelectron spectroscopy data, and here we walk you through how to take your basic data, and start to extract some quantification from it.
Relative Sensitivity Factors #
Relative sensitivity factors (RSFs) in X-ray photoelectron spectroscopy (XPS) are calibration coefficients that account for differences in the efficiency of detecting electrons from various elements and orbitals. These factors are crucial for converting XPS peak intensities into meaningful quantitative elemental concentrations.
In order to ensure accurate quantification, the correct library files must be loaded into CasaXPS. Library files can be found in the ‘Library’ (F10) window, in the ‘Input File’ tab – after selecting ‘Brose Lib. Dir.’
If running using a Kratos instrument, use the CasaXPS_Kratos.lib file. If running using a Thermo instrument, the default file loaded with CasaXPS, using schofield factors, can be used.
Quantifying Wide/Survey Spectra for Known Elements #
If you know what you have in your sample, or you are looking to quantify a certain selection of elements, the Library window (periodic table tab) can be used to add specific elements, and generate quantification regions, and add a quantification table as an annotation in a single click!
Quantifying Wide/Survey Spectra for Unknown Elements #
The library window is also very useful for identifying unknown elements. In the ‘Element Table’ tab, you can click on any part of the spectrum and see which peaks come around this energy range. From here, clicking on an element/orbital will add the peak markers and clicking on ‘Create Regions’ will insert quantification windows, and add a quantification table as before.
Adding Quantification Regions Directly #
If you already know what peaks you have, and where they come, you can also add quantification regions directly, by opening the Quantify (F7) window, and in the ‘Regions’ tab, clicking create. From here, drag and drop the region around the sides of the peak, and name the peak the correct element and transition. Once you have correctly named the peak, you can type ‘#’ (without quotation marks) into the RSF field, and hit enter. This will grab the correct sensitivity factor from the library.
You can view the quantification in the columns in the regions tab. Check the row labelled % Concentr.
You can add a quantification table using the Tile Annotation window (Quantification tab, apply).
