The fit in Figure 1 is guided by the chemical formula for nylon. that a good fit is always achieved by a sufficient number of Gaussian-Lorentzian curves when optimized without constraints. The problem is 1Ĭopyright © 2006 Casa Software Ltd. Sadly, while central to XPS, peak fitting of line-shapes to spectra is far from simple and if treated as a black-box tool will almost always yield incorrect results. The C 1s spectrum clearly contains two chemically shifted C 1s peaks however the more subtle shifts associated with the peaks labelled CH2 are the reason peak fitting is an important tool in XPS.įigure 1: C 1s region measured using a Kratos Axis 165 from a nylon sample. Consider the XPS spectrum (Figure 1) of the carbon 1s electrons measured from a nylon sample the chemical formula for nylon indicates four chemical environments for a carbon atom. These chemically shifted peaks offer information about the chemistry of the surface. In terms of an XPS spectrum, the increase in counts as a function of kinetic energy associated with the excitation of a core level electron appears as an ensemble of peaks rather than a single peak. These variations in the initial and final state energy are due to the environment in which an atom is found and results in electrons ejected from the same element emerging with kinetic energy characteristic of the chemical state in which the element exists. Peak Fitting in XPS Small and sometimes not so small differences between the initial and final state of an atom when a core level electron is excited by an x-ray is fundamental to XPS as an analytical technique. Surface Analysis by Auger and X-Ray Photoelectron Spectroscopyįor further information please e-mail casaxps (at) surfacespectra.Copyright © 2006 Casa Software Ltd.If you would like to try out a free demonstration version email casaxps (at) The results of the data reduction are tabulated then made available in a convenient format for Microsoft products such as Word or Excel.įor more information visit the Casa Software website at Spectra presented in this ISO standard can be viewed, selected and processed in a simple yet powerful way. Although much of the functionality present in CasaXPS is available on the systems that accompany the XPS instruments, CasaXPS offers user-friendly data processing for anyone with a Pentium PC running Microsoft Windows 95 (or later).ĬasaXPS is a data browser for VAMAS (ISO 14976) Surface Chemical Analysis Standard Data Transfer Format. Computer Aided Surface Analysis for X-ray Photoelectron Spectroscopy (CasaXPS) has been written for research scientists who routinely work with XPS spectra.
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