If you ion etch more than that, then you risk changing the chemistry of your surface. After collecting a useful set of chemical state spectra, then you can ion etch the surface, but you should only remove the adventitious carbon layer which is at most 50 ang thick. In general, it is not useful to ion etch any chemical compound before analyzing it. We opted to collect a fast survey and fast chemical state spectra and then repeat with longer scans to check for X-ray induced degradation. All pure elements, except for Silicon, Selenium and single crystals, were ion etched prior to analysis. The details of the experimental protocol used to produce each these spectra are provided in the “Data Collection and Analysis Details” section. The strong signals observed in the wide scan survey spectra are labeled and tabulated together with rough BE values of those strong signals. All narrow scan spectra are peak-fitted to reveal FWHM, peak asymmetry, and peak separation for spin-orbit pairs. If the element is part of insulating chemical compound, then a C (1s) spectrum is included to allow the user to correct for sample charging or remove charge correction. No attempt was made to produce research grade spectra, but many of the spectra are actually research grade spectra because of the self-consistent methods used. These spectra are designed to be practical tools for everyday use and were obtained under practical working conditions. We believe that these spectra will help XPS users to analyze industrial problems, gather reference data, perform basic research, test theories, and teach others. The spectral data contained within this database are designed to assist engineers, scientists, analysts, theoreticians, and teachers who use XPS on an everyday basis under practical working conditions. For practical reasons we used the C (1s) spectra from the naturally formed layer of adventitious hydrocarbons because that signal is the “de facto” standard for charge referencing insulating materials. We have assumed that the most XPS laboratories need practical reference spectra and will not spend the time or money to produce and to analyze pure, clean surfaces under ultimate energy resolution conditions. Our philosophy is to collect spectra under analysis conditions that are practical, readily reproduced, and typically used in laboratories that use monochromatic X-ray sources and work under real world practical analysis conditions. Philosophy for Peak-fitting and Data Processing
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