Abstract
X-ray photoelectron spectroscopy (XPS) has recently been used in various industrial fields because it is a useful analytical method for investigating the nature of the chemical bonding at the surfaces and interfaces of defective products and materials. An analysis of an XPS spectrum requires both the background estimation and peak separation with the results of the analysis generally depending on the restrictions chosen by the analyst. This analyst dependence is one of the biggest problems for the wider practical use of XPS analysis.
To solve this problem, we have recently developed a new algorithm based on the active Shirley method that can effectively estimate both the shape of the background and the automatic peak fitting in the XPS spectrum analysis.
Nevertheless, the new method is still invalid for the application to the XPS spectra that show a large intensity differ ence between the starting point and ending points. In such an XPS spectrum, the estimated background almost intersects to XPS spectrum. The cause of this intersection was found to be the intersection between a tentative background that was initially estimated by the Shirley method and the XPS spectrum. To improve the method, we have introduced a new algorithm that properly selects both initial endpoints for deriving a proper background without intersecting the XPS spectrum. The improved method was named “an active Shirley method with auto-tuning function of
both initial endpoints”.
Using our improved algorithm, we have successfully obtained a better background shape compared to the shape obtained by the active Shirley method. In particular, we could estimate a background without an intersection with the divalent Cu 2p XPS spectrum that shows partial overlap with an Auger peak.
