XPSPeak 4.1 is a free, lightweight software program designed for the analysis and deconvolution of X-ray Photoelectron Spectroscopy (XPS) data

Select your background type (Shirley is the most common for transition metals; Linear is often used for narrow, clean polymer peaks).

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is excellent for general scientific graphing and data analysis but is not XPS-specific. It lacks specialized functions like Shirley background subtraction or mixed Gaussian-Lorentzian peak shapes. Therefore, it's not recommended for rigorous XPS fitting. XPS Peak Fit 4.1 is specialized and provides the correct mathematical models for XPS data.

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“When I was a graduate student, I spent about 1000 hours on XPS peak fitting. In 1994, I wrote a program to convert Kratos XPS files to ASCII. Once that was done, I found the program could easily be converted into a peak‑fitting program.”

Accurate background estimation is the first and most critical step in XPS analysis. The program supports the most common background types:

Enter literature values for spin-orbit splitting, fix FWHM values within reasonable ranges (typically between 0.8 eV and 1.8 eV depending on system resolution), and lock necessary area ratios.

XPSPeak 4.1 is a legacy Windows application (originally for Win 95/98) but remains functional on modern systems. University of Warwick Direct Download

After fitting, export the peak parameters to a .par file. For a given element, sum the areas of all component peaks belonging to that element. Then divide each component’s area by the appropriate relative sensitivity factor (RSF) for that element. Compare normalized areas across elements to obtain atomic percentages.