Commonly Used X-ray Sources for XPS Analysis

For high-energy XPS studies, based on Cu Kai radiation hv = 8047.8 eV), an X-ray source has been constructed by Beamson et al. (2004). This source has been fitted to an ESCA electron spectrometer. The Fe Is and Cr Is core levels (at 7,112 and 5,989 eV binding energy, respectively) are readily observed at good resolution along with their KLL Auger series. It is concluded 

In dual Mg/Al X-ray tube, the anode is bombarded by electrons emitted from two independent filaments that are held at ground potential. The acceleration of electrons is caused by the positively biased anode at 15kV. The accelerated electrons hit only the nearest anode face. These electrons produce core holes in the anode target materials by electron impact ionization. The vacancies can relax by emission of characteristic X-rays that illuminate the sample. By switching the filament, one can get MgKa E = 1253.6eV ) or AlKa ( x = 1486.6 eV) lines with inherent resolution (AF fwhm) of 0.7eV 

Hawn (1983) has described the performance of a dual-anode X-ray source for XPS using various un-collimated and collimated configurations to make it effective in increasing the signal-to-background ratio and reducing anode cross talk without substantial signal loss. 

Out of about 40 synchrotron light sources of the world, six are in USA, four in Germany and an equal number in Japan. Many of the European countries and big Asian countries including UK, France, Italy, Switzerland, Denmark, Sweden, Spain, India, China, Korea, and Thailand have their own synchrotron facilities, SR source is also available in Australia and Russia. 

Kartio et al. (1994) and Laajalehto et al. (1997) have described the use of SR for exciting X-ray photoelectron spectra. The surface sensitivity of the measurement using SR is essentially better than the sensitivity obtained using AIK a or MgKa. However, the damage of the sample surface during the measurement may easily occur, probably, by sample heating when SR excitation is used. 

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