A NUMERICAL-SIMULATION OF TOTAL REFLECTION X-RAY PHOTOELECTRON-SPECTROSCOPY (TRXPS)

Numerical simulations of "total reflection X-ray photoelectron spectroscopy (TRXPS)" are presented. Monochromatized X-rays impinge on a specular sample with a glancing angle smaller than the critical angle of total reflection. Under this condition, the X-rays cannot penetrate deeper than the evanescent length, usually 20-40 angstrom depending on the sample material, the wavelength of the X-rays, and the incident angle. The intensity of X-rays in the evanescent region can be as much as four times stronger than the incident X-ray intensity because of the standing-wave formation on the surface. Therefore, the photoelectron signal of atoms in the surface region is intensified. As a consequence, TRXPS is an even more powerful tool for the study of surface chemistry and physics than ordinary X-ray photoelectron spectroscopy (XPS). Moreover the signal to background ratio is improved at least twice if compared with that of the ordinary XPS because the number of inelastically scattered photoelectrons is reduced.