Core-level lifetimes as determined by x-ray photoelectron spectroscopy measurements

X-ray photoelectron spectroscopy (XPS) has been used to measure lifetime broadening of L, M, N, O, and P core levels with binding energies less than 1500 eV in approximately 25 elements. The results show that the framework provided by previously accepted theoretical estimates of lifetime broadening is sometimes misleading. Lifetimes derived from theory and experiment often differ by a factor of 2 or more. In the transition metals of the first period plots of measured widths of the L₁ (2s), L₂ (2p₁₂), and L₃ (2p₃₂) levels as a function of atomic number show broad maxima which are not adequately described by theory. The origin of this broadening is extensively discussed, as is the overestimation of lifetimes by theory in other areas of the periodic table.