Line shape asymmetry of 2p core level photoemission spectrum of Al(001) single crystal

The Al 2p photoemission spectrum has been measured at low temperature (35 K) with a resolution of 112 meV using synchrotron radiation. From the observed spectrum, the surface component lines were clearly resolved from the bulk. The spectral line shape has been analyzed by a least-squares-fitting method, and the precise values of the singularity index, the lifetime width and the spin-orbit splitting were obtained. We found that the singularity index is 0.058 ± 0.002 and is considerably smaller than those reported previously. (author)