Temperature-dependent line broadening in core-level photoemission spectra from aluminum

The temperature dependence of the Al 2p line width and binding energy has been studied in the range from 80 K up to and beyond the Al bulk melting point (${\mathit{T}}_{\mathit{m}}$=933.5 K). By comparing the experimental data with results from calculations based on a nearest-neighbor force constant model, we find the phononic coupling to be of quadratic rather than linear nature as previously assumed. The temperature dependence of the Al 2p binding energy is interpreted on the basis of thermal expansion and phononic coupling.