Vibrational excitation, hole delocalization, and photoelectron line shapes of molecules

Certain aspects of hole dynamics in electron spectroscopies of quasilocalized states in the condensed phase define the area of concern in this paper. Of special interest are the possible interference effects between low-energy shakeup satellite (electron-hole pairs, phonons, etc.) production and hole decay processes which determine the observed line shapes. As a specific example, the role and interplay of gas-phase Franck-Condon factors and substrate-induced hole delocalization in determining the photoemission line shape from nonchemisorption bonding-valence orbitals in adsorbed and free-space molecules are considered here. The present theory is discussed in the light of recent theoretical work on phonon broadening and hole decay in core-level x-ray emission, absorption, and photoelectron spectroscopy.