Vibrationally resolved core-level photoelectron spectroscopy: Si 2plevels ofSiH4andSiF4molecules

High-resolution photoelectron spectra (total instrumental width ≤0.1 eV) of the Si 2p core levels of ${\mathrm{SiH}}_4$ and ${\mathrm{SiF}}_4$ were obtained using the Aladdin undulator source. The vibrationally resolved Si 2p photoelectron spectrum of ${\mathrm{SiH}}_4$ yields a Si-H stretching energy of 0.295±0.002 eV for the core-hole ion and a lifetime width of ∼45 meV. Numerous vibrational lines are observed in the ${\mathrm{SiF}}_4$ Si 2p photoelectron spectrum. The Z+1 core-equivalent model is assessed and changes in the molecular geometries and bonding properties of the molecules upon ionization are discussed.