Characterization of the electronic structure of SiCl4 probed by X-ray absorption and ion desorption techniques

The high-resolution Si L23-edge X-ray absorption near-edge structure (XANES) total electron yield (TEY) spectrum and Cl+ photon-stimulated ion desorption (PSID) spectrum of condensed SiCl4 have been measured in the energy range 102–115 eV. The CI+ PSID spectrum exhibits higher intensities than the TEY for the higher-energy peaks near 110 eV in the XANES spectrum of condensed SiCl, We assigned most of these higher-energy peaks to excitations of the Si 2p electron to Rydberg orbitals. The enhanced PSID intensities of Rydberg transitions originate from the lower degree of coordination of surface molecules. The non-statistical branching ratio in the L3L2 intensity is explained by the presence of the exchange interaction between the core hole with the excited electron. Due to the reduced electron-core exchange energy in the solid, the solid-bulk TEY and solid-surface Cl+ PSID spectra exhibit a larger L3L2 intensity ratio than the gas-phase absorption spectrum.