DEEXCITATION IN SOLID SICL4 FOLLOWING DEEP-CORE EXCITATION AT THE K-EDGE - RELATION BETWEEN ION DESORPTION AND AUGER DECAY

Photon-stimulated ion desorption from solid SiCl4 following the deep-c ore excitations at the K-edges has been investigated together with the Auger decay spectra using synchrotron radiation. The major Auger-deca y channel following the 1s --> sigma resonance excitation was KLL spe ctator Auger decay, in which the excited electron remains in the sigma orbital during the Auger transition, The photon-energy dependence of the ion desorption yields around the Cl K-edge revealed that the Clions scarcely desorb in the photon energy region where Cl-KLL normal A uger decay happens. This fact indicates that the spectator Anger decay is essential for the Cl+ desorption because the existence of the spec tator electron in the antibonding sigma orbital reduces the Si-Cl bon ding character resulting in the fragmentation, Among the Cl 1s --> sig ma resonances, Cl+ desorption yield is high at the Cl 1s --> sigma*(8 a(1)) resonance compared to that at the Cl 1s --> sigma(9t(2)) resona nce, The result is explained by the higher component of the antibondin g Cl 3p in the 8a(1) orbital, Based on these results, it is concluded that the dissociation of the Si-Cl bond by the Cl 1s --> sigma reson ance excitation is faster than the core hole delay) which means that t he Cl atom moves during the core life time, i.e. ultrafast non-Franfk- Condon-like dissociation happens.