De-excitation 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-core excitations at the K-edges has been investigated together with the Auger decay spectra using synchrotron radiation. The major Auger-decay channel following the 1s --> sigma* resonance excitation was KLL spectator 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 Cl+ ions scarcely desorb in the photon energy region where Cl-KLL normal Auger decay happens. This fact indicates that the spectator Anger decay is essential for the Cl+ desorption because the existence of the spectator electron in the antibonding sigma* orbital reduces the Si-Cl bonding character resulting in the fragmentation, Among the Cl 1s --> sigma* resonances, Cl+ desorption yield is high at the Cl 1s --> sigma*(8a(1)) resonance compared to that at the Cl 1s --> sigma*(9t(2)) resonance, The result is explained by the higher component of the antibonding 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* resonance excitation is faster than the core hole delay) which means that the Cl atom moves during the core life time, i.e. ultrafast non-Franfk-Condon-like dissociation happens.