Photon-stimulated ion desorption from condensed SiCl 4 by resonant excitation at the K-edges

Abstract

Photon-stimulated desorption of fragment and molecular ions from condensed SiCl 4 following the Si 1s and Cl 1s excitations has been investigated using synchrotron radiation. The Si +, Cl +, SiCl + and SiCl + 3 ions were observed almost in comparable intensity at the Si 1s excitation. The presence of atomic Si + ions is interpreted by the formation of SiCl n+ 4 ( n ≥ 3) ions through KLL and successive LVV Auger decay. On the other hand, more than 80% of the desorbed species were Cl + ions by the Cl 1s excitation, which suggests that the multiple charges produced by the Auger decay localize on the chlorine atom. The photon-energy dependence of the Cl + yield revealed that the Cl + yield at the Cl 1 s → σ ∗(8 a 1) resonance excitation is higher than that at the Cl 1 s → σ ∗(9 t 2) resonance excitation. It was also found that the excitation the energy higher than Cl 1 s → σ ∗ resonance scarcely induces the Cl + desorption. The high desorption yield at the Cl 1 s → σ ∗(8 a 1) resonance is interpreted by the fact that the 8a 1 orbital into which the Cl 1s electron is excited is mo composed of the Cl 3p∗ antibonding state, which reduces the binding energy of the SiCl bond.