Vibrational spectra and structures of bare and Xe-tagged cationic SinOm+ clusters

Abstract

Vibrational spectra of Xe-tagged cationic silicon oxide clusters SinOm+ with n = 3-5 and m = n, n +/- 1 in the gas phase are obtained by resonant infrared multiple photon dissociation ( IRMPD) spectroscopy and density functional theory calculations. The SinOm+ clusters are produced in a laser vaporization ion source and Xe complexes are formed after thermalization to 100 K. The clusters are subsequently irradiated with tunable light from an IR free electron laser and changes in the mass distribution yield size-specific IR spectra. The measured IRMPD spectra are compared to calculated linear IR absorption spectra leading to structural assignments. For several clusters, Xe complexation alters the energetic order of the SinOm+ isomers. Common structural motifs include the Si2O2 rhombus, the Si3O2 pentagon, and the Si3O3 hexagon. (c) 2014 AIP Publishing LLC.