Far-UV absorption spectra of SiH2 and dibridged Si2H2 isolated in solid argon

Shu-Yu Lin; Sheng-Lung Chou; Chien-Ming Tseng; Yu-Jong Wu

doi:10.1016/j.saa.2023.123060

Far-UV absorption spectra of SiH₂ and dibridged Si₂H₂ isolated in solid argon

Spectrochim Acta A Mol Biomol Spectrosc. 2023 Dec 5:302:123060. doi: 10.1016/j.saa.2023.123060. Epub 2023 Jun 20.

Authors

Shu-Yu Lin¹, Sheng-Lung Chou², Chien-Ming Tseng³, Yu-Jong Wu⁴

Affiliations

¹ Department of Applied Chemistry and Institute of Molecular Science, National Yang Ming Chiao Tung University, Hsinchu 300093, Taiwan.
² National Synchrotron Radiation Research Center, 101 Hsin-Ann Road, Hsinchu Science Park, Hsinchu 30076, Taiwan.
³ Department of Applied Chemistry and Institute of Molecular Science, National Yang Ming Chiao Tung University, Hsinchu 300093, Taiwan. Electronic address: cmtseng@nycu.edu.tw.
⁴ Department of Applied Chemistry and Institute of Molecular Science, National Yang Ming Chiao Tung University, Hsinchu 300093, Taiwan; National Synchrotron Radiation Research Center, 101 Hsin-Ann Road, Hsinchu Science Park, Hsinchu 30076, Taiwan. Electronic address: yjwu@nsrrc.org.tw.

PMID: 37399612
DOI: 10.1016/j.saa.2023.123060

Abstract

We employ electron bombardment during the deposition of an Ar matrix containing a small proportion of SiH₄ to generate various silicon hydrides. Subsequently, the irradiation of a matrix sample at 365 nm decomposes SiH₂ and dibridged Si₂H₂ in solid Ar, which we identify through infrared spectroscopy. We further recorded the corresponding ultraviolet absorption spectra at each experimental stage. An intense band observed in the range of 170-203 nm is largely destroyed upon 365-nm photolysis, which is assigned to the C¹B₂ ← X¹A₁ transition of SiH₂. Moreover, a moderate band observed in the region of 217-236 nm is reduced slightly, which is assigned to the 3¹B₂ ← X¹A₁ transition of dibridged Si₂H₂. These assignments are made based on the observed photolytic behavior, and the prediction of the vertical excitation energies with the corresponding oscillator strengths by using time-dependent density functional theory and equation-of-motion coupled cluster theory.

Keywords: Electronic transition; Excited states; Matrix isolation; Silicon hydrides.