Infrared spectra of two isomers of protonated carbonyl sulfide (HOCS+ and HSCO+) and t-HOCS in solid Para-hydrogen

Abstract

We report infrared (IR) spectra of HOCS+, HSCO+, t-HOCS, and other species produced on electron bombardment of a mixture of carbonyl sulfide (OCS) and para-hydrogen (p-H-2) during deposition at 3.2 K. After maintenance of the matrix in darkness for 15 h, the intensities of absorption features of HOCS+ at 2945.9 (nu(1)), 1875.3 (nu(2)), and 1041.9 (nu(3)) cm(-1) and those of HSCO+ at 2506.9 (nu(1)) and 2074.2 (nu(2)) cm(-1) decreased through neutralization with trapped electrons. Lines observed at 3563.4, 1394.8, and 1199.0 cm(-1), which decreased slightly in intensity after maintenance in darkness and were nearly depleted after irradiation at 373 nm, are assigned to a t-HOCS radical. The corresponding spectra of their C-13- and D-isotopologues were observed. The IR spectra of HSCO+ and t-HOCS and those of modes nu(2) and nu(3) of HOCS+ are new. The assignments were made according to the expected chemical behavior and a comparison of experimental and calculated wavenumbers and C-13- and D-isotopic shifts. The wavenumber of the OH stretching mode (2945.9 cm(-1)) of HOCS+ in solid p-H-2 is significantly red-shifted from that (3435.16 cm(-1)) reported for gaseous HOCS+; this shift is attributed to partial sharing of a proton between OCS and H-2. The corresponding p-H-2 induced shift is small in HSCO+ because of a much weaker interaction between HSCO+ and H-2. Published by AIP Publishing.