The infrared spectra of OCS+ and OCS- trapped in solid neon

When a Ne:OCS sample was codeposited at approximately 5 K with a beam of ne on atoms that were excited in a microwave discharge, the infrared spectrum of the resulting deposit included absorptions which can be assigned to OCS, OCS-, and one or more dimer ions. Detailed isotopic substitution studies support the assignments offered for OCS+ and OCS-. The CO- and CS-stretchin g absorptions observed for OCS+ isolated in a neon matrix lie close to the corresponding gas-phase band centers. The CO- and CS-stretching fundamental s of OCS- isolated in solid neon were observed for the first time at 1646.4 and 718.2 cm(-1), respectively. These frequencies are in good agreement wi th values previously calculated using ab initio and density functional meth ods. The least-squares force constant fit to the data obtained in isotopic substitution experiments supports the proposed assignment. Dimer ions were also stabilized, but infrared data for these species were insufficient to p rovide definitive assignments. (C) 2001 American Institute of Physics.