A mixture of O(3) and CO(2) was irradiated with light from a KrF laser at 248 nm; time-resolved infrared emission of CO(2) in the region 2000-2400 cm(-1) was observed with a Fourier transform spectrometer. This emission involves one quantum in the asymmetric stretching mode (nu(3)) of CO(2) in highly vibrationally excited states. The band contour agrees satisfactorily with a band shape calculated based on a simplified polyad model of CO(2) and a vibrational distribution estimated through a statistical partitioning of energy of approximately 13,000 cm(-1), approximately 3100 cm(-1) smaller than the available energy, into the vibrational modes of CO(2). From this model, approximately 44% and 5% of the available energy of O((1)D) + CO(2) is converted into the vibrational and rotational energy of product CO(2), respectively, consistent with previous reports of approximately 50% for the translational energy. An extent of rotational excitation of CO(2) much smaller than that expected from statistical calculations indicates a mechanism that causes a small torque to be given to CO(2) when an O atom leaves the complex CO(3) on the triplet exit surface of potential energy, consistent with quantum-chemical calculations.

Irradiation of an Ar matrix sample containing H2S and CO (or OCS) with an ArF excimer laser at 193 nm yields trans-HSCO (denoted t-HSCO). New lines at 1823.3, 931.6, and 553.3 cm(-1) appear after photolysis and their intensity enhances after annealing; secondary photolysis at 248 nm diminishes these lines and produces OCS and CO. These lines are assigned to C-O stretching, HSC-bending, and C-S stretching modes of t-HSCO, respectively, based on results of 13C-isotopic experiments and theoretical calculations. Theoretical calculations using density-functional theories (B3LYP and PW91PW91) predict four stable isomers of HSCO: t-HSCO, c-HSCO, HC(O)S, and c-HOCS, listed in increasing order of energy. According to calculations with B3LYP/aug-cc-pVTZ, t-HSCO is planar, with bond lengths of 1.34 A (H-S), 1.81 A (S-C), and 1.17 A (C-O), and angles angle HSC congruent with 93.4 degrees and angle SCO congruent with 128.3 degrees; it is more stable than c-HSCO and HC(O)S by approximately 9 kJ mol(-1) and more stable than c-HOCS by approximately 65 kJ mol(-1). Calculated vibrational wave numbers, IR intensities, and 13C-isotopic shifts for t-HSCO fit satisfactorily with experimental results. This new spectral identification of t-HSCO provides information for future investigations of its roles in atmospheric chemistry.

Irradiation of an Ar matrix sample containing O(3) and CS(2) with a KrF excimer laser at 248 nm yielded new lines at 1402.1 (1404.7), 1056.2 (1052.7), and 622.3 (620.5) cm(-1); numbers in parentheses correspond to species in a minor matrix site. Secondary photolysis at 308 nm diminished these lines and produced mainly OCS and SO(2). Annealing of this matrix to 30 K yielded a second set of new lines at 1824.7 and 617.8 cm(-1). The first set of lines are assigned to C=S stretching, O-S stretching, and S-C stretching modes of carbon disulfide S-oxide, OSCS; and the second set of lines are assigned to C=O stretching and OCS bending modes of dithiiranone, O(CS(2)), respectively, based on results of (34)S- and (18)O-isotopic experiments and quantum-chemical calculations. These calculations using density-functional theory (B3LYP/aug-cc-pVTZ) predict four stable isomers of OCS(2): O(CS(2)), SSCO, OSCS, and SOCS, listed in order of increasing energy. According to calculations, O(CS(2)) has a cyclic CS(2) moiety and is the most stable isomer of OCS(2). OSCS is planar, with bond angles angle OSC congruent with 111.9 degrees and angle SCS congruent with 177.3 degrees ; it is less stable than SSCO and O(CS(2)) by approximately 102 and 154 kJ mol(-1), respectively, and more stable than SOCS by approximately 26 kJ mol(-1). Calculated vibrational wave numbers, IR intensities, (34)S- and (18)O-isotopic shifts for OSCS and O(CS(2)) fit satisfactorily with experimental results.