UV and Visible Emission Spectra from the Photodissociation of Carbonyl Sulfide Using Synchrotron Radiation at 15–30 eV

The photofragmentation of OCS at photon energies of 15–30 eV has been studied by dispersed fluorescence spectroscopy. The primary photon beam was monochromatized undulator radiation supplied from the UVSOR facility. The following emission-band systems have been identified: OCS+[A2ΠΩ(0,0,0) → X2ΠΩ(0,0,v3′′)], CO+(A2ΠΩ → X2Σ+), CS+(B2Σ+ → A2ΠΩ), and CO(d3Δ → a3Π). All of the transitions, except for OCS+[A2ΠΩ → X2ΠΩ], were first observed in the vacuum UV photodissociation of OCS. The fluorescence excitation spectra for the OCS+[A2ΠΩ(0,0,0) → X2ΠΩ(0,0,v3′′)] and CS+(B2Σ+ → A2ΠΩ) transitions were measured in the photon energy range of 15.1–15.75 and 21.8–26 eV, respectively. The emission spectra obtained at 20.85 and 22.9 eV exhibit atomic transitions of S[nd3Do → 4p3Pe (n = 6–9)], which result from the neutral dissociation of superexcited Rydberg states of OCS into S(nd3Do) + CO. Possible excited states of the counterpart CO are discussed on the basis of the difference in the n distribution between the two spectra.