The Absorption Spectrum of Carbonyl Selenide

Abstract

<p>The absorption spectrum of gas-phase carbonyl selenide (OCSe) in the infrared, ultraviolet and vacuum ultraviolet regions of the electromagnetic spectrum has been recorded under high resolution. A method of synthesis of the compound, which has been used in the preparation of selenium-isotope OCSe, has been described. A description of a novel light source, the emission continuum produced by which is suitable for absorption sepctroscopy of the ultraviolet and vacuum ultraviolet spectral regions, has been included. The ground state fundamental vibrational frequencies of carbonyl selenide have been determined. The spectrum in the ultraviolet and vacuum ultravioelt regions has been assigned to correspond to seventeen electronic transitions of OCSe. Vibrational analyses have been accomplished for each of these, and the symmetries and electron configurations of the excited electronic states have been assigned. The ionization potential of OCSe has been measured. The majority of these transitions have been shown to be Rydberg in nature, Quantum-mechanical calculations have been performed to predict the term values for Rydberg series members and to aid the analysis of the spectrum. The spin-orbit coupling in Rydberg states of OCSe has been shown to be intermediate between the cases (A,S) and (Ωc,ω) and to tend to the latter case as the ionization limit is approached. Some details of the spectra of the isoelectronic molecules OCS and CS2 have been included to support the analysis of the OCSe spectrum.</p>