AN EXPERIMENTAL-STUDY ON THE PHOTOCHEMISTRY AND VIBRATIONAL SPECTROSCOPY OF 3 ISOMERS OF CL2O2 ISOLATED IN CRYOGENIC MATRICES

Chloryl chloride, ClClO2, isolated in cryogenic matrices is subjected to photolysis, producing chlorine chlorite, ClOClO, which in turn is converted into dichlorine peroxide, ClOOCl. ClOClO is also formed by the reactions C1 + OClO and ClOCl + O. The products are identified by means of FTIR spectroscopy using Cl-35/37 and O-16/18 isotopic shifts, with the aid of vibrational spectra of related molecules and results of ab initio calculations. The thresholds for photodecomposition of ClOClO, ClClO2, and ClOOCl isolated in an argon matrix are above wavelengths of 665, 610 and 360 nm, respectively. Two dissociation channels are observed for both ClOClO and ClOOCl. For ClOClO they are (i) Cl + OClO, leading to ClClO2;and (ii) 2ClO, yielding ClOOCl. For ClOOCl they are (i) ClOO + Cl, resulting in Cl-2 + O-2, and (ii) 2ClO, giving rise to ClOClO. The observation of two photolysis paths for ClOOCl is of importance for the catalytic ozone depletion in the polar stratosphere. Irradiation of ClClO2 isolated in a neon matrix resulted in Cl-2 + O-2 as the only products. The UV spectra of ClClO2 in the gas phase and in a neon matrix are reinvestigated. Lower limits for the integral band strengths of ClOClO and ClOOCl are derived relative to those of ClClO2. The vibrational data of this study, in conjunction with results of submillimeter spectroscopic investigations, are used to calculate a general valence force field for ClOOCl.