Ab initio study of XOClO₃ (X = Cl, F, and H): Implications for formation of ClOClO₃ in the stratosphere

Although OClO photolysis was one of the first photochemical reactions to be studied, the primary photochemistry of OClO still remains controversial. Several studies have demonstrated that Cl₂O₄ is one of the major photolysis products of OClO, in addition to ClO + O and ClOO. Thus there is a need to analyze the chemical properties of Cl₂O₄ and its related species. In the present study we have investigated the equilibrium structures and harmonic vibrational frequencies of chlorine perchlorate (Cl₂O₄), fluorine perchlorate (FOClO₃), and hydrogen perchlorate (HOClO₃) at Hartree-Fock and MP2 levels using 6–31G* basis set. Normal mode analysis has been carried out using ab initio derived force fields at the correlation level for the 6–31G* basis set. The calculated frequencies of XOClO₃ (X = Cl, F, and H) molecules are discussed in comparison with those determined from experiment and with the corresponding vibrations of Cl₂O₇. In addition, the paper draws attention to the possible role of C1₂O₄ formation in the polar stratosphere with relevance to ozone layer depletion.