화학공학소재연구정보센터
Journal of Chemical Physics, Vol.106, No.16, 6538-6547, 1997
The Photodissociation Dynamics of Oclo Between 306 and 370 nm - Fragment Translational Energy-Release and Recoil Anisotropy
The photodissociation OClO((A) over tilde (2)A(2))-->ClO((X) over tilde(2)II)+O(P-3) was studied at wavelengths between 306 and 370 nm using photofragment translational energy spectroscopy. The flight time distributions and anisotropies of the recoiling fragments were measured with the photolysis wavelength tuned to 10 maxima of the structured absorption spectrum, corresponding to a vibronic excitation of the parent molecule with 9-18 quanta in the symmetric stretching coordinate on the (A) over tilde(2)A(2) surface, The translational energy distributions show that the ClO fragments are created in highly inverted vibrational state distributions which become extremely broad [v(Cl-O)similar to 1-15] with increasing excitation energy. The large fraction of vibrationally hot ClO fragments produced-particularly at lambda<325 nm-could enhance various thermodynamically unfavorable atmospheric reactions in connection with ozone depletion, The main mechanistic features of the dissociation process, which account for the almost constant average translational energy and linearly increasing vibrational energy of ClO as a function of the excitation energy, can be interpreted, to a first approximation, as vibrational predissociation on the (A) over tilde (2)A(2) potential energy surface involving a relatively late exit barrier. From the measured translational energies the barrier height is estimated to be about 48 kJ/mol.