Quantum dynamical studies for photodissociation of H2O2at 248 and 266 nm

摘要

A new quantum mechanical study on UV photodissociation of H2O2at 248 and 266 nm using a 2D fit to the Schinkendash;Staemmlerrsquo;s (SS) potential energy surface (PES) lsqb;Chem. Phys. Lett.145, 486 (1988)rsqb; is reported. The rotational distributions of the product OH on both theAtilde; andBtilde; surfaces are found to be considerably hotter than those obtained in a previous quantum study lsqb;J. Chem. Phys.98, 6276 (1993)rsqb; using an empirical PES with a very weak dependence on the torsional angle fgr;. The new calculation shows that the rotation distributions in both theAtilde; andBtilde; states are Gaussianlike with a maximum atj=8 on theAtilde; surface and atj=9 on theBtilde; surface at 248 nm. Similar distributions are found at 266 nm, but with the maximum shifting lower by approximately one quanta in both theAtilde; andBtilde; states. The dissociation preferentially produces OH rotations with a highj1sim;j2correlation. These conclusions are in excellent agreement with the classical calculation of Schinkendash;Staemmler at 193 nm photolysis. Although thejdistribution (rotation of OH) is similar on both surfaces, thej12(jdrarr;12=jdrarr;1+jdrarr;2) distribution, which reflects the vector correlation ofjdrarr;1andjdrarr;2, is quite different on two surfaces. Our calculation shows that theAtilde; surface gives rise to more bending excitation than theBtilde; surface, reflected by a hotterj12distribution on theAtilde; surface. TheAtilde; andBtilde; state branching ratio of H2O2is also evaluated at 248 and 266 nm photolysis.