ON THE ROLE OF CONICAL INTERSECTIONS OF 2 POTENTIAL-ENERGY SURFACES OF THE SAME SYMMETRY IN PHOTODISSOCIATION .2. CH3SCH3-]CH3S+CH3

Methyl disulfide, CH3SCH is known to exhibit a strong absorption in the 190-210 nm region leading to photofragmentation to CH3S and CH3. The role of conical intersections of two states of the same symmetry in this photodissociation process CH3SCH3(X(1)A(1)) --> CH3SCH3(1,2(1)A'') --> CH3(X(2)A') + CH3S(X(2)E) is considered. Points on a surface of conical intersections of the 1,2(1)A'' states in the vicinity of the Franck-Condon region of the X(1)A(1) state, accessible with 190-210 nm photons, are determined using configuration interaction wave functions comprised of over 1.2 million configuration state functions. These conical intersections provide an efficient path for the 2(1)A'' state to photodissociate to ground state fragments.