ISSN:
1089-7690
Source:
AIP Digital Archive
Topics:
Physics
,
Chemistry and Pharmacology
Notes:
Full three-dimensional adiabatic potential energy surfaces are presented for the lowest five 3A‘ and five 3A' states of CH2. Both the 1 3A' and 2 3A‘ states are dissociative with respect to the C–H coordinates, consistent with our earlier two-dimensional results. All higher lying states are found to be bound for this coordinate, although the barrier toward dissociation is small for some states. In terms of angle dependence, the 1 3A' state shows a flat behavior, but tends towards larger angles as dissociation proceeds. Most excited 3A' states are somewhat bent with only a small barrier to linearity. Transition dipole moments connecting the ground state with the excited triplet states are presented as well. The 1 3A' state is the only state of that symmetry with a large transition dipole moment in the Franck–Condon region. Other 3A' states exhibit large values only if one bond is stretched compared with the ground state equilibrium geometry. The 1 3A‘, 3 3A‘, and 4 3A‘ states are also slightly bent with a small barrier to linearity. However, the 2 3A‘ state has an absolute minimum at very small angles (less than 60°), and shows a considerable local minimum (∼1.5 eV) for the linear configuration. The 5 3A‘ state prefers the linear shape. The 3 3A‘ state has the largest transition dipole moment function in the Franck–Condon region, but the transition moments to other 3A‘ states can exhibit large values outside this region. The 2 3A‘ and 3 3A‘ states undergo an avoided crossing in the Franck–Condon region, so that a coupled states treatment is necessary for a correct description of the photodissociation dynamics. In order to provide the corresponding transition dipole moments in an appropriate form, a transformation to the principal axes of inertia was performed. The adopted transformations are discussed in detail. © 1995 American Institute of Physics.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1063/1.468947
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