ISSN:
1089-7690
Source:
AIP Digital Archive
Topics:
Physics
,
Chemistry and Pharmacology
Notes:
We present quantitative results on photodissociation of CH2(X˜ 3B1) through the coupled2A′′ and 3A′′ states. A three-dimensional, hybrid quantum dynamical method was used, employing hyperspherical coordinates. The diabatic potential energy surfaces (PES's) used in the dynamics were derived from ab initio calculations. A small product fraction (2.7%) was computed for the CH(A 2Δ)+H channel, in agreement with experiment and approximate dynamical calculations. The dissociation proceeds mostly on a A2-like diabatic surface, into CH(a 4Σ−)+H(93.3%) andC(3P)+H2(4.0%). Resonances of widths in the range 0.1–10 meV affect the photodissociation. Pre-exciting a vibrational mode of CH2(X˜ 3B1) prior to photodissociation does not alter the picture, except if the antisymmetric stretch mode is excited: In this case the product fractions for the C(3P)+H2 andCH(A 2Δ)+H channels collapse to values of 1% or lower, and the resonances disappear. Model calculations show that the large product fraction found for CH(a 4Σ−)+H is due to the initial motion on the "bright"B1-like surface, which biases the outcome of the dissociation in favor ofCH(a 4Σ−)+H. © 1997 American Institute of Physics.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1063/1.475130
