title: Spectroscopic and theoretical characterization of the A2delta-X2pi transition of CH-Ne.
abstract: The A2delta-X2pi transition of CH-Ne was examined using laser-induced fluorescence and fluorescence depletion techniques. The spectrum was found to be particularly congested due to the large number of bound states derived from the CH(A,n=2)+Ne interaction, and the small energy spacings between these states resulting from the relatively weak anisotropy of the van der Waals bond. High-level ab initio calculations were used to generate two-dimensional potential energy surfaces for CH(X)-Ne and CH(A)-Ne. The equilibrium structures from these surfaces were bent and linear for the X and A states, respectively. Variational calculations were used to predict the bound states supported by the ab initio surfaces. Empirical modification of the potential energy surfaces for the A state was used to obtain energy-level predictions that were in good agreement with the experimental results. Transitions to all of the optically accessible internal rotor states of CH(A,n=2)-Ne were identified, indicating that CH performs hindered internal rotations in the lowest-energy levels of the A and X states. The characteristics of the potential energy surfaces for CH-Ne in the X,A,B, and C states suggest that dispersion and exchange repulsion forces dominate the van der Waals interaction.
authors.affiliation: Department of Chemistry and Cherry L. Emerson Center for Scientific Computation, Emory University, Atlanta, Georgia 30322, USA.
authors.forename: Galina
authors.initials: G
authors.lastname: Kerenskaya
authors.forename: Udo
authors.initials: U
authors.lastname: Schnupf
authors.forename: William H
authors.initials: WH
authors.lastname: Basinger
authors.forename: Michael C
authors.initials: MC
authors.lastname: Heaven