Abstract
Potential-energy curves of various electronic states of and are computed using all-electron ab initio molecular-orbital methods. Configuration-interaction effects are treated by perturbative techniques (using Möller-Plesset perturbation theory to fourth order) and by variational methods (using the coupled-cluster approach). In the case of , calculations indicate that the lowest-energy and states are nearly degenerate in the Franck-Condon region but that only the latter is likely to be metastable; the former is expected to predissociate rapidly due to a curve crossing with a purely repulsive state. Experimental measurements have been carried out on the kinetic energy released when metastable ions dissociate by a tunneling mechanism, using an ion-translational-energy spectrometer. The kinetic-energy spectra are measured of fragment ions produced when dissociates via an intermediate highly excited (dissociative) state populated in an electron-capture reaction in collision with He. The experimental results remain difficult to interpret within the framework of the computed potential-energy curves.
- Received 30 May 1991
DOI:https://doi.org/10.1103/PhysRevA.44.5460
©1991 American Physical Society