Nonadiabatic effects in the photodetachment of ClH2(-)

The photoelectron spectra of the ClH2(-) and ClD2(-) anions have been simulated using a Franck-Condon model involving vertical excitation to the four coupled quasidiabatic potential energy surfaces that correlate with Cl(2P)+H2(1 Sigma g +). A careful analysis of the excitation process is presented. All electrostatic, spin-orbit, and Coriolis couplings in the photodetached ClH2 (ClD2) neutral are included. At a resolution of 1 meV, the resulting spectra are dominated by the bound and resonant states of the Cl...H2 and Cl...D2 van der Waals complexes, along with contributions from the associated continua. Only small differences occur between these spectra and those simulated under the assumption that each of the three electronically adiabatic Cl(2P)+H2 states can be treated separately. In particular, photodetachment to form the Cl*(2P 1/2)H2 complex leads to very low intensity of spectral features associated with Cl(2P 3/2)H2. This clearly implies that, while nonadiabatic effects do have some influence on the bound and resonance state energies of both complexes as shown recently by Garand et al. [Science 319, 72 (2008)], nonadiabatic transitions between the two complexes are extremely rare.