Ab initio zero electron kinetic energy spectroscopy of the ArCl- and KrCl-anions

The theory for calculating the energies and relative intensities of the pho todetachment transitions of the weakly bound diatomic anions is implemented for simulations of the zero electron kinetic energy spectra of the ArCl- a nd KrCl- anions using high-quality ab initio potentials. Its key features a re the reduction of the molecular electronic photodetachment transition dip ole moment matrix elements to the combination of atomic ones within the ato ms-in-molecule model and estimation of the latter by well-developed approac hes to the atomic photodetachment processes. The difference in the electron ic photodetachment transition dipole moments for distinct electronic states of the neutral, importance of vibrational-rotational coupling, and rotatio nal structure of vibronic bands are analyzed. It is shown that ab initio si mulations provide almost the same level of agreement with measured spectra as did the empirical potentials adjusted to reproduce the experimental data . The predictive power of the theory is demonstrated by the discovery of th e hidden transitions to the I3/2 state of KrCl which strongy overlap with t hose to X1/2 state. (C) 2001 American Institute of Physics.