Spectroscopy of the AlAr van der Waals Complex: Rotationally Resolved B 2Sigma(+) yields X 2 Pi(1/2) Electronic Transitions

摘要

Diatomic van der Waals molecules consisting of metal atom bound to a rare gasatom (MRg) have received considerable attention in recent years. Studies of the electronic spectra of these molecules have led to determinations of the interatomic potential energy curves for both ground and electronically excited states. These data are of value as they may be used in the analysis of dynamical events such as collisional line broadening, electronic energy transfer, and molecular beam scattering. Additionally, spectroscopic characterization of these molecules provides a data base against which ab initio and semi-empirical theoretical models of weak bonding interactions may be tested. An interesting property of many MRg molecules in dramatic increase in binding energy, and decrease in the equilibrium internuclear separation, which accompanies electronic excitation. This occurs because bonding in the ground state is predominantly mediated by dispersion forces, while the stability of the excited state may be enhanced by increased metal atom polarizability, partial charge transfer, and orbital overlap effects. (JS)