Experimental and theoretical investigation of the c 1Π–a 1Δ transition of NH/D–Ne

Abstract

A study of NH/D–Ne was undertaken to investigate the structure of this complex and examine the ability of high-level theoretical methods to predict its properties. The c 1Π–a 1Δ transition was characterized using laser induced fluorescence measurements. Spectra recorded in the vicinity of the monomer show groups of complex features associated with the monomer P(2), Q(2), and R(2) lines. The present study focused on the low-energy bands associated with P(2). Results from theoretical calculations were used to guide the interpretation of the spectra. Two-dimensional potential energy surfaces were calculated using second-order multireference perturbation theory with large correlation consistent basis sets. The potential surfaces were used to predict the rovibronic structure of the c–a system. Calculated rovibronic energy level patterns could be recognized in the spectra but quantitative discrepancies were found. For the a and c states the ab initio potentials were found to be too shallow, and for the c state the equilibrium intermolecular separation was too short. These errors are attributed to incomplete recovery of the dynamical correlation energy.