Spectroscopic and theoretical studies of ThCl and ThCl+

摘要

The electronic structures of ThCl and ThCl+ have been examined using laser induced fluorescence and two-photon ionization techniques. Rotationally resolved spectra, combined with the predictions from relativistic electronic structure calculations, show that the ground state of the neutral molecule is Th+(7s(2)6d)Cl-, X-2 Delta(3/2). Dispersed fluorescence spectra for ThCl revealed the ground state vibrational levels nu = 0-10 and low energy electronic states that also originate from the atomic ion 7s(2)6d configuration. Pulsed field ionization-zero kinetic energy photoelectron spectroscopy established an ionization energy (IE) for ThCl of 51344(5) cm(-1), and the ThCl+ vibrational term energies of the nu = 1-3 levels. The zero-point level of the first electronically excited state was found at 949(2) cm(-1). Comparisons with high-level theoretical results indicate that the ground and excited states are Th2+(7s6d)Cl- X-3 Delta(1) and Th2+(7s2)Cl-1 Sigma(+), respectively. Relativistic coupled cluster composite thermochemistry calculations yielded an IE within 1.2 kcal/mol of experiment and a bond dissociation energy (118.3 kcal/mol) in perfect agreement with previous experiments. Published by AIP Publishing.