Spectroscopy and MRCI calculations on CrF and CrCl

Abstract

The B 6Π–X 6Σ+ band system of the CrCl radical has been recorded in thermal emission with FTS techniques in the region 6900–11 700 cm−1, using a resolution of 0.025 cm−1. An analysis of the (0,0) band of this system has been carried out. A rotational constant of B0=0.1615 cm−1 and a spin–orbit parameter of A0=51 cm−1 have been estimated for the B 6Π state. Improved values for the γ and λ parameters of the X 6Σ+ ground state have been obtained. MRCI calculations have been performed on CrF and CrCl and comparisons have been made with both experiments and DFT calculations [Bencheikh et al., J. Chem. Phys. 106, 6231 (1997)]. The calculations on CrF have provided valuable aids in the interpretations of the fluorescence excitation and dispersed fluorescence spectra of a state observed at 31 700 cm−1. This state has now been assigned as D 6Π. A number of transitions in the dispersed fluorescence spectra are believed to involve the hitherto unknown C 6Δ state. Spin–orbit-configuration-interaction (SO-CI) calculations have been carried out on both CrF and CrCl. It is shown that the second-order spin–orbit parameters λe of the X 6Σ+ ground states are due mainly to interactions with the B 6Π states.