First observation and electronic spectroscopy of chromium mononitride: The A(4)Pi(r)<-X(4)Sigma(-) transition near 745 nm

We report the first gas phase spectroscopic study of chromium mononitride. CrN molecules were generated in our laser vaporization molecular beam source and studied using laser induced fluorescence techniques. Twelve vibronic subbands of (CrN)-N-14 have been rotationally analyzed in the 745-647 nm region. These bands are assigned to the A (4) Pi(r) <-- X (4) Sigma(-) transition. The assigned ground-state electron configuration 1 delta(2)9 sigma(1) and symmetry are identical to those of the isovalent VO, MoN, and WN molecules. The energy observed for the excited (4) Pi(r) state matches closely the first (4) Pi state energy derived from recent ab initio calculation [J. F. Harrison, J. Phys. Chem: 100, 3513 (1996)]. In addition to the A-X transition, 11 other bands of (CrN)-N-14 have been identified and vibrationally assigned to transitions involving two other excited states, presumably the B-4 Sigma(-), and a (2) Pi state. Comparisons with the isovalent VO, MoN, and WN systems have provided more insights into the bonding and electronic structure of the CrN molecule. (C) 1997 American Institute of Physics.