10min:

R. LAWRUSZCZUK, J. ROSTAS AND B. SOEP, Laboratoire de Photophysique Moléculaire, Université Paris Sud, 91405 Orsay Cédex, France.

The B'² states of CaF and CaCl have been excited directly, under specific experimental conditions, through the B'²-X²⁺ forbidden transition, and detected by collecting the A-X or B-X fluorescence. Rotational analysis of the B'-X(0-0) band provides accurate molecular parameters in good agreement with those obtained previously by Verges et al. in the case of CaF. For CaCl, the B'² state, observed for the first time lies at 19232 cm^-1 above the ground state, in excellent agreement with its position (19319 cm^-1) predicted by the Ligand Field Theory. The spin-orbit coupling constant A^SO for CaF and CaCl are close, indicating that the molecular structure is mainly governed by the Ca⁺ metal ion and only slightly by the ligand. Several excitation and deexcitation mechanisms, which may contribute, will be discussed.