Knowledge Bank

The $B\prime 2\Delta$ states of CaF and CaCl have been excited directly, under specific experimental conditions, through the $B\prime 2\Delta -X2\Sigma +$ forbidden transition, and detected by collecting the A-X or B-X fluorescence. Rotational analysis of the $B\prime -X(0-0)$ band provides accurate molecular parameters in good agreement with those obtained previously by Verges $etal.a$ in the case of CaF. For CaCl, the $B\prime 2\Delta$ state, observed for the first time lies at $19232cm-1$ above the ground state, in excellent agreement with its position $(19319cm-1)$ predicted by the Ligand Field Theory. The spin-orbit coupling constant $ASO$ 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.