Origin of the 454 nm bound→free absorption band of cadmium monoiodide (114CdI).

The bound→free absorption band recently observed in a 114CdI laser discharge [Greene and Eden, Opt. Comm. (1985)] is shown to arise from absorption by the B 2Σ excited state of 114CdI to a previously unobserved level lying ∼4.3×104 cm-1 above ground. Pumping of the absorptive transition with a pulsed blue dye laser strongly suppresses gain (and, hence, laser output power) on the B→X band in the red (657 nm). Therefore, this constitutes the first known report of an ionic excited state→covalent absorption band [i.e., (M+X-)+hω→M*+X; M, X=metal and halogen atoms, respectively] for any of the group IIB metal halides or rare gas–halide laser molecules. Also, ωe for the B 2Σ state of 114CdI is >=110 cm-1 (considerably larger than an existing value in the literature) and the terminal level for this blue absorption band is tentatively assigned to a dissociative 2Σ state correlated with the Cd(5p 3PJ)+I separated atom limit. [ABSTRACT FROM AUTHOR]