High-resolution laser excitation spectroscopy. Analysis of the B²Σ⁺-X²Σ⁺ system of CaCl

Single-mode cw dye laser excitation spectra of the (0, 0), (1, 1), and (2, 2) bands of the B²Σ⁺-X²Σ⁺ system of CaCl have been observed and assigned. Some 300 independent photo-luminescence spectra have been used in making the rotational assignment and demonstrate the power of the technique of line-by-line analysis in unraveling complex spectra. Spectroscopic constants (cm^-1) obtained from a weighted least squares fit of the data are given below. Numbers in parentheses refer to 95% confidence limits in the last digit. {A table is presented} The ground-state rotational constant is in excellent agreement with the previous value obtained from the analysis of the C²Π_r-X²Σ⁺. The B-state spin-rotation interaction constant is consistent with the pure precession estimate of the interaction between the A²Π_r and B²Σ⁺ states, which, in the one electron approximation, both have the unpaired electron in a calcium 4p orbital.