Studies of BrCl by laser-induced fluorescence. Part 1.—Excitation spectra and predissociation in the excited B3Π(0+) state

Abstract

A narrow-bandwidth, nitrogen-pumped dye laser has been used to excite fluorescence in the B3Π(0+)–X1Σ+ system of BrCl. Excitation spectra of BrCl showing rotationally-resolved lines (1 pm resolution) have been obtained for the first time by continuously scanning the frequency of the dye laser. The transition probabilities are low; only bands with 3 ⩽v′⩽ 7 and v″= 1 and 2 have been detected. No fluorescence following excitation of v′ 8 has been observed; this result is discussed in terms of the predissociation caused by the interaction of an 0+ state with the B state. All rotational levels in the v′= 7 energy state are predissociated, and a new upper limit for the dissociation energy of BrCl, D″0⩽ 18 035 cm–1, is obtained.