Potential-energy curves, Franck–Condon factors and laser excitation spectrum for the B3Π(0+)–X1Σ+system of chlorine monofluoride

Abstract

A scannable nitrogen-pumped dye laser has been used to excite fluorescence in the B3Π(0+)–X1Σ+ system of chlorine monofluoride. Low resolution excitation spectra have been obtained for the first time by scanning the wavelength of the dye laser, with 0.01 nm bandwidth, from 465 to 520 nm. This region covers B–X transitions with 17 v′ 3; however, no fluorescence following excitation of levels with v′ 10 has been observed. Onset of predissociation as evidenced by a break-off in the excitation spectrum was observed at v′, J′= 9,23 which provides an upper limit for the ground-state dissociation energy of 35ClF, D″0⩽ 21 126 ± 6 cm–1.Values of the spectroscopic constants for the B3Π(0+) and X1Σ+ states of ClF have been evaluated. These have then been used to derive the RKR potential functions which in turn were used to calculate r-centroids and Franck–Condon factors for the B–X system.