Characterization of the Ground State of Br(2) by Laser-Induced Fluorescence Fourier Transform Spectroscopy of the B(3)Pi(0(+))(u)-X(1)Sigma(+)(g) System.

The laser-induced fluorescence (LIF) spectrum of the B(3)Pi(0(+))(u)-X(1)Sigma(+)(g) system of Br(2) was recorded by Fourier transform spectroscopy (FTS). The LIF spectra were obtained by using continuous-wave dye laser excitation in the spectral region 16 800-18 000 cm(-1). About 1800 rotationally resolved lines were recorded in 96 fluorescence progressions, originating from the 10 </= v' </= 22 vibrational levels of the B(3)Pi(0(+))(u) state and involving the 2 </= v" </= 29 levels of the X(1)Sigma(+)(g) ground state of the three isotopomers of bromine, (79)Br(2), (81)Br(2), and (79,81)Br(2). These data, together with (79)Br(2) data from a previous FTS absorption study [S. Gerstenkorn, P. Luc, A. Raynal, and J. Sinzelle, J. Phys. (France) 48, 1685-1696 (1987)], were analyzed to yield improved Dunham constants for the ground state. A Rydberg-Klein-Rees (RKR) potential energy curve was computed for the X(1)Sigma(+)(g) state (v" = 0-29). The equilibrium bond length was found to be R(e)(X(1)Sigma(+)(g)) = 2.2810213(20) Å. Copyright 2000 Academic Press.