HIGH-RESOLUTION FOURIER-TRANSFORM SPECTRUM AND ROVIBRATIONAL ANALYSIS OF THE 2-NU(6) OVERTONE BANDS OF MONOISOTOPIC (H3SIBE)-BR-79

The Fourier transform spectrum of monoisotopic (H3SiBr)-Br-79 has been recorded in the spectral range 1147-1384 cm-1, with a resolution of 0.0027 cm-1. The spectrum has been used to analyze the rotational structure of the overtone bands (2nu6)0 (parallel band) and (2nu6)+/-2 (perpendicular band), to deduce improved rotational constants for the ground state, and to determine those for the excited levels. More than 3000 transitions were fitted with a standard deviation sigma = 0. 153 X 10(-3) cm-1. The data fit with 20 free parameters accounted for the 1(2, 2)-type resonance. The bandcenters were found at 1264.438862 ( 15) and 1267.370983 ( 13) cm-1 for the parallel and the perpendicular bands, respectively. An evaluation of the M(parallel-to)/M(perpendicular-to) transition dipole moment ratio has been made. Comparison of line intensities in the observed spectrum and in simulated spectra yielded for this ratio \M(parallel-to)/M(perpendicular-to)\ = 2.2 +/- 0.2. (C) 1994 Academic Press, Inc.