REDETERMINATION OF THE GROUND-STATE CONSTANTS OF (H3SIBR)-BR-79 INCLUDING A(O) AND D-K(O) FROM V(6), 2V(6)(+/-2)-V(6)(+/-1), AND 2V(6)(-/+2) ROVIBRATIONAL BANDS AND MILLIMETER-WAVE SPECTRA

High-resolution (0.003 cm(-1)) FTIR spectra of monoisotopic (H3SiBr)-Br-79 have been studied in the nu(3) and nu(6) regions near 430 and 630 cm(-1). We have fitted 2016 transitions for nu(3), 631 for 2 nu(3)-nu(3), 1987 for (nu(3) + nu(6))-nu(3), and 3251 for nu(6), with standard deviations of the residuals of 0.206 x 10(-3), 0.378 X 10(-3), 0.370 X 10(-3), and 0.113 X 10(-3) cm(-1), respectively, taking into account the l(2, 2) resonance within both the upsilon(3) = upsilon(6) = 1 and the upsilon(6) = 1 levels. In order to deduce precise ground state and excited state constants, we have also studied the upsilon = 0 and upsilon(6) = 1 pure rotational transitions up to J = 53. Improved ground state parameters B-0, D-J(0), D-JK(0), H-J(0), H-JK(0), and H-KJ(0) were determined. The hot bands 2 nu(6)(0)+1/6 (only (P)Q(1) and (R)Q(2) series) and 2 nu+2/6-v+1/6 have been assigned. Using high-resolution spectra of the fundamental band nu(6), of the overtone band 2 nu+2/6 previously studied, and of the hot band 2 nu+2/6-nu+1/6, the ground state constants A(0) and D-K(0) for the (H3SiBr)-Br-79 molecule have been determined. Ground state differences Delta(K, J) = F(K, J) - F(K - 3, J) were calculated for seven K values: K = 3, 4, 5, 6, 7, 8, and 9. By a least-squares fit of 370 such differences the following results (in cm(-1)) were obtained: A(0) = (2.843016 +/- 0.000014)and D-K(0) = 12.6665 +/- 0.0069) x 10(-5). (C) 1995 Academic Press, Inc.