Redetermination of the Ground State Constants of H3Si79Br Including A0 and D0K from ν6, 2ν±26−ν±16, and 2ν±26 Rovibrational Bands and Millimeter-Wave Spectra

Abstract High-resolution (0.003 cm −1 ) FTIR spectra of monoisotopic H 3 Si 79 Br have been studied in the ν 3 and ν 6 regions near 430 and 630 cm −1 . We have fitted 2016 transitions for ν 3 , 631 for 2ν 3 −ν 3 , 1987 for (ν 3 + ν 6 )−ν 3 , and 3251 for ν 6 , with standard deviations of the residuals of 0.206 × 10 −3 , 0.378 × 10 −3 , 0.370 × 10 −3 , and 0.113 × 10 −3 cm −1 , respectively, taking into account the l (2, 2) resonance within both the ν 3 = ν 6 = 1 and the ν 6 = 1 levels. In order to deduce precise ground state and excited state constants, we have also studied the ν = 0 and ν 6 = 1 pure rotational transitions up to J = 53. Improved ground state parameters B 0 , D 0 J , D 0 JK , H 0 J , H 0 JK , and H 0 KJ were determined. The hot bands 2ν 0 6 −ν ±1 6 (only P Q 1 and R Q 2 series) and 2ν ±2 6 −ν ±1 6 have been assigned. Using high-resolution spectra of the fundamental band ν 6 , of the overtone band 2ν ∓2 6 previously studied, and of the hot band 2ν ±2 6 −ν ±1 6 , the ground state constants A 0 and D 0 K for the H 3 Si 79 Br molecule have been determined. Ground state differences Δ( 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 0 K = (2.6665 ± 0.0069) × 10 −5 .