High-Resolution Study of the First Stretching Overtones of H3Si79Br

• Published in: Journal of molecular spectroscopy Vol. 192; no. 1; pp. 47 - 60
• Main Authors: Ceausu, A., Graner, G., Bürger, H., Mkadmi, E.B., Pracna, P., Lafferty, W.J.
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 01.11.1998
• ISSN: 0022-2852; 1096-083X
• DOI: 10.1006/jmsp.1998.7669

The Fourier transform infrared spectrum of monoisotopic H3Si79Br (resolution 7.7 × 10−3cm−1) was studied from 4200 to 4520 cm−1, in the region of the first overtones of the Si–H stretching vibration. The investigation of the spectrum revealed the presence of two band systems, the first consisting of one parallel (ν0= 4340.2002 cm−1) and one perpendicular (ν0= 4342.1432 cm−1) strong component, and the second of one parallel (ν0= 4405.789 cm−1) and one perpendicular (ν0= 4416.233 cm−1) weak component. The rovibrational analysis shows strong local perturbations for both strong and weak systems. Seven hundred eighty-one nonzero-weighted transitions belonging to the strong system [the (200) manifold in the local mode picture] were fitted to a simple model involving a perpendicular component interacting by a weak Coriolis resonance with a parallel component. The most severely perturbed transitions (whose ‖obs–calc‖ values exceeded 3 × 10−3cm−1) were given zero weights. The standard deviations of the fit were 1.0 × 10−3and 0.69 × 10−3cm−1for the parallel and the perpendicular components, respectively. The weak band system, severely perturbed by many “dark” perturbers, was fitted to a model involving one parallel and one perpendicular band, connected by a Coriolis-type resonance. The K" · ΔK = +10 to +18 subbands of the perpendicular component, which showed very high observed − calculated values (∼0.5 cm−1), were excluded from this calculation. The standard deviations of the fit were 11 × 10−3and 13 × 10−3cm−1for the parallel and the perpendicular components, respectively.