Millimeter-Wave Spectra of CH3SiH3in the Two Interacting Torsional States (v12= 0,v6= 3) and (v12= 1,v6= 0)

✍ Scribed by N. Moazzen-Ahmadi; I. Ozier; G.A. McRae; E.A. Cohen

• Publisher: Elsevier Science
• Year: 1996
• Tongue: English
• Weight: 291 KB
• Volume: 175
• Category: Article
• ISSN: 0022-2852
• DOI: 10.1006/jmsp.1996.0008

✦ Synopsis

Pure rotational spectra of gaseous CH 3 SiH 3 in the two interacting torsional states (£ 12 Å 0, £ 6 Å 3) and (£ 12 Å 1, £ 6 Å 0) were observed in the region from 87 to 197 GHz using a mm-wave spectrometer. Here £ 12 and £ 6 are, respectively, the principal quantum numbers for the silyl rocking mode and for the torsion. A total of 79 rotational frequencies were measured for J Å 4 R 3 to J Å 9 R 8. These new measurements, 22 rotational frequencies in the (£ 12 Å 0, £ 6 Å 3) state reported previously, but not analyzed satisfactorily, and 2607 frequencies from a variety of other earlier experiments were fitted to within the experimental uncertainty by an effective Hamiltonian which included 22 parameters for the ground vibrational state, 12 parameters for the (£ 12 Å 1) vibrational state, and 3 parameters which characterize the interactions between these two states. Some of the mm-wave lines are perturbed by about 600 MHz. The form of the effective Hamiltonian is severely constrained by the large number of precision data on various torsional levels in the ground vibrational state, 0 £ £ 6 £ 3, and on the excited vibrational state (£ 12 Å 1, £ 6 Å 0). The model predictions for the (£ 12 Å 0, £ 6 Å 4) torsional state and the measurements reported by Wong et al. (J. Mol. Spectrosc. 102, 89, 1983) agree to better than 500 kHz.