Torsional Splitting in the Degenerate Vibrational States of 70Ge2H6: Rotation–Torsion Analysis of the ν7 and ν9 Fundamentals

✍ Scribed by F. Lattanzi; C. di Lauro; H. Bürger; E.B. Mkadmi

• Publisher: Elsevier Science
• Year: 2000
• Tongue: English
• Weight: 147 KB
• Volume: 203
• Category: Article
• ISSN: 0022-2852
• DOI: 10.1006/jmsp.2000.8162

✦ Synopsis

The rotational and torsional structure of the 7 and 9 degenerate fundamentals of 70 Ge 2 H 6 has been analyzed under high resolution. The torsional structure of both v 7 ϭ 1 and v 9 ϭ 1 states can be fitted by a simple one-parameter formula. The x,y-Coriolis interaction with the parallel 5 fundamental was accounted for in the analysis of 7 . A strong perturbation of the J structure of the E 3s torsional component of the K⌬K ϭ Ϫ2 subbranches of 9 can be explained by the resonance with an E 3s excited level of the pure torsional manifold. The perturber is centered at 361.58 cm Ϫ1 , very close to the value estimated with a barrier height of 285 cm Ϫ1 . This confirms that the fundamental torsional wavenumber is close to 103 cm Ϫ1 , in good agreement with the "ab initio" prediction. The torsional splittings of all the infrared active degenerate fundamentals, 7 , 8 , and 9 , follow the trend predicted by theory, and have been fitted by exploratory calculations accounting only for the torsional Coriolis-coupling mechanism of all degenerate vibrational fundamentals in several torsional states. This confirms that torsional Coriolis coupling is the dominant mechanism responsible for the decrease of the torsional splitting in the degenerate vibrational states. A higher value of the barrier had to be used for the 9 mode.