The Near Degenerate ν3 and ν6 States of HSiD3 Revealing Δ(k − l) = 0, ±3, and ±6 Interactions

✍ Scribed by Hans Bürger; Helmut Ruland; Lauri Halonen

• Publisher: Elsevier Science
• Year: 2000
• Tongue: English
• Weight: 204 KB
• Volume: 202
• Category: Article
• ISSN: 0022-2852
• DOI: 10.1006/jmsp.2000.8100

✦ Synopsis

The infrared spectrum of HSiD 3 has been recorded with a resolution of 3.3 ϫ 10 Ϫ3 cm Ϫ1 in the 600 -775 cm Ϫ1 region. The fundamentals 3 ( A 1 ), 0 ϭ 675.501 cm Ϫ1 , and 6 (E), 0 ϭ 682.687 cm Ϫ1 have been measured and rotationally assigned up to JЈ ϭ 30. Owing to the closeness of the band centers and the strength of the x, y-Coriolis interaction, 36 y ϭ 0.62, perturbations both of positions and intensities are strong. Since HSiD 3 is an oblate top near the spherical top limit, the rotational energy level structure is such that numerous avoided crossings with ⌬(k Ϫ l ) ϭ Ϯ3 and Ϯ6 are called forth by the Coriolis resonance. These give rise to "forbidden" transitions, 209 of which with JЉ and KЉ Յ 30, and ⌬K up to Ϯ6, were observed. These enabled a significant improvement of the coefficients of the K-dependent ground state energy terms, C 0 ϭ 1.433 4268(12) cm Ϫ1 , D K 0 ϭ 2.851 6(57) ϫ 10 Ϫ6 cm Ϫ1 , and H K 0 ϭ Ϫ1.728(85) ϫ 10 Ϫ10 cm Ϫ1 . Parameters of the v 3 ϭ 1 and v 6 ϭ 1 excited states were determined with two models corresponding to two different effective Hamiltonians. The model strictly obeying the constraints proposed by E. I. Lobodenko, O. N. Sulakshina, V. I. Perevalov, and V. G. Tyuterev (J. Mol. Spectrosc. 126, 159 -170 (1987)) requires 45 adjustable parameters and fits the data with J Ն 22 only poorly while, with an alternative model employing 44 free parameters, all data up to JЈ ϭ 30 were fitted with ϭ 1.72 ϫ 10 Ϫ4 cm Ϫ1 . A positive sign of the Coriolis intensity perturbation was found, and the transition moment ratio was determined, ͉M 6 :M 3 ͉ ϭ 0.70(5).