QQ and RQ—QP branch separations in type B band envelopes of asymmetric top molecules

• Published in: Journal of molecular structure 1978-01, Vol.50 (1), p.29-41
• Main Author: Seth-Paul, W.A.
• Format: Article
• Language: English
• ISSN: 0022-2860; 1872-8014
• DOI: 10.1016/0022-2860(78)87095-1

Analysis of observed QQ and RQ—QP branch separations of type B band envelopes displayed by prolate and oblate asymmetric top molecules revealed that these separations can be estimated by means of the equation Δν(QQ) = S(ϱ, κ) S B where S B is the calculated [3] PR-separation of the corresponding type B band. The separation function S (ϱ, κ) is a product of two functions S(ϱ,κ) = φ(ϱ)φ(ϱ, κ) one of which is a function of ϱ. The second depends upon the shape of the molecule (prolate or oblate), ϱ and κ or merely κ depending upon whether ϱ is smaller or larger than 1 2 . Agreement with observed separations is quite satisfactory for molecules with parameters 0 < ϱ < 4 and −1 < κ < + 1. The formulas are therefore proposed to substitute for the inter- and extrapolation technique usually applied to the theoretical curves of Badger and Zumwalt [1].