PR separations of band envelopes produced by prolate and oblate top molecules

Abstract

A study of PR separations produced by a relatively large number of prolate and oblate asymmetrical top molecules reported in the literature revealed that under certain conditions the branch separations of type A(z.snfc;), type B() and type C() bands (prolate molecules) are in the proportion of 1:1/S(ß):3/2 whereas the separations produced by type A(), type B() and type C(z.snfc;) bands (oblate molecules) are in the proportion of :1/S(ß):1 and ::1 for planar oblate compounds. The branch separation of the parallel bands is found to obey the relation: Δν(PR) = 10S(ß)(BT/9)1/2 cm−1 For * and −1 χ +1 the proposed ξ values fairly match those as calculated by Gerhard and Dennsion and Badger and Zumwalt as well. The method of predicting branch separations is therefore simplified while the agreement with the values observed by experiment is quite satisfactory.