ANALYSIS OF THE RESONANCES PERTURBING THE $\nu_{5}$ BAND OF METHYL IODIDE.

Author Institution: National Bureau of Standards; Mellon Institute, Pittsburgh, Pennsylvania, 15213.The $\nu_{5}$ band of $CH_{3}I$ is perturbed by both a Fermi resonance and a Coriolis resonance with the $\nu_{3}+\nu_{6}$ band. A computer program has been written for calculating band contours with any degree of resolution. This program takes both these perturbations into account and calculates the correct intensity and position of each line. With this program both the $\nu_{5}$ and $\nu_{3}+\nu_{6}$ bands have been analyzed and the experimental absorption curve has been duplicated. The Coriolis resonance between the $K=4,-l$ level of $\nu_{3}+\nu_{6}$ and the $K = 3,+l$ level of $\nu_{5}$ makes it possible to locate the normally forbidden transition $\nu_{3}+|nu_{6} (K = 4,-l)\leftarrow \nu_{0} (K = 2)$. From the position of this transition and the $^{P}Q_{5} (\nu_{3}+\nu_{6})$ transition we have been able to determine the value of the $A_{0}$ rotational constant without using the zeta sum rule. The perturbation of the $\nu_{4}$ band of methyl chloride will also be discussed