Knowledge Bank

The theory of the second overtones of infrared active fundamentals of tetrahedral $XY4$ molecules is developed. Vibration-rotation interactions are treated by the modern theory of angular momentum coupling first applied to infrared active fundamentals by $Hecht,1$ and later applied to the first $overtones.2$ Energy levels and relative intensities are calculated in both the conventional representation and the new representation introduced in Ref. 2. Preliminary results are presented and compared with the available spectra of $3\nu 3$ of $CD43$ and $CH4.4$ Research supported in part by the U. S. Air Force Cambridge Research Laboratories and in part by the National Aeronautics and Space Administration under Research Grant NSG 539.