Intensities in Raman spectra - II. Normal co-ordinates for the chloro- and bromo-methanes

Application of the intensity theory presented in part I of this series requires a knowledge of the coefficients $\scr{l}_{t\xi,p\sigma}$ and $\scr{l}_{p\sigma,t\xi}^{-1}$ relating the symmetry co-ordinates and the normal co-ordinates. The present paper gives an account of the calculation of these coefficients for the molecules, CCl$_{4}$, CHCl$_{3}$, CH$_{2}$Cl$_{2}$, CH$_{3}$Cl, CBr$_{4}$, CHBr$_{3}$, CH$_{2}$Br$_{2}$ and CH$_{3}$Br. The force field used was that deduced by Decius. An outline of the theory involved in this type of calculation is presented together with some aspects of the numerical manipulation. General expressions for the Wilson $\scr{G}$-matrices for these types of compound are quoted and tables of the transformation coefficients for the eight compounds are given.