Intensities of Rotation Lines in Absorption Bands

An alternate method of computing the influence of vibration-rotation interaction on the intensities of lines in the band spectra of molecules from that discussed by Herman and Wallis and by Herman and Rubin is presented. The method consists of transforming the Hamiltonian of the molecule by a contact transformation so that the wave functions remain those for a harmonic oscillator-rotator. The electric moment must then also be transformed by the same contact transformation before the matrix elements of the electric moment are computed. The method is applied to a diatomic molecule and gives the same results as those stated by Herman and Wallis.