Intensities of binary overtone and combination bands in the i.r. spectrum of NF 3

Abstract

The intensities of the binary overtone and combination bands in the i.r. spectrum of NF 3 have been measured in the gas phase and in liquid—argon solution. The observed intensities have been interpreted in terms of a simple model which ascribes all the intensity of the binary overtones and combinations to anharmonic coupling with the fundamentals; i.e., a model in which the second derivatives of the dipole moment with respect to the normal coordinates are assumed to be zero. The agreement between the observed intensities and the calculated ones is extremely good for the bending modes but less satisfactory for the stretching modes. The use of a polar-tensor model to predict the intensities of the vibrational fundamentals is also explored.