Laser-Induced Vibrational Frequency Shift
  A mechanism is explored whereby intense laser radiation induces an optical force between the constituent atoms of a molecule. In the case of a diatomic molecule the effect results in a modification of the vibrational potential, and using perturbation theory it is shown that this reduces the stretching frequency. Model calculations on selected diatomics indicate that the extent of the frequency shift should, under suitable conditions, be detectable by Raman spectroscopy. 
D. L. Andrews R. G. Crisp