Limitations of the rotating wave approximation in the theory of molecular collisions in a laser field

The radiative transition in a molecular collision system is usually described as a motion on so-called electronic-field potential surfaces, obtained by application of the rotating wave approximation (RWA). The RWA is shown to be valid if the time of interaction in the resonance region is larger than a third of the light period T/3. The interaction time is estimated for a radiation X3/2→X1/2 transition in the F+H2 and Br+H2 systems.