Infrared multiple photon absorption in a static electric field

Abstract
The infrared multiple photon process in the presence of a static electric field has been examined theoretically by employing a classical model. It is found that even a relatively small electric field (in comparison to the electric field of the laser) can significantly increase the fraction of molecules in an ensemble that absorbs energy from the laser. This effect is most prominent at low laser powers. Although these results are for hydrogen fluoride they are in qualitative agreement with recent experiments for CF2HC1.