On the Possibility of Infrared Laser‐induced Chemistry*

Abstract— –We examine whether chemical reactions can be selectively stimulated by the absorption of infrared photons which individually do not satisfy activation energy requirements. By a modification of available rate theory we demonstrate that a non‐thermal enhancement of a chemical reaction is in principle possible, and is primarily dependent upon the extent to which a molecular mode can be coherently driven. An assumed coherent response to laser radiation leading to a minimally detectable rate enhancement places realistic constraints on the allowable magnitudes of vibrational and phase relaxation times for the mode. The inclusion of anharmonic limitations on the amount of energy stored in the mode results in the placement of more stringent though not impossible limitations on the relaxation times. A non‐linear reaction rate dependence on light intensity suggests that a Q‐spoiled laser be used. Optimum experimental conditions should involve the use of liquids at a temperature where thermal rates are just beneath the level of detection.