Characterization of Chemical Reactions by Thermal Lens Spectrometry

Abstract

Theoretical models describing the formation of the thermal lens during chemical reactions were derived and the effects of changing concentration on the thermal lens strength were evaluated. It was estimated that gas phase reactions on a μs time scale can be followed by this technique. An instrument for simultaneous measurement of absorbance and thermal lens effect was developed and used to verify calculated values. For the SN 2Ar* photochemical reaction of 1,2-dimethoxy-4-nitrobenzene, the rate constants determined by the thermal lens technique agree well with those by conventional absorption measurements.