Application of stepwise two-color excitation time-resolved thermal lensingtechnique to the study on excited 2-methylbenzophenone enols

Stepwise two-color excitation time-resolved thermal lensing (TC-TRTL) techn ique was applied to the study on excited state dynamics of transient specie s. When a XeCl excimer laser and a dye laser pumped by a Nd3+:YAG laser wer e synchronously irradiated into the sample solution, a thermal lens formed through the nonradiative processes for the excited transient was monitored with a cw He-Ne laser. Some spatial arrangements for three laser beams were tested to obtain good S/N ratio. The TC-TRTL technique coupled with stepwi se two-color excitation transient absorption was successfully applied to th e investigation of reaction dynamics on excited states of two kinds of enol s (Z- and E-) for 2-methylbenzophenone (MBP). The E-enol was found to intra molecularly react alter the excitation. The heat of reaction was estimated by the TC-TRTL. The reaction channel was also discussed.