Reaction Using Two-Photon Excitation

Noru esonant two-photon (NRTP) reaction of intramolecular charge transfer-type 4-disilanyl-4 -trifluoromethylstilbene (DTS) has been reported [46]. One-photon irradiation of a methanol solution of trans-DTS with 266-nm laser pulses induced solvolysis to give 4-dimethylsilyl-4 -trifluoromethylstUbenes (HTS). In contrast, NRTP excitation of trans-DTS in methanol with 532-nm laser pulses induced predominantly cis-trans isomerization and solvolytic reactions were suppressed. The photochemical decomposition of trans-stUbene and its derivatives in ethanol exposed to radiation of the second harmonic of a Nd YAG laser (532 nm) of 

Nonresonant two-photon excitation of trans-stilbene in the presence of an excess amount of tetramethylethylene was found to induce predominantly cis-trans isomerization [52]. Under the same condition, one-photon excitation gave a [2 + 2] cydoadduct as the main product Action spectra for the isomerization indicated that isomerization occurred from the exdted Ag state of trans-stilbene. Nonresonant two-photon excitation of trans-stilbene in the presence of tetramethylethylene-in-duced predominantly cis-trans isomerization whereas the [2 + 2] intermolecular cycloaddition pathway was found to be suppressed [53]. In contrast, the one-photon excitation under similar conditions the cydoaddition occurred as the major pathway. 

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