Influence of solvent polarity on the radiationless decay of the intramolecular exciplexes of .omega.-phenyl-.alpha.-(dimethylamino)alkanes

Using optoacoustic spectroscopy, the radiationless decay processes of intramolecular exciplexes of ω-phenyl-α-N,N-dimethylaminoalkanes are investigated. Upon increase of the solvent polarity, the relative efficiency of the intersystem crossing process from the singlet exciplex to the locally excited triplet decreases compared to the efficiency of the internal conversion process. These results can be rationalized in the framework of the current electron-transfer theory and compared to the results obtained for other ω-aryl-α-N,N-dimethylaminoalkanes