PHOTOINDUCED INTRAMOLECULAR CHARGE SEPARATION OF P-N,N-DIMETHYLAMINO-P'-CYANO-DIPHENYLACETYLENE IN POLAR-SOLVENTS

By using picosecond transient absorption measurement techniques, we ha ve investigated the intramolecular charge separation process and the d ynamic spectral shift of p-N,N-dimethylamino-p'-cyano-diphenylacetylen e in various polar solvents. In alcohols the spectral shift of the int ramolecular charge-separated state was observed in the tens of picosec ond time scale, while in aprotic polar solvents the spectral shift was too fast to measure with our time resolution. The dipole moment of th e intramolecular charge-separated state, which gives a transient absor ption spectrum in the red region, is about 36 D. (C) 1997 Elsevier Sci ence B.V.