FEMTOSECOND POLARIZED TRANSIENT ABSORPTION-SPECTROSCOPY OF A C-3-SYMMETRICAL AMINO-SUBSTITUTED PHENYLBENZENE DERIVATIVE

The excited-state relaxation processes of an amino-substituted triphen ylbenzene derivative (p-EE;TP) and its biphenyl-model compound (p-EFBP ) were investigated by femtosecond polarized transient absorption spec troscopy. The S-1-S-n absorption was detected upon pumping at 360 nm a nd probing at 470 nm. Both compounds presented a polarization-dependen t component in the transient decay, For p-EFBP a decay time of 97 +/- 20 ps was obtained which agrees with the rotational diffusion time det ermined by time-resolved fluorescence anisotropy. For the symmetric p- EFTP a decay time of 8 +/- 2 ps was detected. This value correlates wi th the intramolecular dipole reorientation time deduced from time-reso lved microwave conductivity measurements. (C) 1998 Elsevier Science B. V. All rights reserved.