Chemical Physics Letters vol:295 issue:1-2 pages:11-16
The excited-state relaxation processes of an amino-substituted triphenylbenzene derivative (p-EE;TP) and its biphenyl-model compound (p-EFBP) were investigated by femtosecond polarized transient absorption spectroscopy. The S-1-S-n absorption was detected upon pumping at 360 nm and probing at 470 nm. Both compounds presented a polarization-dependent component in the transient decay, For p-EFBP a decay time of 97 +/- 20 ps was obtained which agrees with the rotational diffusion time determined by time-resolved fluorescence anisotropy. For the symmetric p-EFTP a decay time of 8 +/- 2 ps was detected. This value correlates with the intramolecular dipole reorientation time deduced from time-resolved microwave conductivity measurements. (C) 1998 Elsevier Science B.V. All rights reserved.