Stationary and time-resolved spectra of 2,2′:5′,2"-terthiophene

By analyzing the stationary absorption spectrum of 2,2':5',2 "-terthiophene in dichloromethane at room temperature, the zero-zero S-1 --> S-0 transition energy is determined, Time-resolved fluorescence measurements show that the S-1 --> S-0 radiative relaxation in various solvents decays exponentially with a common time constant of 170 +/- 10 ps. The fluorescence anisotropy of 2,2':5',2 "-terthiophene in dichloromethane is also studied and the transient dichroism is interpreted in terms of the revolution of a hydrodynamic prolate ellipsoid with the emission dipole aligned parallel to the long molecular axis. (C) 1997 Elsevier Science B.V.