Excited-state structure and dynamics of 1,3,5-tris(phenylethynyl)benzene as studied by Raman and time-resolved fluorescence spectroscopy.
Excited-state structure and dynamics of 1,3,5-tris(phenylethynyl)benzene (TPB) have been studied in n-hexane and n-heptane solutions. Time-resolved fluorescence spectra, fluorescence anisotropy, and lifetime of TPB were recorded with femtosecond to nanosecond time resolution. Raman depolarization ratio was also measured to elucidate a nonplanar structure of the ground state. Two fluorescence components, the short-lived component with 150 fs lifetime and the long-lived component with 10 ns lifetime, were observed. The analysis of the fluorescence anisotropy values combined with the Raman depolarization data has led to a conclusion that TPB is primarily excited to a short-lived excited singlet state with a nonplanar structure, and then it relaxes to a long-lived excited singlet state with a 3-fold axis. A rapid structural change from a nonplanar to a planar structure is suggested to take place in the process of relaxation.
Nomoto
Tomonori
T
Department of Chemistry, School of Science, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan.
Hosoi
Haruko
H
Fujino
Tatsuya
T
Tahara
Tahei
T
Hamaguchi
Hiro-o
HO