title: 1(1)B(u) (S2) and 2(1)A(g) (S1) fluorescence and the 2(1)A(g) state of alpha,omega-dithienylbutadiene and alpha,omega-dithienylethylene.
abstract: Fluorescence and absorption spectra and fluorescence lifetimes have been measured for alpha,omega-dithenylbutadiene (DTB) and alpha,omega-dithenylethylene (DTE) in different solvents and at different temperatures as well as in the vapor phase. It is shown that the emission of DTB consists of the S(2) (1(1)B(u)) and S(1) (2(1)A(g)) fluorescence, while the emission of DTE consists of solely the S(1) (1(1)B(u)) fluorescence. The 2(1)A(g) and 1(1)Bu state levels of DTB are found to invert in solvents with the polarizability of near 0.32. All the available data for DTB on temperature and solvent dependence of the absorption and fluorescence spectra and the fluorescence lifetime support the presence of the lowest excited singlet state, 2(1)A(g), located below the strongly allowed 1(1)B(u) state. Quantitative analyses of the spectral data provide the physical parameters that characterize the excited state dynamical behavior of DTB.
authors.affiliation: Graduate School of Integrated Arts and Sciences, Hiroshima University, 1-7-1 Kagamiyama, Higashi-Hiroshima City, 739-8521 Japan. titoh@hiroshima-u.ac.jp
authors.forename: Takao
authors.initials: T
authors.lastname: Itoh
authors.forename: Minoru
authors.initials: M
authors.lastname: Yamaji