Journal of Physical Chemistry A vol:106 issue:10 pages:2067-2073
Excited-state dynamics of 9,9'-biantryl (BA) adsorbed on the porous glass, where the large motion of the surrounding medium or intramolecular motion of BA was not plausible, and temperature effects on it were investigated by means of steady-state fluorometry, absorption measurement, picosecond transient absorption spectroscopy, and time-resolved fluorescence measurement. Steady-state fluorescence and transient absorption spectroscopy revealed that the electronic structure of excited BA had strong charge transfer (CT) character as comparable as in the polar solutions both at room temperature and at 77 K, although the dielectric environments estimated by other inter- and intramolecular CT systems were in nonpolar or very weakly polar environments. The time constant of CT was determined to be 5-10 ps at 294 K. The CT time constant was slightly slower (ca. 20 ps) at 77 K but was much faster than that of BA in alcoholic solutions at room temperature. By integrating these results with those in solutions, the rapid CT state formation and the stabilization of the CT state were discussed from the viewpoint of the symmetry breaking in the ground state because of the heterogeneous adsorption of BA onto the glass surface.