Electron transfer and solvation in 9,9 '-bianthryl and derivatives: a sub-ps fluorescence upconversion study

The time-evolution of the fluorescence spectra of 9,9 ' -bianthryl and 9-ca rbazolyl-anthracene in ethanol and butanol have been studied with subpicose cond time-resolution by the fluorescence upconversion technique. For both c ompounds, an initial phase (<1 ps) with a structured anthracene-type fluore scence spectrum could be observed which transforms into an unstructured red shifted emission spectrum further shifting to the red on the time scale of the slow component of solvent relaxation. The results are compared to recen t transient absorption studies and are interpreted as evidence for a subpic osecond relaxation process (ca 0.4 ps) occurring prior to electron transfer in these compounds. (C) 2001 Elsevier Science B.V. All rights reserved.