Photoelectron spectroscopy and dynamics of excitons in C-60 and photopolymerized C-60 films

Pump-probe photoelectron spectroscopy is used to study excited states in pr istine and photopolymerized C-60. For the first time in a molecular solid, vibrationally broadened singlet (SI) and triplet (TI) exciton photoemission spectra are temporally isolated and unambiguously assigned. Complex transi ent behaviors of S, and T, populations, including non-Markovian decays and a strongly enhanced production of T, states at high excitation, provide evi dence for interactions among excitons and free carriers. A new rate-equatio n model reproduces a wide range of both laser- and synchrotron-based data f rom polymerized films. (C) 2001 Published by Elsevier Science B.V.