Femtosecond electron transfer dynamics of 9,9′-bianthryl in acetonitrile as studied by time-resolved near-infrared absorption spectroscopy

Photoinduced intramolecular electron transfer reaction in 9,9′-bianthryl has been studied with femtosecond time-resolved near-infrared absorption spectroscopy. In acetonitrile, a strong locally excited (LE) band at 1020 nm and a broad charge transfer (CT) band at 1250 nm are observed simultaneously. The decay of the LE band and the rise of the CT band have time constants of (0.38 ± 0.01) and (0.3 ± 0.1) ps, respectively. There is no intermediate with a sub-picosecond lifetime observed between the LE and CT states. In heptane, the LE band shape changes with a time constant of 1.4 ps, which probably reflects a conformational change around the central C–C bond.