The photophysical properties of C70 excited states were investigated by some time-resolved spectroscopic techniques. The absorption bands of singlet excited state (1C70*) and triplet excited state (3C70*) in the visible region were observed by time-resolved absorption spectroscopy using a streak camera. The intersystem crossing rate constant kisc from 1C70* to 3C70* was determined to be 1.25 × 109 s-1 by the analysis of the absorption-time profiles considering the overlap of the decay of 1C70* and the growth of 3C70*, where the curve fitting was carried out by using the decay rate constant of 1C70* (1.61 × 109 s-1) determined by the picosecond time-resolved emission spectroscopy. The picosecond time-resolved near-IR spectra of 3C70* were obtained by the pump-probe technique, using a probe beam based on the broad-band optical parametric generation (OPG) of a β-barium borate (BBO) crystal pumped by 532-nm laser pulse. The lowest transition band of the T-T absorption of 3C70* was found in the near-IR region (960 nm) by the new technique.
ASJC Scopus subject areas
- Physical and Theoretical Chemistry