Dynamics of photoexcited donor-acceptor complexes between C60 andN,N-diethylaniline. Polarization picosecond spectroscopy study

Abstract

The kinetics of the formation and decay of photoexcited radical ion pairs of donoracceptor charge-transfer complexes between C60 andN,N-diethylaniline (DEA) in chlorobenzene was studied by picosecond laser-induced diffraction gratings. It was established that the anisotropy of polarization of the diffraction signal decreases as the concentration of DEA increases. The radical ion states of the photoexcited C60−...DEA+ complex have zero anisotropy. This effect is likely due to the isotropic intracomplex transfer of an electron from the local excited state to the radical ion state. The rate constant of quenching of the singlet excited C60 byN,N-diethylaniline (1.4·1010 L mol−1 s−1) and the lifetimes of the solventseparated C60−...DEA+ and tight [C60−...DEA+] (95±7 and 31±4 ps, respectively) radical ion pairs were measured.