Observation of ultrafast internal conversion in fullerene anions in solution

Abstract

a b s t r a c tThe ultrafast decay rates of photoexcited C À 60 and C 2À 60 ions have been measured in the condensed phase. The mechanism for decay is internal conversion, and the decay rate is a strong function of the charge on the ion. A bottleneck in the ground state recovery has also been detected, and its interpretation is discussed.

The excited-state dynamics of the radical anions of cyanoanthracenes

“…These very short excited-state lifetimes are consistent with of those reported previously with other open-shell ions in 4,[16][17][18][19][20][21][22][23][24][25][26][35][36][37][38][39] They are usually explained by the presence The excited-state lifetime of DCA •− is much shorter than the 4 ns value deduced from quenching measurements of DCA •− * produced by photoexcitation with a 5 ns pulse. 33 The excitedstate lifetime was estimated from the decrease of the DCA •− bleach signal in the presence of an electron acceptor and by assuming a diffusion-controlled quenching.…”

Dual electron transfer pathways from the excited C60 radical anion: enhanced reactivities due to the photoexcitation of reaction intermediates

“…27,47,48 Assuming that the relaxation processes include the internal conversion (IC) from D 1 to D hot 0 and the cooling of D hot 0 to generate the relaxed ground state (D 0 ), the global analysis provided 3.3 and 85 ps decay lifetimes of D 1 and D hot 0 states, respectively. The D 1 state lifetime corresponds to the reported value, 24 which was generated by photoexcitation of electrochemically reduced C 60 , thus indicating that TDAE + has no effect on the excited state dynamics.…”

“…1) were selected as acceptors for the excited C 60 À because of their strong and sharp absorption bands upon reduction, 13 which are convenient for the transient absorption study. Hope et al measured the lifetime of the D 1 state of C 60 À , 24 however, because their study is limited to the recovery of D 0 state bleaching, important characteristics, such as the transient absorption spectrum of the D 1 state, have not been reported. Thus, in the initial part of the present study, spectroscopic characterization of the D 1 states of C 60 À and its derivative (C 60 H) was carried out.…”

“…Because the D value tends to become smaller for ET processes from excited radical ions, fast and efficient ET processes are expected from these states as demonstrated in the present study.conversions. [16][17][18][19][20][21][22][23][24][25][26][27] Despite these studies, the characteristics of the ET processes from excited radical ions have not been well clarified, because of the lack of a systematic study. Therefore, differences between the ET processes in the excited and in the ground state have not been discussed.Recently, we reported the investigation of inter-and intramolecular ET processes from the excited naphthalene 1,4,5,8-tetracarbonyldiimide radical anion (NDI À *).…”

“…conversions. [16][17][18][19][20][21][22][23][24][25][26][27] Despite these studies, the characteristics of the ET processes from excited radical ions have not been well clarified, because of the lack of a systematic study. Therefore, differences between the ET processes in the excited and in the ground state have not been discussed.…”