Femtosecond Dynamics of Electron Transfer Reaction in Double Metal Complex Crystals

点击翻译按钮获取中文摘要

1. Photoprimary processes of various thin crystals of oxotitanium (IV) phthalocyanine (OTiPc)_n revealed by femtosecond laser photolysis. A rapid change of the transient absorption spectrum showed that a part of the exciton of β-OTiPc was in 1 ps converted to an one-electron oxidized species, (OTiPc)_n^+, then the hole disappeared in 20 ps. Most of the ground-state was recovered within 50 ps. The conversion to (OTiPc)_n^+ was less clear for α-OTiPc. Quantum yields and lifetimes of fluorescence for the crystals of OTiPc were also determined. A fluorescence with a peak at 10,420cm^<-1> from α-OTiPc exhibited biexponential decay of a major relaxed exciton with 35-65 ps and a minor relaxed exciton with 100-424 ps. An increase in the initial intensity of the short-lived fluorescence at 77 K indicates that the relaxed exciton is a minor product of the excitation of α-OTiPc at 298 K.A charge-carrier formation by photo-excitation seems to be much faster than the internal conversion to the rela … More xed exciton.2. Determination of distance-dependent rate-constants of excitation energy transfer and hopping in the crystalline solids of [Os_xRu_<1-x>(bpy)_3]X_2 with various counter ions. Non-linear decays of the emission in the crystals of [Ru(bpy)_3]X_2 doped with Os(II) have been analyzed and simulated by a Monte Carlo method. Molecular interaction via electron exchange type is predominant for the energy transfer of ^3MLCT(Ru) to Os^<2+> in the close proximity and for the hopping of ^3MLCT(Ru) to the nearest neighbor. The rate constants for the energy transfer to Os^<2+> and hopping were determined at various distances. A distance attenuation factor (12.5 nm^<-1>) obtained for the electronic exchange interaction was small compared with reference values.Time-resolved absorption spectroscopy for the neat crystal revealed that T-T annihilation produced the one-electron transferred products. Rate of electron transfer between ^3MLCT in the neat crystal of [Ru(bpy)_3](PF_6)_2 was estimated to be more than 5x10^<10>s^<-1>. Less