Reaction Control by Cluster-Mediaipd Chemistry

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One of the fundamental issues regarding chemical reactions concerns the effects of week interactions exerted by solvent on the reaction dynamics. In the present study, our efforts have been focused on the following research projects to investigate the effects of "microsolvation" in chemical reactions and to explore the new field of cluster-mediated chemistry :1. Structure of (C0_2)^-_n as a gas-phase nucleophile : The electronic structures of (CO_2)^-_n and [(CO_2)_nROH]^- (R = H, CH_3) are investigated by photoelectron spectroscopy combined with ab initio calculations, demonstrating the coexistence of isomers having different electronic structures. These "electronic isomers" are well described as [C_2O^-_4磁ROH(CO_2)_<n-2>] and [CO^-_2磁ROH(CO_2)_<n-1>]. The calculations have also revealed quantitatively the behavior of the excess charge flow during the CO^-_2磁CO_2 。レtautomer。ロ C_2O^-_4 electronic isomerization, which might play a crucial role in the reductive activation of carbon dioxi … More de in the course of gas-phase reactions mediated via (CO_2)^-_n.2. Single-molecule solvent effects in I^-_3 photodissociation。。:。。Photodissociation dynamics of gas-phase I^-_3 along with its weakly bound clusters, I^-_3磁M (M = CH_3CN, C_2H_5OH), was investigated for a microscopic understanding of solvent effects on the photodissociation dynamics. The experimental results demonstrate convincingly that even single-molecule solvation results in a drastic change in the I^-/I^-_2 product branching, which opens up a possibility of controlling the photofragmentation process by exploiting week intermolecular interactions. We also performed ab initio SOCI calculations of the I^-_3 potential energy surfaces, which have revealed a strong nonadiabatic nature of the I^-_3 dissociation dynamics involving dense avoided crossings among the excited-state potentials.3. Development of a cluster anion-molecule reaction apparatus : New apparatus has been developed for the investigation of collisional reactions between mass-selected negatively-charged clusters with neutrals in the collision energies ranging from few electron volts to several tens of eV. Less