An Approach to the microscopic features of liquid phase reactions using solvation clusters of known structure

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The aim of this project is to determine the structure of solvation clusters by means of the rotational coherence spectroscopy and, based on the determined structure of the clusters, to understand the precise dynamics of cluster reactions. The following subjects have been intensively studied during the period of this project.1. The development of the method for determining the structure of large solvation clustersFor the determination of the structure of large molecules like solvation clusters, the rotational coherence spectroscopy (RCS) is much more suitable than the ordinary high-resolution spectroscopy. RCS directly determines the rotational constants of a cluster by observing the rotational period in the time domain. We constructed an RCS system consisting of a Ti : Al_2O_3 ps laser and a molecular beam apparatus.The RCS of 9,9'-bianthryl (BA)The observation of RCS of 9,9'-bianthryl revealed that the RCS signal reflected the average rotational angle of each twisting vibrational leve … More l in its intensity and the coherence time.3. The structure of 9,9'-bianthryl complexesBy using the hole-burning spectroscopy, the detailed spectra of BA complexes were obtained and the potentials for the internal rotation were determined for the complexes. In a He complexe the small perturbation slightly splits the degenerate twisting levels whereas in Ar and H_2O complexes the shape of the potential is drastically changed ; one well of the double well potential disappears.The RCS of these complexes could not be obtained with the time-correlated single photon counting method which detected the coherence of the excited state. On the other hand the time-resolved fluorescence depletion method which detects both the ground and excited state coherence provided information of the rotational constants of BA-Ne, BA-Ar, and BA-H_2O complexes. With the aid of structure optimization based on the empirical atom-atom interaction potentials, the structure of these complexes were determined.4. The internal rotation and the charge-transfer reaction of 4- (9-anthryl) aniline (AA)An compound, 4- (9-anthryl) aniline(AA), whose behavior is essentially the same for the typical charge-transfer compounds 4- (9-anthryl) -N,N-dimethylaniline (ADMA), was first synthesized and studied under supersonic jet conditions. The potential for the internal rotation was determined and the presence of a new electronic state of CT character was proposed. Less