Katsumi Kimura

Bio: Katsumi Kimura is an academic researcher from University of Tokyo. The author has contributed to research in topics: Ionization & Photoionization. The author has an hindex of 28, co-authored 85 publications receiving 1987 citations.

The Vacuum Ultraviolet Absorption Spectra of Aniline and Some of Its N-Derivatives

Abstract: The vacuum ultraviolet absorption spectra of anilne, N-methylaniline, N-ethylaniline, N,N-dimethylaniline, N,N-diethylaniline and N-n-butylaniline have been measured in the vapor phase by a recording vacuum ultraviolet spectrophotometer, with which the absorption measurements have been extended down to 1500 A. Some new bands have been found in the vacuum ultraviolet region, and in total five π→π* transtion bands with molar extinction coefficients larger than 1500 have been observed commonly for the anilines. In order to clarify the nature of these bands, a theoretical treatment has been made by considering the configuration interaction among the ground, locally excited and charge-transfer configrations. An excellent agreement has been obtained between the experimental and the calculated result. It has been concluded the the anilines studied here exhibit intramolecular charge-transfer bands characteristic if the electron trasfer interaction between the substituent and benzene ring.

Ab initio studies of cyclic water clusters (H2O)n, n=1–6. I. Optimal structures and vibrational spectra

Abstract: The optimal structures and harmonic vibrational frequencies of cyclic water clusters, (H2O)n, have been determined at the Hartree–Fock (for n=2–6) and second order perturbation theory (for n=2–4) levels of theory with an augmented correlation consistent double zeta basis set At the MP2 level this basis set yields very accurate results for the structure, dipole moment, and polarizability of the water monomer as well as results of comparable accuracy for the structure, binding energy, and harmonic vibrational frequencies of the water dimer The optimal structure of (H2O)4 and the harmonic frequencies of (H2O)3,4 are the first ones reported at a correlated level for these species Analysis of the structural trends reveals that the separation between neighboring oxygen atoms decreases exponentially with increasing cluster size The predicted R0(O–O) for the ring hexamer is less than 002 A shorter than the interoxygen separation in ice Ih Furthermore, the trends in the harmonic vibrational frequencies sugge

Cooperative (nonpairwise) effects in water trimers: An ab initio molecular orbital study

Abstract: High levels of ab initio molecular orbital theory were used to study the structures and binding energies of water trimers. These calculations included HF/6‐311++G(2df,2p) geometry optimizations for the 17 structures considered. Harmonic vibrational energies were obtained at the HF/6–311++G(2d,2p) level. The HF potential energy surface present three minima whose geometries were refined at the MP2/6–311+G(d,p) level. The global minimum corresponds to an asymmetric cyclic structure which presents significant cooperative effects with respect to the Cs dimer. To properly describe these nonpairwise effects, ZPE (zero point energy) and correlation corrections must be taken into account. They are reflected in a stiffer intermolecular potential, shorter O–O distances, longer donor O–H bond lengths, larger energies per hydrogen bond (HB), and greater shifts of the donor O–H bond stretching frequencies than the Cs dimer. Contrarily, the other two local minima present HBs which are weaker than those of the dimer. The...

The Circular Dichroism Spectra of the β-Cyclodextrin Complex with Naphthalene Derivatives

Abstract: The circular dichroism spectra of β-cyclodextrin complexes with naphthalene derivatives were investigated. A remarkable difference in the spectra was observed between the 1-substituted naphthalene complex and the 2-substituted naphthalene complex, indicating that the steric effect of substituents on the formation of the complex is so strong that the structures may be different for these complexes. The calculation of the rotational strength by the method of Kirkwood-Tinoco revealed that the structure of the 2-substituted naphthalene complex is an axial inclusion.

Photophysics of diimine platinum(II) bis-acetylide complexes

Abstract: A comprehensive photophysical investigation has been carried out on a series of eight complexes of the type (diimine)Pt(−C⋮C−Ar)2, where diimine is a series of 2,2‘-bipyridine (bpy) ligands and −C⋮C−Ar is a series of substituted aryl acetylide ligands. In one series of complexes, the energy of the Pt → bpy metal-to-ligand charge transfer (MLCT) excited state is varied by changing the substituents on the 4,4‘- and/or the 5,5‘-positions of the bpy ligand. In a second series of complexes the electronic demand of the aryl acetylide ligand is varied by changing the para substituent (X) on the aryl ring (X = −CF3, −CH3, −OCH3, and −N(CH3)2). The effect of variation of the substituents on the excited states of the complexes has been assessed by examining their UV−visible absorption, variable-temperature photoluminescence, transient absorption, and time-resolved infrared spectroscopy. In addition, the nonradiative decay rates of the series of complexes are subjected to a quantitative energy gap law analysis. The ...