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Saeko Shin

Publications and source records attributed to Saeko Shin.

3 recordsLinked to original sources

Analysis of vibrational circular dichroism spectra of (s)-(+)-2-butanol by rotational strengths expressed in local symmetry coordinates.

The vibrational circular dichroism (VCD) spectra of (S)-(+)-2-butanol have been observed in dilute CS(2) solutions. Two strong VCD bands are assigned mainly to the OH bending modes with the aid of quantum chemical calculations. The calculated VCD spectra corresponding to these bands are shown to depend on the conformation of the OH group. To understand this feature, we have calculated the contribution of each local vibrational mode to the rotational strengths and concluded that the coupling of the group vibrations between the in-plane and out-of-plane modes about the locally assumed symmetry planes play a significant role in VCD. This finding has provided a new scope of VCD in relation to molecular vibrations.

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High Resolution FTIR Study on NH(2)Cl Molecule: Inversion and Anharmonicity.

The high-resolution FTIR absorption spectra of the NH(2)Cl molecule have been measured in the region 500-3600 cm(-1). The rotational structures of all the fundamental bands and a number of overtone and combination bands have been analyzed. Every rotational line of the observed bands except the NH(2) twisting and stretching fundamental bands splits into two components due to the amino inversion motion. The vibrational anharmonicity and the direction of the transition moments have been studied with the help of B3LYP/6-31++G(**) calculations. The amount of inversion splitting depends on the molecular rotation, and the J,K-dependence of the inversion splitting has been determined. Copyright 2001 Academic Press.

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Vibrational circular dichroism spectrum of 1-amino-2-propanol.

Vibrational circular dichroism (VCD) spectra of 1-amino-2-propanol, of neat sample and in dilute solution of CDCl3, were measured in 2000 to 800 cm(-1) region. Two VCD bands, which appear at 1272 and 1412 cm(-1) in dilute solution, were assigned, respectively, to the OH bending mode and the mode that is influenced by the OH bending of the most stable conformer. The assignments were confirmed according to the prediction by a high-level density function theory (DFT) calculation and the isotope shift of deuterated samples. The joint analysis of the spectra obtained by the VCD and ordinary infrared (IR) measurements seems to be a useful way of using vibrational spectroscopy to investigate the hydrogen bonding system in solution.

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