Kentaroh Kosugi

Low-frequency Raman spectra of crystalline and liquid acetic acid and its mixtures with water.: Is the liquid dominated by hydrogen-bonded cyclic dimers?

Abstract Low-frequency Raman spectra of crystalline and liquid acetic acid, and acetic acid–water binary solutions with varying mole fractions of acetic acid ( x A ), are presented in the form of the relative scattering activities, R( ν ) spectra. The spectrum of scattered light I( ν ) from crystalline acetic acid at 285 K shows five distinctive bands. Upon the melting, however, the liquid exhibited conspicuous difference in its appearance, although the R( ν ) spectrum shows two peaks and a shoulder at similar wavelengths to those of the crystalline bands. The spectral change does not directly support the dominance of the cyclic dimers in the liquid. R( ν ) spectra of acetic acid–water binary solutions suggest a three-state model composed of acetic acid associates, binary associates and water associates for the local structure of the mixtures.

Formation of air stable carbon-skinned iron nanocrystals from FeC2

Charge neutralization reaction in ionic salt of Fe2+C22− is found to produce carbon-skinned Fe nanocrystals. FeC2 is formed as an intermediate product in the reaction of FeCl2 solved in acetonitrile with CaC2 fine powder and also able to be isolated as black nanocrystals. Heating of FeC2 at temperature higher than 250 °C induces segregation of metallic iron. The segregated carbons grow as graphitic sheets parallel to the growing Fe lattice plane. This direct bonding is due to an accidental matching of the Fe–Fe distance (2.866 A) with that of the C1–C4 distance (2.842 A) of the hexagonal rings in graphite. The x-ray diffraction pattern indicates that the particles are composed of α-Fe and graphitic carbon. The thickness of the skin is almost constant as thick as 3.5 nm independent of the body size. The particles with an average size of 30 nm exhibit temperature dependence of the magnetic cohesive force as function of T−0.275.

Formation and magnetic characteristics of cobalt–carbon nanocluster magnets embedded in amorphous carbon matrices

Abstract Co–C 2 nanocluster magnets are formed in amorphous carbon by high pressure reaction of Co 4 (CO) 12 and CH 2 Cl 2 . The average size of the clusters is 12 nm. Structural characteristics are investigated by transmission electron microscope (TEM), electron energy loss spectroscopy (EELS), extended X-ray absorption fine structure (EXAFS) analyses, and infrared spectroscopy suggesting that the clusters are (CoC 2 ) n with π bonds in C 2 2− . The magnetization decreases with decreasing temperatures from room temperature to 20 K, while 10 Oe field-cooling (FC) results in increasing magnetization at lower temperatures.

Charge transfer interaction in the acetic acid–benzene cation complex

Geometrical and electronic structures of the acetic acid–benzene cation complex, (CH3COOH)⋅(C6H6)+, are studied experimentally and theoretically. Experimentally, a vibrational spectrum of (CH3COOH)⋅(C6H6)+ in the supersonic jet is measured in the 3000–3680 cm−1 region using an ion-trap photodissociation spectrometer. An electronic spectrum is also observed with this spectrometer in the 12 000–29 600 cm−1 region. Theoretically, ab initio molecular orbital calculations are performed for geometry optimization and evaluation of vibrational frequencies and electronic transition energies. The vibrational spectrum shows two distinct bands in the O–H stretching vibrational region. The frequency of the strong band (3577 cm−1) is close to that of the O–H stretching vibration of acetic acid and the weak one is located at 3617 cm−1. On the basis of geometry optimizations and frequency calculations, the strong band is assigned to the O–H stretching vibration of the cis-isomer of acetic acid in the hydrogen-bonded comp...