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Volume 31 (2004)
- Issue 5 Pages 227-
- Issue 4 Pages 164-
- Issue 3 Pages 100-
- Issue 2 Pages 62-
- Issue 1 Pages 2-
Volume 31, Issue 1
Displaying 1-7 of 7 articles from this issue
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Hiroshi Fukui, Tomoo Katsura, Osamu Ohtaka2004 Volume 31 Issue 1 Pages 2-5
Published: January 25, 2004
Released on J-STAGE: September 07, 2009
JOURNAL FREE ACCESSDehydration of brucite was measured by means of high-pressure differential thermal analysis (HP-DTA). The enthalpy of the dehydration was derived as a function of temperature and pressure from thermodynamic quantities of brucite, periclase, and H2O fluid. The dehydration of brucite is likely to be used to quantify an HP-DTA system up to 6GPa. The system calibration factor was determined to be 1.2×10-3JK-1s-1.View full abstractDownload PDF (1081K) -
Shinji Saito, Masakazu Matsumoto, Iwao Ohmine2004 Volume 31 Issue 1 Pages 6-13
Published: January 25, 2004
Released on J-STAGE: September 07, 2009
JOURNAL FREE ACCESSVarious aspects of Water Dynamics are discussed; (1) Fluctuation and relaxation in hydrogen bond network rearrangement and their observation, (2) Mechanism of water freezing, and (3) Proton transfer in liquid water and ice.
Liquid water yields the intermittently collective motions accompanied with large fluctuations. Various relaxation processes associated with these collective motions in liquid water yield so-called 1/f spectra. We present the result of our analysis on a method, called 2-dimensional Raman/IR spectroscopy. This method will be able to deal with the mechanism of these intermittent collective motions.
Upon cooling, water freezes into ice. This process is a most familiar phase-transition, occurring in many places in nature, but has never been successfully simulated by a computer simulation. We report the first successful simulation for the pure water freezing process, which gives a molecular level picture of, particularly, how an initial nucleus is created and grows.
The proton transfer is a most basic reaction in chemistry and biochemistry. It is found that the mechanism of the proton transport in ice is completely different from that in liquid water. The repulsion from fourth coordinated water makes the facile proton transfer possible. The long range solvation is essential for the smooth transport of the proton in ice.View full abstractDownload PDF (3646K) -
Masaru Nakahara2004 Volume 31 Issue 1 Pages 14-22
Published: January 25, 2004
Released on J-STAGE: September 07, 2009
JOURNAL FREE ACCESSFirst we explain the importance of the investigation on the structure and properties of supercritical water in relation to the chemical evolution and the environmental and energy issues of the 21st century. Molecular interpretations are given to the temperature dependence of the density, dielectric constant, and viscosity, hydrogen-bonding structure, and dynamics of supercritical water. The three-dimensional network structure, characteristic of ambient water, is broken down in hot expanded water at temperatures higher than ∼200°C and densities lower than ∼0.9g cm-3. The number of hydrogen bonds per molecule has been determined by the NMR method combined with computer simulation; it decreases from ∼4 for ambient water to 1-2 for supercritical water at 400°C and the critical density (∼0.32g cm-3). The NMR rotational correlation time (τ2R) for supercritical water at the medium densities is in the range of 50-70 fs, two orders of magnitude smaller than the ambient value (2 ps). Supercritical water is shown to be an alternative to hazardous organic solvents; there are being found new hydrothermal organic reactions without catalyst for the development of green chemistry.View full abstractDownload PDF (2582K) -
Osamu Mishima2004 Volume 31 Issue 1 Pages 23-28
Published: January 25, 2004
Released on J-STAGE: September 07, 2009
JOURNAL FREE ACCESSLiquid water shows the eccentric properties at low temperatures such as the maximum density at 4°C. The amorphous solid form of water also shows a peculiar phenomenon known as polyamorphism. Poole et al. has proposed the second-critical-point hypothesis of water and explained these properties. The experimental and theoretical studies support the hypothesis, but further proofs are required.View full abstractDownload PDF (2279K) -
Makoto Sakata, Eiji Nishibori, Masaki Takata2004 Volume 31 Issue 1 Pages 29-36
Published: January 25, 2004
Released on J-STAGE: September 07, 2009
JOURNAL FREE ACCESSThe accurate charge density studies by the Maximum Entropy Method (MEM) utilizing X-ray diffraction is outlined with some examples. The basic concept of the method is stated in some details. In addition, some experimental charge densities are given to demonstrate the usefulness of the method, such as endohedral metallofullerenes, metal hydride and intermetallic compounds. In La2@C80 metallofullerene case, the extraordinary charge density distribution is revealed, that is two La atoms form pentagonal dodecahedron charge density due to the hopping motion inside fullerene cage. In MgH2 metal hydride case, charge density peaks of hydrogen atoms are clearly found in MEM charge density map, whereas no such charge density peaks are found in direct Fourier charge density map.View full abstractDownload PDF (1852K) -
2004 Volume 31 Issue 1 Pages 37
Published: January 25, 2004
Released on J-STAGE: September 07, 2009
JOURNAL FREE ACCESSDownload PDF (155K) -
T. Fujii2004 Volume 31 Issue 1 Pages 38
Published: January 25, 2004
Released on J-STAGE: September 07, 2009
JOURNAL FREE ACCESSDownload PDF (219K)
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