Structure of water in the liquid and supercritical states by rapid x-ray diffractometry using an imaging plate detector

• Koji Yamanaka

  Department of Chemistry, Faculty of Science, Fukuoka University, Nanakuma, Jonan-ku, Fukuoka 814-01, Japan

• Toshio Yamaguchi

  Department of Chemistry, Faculty of Science, Fukuoka University, Nanakuma, Jonan-ku, Fukuoka 814-01, Japan

• Hisanobu Wakita

  Department of Chemistry, Faculty of Science, Fukuoka University, Nanakuma, Jonan-ku, Fukuoka 814-01, Japan

抄録

The structure of water in the liquid and supercritical states has been investigated with a newly developed rapid liquid and amorphous x-ray diffractometer using an imaging plate area detector. This new method has enabled us to reduce the measuring time to only one hour for each sample, which is less by a factor of about 100 than the time usually needed with a conventional θ–θ type diffractometer, and thus to measure x-ray scatterings of water at high temperatures and pressures, including supercritical state. In this study the temperature range of 300–649 K with pressures of 0.1–98.1 MPa was covered (Tc=647.3 K, Pc=22.12 MPa, ρc=0.322 g/cm3 for water). Densities of sample water were kept constant at 1.0, 0.95, 0.9, 0.8, and 0.7 g/cm3 by controlling temperature and pressure. The radial distribution functions (RDFs) have shown that the peaks for the second and further neighbors interactions disappear over 416 K and 0.95 g/cm3, showing the breakdown of local tetrahedral icelike structure in water. The analysis of the first peak of the RDFs has revealed that with increasing temperature the coordination number of the first neighbor interaction around 2.9 Å decreases from 3.1 at 300 K and 1.0 g/cm3 to 1.6 at 649 K and 0.7 g/cm3, whereas the interaction around 3.4 Å increases from 1.3 to 2.3 at the corresponding temperatures, resulting in a constant coordination number of around four in the first shell under the nearly constant densities. These findings are discussed with the recent results of computer simulation, neutron scattering, and Raman spectroscopic studies on water at high temperatures and pressures.

収録刊行物

• The Journal of Chemical Physics

  The Journal of Chemical Physics 101 (11), 9830-9836, 1994-12-01

  AIP Publishing

キーワード

• Physical and Theoretical Chemistry
• General Physics and Astronomy

詳細情報

• CRID: 1363388845743797248
• NII論文ID: 30015652381
• DOI: 10.1063/1.467948
• ISSN: 10897690
• ISSN: 00219606
• Web Site: https://pubs.aip.org/aip/jcp/article-pdf/101/11/9830/19049184/9830_1_online.pdf
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