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Structure and Properties of Supercritical Water: Experimental and Theoretical Characterizations. J 2021. [DOI: 10.3390/j4040049] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Water in the supercritical region of the phase diagram exhibits a markedly different structure and properties from that at ambient conditions, which is useful in controlling chemical reactions. Nonetheless, the experimental, as well as theoretical, characterization of the substance is not easy because the region is next to the critical point. This article reviews the experimental as well as theoretical studies on water in the supercritical region and its properties as a solvent for chemical reactions, as carried out by the authors and based on small-angle X-ray scattering and the statistical mechanics theory of molecular liquids, also known as reference interaction-site model (RISM) theory.
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Excess volume, isothermal compressibility, isentropic compressibility and speed of sound of carbon dioxide+n-heptane binary mixture under pressure up to 70 MPa. II. Molecular simulations. J Supercrit Fluids 2020. [DOI: 10.1016/j.supflu.2020.104890] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
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Ploetz EA, Smith PE. Gas or Liquid? The Supercritical Behavior of Pure Fluids. J Phys Chem B 2019; 123:6554-6563. [DOI: 10.1021/acs.jpcb.9b04058] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Elizabeth A. Ploetz
- Department of Chemistry, Kansas State University, 213 CBC Building, 1212 Mid Campus Dr. North, Manhattan, Kansas 66506-0401, United States
| | - Paul E. Smith
- Department of Chemistry, Kansas State University, 213 CBC Building, 1212 Mid Campus Dr. North, Manhattan, Kansas 66506-0401, United States
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Shibuta S, Imamura H, Nishikawa K, Morita T. Fluctuational parameters based on the Bhatia–Thornton theory for supercritical solutions: Application to a supercritical aqueous solution of n -pentane. Chem Phys 2017. [DOI: 10.1016/j.chemphys.2017.02.003] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
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5
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Significant difference in the attractive energies of ethane and ethanol in supercritical CO2. J Supercrit Fluids 2017. [DOI: 10.1016/j.supflu.2016.05.050] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
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Yoon TJ, Ha MY, Lee WB, Lee YW. Monte Carlo simulations on the local density inhomogeneities of sub- and supercritical carbon dioxide: Statistical analysis based on the Voronoi tessellation. J Supercrit Fluids 2017. [DOI: 10.1016/j.supflu.2016.09.001] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
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Affiliation(s)
- Bo Bao
- Department of Mechanical
and Industrial Engineering, University of Toronto, 5 King’s
College Road, Toronto, M5S3G8, Ontario, Canada
| | - Jason Riordon
- Department of Mechanical
and Industrial Engineering, University of Toronto, 5 King’s
College Road, Toronto, M5S3G8, Ontario, Canada
| | - Yi Xu
- Department of Mechanical
and Industrial Engineering, University of Toronto, 5 King’s
College Road, Toronto, M5S3G8, Ontario, Canada
| | - Huawei Li
- Department of Mechanical
and Industrial Engineering, University of Toronto, 5 King’s
College Road, Toronto, M5S3G8, Ontario, Canada
| | - David Sinton
- Department of Mechanical
and Industrial Engineering, University of Toronto, 5 King’s
College Road, Toronto, M5S3G8, Ontario, Canada
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Kajiya D, Imanishi M, Saitow KI. Solvation of Esters and Ketones in Supercritical CO2. J Phys Chem B 2016; 120:785-92. [PMID: 26741296 DOI: 10.1021/acs.jpcb.5b11740] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Vibrational Raman spectra for the C═O stretching modes of three esters with different functional groups (methyl, a single phenyl, and two phenyl groups) were measured in supercritical carbon dioxide (scCO2). The results were compared with Raman spectra for three ketones involving the same functional groups, measured at the same thermodynamic states in scCO2. The peak frequencies of the Raman spectra of these six solute molecules were analyzed by decomposition into the attractive and repulsive energy components, based on the perturbed hard-sphere theory. For all solute molecules, the attractive energy is greater than the repulsive energy. In particular, a significant difference in the attractive energies of the ester-CO2 and ketone-CO2 systems was observed when the methyl group is attached to the ester or ketone. This difference was significantly reduced in the solute systems with a single phenyl group and was completely absent in those with two phenyl groups. The optimized structures among the solutes and CO2 molecules based on quantum chemical calculations indicate that greater attractive energy is obtained for a system where the oxygen atom of the ester is solvated by CO2 molecules.
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Affiliation(s)
- Daisuke Kajiya
- Natural Science Center for Basic Research and Development (N-BARD) and ‡Department of Chemistry, Graduate School of Science, Hiroshima University , 1-3-1 Kagamiyama, Higashi-hiroshima, Hiroshima 739-8526, Japan
| | - Masayoshi Imanishi
- Natural Science Center for Basic Research and Development (N-BARD) and ‡Department of Chemistry, Graduate School of Science, Hiroshima University , 1-3-1 Kagamiyama, Higashi-hiroshima, Hiroshima 739-8526, Japan
| | - Ken-ichi Saitow
- Natural Science Center for Basic Research and Development (N-BARD) and ‡Department of Chemistry, Graduate School of Science, Hiroshima University , 1-3-1 Kagamiyama, Higashi-hiroshima, Hiroshima 739-8526, Japan
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Kajiya D, Saitow KI. Investigation of attractive and repulsive interactions associated with ketones in supercritical CO2, based on Raman spectroscopy and theoretical calculations. J Chem Phys 2013; 139:054509. [DOI: 10.1063/1.4817190] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
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10
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Wei S, Saitow KI. In situ multipurpose time-resolved spectrometer for monitoring nanoparticle generation in a high-pressure fluid. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2012; 83:073110. [PMID: 22852674 DOI: 10.1063/1.4737886] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/12/2023]
Abstract
We developed a multipurpose time-resolved spectrometer for studying the dynamics of nanoparticles generated by pulsed-laser ablation (PLA) in a high-pressure fluid. The apparatus consists of a high-pressure optical cell and three spectrometers for in situ measurements. The optical cell was designed for experiments at temperatures up to 400 K and pressures up to 30 MPa with fluctuations within ±0.1% h(-1). The three spectrometers were used for the following in situ measurements at high pressures: (i) transient absorption spectrum measurements from 350 to 850 nm to investigate the dynamics of nanoparticle generation from nanoseconds to milliseconds after laser irradiation, (ii) absorption spectrum measurements from 220 to 900 nm to observe the time evolution of nanoparticles from seconds to hours after laser ablation, and (iii) dynamic light scattering measurements to track nanoparticles with sizes from 10 nm to 10 μm in the time range from seconds to hours after laser ablation. By combining these three spectrometers, we demonstrate in situ measurements of gold nanoparticles generated by PLA in supercritical fluids. This is the first report of in situ time-resolved measurements of the dynamics of nanoparticles generated in a supercritical fluid.
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Affiliation(s)
- Shaoyu Wei
- Department of Chemistry, Graduate School of Science, Hiroshima University, 1-3-1 Kagamiyama, 739-8526 Higashi-hiroshima, Japan
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Nishiyama Y, Wada T, Kakiuchi K, Inoue Y. Entrainer Effects on Enantiodifferentiating Photocyclization of 5-Hydroxy-1,1-diphenylpentene in Near-Critical and Supercritical Carbon Dioxide. J Org Chem 2012; 77:5681-6. [DOI: 10.1021/jo300816w] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Yasuhiro Nishiyama
- Graduate School of Materials
Science, Nara Institute of Science and Technology (NAIST), Takayama, Ikoma 630-0192, Japan
| | - Takehiko Wada
- Institute of Multidisciplinary
Research for Advanced Materials, Tohoku University, Katahira, Aoba, Sendai 980-8577, Japan
| | - Kiyomi Kakiuchi
- Graduate School of Materials
Science, Nara Institute of Science and Technology (NAIST), Takayama, Ikoma 630-0192, Japan
| | - Yoshihisa Inoue
- Department of Applied Chemistry, Osaka University, Yamada-oka, Suita 565-0871, Japan
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12
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Kajiya D, Saitow KI. Significant substitution effects in dipolar and non-dipolar supercritical fluids. J Chem Phys 2011; 134:234508. [DOI: 10.1063/1.3602159] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
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13
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Kajiya D, Saitow KI. Site-Selective Solvation in Supercritical CO2Observed by Raman Spectroscopy: Phenyl Group Leads to Greater Attractive Energy than Chloro Group. J Phys Chem B 2010; 114:16832-7. [DOI: 10.1021/jp107820j] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Daisuke Kajiya
- Natural Science Center for Basic Research and Development (N-BARD) and Department of Chemistry, Graduate School of Science, Hiroshima University, 1-3-1 Kagamiyama, Higashi-hiroshima, Hiroshima 739-8526, Japan
| | - Ken-ichi Saitow
- Natural Science Center for Basic Research and Development (N-BARD) and Department of Chemistry, Graduate School of Science, Hiroshima University, 1-3-1 Kagamiyama, Higashi-hiroshima, Hiroshima 739-8526, Japan
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Kajiya D, Saitow KI. Solute−Solvent Intermolecular Interactions in Supercritical Xe, SF6, CO2, and CHF3 Investigated by Raman Spectroscopy: Greatest Attractive Energy Observed in Supercritical Xe. J Phys Chem B 2010; 114:8659-66. [DOI: 10.1021/jp101217s] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Daisuke Kajiya
- Natural Science Center for Basic Research and Development (N-BARD), Hiroshima University, 1-3-1 Kagamiyama, Higashi-Hiroshima, Hiroshima 739-8526, Japan, and Department of Chemistry, Graduate School of Science, Hiroshima University, 1-3-1 Kagamiyama, Higashi-Hiroshima, Hiroshima 739-8526, Japan
| | - Ken-ichi Saitow
- Natural Science Center for Basic Research and Development (N-BARD), Hiroshima University, 1-3-1 Kagamiyama, Higashi-Hiroshima, Hiroshima 739-8526, Japan, and Department of Chemistry, Graduate School of Science, Hiroshima University, 1-3-1 Kagamiyama, Higashi-Hiroshima, Hiroshima 739-8526, Japan
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15
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Ghosh SK, Tsujii K. Unique diffusion behavior observed in supercritical ethanol. J Chem Phys 2010; 132:144503. [DOI: 10.1063/1.3373404] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
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16
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Kajiya D, Saitow KI. Solvation Structures of cis- and trans-1,2-Dichloroethylene in Supercritical CO2 Investigated by Raman Spectroscopy and Attractive Energy Calculations. J Phys Chem B 2009; 113:13291-9. [DOI: 10.1021/jp903240v] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Affiliation(s)
- Daisuke Kajiya
- Natural Science Center for Basic Research and Development (N-BARD), Hiroshima University, 1-3-1 Kagamiyama, Higashi-hiroshima, Hiroshima 739-8526, Japan, Department of Chemistry, Graduate School of Science, Hiroshima University, 1-3-1 Kagamiyama, Higashi-hiroshima, Hiroshima 739-8526, Japan, and PRESTO, Japan Science and Technology Agency, 4-1-8 Honcho, Kawaguchi, Saitama 332-0012, Japan
| | - Ken-ichi Saitow
- Natural Science Center for Basic Research and Development (N-BARD), Hiroshima University, 1-3-1 Kagamiyama, Higashi-hiroshima, Hiroshima 739-8526, Japan, Department of Chemistry, Graduate School of Science, Hiroshima University, 1-3-1 Kagamiyama, Higashi-hiroshima, Hiroshima 739-8526, Japan, and PRESTO, Japan Science and Technology Agency, 4-1-8 Honcho, Kawaguchi, Saitama 332-0012, Japan
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Skarmoutsos I, Dellis D, Samios J. The Effect of Intermolecular Interactions on Local Density Inhomogeneities and Related Dynamics in Pure Supercritical Fluids. A Comparative Molecular Dynamics Simulation Study. J Phys Chem B 2009; 113:2783-93. [DOI: 10.1021/jp809271n] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Affiliation(s)
- Ioannis Skarmoutsos
- Department of Chemistry, Laboratory of Physical Chemistry, University of Athens, Panepistimiopolis 157-71, Athens, Greece
| | - Dimitris Dellis
- Department of Chemistry, Laboratory of Physical Chemistry, University of Athens, Panepistimiopolis 157-71, Athens, Greece
| | - Jannis Samios
- Department of Chemistry, Laboratory of Physical Chemistry, University of Athens, Panepistimiopolis 157-71, Athens, Greece
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18
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Tanneur V, Joussot-Dubien C, Fournel B, Sarrade S, Freiss B, Marciacq F, Rios G. Group A particle fluidization in supercritical carbon dioxide: Effect of operating conditions on fluidization efficiency. POWDER TECHNOL 2008. [DOI: 10.1016/j.powtec.2008.02.011] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
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19
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Nishiyama Y, Kaneda M, Asaoka S, Saito R, Mori T, Wada T, Inoue Y. Mechanistic Study on the Enantiodifferentiating Anti-Markovnikov Photoaddition of Alcohols to 1,1-Diphenyl-1-alkenes in Near-Critical and Supercritical Carbon Dioxide. J Phys Chem A 2007; 111:13432-40. [DOI: 10.1021/jp076179i] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Yasuhiro Nishiyama
- Department of Applied Chemistry and PRESTO (JST), Osaka University, 2-1 Yamada-oka, Suita 565-0871, and Japan and Entropy Control Project, ICORP, JST, 4-6-3 Kamishinden, Toyonaka 560-0085, Japan
| | - Masayuki Kaneda
- Department of Applied Chemistry and PRESTO (JST), Osaka University, 2-1 Yamada-oka, Suita 565-0871, and Japan and Entropy Control Project, ICORP, JST, 4-6-3 Kamishinden, Toyonaka 560-0085, Japan
| | - Sadayuki Asaoka
- Department of Applied Chemistry and PRESTO (JST), Osaka University, 2-1 Yamada-oka, Suita 565-0871, and Japan and Entropy Control Project, ICORP, JST, 4-6-3 Kamishinden, Toyonaka 560-0085, Japan
| | - Ryota Saito
- Department of Applied Chemistry and PRESTO (JST), Osaka University, 2-1 Yamada-oka, Suita 565-0871, and Japan and Entropy Control Project, ICORP, JST, 4-6-3 Kamishinden, Toyonaka 560-0085, Japan
| | - Tadashi Mori
- Department of Applied Chemistry and PRESTO (JST), Osaka University, 2-1 Yamada-oka, Suita 565-0871, and Japan and Entropy Control Project, ICORP, JST, 4-6-3 Kamishinden, Toyonaka 560-0085, Japan
| | - Takehiko Wada
- Department of Applied Chemistry and PRESTO (JST), Osaka University, 2-1 Yamada-oka, Suita 565-0871, and Japan and Entropy Control Project, ICORP, JST, 4-6-3 Kamishinden, Toyonaka 560-0085, Japan
| | - Yoshihisa Inoue
- Department of Applied Chemistry and PRESTO (JST), Osaka University, 2-1 Yamada-oka, Suita 565-0871, and Japan and Entropy Control Project, ICORP, JST, 4-6-3 Kamishinden, Toyonaka 560-0085, Japan
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Skarmoutsos I, Samios J. Local intermolecular structure and dynamics in binary supercritical solutions. A molecular dynamics simulation study of methane in carbon dioxide. J Mol Liq 2006. [DOI: 10.1016/j.molliq.2005.11.023] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
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21
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Kajiya D, Nishikawa K, Saitow KI. Time Evolution of Density Fluctuation in the Supercritical Region. 2. Comparison of Hydrogen- and Non-hydrogen-Bonded Fluids. J Phys Chem A 2005; 109:7365-70. [PMID: 16834103 DOI: 10.1021/jp0522056] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
The time evolution of the density fluctuation of molecules is investigated by dynamic light scattering in six neat fluids in supercritical states. This study is the first to compare the dynamics of density inhomogeneity between hydrogen- and non-hydrogen-bonded fluids. Supercritical methanol and ethanol are used as hydrogen-bonded fluids, whereas four non-hydrogen-bonded fluids were used: CHF(3), C(2)H(4), CO(2), and Xe. We measure the time correlation function of the density fluctuation of each fluid at the same reduced temperatures and densities and investigate the relationship between the dynamic and static density inhomogeneities of those supercritical fluids. In all cases, the profile of the time correlation function of the density fluctuation is characterized by a single-exponential function, whose decay is responsible for the dynamics characterized by hydrodynamic conditions. We obtain correlation times from the time correlation function and discuss dynamic and static inhomogeneity using the Kawasaki theory and the Landau-Placzek theory. While the correlation times in the six fluids show noncoincidence, those values agree well with each other except for the supercritical alcohols when scaled to a dimensionless parameter. Although the principle of corresponding state is observed in the non-hydrogen-bonded fluids, both the supercritical methanol and ethanol deviate from that principle. This deviation is attributed to the presence of hydrogen bonding among alcohol molecules at high temperature and low density. The average cluster size of each fluid is estimated under the same thermodynamic conditions, and it is shown that the clusters of supercritical alcohols are on average 1.5-1.7 times larger than those of the four non-hydrogen-bonded fluids. Moreover, the thermal diffusivity of each neat fluid is obtained over wide ranges of density and temperature.
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Affiliation(s)
- Daisuke Kajiya
- Division of Diversity Science, Graduate School of Science and Technology, Chiba University, Yayoi, Inage, Chiba 263-8522, Japan
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Saitow KI, Sasaki J. Attractive and repulsive interactions among methanol molecules in supercritical state investigated by Raman spectroscopy and perturbed hard-sphere theory. J Chem Phys 2005; 122:104502. [PMID: 15836327 DOI: 10.1063/1.1858442] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
The short-range structure of supercritical methanol (CH(3)OH) is investigated by measuring the spontaneous Raman spectra of the C-O stretching mode. The spectra are obtained at a reduced temperature, T(r)=T/T(c)=1.02 (522.9 K), which permits the neat fluid to be studied isothermally as a function of density. As the density increases, the spectral peaks shift toward the lower energy side and the spectra broaden. In the supercritical region, the amount of shifting shows nonlinear density dependence and the width becomes anomalously large. We use the perturbed hard-sphere model to analyze these density dependencies along the vibrational coordinate. The amount of shifting is decomposed into attractive and repulsive components, and the changes in attractive and repulsive energies are evaluated as functions of density and packing fraction, both of which are continuously varied by a factor of 120. Here we show that the shift amount consists principally of the attractive component at all densities, since the attractive energy is about eight times the repulsive energy. The density dependence of the widths is analyzed by calculating homogeneous and inhomogeneous widths as a function of density. The results show that, although vibrational dephasing and density inhomogeneity contribute similarly to the width at low and middle densities, at high density the main contributor turns out to be the vibrational dephasing. We estimate the local density enhancements of supercritical CH(3)OH as function of bulk density by two methods. The results of these analyses show common features, and both the estimated local density enhancements of CH(3)OH are considerably larger than the local density enhancements of simple fluids, i.e., those having nonhydrogen bonding. It is revealed that the local density of supercritical CH(3)OH is 40%-60% greater than the local densities of the simple fluids. We also estimate the local density fluctuation using the obtained values of attractive shift, inhomogeneous width, and local density. The density fluctuation in the vicinity of a vibrating molecule is compared to the fluctuation of bulk density, which is obtained from the thermodynamic calculation.
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Affiliation(s)
- Ken-ichi Saitow
- Department of Physics, Faculty of Science, Chiba University, Yayoi, Inage, Chiba 263-8522, Japan.
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Saitow KI. Silicon Nanoclusters Selectively Generated by Laser Ablation in Supercritical Fluid. J Phys Chem B 2005; 109:3731-3. [PMID: 16851418 DOI: 10.1021/jp0442551] [Citation(s) in RCA: 61] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
A novel method for generating nanomaterials is developed by performing laser ablation of silicon crystals in supercritical fluid. The method is shown to successfully generate silicon nanoclusters, and to allow for the selective generation of clusters having different electronic structures. This selective fabrication enables us to obtain the nanoclusters via a dry process, by changing only the fluid density and/or temperature when ablation is performed. The experimental procedures are not highly specialized, and a variety of researchers unfamiliar with wet chemical processes are able to obtain nanoclusters with different properties in only a few minutes. This new method can also be used to selectively obtain other semiconductor or metal nanomaterials with different properties.
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Saitow KI, Kajiya D, Nishikawa K. Time Evolution of Density Fluctuation in Supercritical Region. I. Non-hydrogen-bonded Fluids Studied by Dynamic Light Scattering. J Phys Chem A 2004; 109:83-91. [PMID: 16839091 DOI: 10.1021/jp046555o] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
The time evolution of the density fluctuation of molecules inhomogeneously dispersing in a mesoscopic volume is investigated by dynamic light scattering in several fluids in supercritical states. This study is the first time-domain investigation to compare the dynamics of density fluctuation among several fluids. The samples used are non-hydrogen-bonded fluids in the supercritical states: CHF(3), C(2)H(4), CO(2), and xenon. These four molecules have different properties but are of similar size. Under these conditions, the relationship between dynamic and static density inhomogeneities is studied by measuring the time correlation function of the density fluctuation. In all cases, this function is characterized by a single exponential function, decaying within a few microseconds. While the correlation times in the four fluids show noncoincidence, those values agree well with each other when scaled to a dimensionless parameter. From the results of this scaling based on the Kawasaki theory and Landau-Placzek theory, the relation between dynamics and static structures is analyzed, and the following four insights are obtained: (i) viscosity is the main contributor to the time evolution of density fluctuation; (ii) the principle of corresponding state is observed by the use of time-domain data; (iii) the Kawasaki theory and the Landau-Placzek theory are confirmed to be applicable to polar, nonpolar, and nondipolar fluids that have no hydrogen bonding, at temperatures relatively far from critical temperature; and (iv) the density fluctuation correlation length and the value of density fluctuation are estimated from the time-domain data and agree with the values from other experiments and calculations.
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Affiliation(s)
- Ken-Ichi Saitow
- Department of Physics, Faculty of Science, Chiba University, Yayoi, Inage, Chiba 263-8522, Japan.
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Saitow KI, Nakayama H, Ishii K, Nishikawa K. Attractive and Repulsive Intermolecular Interactions of a Polar Molecule: Short-Range Structure of Neat Supercritical CHF3 Investigated by Raman Spectroscopy. J Phys Chem A 2004. [DOI: 10.1021/jp049225c] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Affiliation(s)
- Ken-ichi Saitow
- Department of Physics, Faculty of Science, Chiba University, Yayoi, Inage, Chiba 263-8522, Japan
| | - Hideyuki Nakayama
- Department of Chemistry, Faculty of Science, Gakushuin University, Mejiro, Toshima, Tokyo 171-8588, Japan
| | - Kikujiro Ishii
- Department of Chemistry, Faculty of Science, Gakushuin University, Mejiro, Toshima, Tokyo 171-8588, Japan
| | - Keiko Nishikawa
- Division of Diversity Science, Graduate School of Science and Technology, Chiba University, Yayoi, Inage, Chiba 263-8522, Japan
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Nishiyama Y, Kaneda M, Saito R, Mori T, Wada T, Inoue Y. Enantiodifferentiating Photoaddition of Alcohols to 1,1-Diphenylpropene in Supercritical Carbon Dioxide: Sudden Jump of Optical Yield at the Critical Density. J Am Chem Soc 2004; 126:6568-9. [PMID: 15161281 DOI: 10.1021/ja0494609] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
In the enantiodifferentiating photoaddition of ROH (R = Me, Et, i-Pr) to 1,1-diphenylpropene sensitized by fructosyl 1,4-naphthalenedicarboxylate in supercritical carbon dioxide, the enantiomeric excess of photoadduct increased with increasing bulkiness of the alcohol at all pressures used, with an accompanying sudden jump at the critical density, for which the enhanced clustering of alcohol, particularly in the subcritical pressure region, was revealed to be responsible from the fluorescence spectral examinations.
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Affiliation(s)
- Yasuhiro Nishiyama
- Department of Molecular Chemistry and PRESTO (JST), Osaka University, 2-1 Yamada-oka, Suita 565-0871, Japan
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