“…Comparison with our previous results in carbon dioxide was carried out. Figure shows the excess density around the AP−TMB exciplex in carbon dioxide . Solid lines are derived by Weibull function fitting.…”
Section: Resultsmentioning
confidence: 99%
“…Our results show that the ratios of the solute−solvent and solvent−solvent interactions are comparable between these two systems as discussed in a later section. 7 Excess density around exciplex at various temperatures and densities in supercritical carbon dioxide . Markers are experimental data.…”
Section: Resultsmentioning
confidence: 99%
“…Excess density around exciplex at various temperatures and densities in supercritical carbon dioxide . Markers are experimental data.…”
Section: Resultsmentioning
confidence: 99%
“…In previous work, we clarified the local density augmentation that occurs around transient species with a time-resolved method. [15][16][17] Most studies on local density augmentation have focused on supercritical carbon dioxide or other supercritical fluids for which the critical temperature is not too high. There have been few studies on water in its supercritical state, because of the difficulty in performing spectroscopic measurements at highpressure and high-temperature conditions.…”
Section: Introductionmentioning
confidence: 99%
“…Since local density augmentation is a result of short-range interactions, it has been actively researched by observing probe molecules with spectroscopic methods such as NMR, UV/Vis, electron paramagnetic resonance, and fluorescence spectroscopy. In previous work, we clarified the local density augmentation that occurs around transient species with a time-resolved method. − …”
Local density augmentation around exciplex between acetophenone and N,N,N',N'-tetramethylbenzidine in supercritical water was measured by observing the peak shift of transient absorption spectrum at temperatures from 380 to 410 degrees C and at pressures from 6 to 37 MPa. Large local density augmentation was observed at lower solvent densities. Local density augmentation was evaluated by the excess density, which was defined as the difference between local density and bulk density, and the density enhancement factor, which was defined by the ratio of the local density to the bulk density. The number of solvating molecules was estimated with a Langmuir adsorption model. The excess density was found to exhibit a maximum at approximately 0.15 g cm(-3), which decreased with increasing temperature. The density enhancement factor was found to decrease with increasing temperature; however, its value was much greater than unity at 410 degrees C, which provides evidence that exciplex-water interactions still exist at these conditions. The temperature dependence of local density augmentation around the exciplex in supercritical water was comparable with that in supercritical carbon dioxide, which suggests that the ratios of the solute-solvent and solvent-solvent interactions are comparable between these two systems.
“…Comparison with our previous results in carbon dioxide was carried out. Figure shows the excess density around the AP−TMB exciplex in carbon dioxide . Solid lines are derived by Weibull function fitting.…”
Section: Resultsmentioning
confidence: 99%
“…Our results show that the ratios of the solute−solvent and solvent−solvent interactions are comparable between these two systems as discussed in a later section. 7 Excess density around exciplex at various temperatures and densities in supercritical carbon dioxide . Markers are experimental data.…”
Section: Resultsmentioning
confidence: 99%
“…Excess density around exciplex at various temperatures and densities in supercritical carbon dioxide . Markers are experimental data.…”
Section: Resultsmentioning
confidence: 99%
“…In previous work, we clarified the local density augmentation that occurs around transient species with a time-resolved method. [15][16][17] Most studies on local density augmentation have focused on supercritical carbon dioxide or other supercritical fluids for which the critical temperature is not too high. There have been few studies on water in its supercritical state, because of the difficulty in performing spectroscopic measurements at highpressure and high-temperature conditions.…”
Section: Introductionmentioning
confidence: 99%
“…Since local density augmentation is a result of short-range interactions, it has been actively researched by observing probe molecules with spectroscopic methods such as NMR, UV/Vis, electron paramagnetic resonance, and fluorescence spectroscopy. In previous work, we clarified the local density augmentation that occurs around transient species with a time-resolved method. − …”
Local density augmentation around exciplex between acetophenone and N,N,N',N'-tetramethylbenzidine in supercritical water was measured by observing the peak shift of transient absorption spectrum at temperatures from 380 to 410 degrees C and at pressures from 6 to 37 MPa. Large local density augmentation was observed at lower solvent densities. Local density augmentation was evaluated by the excess density, which was defined as the difference between local density and bulk density, and the density enhancement factor, which was defined by the ratio of the local density to the bulk density. The number of solvating molecules was estimated with a Langmuir adsorption model. The excess density was found to exhibit a maximum at approximately 0.15 g cm(-3), which decreased with increasing temperature. The density enhancement factor was found to decrease with increasing temperature; however, its value was much greater than unity at 410 degrees C, which provides evidence that exciplex-water interactions still exist at these conditions. The temperature dependence of local density augmentation around the exciplex in supercritical water was comparable with that in supercritical carbon dioxide, which suggests that the ratios of the solute-solvent and solvent-solvent interactions are comparable between these two systems.
The sections in this article are
Introduction
“Solvent” Properties of Supercritical Fluids
Scope of This Chapter
Experimental Considerations
Photochemical Reactions in Supercritical Fluid Solvents
Geometric Isomerization
Photodimerization
Carbonyl Photochemistry
Photosensitization and Photo‐induced Electron Transfer
Photo‐oxidation Reactions
Photo‐initiated Radical Chain Reactions in Supercritical Fluid Solvents
Free Radical Brominations of Alkyl Aromatics in Supercritical Carbon Dioxide
Free Radical Chlorination of Alkanes in Supercritical Fluid Solvents
Conclusion
Acknowledgment
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