Maximising the efficiency of continuous photo-oxidation with singlet oxygen in supercritical CO2 by use of fluorous biphasic catalysis

Using a continuous fluorous biphasic separation, a photo-oxidation catalyst can be recycled, with increased productivity and a ×20 fold decrease in the amount of catalyst required.     

Comparison between IR absorption and raman scattering spectra of liquid and supercritical 1-butanol

Raman spectra of 1-butanol have been obtained at a constant pressure of 500 bar up to 350 degrees C and along isotherms 250, 300, and 350 degrees C up to 600 bar. The purpose of the experiment was to compare responses of Raman and IR absorption spectroscopy to the forming of O-H...O bonds in alcohols. As a result, some important inferences were drawn from the experiment. In particular, it has been estimated quantitatively how the intensity of Raman scattering in the region of the OH band depends on the extent of hydrogen bonding. As might be expected, the dependence is much weaker than in the case of the IR absorption. As was shown, the ratio of integrated intensities of bonded molecules in the absorption and scattering spectra is a constant and does not depend on temperature and density. The effect of cooperativity of hydrogen bonds is confirmed. It was also found that even at high pressures, a noticeable amount of nonbonded molecules exists at room temperature.     

Vibrationally resolved photoionization dynamics of CF4 in the D 2A1 state

Vibrationally resolved photoelectron spectroscopy of the CF4+ (D 2A1) state is studied for the first time over an extended energy range, 26.5相似文献   

Reflectometric studies of the etching of a silica fiber with a germanium silicate core in sub- and supercritical water

Fiber optic reflectometry (FOR) and scanning electron microscopy (SEM) were used to study the regularities of the etching of a single-mode optical silica fiber with a germanium silicate core in subcritical and supercritical water. It was demonstrated that the rate of etching of the germanium silicate core, being higher than that of etching of the silica cladding, was responsible for the formation of a well at the fiber end face, the depth of which increased with the time of etching. The temporal behavior of the FOR signal was of oscillatory character, an observation that accounted for the interference effects that accompany the reflection of radiation (from the photodiode used in the FOR) from the fiber end face during its etching (well deepening). The interference-controlled character of the FOR signal made it possible to directly measure the rate of etching of the fiber end face in water in its different phase states (gaseous, liquid, and supercritical) at various temperatures and pressures. The lowest measured rate of etching of the germanium silicate core (at 200°C and 54 atm) was 10⁻³ nm/s, whereas the highest measured rate was 30 nm/s (at 400°C and 246 atm). The temperature dependence of the etching rate was demonstrated to obey the Arrhenius law, with an activation energy of 58 ± 3 kJ/mol. At later stages of etching, the FOR signal changed from regular oscillatory to irregular noisy due to the formation defects of various sizes, as could be clearly seen in SEM images.