Xenon critical density

Sir William Ramsay (1852-1916) and Morris William Travers (1872-1961) discovered three new elements in just three months in 1898. They were krypton (May), neon (June), and xenon (July). The most difficult to identify was xenon because Ramsay and Travers needed to produce 10,000 pounds of liquid krypton in their refrigeration equipment in order to obtain just one pound of xenon. This was possible because of xenon s high critical temperature and because xenon s density is greater than oxygen s. 

Figure 1. Log-log plot of the density difference di — da between the liquid and vapor phase of ammonium chloride [34] and bismuth chloride [60] versus the temperature distance T— Tc from the critical temperature Tc. For comparison, data are also shown for xenon and ammonia. The slope of the straight line for NH4C1 is f = 0.5. The slopes of the other lines are / = 0.326. Redrawn with permission from M. Buback, Thesis, Karlsruhe 1969.

Very few experiments have been performed on vibrational dynamics in supercritical fluids (47). A few spectral line experiments, both Raman and infrared, have been conducted (48-58). While some studies show nothing unique occurring near the critical point (48,51,53), other work finds anomalous behavior, such as significant line broadening in the vicinity of the critical point (52,54-60). Troe and coworkers examined the excited electronic state vibrational relaxation of azulene in supercritical ethane and propane (61-64). Relaxation rates of azulene in propane along a near-critical isotherm show the three-region dependence on density, as does the shift in the electronic absorption frequency. Their relaxation experiments in supercritical carbon dioxide, xenon, and ethane were done farther from the critical point, and the three-region behavior was not observed. The measured density dependence of vibrational relaxation in these fluids was... 

The pulsed xenon lamp source in Table III merits special attention. It is a well recognized fact that pulsing xenon lamps significantly increases their output below 300 nm. In addition, photon flux densities produced by pulsing xenon lamps are extremely high and can lead, under the correct circumstances, to efficient curing of highly filled, very thick films or composites. Both the output below 300 nm and the hig pulse densities make pulsed xenon lamp sources a choice which should be considered for certain critical applications. 

Huang, S.S.S. and Freeman, G.R., 1978, Electron mobilities in gaseous, critical, and liquid xenon Density, electric field, and temperature effects Quasi localization, J. Chem Phys., 68 1355. 

By contrast, excess electrons in non-polar solvents can exhibit delocalized behavior as well, MCPI simulatioas have revealed cavity formation in a helium environment and delocalized behavior in the more polarizable xenon. Similar patterns were observed in alkane solvents. While the electron always exists in an extended state in a methane. solvent, a transition to a self-trapping state was found in the case of ethane at a critical value of the fluid density. ... 

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