Xenon critical point

Values extracted and in some cases rounded off from those cited in Rabinovich (ed.), Theimophysical Propeities of Neon, Ai gon, Krypton and Xenon, Standards Press, Moscow, 1976. m = melting point c = critical point. The notation 6.654.-4 signifies 6.654 X 10 . This source contains values for the compressed state up to 1000 bar, etc. This book was published in English translation by Hemisphere, New York 1988 (604 pp.). 

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... 

R. H. Huiser, A. C. Michels, H. M. J, Boots, and N. J. Trappeniers. The Depolarization Factor of Light Scattered from Xenon near Its Critical Point. In B. Vodar and Ph. Marteau (ed.,) High Pressure Science and Technology, Pergamon, New York, 1980, pp. 727-729. 

A supercritical fluid is defined as a substance above its critical temperature (Tc) and critical pressure (Pc). The critical point represents the highest temperature and pressure at which the substance can exist as a vapor and liquid in equilibrium (Tables 3 and 4). Supercritical fluids are highly compressed fluids that combine properties of gases and liquids in a synergistic manner. Fluids such as supercritical xenon, ethane, and carbon dioxide (CO2) offer a range of unusual chemical possibilities in both synthetic and analytical chemistry. 

Figure 8.20 Critical mixture curves for methanol with methane, ethane, ethylene, xenon, and carbon dioxide (Robinson, Peng, and Chung, 1985 Brunner, 1985 Francesconi, Lentz, and Franck, 1981). The P-T traces for the ethane, ethylene, xenon, and carbon dioxide systems are virtually indistinguishable in the region shown in the graph. But near —50°C the ethane-methanol critical mixture curve turns up abruptly. Not shown in this figure are the three phase lines exhibited by the ethylene-methanol and the ethane-methanol systems at conditions close to their respective critical points.

Garland, C.W. and Williams, R.D. Low-frequency sound velocity near the critical point of Xenon. Phys. Rev. A 10 (1974), 1328-1332. 

The acentric factor increases with the size of the molecule, but only in extreme cases values >1 can be obtained, for example, for hydrocarbons with a molar mass >300. Helium (o) = —0.39) and hydrogen (co = —0.216) have negative acentric factors as so-called quantum gases. Methane and the noble gases argon, krypton, xenon, and neon have acentric factors close to 0. Otherwise, co < 0 can be ruled out. If such a value is evaluated, something is wrong with the vapor pressure curve or the critical point. 

Pavlovskaya G, Blue AK, Gibbs SJ, Haake M, Cros F, Malier L, Meersmann T (1999) Xenon-131 Surface Sensitive Imaging of Aerogels in Liquid Xenon near the Critical Point J Magn Reson 137 258-264... 

Pathway C offers the most direct pV route. However, for the xenon to travel C, a large number of heat reservoirs must be switched, one for every temperatnre state encountered. Regarding pathways A and B, some of the qnirks are dne to the system undergoing a phase change. Equation (5.1) famonsly predicts critical point values ... 

I wish to report the calculation of the mobility of electrons injected in liquid methane, argon, and xenon between their respective triple and critical points. The calculation was carried out as if all these molecules were rare gases. 

Fig. 3.24 Test of the tensile strength hysteresis of hysteresis (Everett and Burgess ). TjT, is plotted against — Tq/Po where is the critical temperature and p.. the critical pressure, of the bulk adsorptive Tq is the tensile strength calculated from the lower closure point of the hysteresis loop. C), benzene O. xenon , 2-2 dimethyl benzene . nitrogen , 2,2,4-trimethylpentane , carbon dioxide 4 n-hexane. The lowest line was calculated from the van der Waals equation, the middle line from the van der Waals equation as modified by Guggenheim, and the upper line from the Berthelot equation. (Courtesy Everett.)...

Ewald22 studied this system at 150° and 155°K. These temperatures are above the critical temperature of pure nitrogen, 126°K, but he found that they are below the lower critical end point of the mixture. The saturated vapor pressure of the system was 50 atm at 150°K and 57 atm at 155°K. The mole fraction of xenon in the saturated gas (X in Figs. 5 and 9) was 0.035 and 0.045 at these temperatures, respectively. 

The critical temp rat ore of xenon is above the melting point of ice. Consequently in a cool room the gus may lie condensed without artificial cooling, a pressure of 58.2 atmospheres I icing noeesHury. 

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