Krypton applications

Krypton clathrates have been prepared with hydroquinone and phenol. 85Kr has found recent application in chemical analysis. By imbedding the isotope in various solids, kryptonates are formed. The activity of these kryptonates is sensitive to chemical reactions at the surface. Estimates of the concentration of reactants are therefore made possible. Krypton is used in certain photographic flash lamps for high-speed photography. Uses thus far have been limited because of its high cost. Krypton gas presently costs about 30/1. 

Besides its application in high-quality light bulbs, krypton is being increasingly used in the production of powerful lasers. 

The conclusions from this work were (i) that the mechanism that operates is of wide applicability, (ii) that exchange proceeds by either the dissociative chemisorption of benzene or by the dissociation of benzene which has previously been associatively chemisorbed, and (iii) that M values of about 2 indicate that further dissociation of surface-area measurements. Surface areas of metal films determined by the chemisorption of hydrogen, oxygen, carbon monoxide, or by physical adsorption of krypton or of xenon concur... 

Application of continuous anti-Stokes excitation makes it possible to record the emission from the S2 state when the PF S2 > Sq is absent ( ). Prompt S2 > Sq fluorescence has been measured at direct Sq > 2 excitation (krypton laser ... 

In the pressure range useful for krypton adsorption the mean free path is approximately equal to the diameter of the stem of the sample cell. Equation (14.16) is not applicable in this range and an empirical equation devised by Rosenberg must be used. His equation is... 

Organic solids have received much attention in the last 10 to 15 years especially because of possible technological applications. Typically important aspects of these solids are superconductivity (of quasi one-dimensional materials), photoconducting properties in relation to commercial photocopying processes and photochemical transformations in the solid state. In organic solids formed by nonpolar molecules, cohesion in the solid state is mainly due to van der Waals forces. Because of the relatively weak nature of the cohesive forces, organic crystals as a class are soft and low melting. Nonpolar aliphatic hydrocarbons tend to crystallize in approximately close-packed structures because of the nondirectional character of van der Waals forces. Methane above 22 K, for example, crystallizes in a cubic close-packed structure where the molecules exhibit considerable rotation. The intermolecular C—C distance is 4.1 A, similar to the van der Waals bonds present in krypton (3.82 A) and xenon (4.0 A). Such close-packed structures are not found in molecular crystals of polar molecules. 

Adsorption of Radionuclides. Other applications that depend on physical adsorption include the control of krypton and xenon radionuclides from nuclear power plants (92). The gases are not captured entirely, but their passage is delayed long enough to allow radioactive decay of the short-lived species. Highly microporous coconut-based activated carbon is used for this service. 

The radionuclides commercially available and most commonly used for a number of the foregoing applications include anhmony-125 banum-133, 207 bismuth-207 bromine-82 cadmium-109, 115 m calcium-45 carbon-14 cerium-141 cesium-134, 137 chlorine-36 chromium-51 cobalt-57, 58, 60 copper-64 gadolimum-153 germanium-68 gold-195. 198 hydrogen-3 (tritium) indium-111, 114 m iodine-125, 129, 131 iron-55, 59 krypton-85 manganese-54 mercury-203 molvbdenum-99 nickel-63 phosphorus-32. 33 potassium-42 promethium-147 rubidium-86 ruthenium-103 samarium-151 scandium-46 selenium-75 silver-110 m sodium-22, strontium-85 sulfur-35 technetium-99 thallium-204 thulium-171 tin-113, 119 m, 121 m. titamum-44 ytterbium-169, and zinc-65. 

In most applications, measurement of specific surface area is synonymous with the use of nitrogen and the BET isotherm. For most commercial surface area instruments, at least 1 m2 of surface area must be present in the sample cell for the measurement to be repeatable. This requires that a significant mass of material (> 1 g) must be present in the sample cell for low surface-area materials. When these conditions cannot be met due to material availability, an instrument that uses krypton as the adsorbate should be utilized. Krypton allows specific surface area measurement with as little as 0.1 m2 present in the sample. 

The sonic nozzle is capable of providing a constant gas flow irrespective of the change of downstream pressure. Its successful application is dependent on the maintenance of a high upstream pressure. In theory, the pressure ratio should be at least 2, but in practice it is advisable to keep the pressure ratio above 6. At present, the sonic nozzle technique is the only reliable method for controlling low gas flow (e.g. -0.01 cm3 h 1, which is required for krypton adsorption measurements on powders of low surface area). 

By optical excitation with argon and krypton laser lines, continuous laser oscillation on A -> X and B -> X transitions of Li Na2 and K molecules can be achieved dimer lasers show such interesting features as multiline emission, extremely low threshold pump intensities and forward-backward amplification asymmetry. Basic principles, operating conditions and applications of these lasers will be discussed. The dimer lasers operate between bound electronic states, resulting in the emission of discrete lines. To achieve tunable laser oscillation, continuous emission bands from bound-free transitions have to be considered. Some possibilities for alkali dimers are outlined and recent spectroscopic investigations on UV excited diffuse bands are reported. 

Janssens H, Vanmarcke M, Desoppere E, Lenaerts J, Boucique R, Wieme W. (1987) A general consistent model for formation and decay of rare gas excimers in the 10 Vio+ mbar pressure range, with application to krypton. / Chem Phys 86 4925 934. 

Severinghaus J. P., Grachev A., Luz B., and Caillon N. (2003) A method for precise measurement of argon 40/36 and krypton/argon ratios in trapped air in polar ice with applications to past firn thickness and abrupt climate change... 

Air is a mixture of primarily nitrogen (78 percent) and oxygen (21 percent), with trace amounts of argon, neon, helium, and krypton. These pure elements have many applications. They are separated and purified by cooling air in a process known as fractionation. As air cools, the different elements liquefy based on their boiling points. In what order do the elements liquefy Use Table D.4. 

Various broadband sources employed to optically pump Ha include tungsten, mercury, xenon, and krypton lamps. The last source provides an especially good spectral match to the near-infrared absorption bands of Nd3+ in YAG. To reduce lattice heating resulting from the multiphonon emission decay to the F3/2 state, semiconductor diodes and laser sources at 0.8-0.9 ym nave pumped Nd lasers (58). Sun-pumped Nd and chromium-sensitized Nd lasers have been demonstrated and considered for space applications (59). Lasing of Nd3+ by electron beam excitation has also been reported (bO). 

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