Liquid krypton

The new dinitrogen complex [Ni(CO)3N2] can be generated in a pressure cell by UV photolysis of tetracarbonylnickel in liquid krypton, doped with N2 at 114K. The decomposition of this complex was followed over the temperature range 122-127 K and a value of the Ni—N2 bond dissociation energy estimated at lOkcal moN1.2474... 

The more nitrogen the complexes contain, the less stable they are. The last member of the series, chromium hexanitrogen, was not detected, probably because it is too unstable at the temperature of liquid xenon. Other complexes and reactions were also studied, using liquid xenon or liquid krypton as the solvent. A list is given in Table 1. 

The difference in the ionization potentials of xenon and krypton (1170 versus 1351 kj/mol) indicates that krypton should be the less the reactive of the two. Some indication of the difference can be seen from the bond energies, which are 133 kj/mol for the Xe-F bond but only 50 kj/mol for the Kr-F bond. As a result, XeF2 is considerably more stable of the difluorides, and KrF2 is much more reactive. Krypton difluoride has been prepared from the elements, but only at low temperature using electric discharge. When irradiated with ultraviolet light, a mixture of liquid krypton and fluorine reacts to produce KF2. As expected, radon difluoride can be obtained, but because all isotopes of radon undergo rapid decay, there is not much interest in the compound. In this survey of noble gas chemistry, the... 

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. 

Khan, A. Radial Distribution Functions of Liquid Krypton. Phys. Rev. 136, A 1259 (1964). 

AprUe E, Bolotnikov A, Chen D, Mukherjee R. (1993) W value in liquid krypton. Phys Rev A 4B 1313-1318. 

The matter discussed in sec. 2.3 concerned the phenomenology of adsorption from solution. To make further progress, model assumptions have to be made to arrive at isotherm equations for the individual components. These assumptions are similar to those for gas adsorption secs. 1.4-1.7) and Include issues such as is the adsorption mono- or multlmolecular. localized or mobile is the surface homogeneous or heterogeneous, porous or non-porous is the adsorbate ideal or non-ideal and is the molecular cross-section constant over the entire composition range In addition to all of this the solution can be ideal or nonideal, the molecules may be monomers or oligomers and their interactions simple (as in liquid krypton) or strongly associative (as in water). 

Matrix-IR spectra of CO/N2H4 mixtures show the formation of 3 weak complexes, identified by comparison with ab initio and DFT calculations.521 The variable-temperature IR spectra (—105 — 150°C) of Me2NNH2 in liquid krypton show that only the gauche conformer is present.522 DFT calculations gave vibrational wavenumbers for (XMYH)n rings and clusters, where M = Al, Ga or In Y = N, P or As n = 1-6.523... 

There are two predominant challenges to direct observation of alkanes coordinated to transition metals (1) the short-lived nature of metal/alkane complexes and (2) competition for coordination of the alkane to the metal center. Because of the weak binding energy, alkane coordination is typically short-lived. Thus, fast spectroscopy techniques are required, and these techniques are often coupled with low temperatures in order to slow processes that result in alkane dissociation. In addition to the rapid dissociation of alkanes, most organic substrates will effectively compete (kinetically and thermodynamically) with alkanes for coordination to metals. Thus, the reaction medium is an important consideration since most common solvents are better ligands than alkanes, and attempts to observe alkane coordination have been commonly performed in the gas phase, in hydrocarbon matrices, or in liquid krypton or xenon. Finally, photolysis is generally required to dissociate a ligand at low temperature to create a transient coordination site for the alkane. 

Similarly, the transient Ni(CO)3(N2) has been identified following its generation by photolysis of Ni(CO)4 in liquid krypton doped with N2 at 114 K. Ultraviolet irradiation establishes a steady-state concentration of Ni(CO)3(N2) as soon as the photolysis source is switched off, the dinitrogen complex begins to decay, reacting thermally with CO to regenerate Ni(CO)4. The kinetics of the decay reaction,... 

The investigation [20a] of the photoinitiated reaction of Cp Rh(CO)2 with neopentane in liquid krypton by low-temperature IR flash kinetic spectroscopy gave the results that are consistent with a pre-equilibrium mechanism. According to this mechanism, an initially formed transient krypton complex Cp Rh-(CO)(Kr) is in rapid equilibrium with a transient (uninserted) alkane complex... 

The commonly used method for the preparation of krypton difluoride, which is based on passing an electric discharge through a gaseous mixture of krypton and fluorine at low temperature and reduced pressure, is rather tedious because of the relatively low yield. However, the irradiation of a liquid krypton-fluorine mixture at — 196°C proved to be a very successful method for the preparation of krypton difluoride in quantities up to 10 g in a single run. 

If liquid krypton contacts the skin, flush the affected area with water. If extensive burns result, contact a physician. 

VELOCITY OF SOUND IN LIQUID KRYPTON, XENON, AND METHANE. 

The radial distrihution function, g(r), for liquid argon was shown in Eigure 6.4. How would you expect the g(r) for liquid krypton to differ from that for argon ... 

Phosphorus. - The near-IR spectrum of PH3 has been reported in the P-H stretch overtone region." The IR spectrum of CH2=CHPH2 contains bands due to both syn and gauche conformers - assignments were backed by DFT calculations." Variable-temperature IR studies on C1CH2P(S)F2 in liquid krypton and xenon solutions show that the trans form is more stable than the gauche. ... 

While the foregoing discussion concerned low field mobility, added solutes also influence the drift velocity at high field strengths where a subproportional dependence of Vj on E is observed. In Figure 14, the influence of methane, ethane, and butane on the electron drift velocity in liquid krypton is shown. Two features have to be noted first, the drift velocity exceeds the values of the pure krypton and... 

Honda, K., Endou, K., Yamada, H., Shinsaka, K., Ukai, M., Kouchi, N., and Hatano, Y., Electron-ion recombination rate constants in gaseous and liquid krypton, /. Chem. Phys.,... 

Figure 18 Temporal variation of the electronic component of the ionization current. A, liquid xenon A, solid xenon o, liquid krypton , solid krypton , liquid argon , solid argon. (Redrawn from the data of Sowada, U., Warman, J.M., and deHaas, M.R,P/iys. Rev., B25,3434, 1982.)...

As a subcooled liquid. Krypton is actually a solid in the lower temperature ranges, but liquid values are employed in surface area evaluation. 

The first experiments to suggest that these mobility maxima should occur were conducted by Schnyders, Rice, and Meyer (1965, 1967) especially in their results on liquid krypton The definitive experimental work is that of Jahnke et al. (1971) on fluid argon. 

Jacobsen, F.M., Gee, N., and Freeman, G.R., 1986, Electron mobility in liquid krypton as functions of density, temperature, and electric field strength, Phys. Rev. A, 34 2329. 

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