Rare gases fractionation

Ozima, M., Alexander, Jr., E. C. (1976) Rare gas fractionation patterns in terrestrial samples and the earth-atmosphere evolution model. Rev. Geophys. Space Phys., 14, 385-90. 

We postulate, in view of these constraints, that rare gases were delivered to the Earth and fractionated in the atmosphere mainly within the first 100 Ma, possibly within 50 Ma, when most of the terrestrial accretion took place. During this period, atmosphere and proto-mantle rare gases were actively exchanged and rare gas fractionation took place following a combination of impact degassing, atmospheric escape and... 

Fig. Ill-13. (a) Plots of molecular density versus distance normal to the interface a is molecular diameter. Upper plot a dielectric liquid. Lower plot as calculated for liquid mercury. (From Ref. 122.) (b) Equilibrium density profiles for atoms A and B in a rare-gas-like mixmre for which o,bb/ o,aa = 0.4 and q,ab is given by Eq. III-56. Atoms A and B have the same a (of Eq. m-46) and the same molecular weight of SO g/mol the solution mole fraction is jcb = 0.047. Note the strong adsorption of B at the interface. [Reprinted with permission from D. J. Lee, M. M. Telo de Gama, and K. E. Gubbins, J. Phys. Chem., 89, 1514 (1985) (Ref. 88). Copyright 1985, American Chemical Society.]...

The various observations leave little doubt that recombination of rare-gas dimer ions can produce excited atoms, but it is quite possible that formation of radiating excited states occurs only in a small fraction of recombination events. If this is true, then the observed line shapes do not reflect the dominant recombination mecha-... 

Polar molecules like II2O show apparent polymerization to an extent quite impossible in the gas phase at low pressures. The dipole field interaction, which is of the order of 1 ev., results in an artificial multilayer physical adsorption at pressures and temperatures where ordinarily only a minute fraction of the first layer would exist. Since multilayer adsorption is quite liquid-like, the high degree of polymerization can be explained. It is interesting to note that at low fields individual peaks show some substructure, which could be due to alignment differences at the time of ionization or could correspond to ionization from different layers within the adsorbate. It is hoped to study physical adsorption near the condensation point at low pressure with nonpolar rare gas atoms to see if layer structure can be elucidated in this way. 

Still an alternative way for tuning is to mix fix-frequency terawatt radiation (cOf) with tuneable radiation (o from an optical parametric oscillator/amplifier [29], which is pumped by a fraction of the fixed-frequency output. This is done in a pulsed rare-gas jet, where new frequency components ncOf mco are generated. Here, n normally is a large number and m a small number. Promising results have been obtained [30,31]. 

Pu-Xe dating. Decay of Pu can be used as a chronometer of the first 100 Ma for some specific meteorite parent bodies. Both Pu and the LREE tend to be concentrated in refractory minerals like phosphates. Which LREE is the best proxy for Pu Various authors have suggested Nd (Lugmair and Marti 1977), Sm (Jones and Burnett 1987), or Pr or Ce (Boynton 1978). There are no neutron-induced reactions that produce a rare gas from any of the LREE, but all of these, particularly Nd, do produce the light xenon isotopes like Xe and Xe through cosmic-ray-induced spallation reactions (Wider 2002, this volume). In fact, in many cases, the LREE (and presumably Pu), are probably not fractionated much from each other. Hence, if the cosmic ray dose (i.e., the cosmic ray exposure age) is known, and the production rate of isotopes like " Xe and Xe is also known, then the abundance of the LREE can be calculated. Then the ratio of Xe244 (Pu-... 

TABLE VIL Fractions of Rare Gas Ions Mixtures with Benzene"... 

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