Rare gas interactions

For the studies of intermolecular potentials, the principle of corresponding states has been a useful guide. Reasonably accurate models of the equation of state have been proposed that have just two adjustable parameters (e.g., van der Waals equation). It has been argued that the success of such models suggests that all (the isotropic) intermolecular potentials should be of the same form and functions of just two parameters (such as well depth and position of the minimum). While current research does not exactly bear out this conclusion, not even if the scope is limited to rare gas interactions, it is probably fair to say that the idea of the principle of corresponding states is still being tested and tried in many laboratories around the world, for various purposes and motivations. 

The energy shift due to a rare gas atom at R due to the electron-rare gas interaction is given by... 

Wormer PES, Hettema H, Thakkar AJ (1993) Intramolecular bond length dependence of the anisotropic dispersion coefficients for H2-rare gas interactions. J Chem Phys 98 7140-7144... 

Alkali-rare gas interaction potentials are easier to calculate. For the pairs Cs(7S)-RG and Cs(5D)... 

A. K. Dham and W. J. Meath, Mo/. Rhys., 88, 339 (1996). Multi-Property Predictions from Recent He-CO Potential-Energy Surfaces and Related Comments on the Nature of Hetero-nuclear Rare Gas Interactions. 

The study of the H-rare gas interaction potentials is mainly based on measurements of the total cross section. Fig. 19 shows results obtained by Bickes et al. (1973a). Because of the small B-values (B = 2-50) and the velocity range of the H-beam source we are in the transition region where the information content on the potential is small. Furthermore, a cancellation of attractive and repulsive forces makes it rather difficult to ascertain which... 

Other, more complex forms of U(R) have been proposed [81-mai/rig] which have proved very satisfactory for the representation of specific rare gas interactions, for example. However, for the correlation and prediction of second virial coefficient data, empirical methods are generally used. Those methods which are based on the corresponding states principle usually represent the second virial coefficient by a series of terms in inverse powers of temperature, as suggested by results for the (n-6) potentials, but usually with integer powers. 

Values of and r) for rare gas mixtures are given in Tables 1 and 2, respectively. They are derived from the work of Lin and Robinson who obtained potential parameters for like and unlike rare-gas interactions by fitting second virial coefficients with the Dymond-Alder potential. Quantum corrections were included in their analysis. For helium the correction procedure is valid only above 40 K, hence they excluded data for He taken at lower temperatures. Different parameters would be found if the analysis were based on another potential, but the relative values would be little changed. ... 

Scattering of atoms fix)m the adsorbed rare gas monolayers is a very convenient for theoretical analysis phenomenon. The pair potentials for rare gas-rare gas interactions are well known from gas phase experiments, and the potential of adatom-adsorbed layer interaction may be calculated as a sum of these pair potentials (Chung et al. 1985, 1986). Processes involving electron degrees of freedom do not play significant role in this case. 

The film condensation. The ions, electrons and energetic neutrals induce chemical and structural modifications of the growing sputtered films. This fact has been shown recently in the case of rare gas interactions on ethylene-tetrafluoroethylene copolymers . During the deposition these interactions eliminate fluorine atoms and also small fragments to form cross links, unsaturated and free radicals in the deposited polymer. These free radicals and un-... 

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