Scattering cross section transport properties

Well depths for Ne + Ar, -t- Kr, and + Xe are also found to be closely similar, but in this case deeper than those obtained from virial coefficients alone. On the other hand, the He + Ar scattering cross sections of Smith et a/., when combined with virial coefficients and transport properties, lead to a well depth 30 per cent deeper than that obtained by Chen et The larger fixa is in excellent agreement with the Lin and Robinson estimate. More recently, Derderian and Steele have found that their measurements of the adsorption of He on Xe are consistent with a value of ei2 in good agreement with that derived by Lin and Robinson. Clearly even for optimal systems the determination of unlike interactions remains difficult. 

One calculates transport properties by correlating the resistivity with the total scattering cross-section. The electrical resistivity is found to be temperature insensitive at low temperatures, has the ln T/T ) dependence near T , and decreases steadily for T > Tq. The shape of the resistivity curve will be discussed in section 3.3. Clearly the low-temperature resistivity is in disagreement with experiments, which indicate the type Fermi liquid behavior. The discrepancy comes from the implicit assumption that the impurity atoms scatter the conduction electrons Incoherently. How the system achieves coherence at low temperatures is now studied in terms of the spin fluctuation resonance model, but the analysis has not yet reached the level of sophistication of the single-impurity problem. 

All of the effective collision cross sections introduced above can, in principle, be evaluated from a knowledge of the intermolecular pair potential by means of equation (4.17) and the definition of the collision operator (4.5). This process would then make it possible to predict the transport properties of dilute gases from first principles. However, such a procedure would require that it is possible to evaluate the inelastic differential scattering cross section ajj or an equivalent to it which enters (4.5). Until very recently this could only be accomplished for dilute monatomic gases. There were two reasons for this first, only for such systems are accurate intermolecular potentials available (Aziz 1984 Maitland et al. 1987 van der Avoird 1992) second, only for such systems was the... 

---