Contact interaction parameter

Table 3. Flory x (x ) parameters and X12 contact interaction parameters in poly(dimethyl siloxane) at 25 °C...

A new interaction parameter, x (23). d the contact interaction parameter, are thus introduced which can be determined by GC [cf. Eqs. (10) to (12)] from the pure (A"i3, Z12) and mixed stationary phases. The equivalent of the normalized interaction parameter of Eq. (18) is Xij/si where s,- is the molecular surface to volume ratio. 

Vi, Pj , Tj reduced molar volume of solvent, pressure and temperature crmsequently Xi2 contact interaction parameter. 

When we can neglect the length n of the end chain compared to n, the effective contact interaction parameter is approximately... 

The contact interaction parameter, can be estimated from the experimental values of Xi2 using characteristic parameters from literature data. The difference between interaction parameters at infinite dilution, when concentrations are expressed in terms of volume fractions, Xjj, and in terms of segment fractions, is [4] ... 

For effective radial parameters have been derived [27] from seven experimental A values and from six experimental B values [15], some parameters being constrained to vary in the ratio of the spin-orbit parameters derived from the fine structure analysis. Preliminary values for Ir are given in [29] and for both isotopes Ir and in [9]. The contact-interaction parameter aj° is discussed for Ir in a survey of the 56 6s configurations [30]. The fitted parameters (in MHz) collected below are from [27]. 

The mean values (A ) begin to split with each other at a density where U a becomes finite. We d like to make a comment here. One may be surprised to see their value of O(GeV), coming from our parameter choice. However, what we d like to reveal here is not their realistic values but a possibility of color magnetic superconductivity and its qualitative features. More realistic study, of course, is needed by carefully checking our approximations, especially the contact interaction and the sharp cutoff at the Fermi surface. 

The smaller contribution to solvent proton relaxation due to the slow exchanging regime also allows detection of second and outer sphere contributions (62). In fact outer-sphere and/or second sphere protons contribute less than 5% of proton relaxivity for the highest temperature profile, and to about 30% for the lowest temperature profile. The fact that they affect differently the profiles acquired at different temperature influences the best-fit values of all parameters with respect to the values obtained without including outer and second sphere contributions, and not only the value of the first sphere proton-metal ion distance (as it usually happens for the other metal aqua ions). A simultaneous fit of longitudinal and transverse relaxation rates provides the values of the distance of the 12 water protons from the metal ion (2.71 A), of the transient ZFS (0.11 cm ), of the correlation time for electron relaxation (about 2 x 10 s at room temperature), of the reorienta-tional time (about 70 x 10 s at room temperature), of the lifetime (about 7 x 10 s at room temperature), of the constant of contact interaction (2.1 MHz). A second coordination sphere was considered with 26 fast exchanging water protons at 4.5 A from the metal ion (99), and the distance of closest approach was fixed in the range between 5.5 and 6.5 A. 

One interesting feature of the functional form derived here is the direct relationship of the activity coefficients and composition between the micellar and surface psuedo-phases. This allows a comparison of nonideal interactions in the micelle and monolayer as modeled by their respective net interaction parameters. In principle, this form may also allow extension to more complicated situations such as the treatment of contact angles in nonideal mixed surfactant systems. Here, the functional form derived above depends on differences in surface pressures and these may be directly obtained from experimentally measured parameters under the proper conditions (30). 

In conclusion, a generalized nonideal mixed monolayer model is presented which uses a single net interaction parameter to model nonideal interactions in binary micellar systems, and depends only on experimental information that is readily available from surface tension measurements used to obtain erne s. The form of this simplified model is designed to allow for future generalization to multiple components, other interfaces and the treatment of contact angles. 

Here, also we have extended (10) our treatment of synergism to 2-phase liquid systems and have derived equations that are completely analogous to those obtained for solutions in contact with air, when the nonaqueous phase is a hydrocarbon. The interaction parameter,... 

This definition of interaction parameters is asymmetric, i.e., the interaction parameter of a segment i with a segment j is different from the interaction parameter of j with i. This is physically counter-intuitive, and has indeed caused a lot of discussion in the literature because it leads to a mathematical inconsistency in the contact probabilities of i and j [86]. Its explicit solution for general number of surface types made UNIQUAC easy to use in the times when computers where rare and slow. Therefore, UNIQUAC... 

---