A compilation of infinite dilution resonance integrals,II

In this second part the list of resonance integrals is completed with 63 values for (n, γ) reactions mainly from the second part of the periodic system. The resonance integral for (n, fission) of²³⁵U is included as well as thermal and epithermal self-shielding curves for the elements Sm, Eu, Gd, Dy and Cd.     

A compilation of resonance integrals

This section of the compilation is a continuation of Part I, Z=1–52 (Hydrogen-Tellurium) which appeared in this Journal.¹ This part lists the resonance integrals of reactor neutron capture and fission reactions for nuclides from Z=53 to Z=100; the thermal cross-sections of the corresponding nuclides are also included. The theoretical explanation and physical meaning of resonance integral obtained by different experimental approaches are discussed in Part I.     

A compilation of resonance integrals part I,Z=1–52 (hydrogen-tellurium)

The resonance integrals of reactor neutron capture reactions for nuclides up to Z=52 are compiled, while the thermal cross-sections of the corresponding nuclides are also included. The original values from the literature and the normalized ones for the excess of 1/v tailing are presented in parallel. The physical meaning of resonance integral obtained by different experimental approaches is briefly discussed.     

A compilation of resonance integrals from hydrogen to fermium

The compilation comprises the experimental and calculated resonance integrals of nuclides (hydrogen to fermium), for neutron capture and fission reactions. The thermal cross-sections of the corresponding reactions are also included. Whenever possible, in addition to original values of the resonance integrals, normalized values are also given. The theoretical explanation and physical meaning of the resonance integrals determined by different approaches are briefly discussed.     

Infinite dilution resonance integrals for some short-lived radioisotopes

The infinite dilution resonance integrals of fifteen (n,γ)reactions leading to the production of short-lived radioisotopes were determined. The irradiation parameters were checked by comparing the results of different methods and the measuring equipment was carefully controlled.     

Depletion potential in the infinite dilution limit

The depletion force and depletion potential between two in principle unequal "big" hard spheres embedded in a multicomponent mixture of "small" hard spheres are computed using the rational function approximation method for the structural properties of hard-sphere mixtures [S. B. Yuste, A. Santos, and M. Lopez de Haro, J. Chem. Phys. 108, 3683 (1998)]. The cases of equal solute particles and of one big particle and a hard planar wall in a background monodisperse hard-sphere fluid are explicitly analyzed. An improvement over the performance of the Percus-Yevick theory and good agreement with available simulation results are found.     

Activity coefficients at infinite dilution for surfactants

A new alternative is presented for activity coefficients at infinite dilution determination via surface tension data of low vapour pressure substances. It was found that experimental data for surfactants follows Volmer's surface equation of state behaviour over the diluted region until the critical micelle concentration. The key operations are: the choice of the same standard conditions for the bulk and the surface phases, the combination of Gibbs and Volmer equations and the use of the symmetric activity coefficients convention. An exact relation between the activity coefficient at infinite dilution and the reciprocal of the critical micelle mole fraction was found which allowed us the verification of the model.     

Halomethanes in tri-n-octylamine and squalane mixtures at infinite dilution

The retention behavior of eight halomethanes and four saturated hydrocarbons was measured in gas chromatographic stationary phases consisting in tri-n-octylamine (TOA), squalane (SQ) and six TOA+SQ mixtures, at 55.0, 58.5, 62.5 and 65.0°C. Equlibrium constants for complex formation were extracted from experimental data by using a lattice model developed by Martire. The results may be interpreted in terms of the formation of weak hydrogen-bonded complexes, with sociation constants of about 0.13 L-mol^–1 for haloforms and 0.07 L-mol^–1 for dihalomethanes at 60°C.     

Molecules-in-molecules calculations with fixed resonance integrals

A simple equation for the evaluation of resonance integrals from overlap integrals and ionization potentials of the molecular fragments is suggested for molecules-in-molecules π electron calculations. The singlet π → π* transition energies of some benzene derivatives containing donor substituents were calculated. The best results were obtained if in the expression of the resonance integral the first experimental ionization potential of the methyl derivative of the donor groups is used.     

A new method to evaluate the STO overlap integrals for compilation of an EHMO program containing f orbitals

In this paper, a calculation method to evaluate to STO overlap integrals that have integer or non-integer effective quantum number is reported. Using this method, the overlap integrals of 4f orbitals are calculated and some results are given.     

On the interaction between macroions in solution at infinite dilution

The pair interaction potential for charged macromolecules in solution is calculated from the Ornstein-zernike equation with MSA-closure for the salt-ion/salt-ion and salt-ion/macroion interaction, and HNC-closure for the macroion/macroion interaction. Two different limiting cases are considered: low salt-ion concentration or zero hardcore volume of the macroion. It is found that if the Debye screening length is much larger than the smallest linear dimension of the macroion, the potential is simply a superposition of point-point interaction potentials (screened Coulomb potentials).     

Many-Electron,multicenter integrals in superposition of correlated configurations method. I. one- and two-electron integrals

The calculations by means of the superposition of correlated configurations method (Hylleraas-CI ), that is, the combination of configuration interaction with the Hylleraas-type correlation factors, needs the effective evaluation of some nontrivial integrals. This series of papers gives the formulas for all types of integrals needed for molecular calculations when Gaussian lobe functions are used as a basis set. The formulas for two-electron integrals are given in the present paper. The preliminary results for two-electron systems are presented.     

Prediction of infinite dilution activity coefficients of sulfur dioxide in organic solvents

Infinite dilution activity coefficients of sulfur dioxide in various organic solvents were correlated with two basicity scales: the solvent Gutmann donor number and Arnett heat of hydrogen bonding. Linear correlations were observed for both basicity scales, and the accuracy of activity coefficient prediction is estimated to be ±20 to 25%. Infinite dilution activity coefficients of sulfur dioxide in over 80 organic solvents were estimated from the correlations.     

环己烷在聚乙烯和聚异丁烯中无限稀释扩散系数 的测定

采用填充柱的反相气相色谱方法,基于Hadj-Romdhane-Danner色谱过程的数学模型,在323.2～363.2K温度范围内测定了环己烷在聚异丁烯和聚乙烯膜中的无限稀释扩散系数。从实验数据可以看出,环己烷更容易在PIB中发生扩散。对实测扩散数据进行了自由体积理论关联,结果表明,采用空穴自由体积替代Vrentas-Duda自由体积理论方程中自由体积项的修正方程能很好地描述溶剂分子扩散系数随温度的变化关系。     

Estimation of infinite dilution activity coefficients in aqueous mixtures via molecular simulation

Molecular dynamics simulations are employed to calculate infinite dilution activity coefficients of water and methanol-like species in binary mixtures using a variant of the Kirkwood coupling parameter method. Differences in residual Gibbs free energies are obtained as integrals over ensemble averages of the derivatives of total potential energy with respect to simple functions of the intramolecular potential energy parameters. The calculated limiting activity coefficients are compared with the experimental values at the same temperature obtained by direct measurement of the water/methanol binary and via extrapolation from vapor–liquid equilibria data.