Polarizability Volume Research Articles

Enthalpies of interaction of nonpolar solutes with nonpolar solvents. The role of solute polarizability and molar volume in solvation

Heats of solution of 10 nonpolar solutes (carbon tetrachloride, perfluoroheptane, diiodomethane, benzene, hexane, decane, hexadecane, cyclohexane, toluene, and mesitylene) in 11 nonpolar solvents (heptane, cyclohexane, carbon tetrachloride, benzene, carbon disulfide, diiodomethane, toluene, mesitylene, tetrachloroethylene, 1,1,2-trichlorotrifluoroethane, and hexadecane) have been combined with solute heats of vaporization to give enthalpies of transfer from vapor to solvent (ΔH(v → S)). The heat of vaporization of diiodomethane has been measured (11.70 ± 0.01 kcal/mol). Correlations of the form ΔH(v → S) = a + bMMR + cMV describe the solvent–solute interaction enthalpies with high precision (correlation coefficients 0.991–0.999). Earlier correlations with only the molar refraction are limited to solutes of similar refractive index. In each solvent ΔH(v → S) becomes more exothermic with an increase in the solute molar refraction term, and less exothermic with an increase in the solute molar volume term. These terms represent solvent–solute dispersion interaction enthalpies, and solvent cavity formation enthalpies, respectively.

Donor dependence of polarizability and electron wave-function volume for shallow states in semiconductors.

Donor dependence of polarizability and electron wave-function volume for shallow states in semiconductors.

Analysis of Photoelastic Behaviour of Fluorite‐Structure Crystals

AbstractAn analysis of the photoelastic behaviour of fluorite‐structure crystals is performed by considering the existing theories of electronic polarizabilities of ions. On the basis of experimental and theoretical information available for electronic polarizabilities it is assumed that the change in polarizability due to strain under the effect of hydrostatic pressure is mainly arising from the change in anion polarizability. Values of strain polarizability parameters and volume derivatives of refractive index or electronic dielectric constant are evaluated and compared with experimental data for CaF2, SrF2, BaF2, PbF2, Sr(NO3)2, Ba(NO3)2, and Pb(NO3)2 crystals.

Novel porous carbon packings in reversed-phase high-performance liquid chromatography

Porous carbon packings of particle size 5–20 μm were prepared by calcination of purified active carbons and cokes having narrow size ranges. Highly efficient columns packed with 10-μm particles were obtained by means of the high-viscosity slurry technique, and exhibited about 3000 theoretical plates at 100 mm length and optimal eluent flow-rate. The loading of columns, θ 0.1, was determined to be 25–50 μg of solute per gram of packing. Eluotropic series of solvents were found to be similar to those on pyrocarbon-modified carbons and silicas. The log k′ values for homologous compounds increased linearly with the hydrocarbonaceous surface area at constant eluent composition. Studies with polar solutes indicated that the volume polarizability rather than dipole moment was the decisive molecular property of the solute with respect to retention. The successful application of carbon packings in aqueous organic eluents having a pH > 8.5 was demonstrated.

Thermodynamic and physical behaviour of some water + polyethyleneglycol mixtures. II. Dielectric properties

Dielectric constants of water + glycol (mono-, di-, tri-, and tetraethyleneglycol) mixtures have been measured at 298.15 K over the entire composition range. The mixtures involving monoethyleneglycol have also been studied at temperatures from 308.15 to 288.15 K. Calculated deviations from ideality are always positive and show one maximum. Related properties have been computed: polarizability volume and excess polarizability volume, correlation factor of mixtures, and dipole moments of both components using the Mecke–Reuter treatment. Results support conclusions previously deduced from excess and partial molar volumes; they suggest that the addition of glycol molecules gives rise to a slight enhancement of the water-lattice in the water-rich region, followed by a progressive destructuring; the ether functions do not seem to play a prominent role.

The static dielectric constant of solutions of water inn-alcohols at 15, 25, 35, and 45°C

Dielectric constants (measured at 1 MHz) are reported for solutions of water (concentration range 0 to 0.2 mole fraction) in 1-propanol at 25/sup 0/C, and in 1-butanol, 1-pentanol, and 1-hexanol at 15, 25, 35, and 45/sup 0/C. These results, together with literature values for solutions of water in methanol, ethanol, 1-heptanol, and 1-octanol, show that water interacts with alcohols in at least two ways: (1) it can participate in the formation of dynamic hydrogen-bonded chains, thereby raising the polarizability; (2) it can form relatively stable structures such as H/sub 2/O(ROH)/sub 4/ which have zero net dipole moment and consequently diminish volume polarizability. For C/sub n/H/sub 2n + 1/OH alcohols, n greater than or equal to 4, most of the initially added water forms complexes: consequently, addition of water to these alcohols lowers the dielectric constant.

Electron paramagnetic resonance investigations of Cr3 doped ferroelectric triglycine sulphate monocrystals

Polarization reversal, ferroelectric static hysteresis loops and switching processes were investigated in chromium(III) and vanadium(IV) doped TGS by means of epr. By analyzing the shape of the static hysteresis loops a relation between the domain volumes and the internal bias field is obtained. The switching behaviour depends upon the direction of the applied dc field also explainable by a bias field. Investigations of the polarization reversal on the aged doped crystals show that up to 50% of the polarizable crystal volume is stabilized in the preferred direction of the polarization.