bluuebunny/crossref_metadata_2025_split huggingface dataset:
Gallium: Thermal Conductivity; Supercooling; Negative Pressure
Authors: Briggs Lyman J. 
Published: January 2005

The thermal conductivity of liquid gallium does not appear to have heretofore been measured. The method employed involved a comparison with the known thermal conductivity of mercury. The two liquids were sealed in two thin-walled glass tubes (30 cm long, 10 mm bore), the upper ends being inserted vertically through the bottom of a boiler containing boiling water. The tubes were coated to secure the same thermal emissivity. Two thermocouple loops which could be moved along the tubes served to establish points having the same temperature on the two tubes. The ratio of the squares of the lengths from the thermocouple junctions to the bottom of the boiler gave 3.51±0.03 as the relative thermal conductivity of gallium to that of mercury, or 0.336±0.005 watt/cm (°C) as the thermal conductivity of gallium between 30° and 100°C, based upon 0.0958 for mercury.
It was found possible to supercool liquid gallium to —28°C, or 58°C below its melting point, by exposing small drops on paper to a slowly decreasing temperature in a deep-freeze chamber with a circulating atmosphere.
An attempt to measure the negative pressure of gallium proved disappointing, for it was found that gallium does not ``wet'' the wall of an evacuated tube. With a partial evacuation, low negative pressures were measured which decreased (like water) as the melting point was approached.
Infrared Spectra of HDO in Water and Ionic Solutions
Authors: Waldron Robert D. 
Published: January 2005

The infrared spectra of HDO in water and saturated metal halide solutions were investigated to study the interactions between ions and solvent molecules and the nature of hydrogen bonding in aqueous systems.
The fundamental and overtone bands of the OH and OD stretching vibrations are shifted to lower frequencies and the bending vibration shifts to higher frequencies as one passes from the gaseous to the liquid state. Similar shifts occur for the metal halide solutions, the magnitudes of which are sensitive to the anion species but relatively independent of the cations. The frequency shifts for ionic solutions increase in the order I-, Cl-, F-, with the shift in ion-free water about equal to that for Cl-. The data are analyzed in terms of four probable nearest-neighbor configurations in these solutions.
The vibrational anharmonicity of the OH stretching vibration in solution is nearly independent of the frequency shift and only slightly larger than the gas value. The dependence of frequency shift on the shortening of hydrogen bonds (volume contraction) and H-bond energy were studied and gave qualitative agreement with other systems previously investigated.
Generalized Equations for the Ionization of Solid Particles
Authors: Einbinder Harvey 
Published: January 2005

A generalized formula is derived for the ionization of spherical solid particles of submicroscopic size by allowing for multiple ionization. A system of simultaneous equilibrium equations is set up connecting successive states of ionization. Its solution yields a generalized formula that reduces to the Saha equation when only single ionization can occur. When the particles are multiply ionized, the equation can be simplified by the method of steepest descents, Ne/N(rkT/e2) ln(K/Ne)+12,  (Ne/N≳3),where Ne is the electron concentration, N is the number density of solid particles, r their radius and K=2(2πmkT/h2)32 exp(—[open phi]/kT).
This equation is applied to the observations of Shuler and Weber on the ionization of free carbon particles produced in rich acetylene-oxygen flames. Their data are consistent with a work function [open phi] = 4.35 ev, identical with that of graphite, and particle radii between 55 and 85 A.
Relationship of the Second Virial Coefficient to Polymer Chain Dimensions and Interaction Parameters
Authors: Orofino T. A. , Flory P. J. 
Published: January 2005

A useful approximation has been found for the excluded volume integral for the interaction of a pair of polymer molecules, represented by Gaussian distributions of chain segments about their respective centers of gravity. By means of this approximation, the theoretical expression for the second virial coefficient in the expansion of the osmotic pressure is represented over the entire range of polymer-solvent interaction by A2=const ([η]/M) ln[1+(π12/4)X1+(π12332/32)X2].X1 and X2 are related to the thermodynamic interaction parameters χ1 and χ2, respectively, in the semiempirical expression for the solvent chemical potential μ1—μ10=RT[ln(1—v2)+(1–1/x)v2+χ1v22+ χ2v23+···] where v2 is the volume fraction of polymer and x the ratio of molar volumes of polymer and solvent. Inclusion of the higher term χ2v23 (and X2) constitutes a refinement over the treatment previously published. It is shown that the influence of X2 may be appreciable for low molecular weights and in poor solvents; its effect vanishes as the molecular weight becomes large. However, if X2≠0, the temperature at which A2 for a given polymer-solvent pair becomes zero will, in general, depend upon the molecular weight. The similar influence of this term on the expression for the intramolecular expansion factor is smaller, although not necessarily negligible.
Interaction parameters (χ1) are calculated from second virial coefficients for a number of polymer-solvent systems, and these are compared with the χ1 values obtained from intrinsic viscosities (intramolecular theory). The good agreement obtained offers strong evidence for the general validity of the intermolecular (A2) and intramolecular theories.
A 2 increases slightly more rapidly with decrease in M than theory predicts. On the whole, however, the consistency of results is gratifyingly good.
The intrinsic viscosity increases linearly with A2M in poor solvents. This relation must be replaced by one of approximate direct proportionality in good solvents.
Relaxation-Time Model for Free-Radical Concentration
Authors: Giddings J. Calvin 
Published: January 2005

The accuracy of the quasi-equilibrium approximation in chemical kinetic studies is examined using a relaxation-time model. Two distinct cases arise: the time-lag case and the diffusion case. In each case, the proposed model leads to exactly the same result as an approximate mathematical treatment.
The kinetic processes in a flame front are examined, and are shown to involve both the time-lag and diffusion cases. Again, the model is justified by an independent approximate method. The model is next examined in that region of the flame where the kinetic processes are most important, that is, near the point of maximum reaction rate. A very simple expression is found for the radical concentration at this point. This expression is justified through numerical examples.
Intensities of Infrared Bands in Solution. I. Benzene Solutions
Authors: Ferguson Eldon E. 
Published: January 2005

It is shown that the molar extinction coefficients of band maxima of infrared ``inactive'' fundamentals of benzene in solution are markedly sensitive to the nature of the solvent. CS2, C6H5Br, C6H5Cl, and C5H6N enhance the inactive benzene fundamentals while CCl4, cyclohexane, and several normal paraffins diminish the extinction coefficients. The extinction coefficients are shown to change linearly with solvent concentration for C6H6–CCl4 and C6H6–CS2 solutions. The intensity changes in solution are shown to correlate with an approximate calculation of intermolecular dispersion forces between benzene and solvent molecules.
The inactive fundamentals of several methylene halides also exhibit this ``solution sensitivity.'' The technique of enhancing inactive fundamentals in solutions is shown to be useful for the purpose of identification of these fundamentals in infrared spectra.
Lattice Vacancy Theory of the Liquid State
Authors: Mueller Charles R. , Stupegia Donald C. 
Published: January 2005

Using the simple lattice vacancy or ``hole'' theory of the liquid state as a starting point, various modifications were investigated. The best partition function found involves changes only of the term (Na+Nb)!/Na!Nb! in the simple ``hole'' theory. Na and Nb are the number of molecules and holes, respectively. This model involves a change in analogy with the Flory approximation for solutions and corresponds roughly to utilizing holes one-third the size of molecules. For the usual average of the rare gases the critical temperatures are about 5% too high, critical volumes 27% too high, a PcVc/RTc about 8% too high.
The slope of the plot of lnP/Pc vs Tc/T is about 5% in error. The slope of the rectilinear diameter plot is about 10% in error. Co-existing phase densities are reasonably good in the liquid region and, in addition, rather remarkable results are obtained for the vapor phase.
The model has been extended to binary solutions and predicts the thermodynamic quantities of mixing quite well for the few cases where calculations have been made.
Quantum-Mechanical Effects in Gas Dynamics
Authors: Laitone E. V. 
Published: January 2005

Recent analytical studies by Morgenstern led him to conjecture that the Boltzmann equation, describing the kinetic theory of a rarefied gas, cannot predict general spatially nonhomogeneous solutions. Morgenstern proposed a modified collision integral that can provide more general solutions, but still reduces to that of Boltzmann for the spatially homogeneous case.
The present paper points out that this proposed collision integral can be made physically plausible by introducing recent contributions from the quantum-mechanical studies of transport processes by Ross and Kirkwood. However, it is indicated that when the higher order corrections beyond the Navier-Stokes order of approximation are to be considered then the density-dependent symmetry effects due to Bose-Einstein statistics, and other quantum-mechanical effects, in addition to the introduction of the scattering cross section, may have to be included.
Vibrational Spectrum and Structure of Metal-Cyanide Complexes in the Solid State. I. KAg(CN)2
Authors: Jones Llewellyn H. 
Published: January 2005

The infrared spectra of solid KAg(CN)2 and the mono- and di-substituted C13 and N15 species have been observed. The seven fundamental vibrations of the linear, symmetrical Ag(CN)2— ion have been assigned at 2146, 360, 2140, 390, 250, 310, and 107 cm—1 for the species containing C12 and N14.
From the observed frequencies of the normal and isotopic species, force constants were calculated for two possible structures: N–C–Ag–C–N and C–N–Ag–N–C. It is shown that the latter structure gives unreasonable force constants, and that therefore the cyanides are probably bound to the silver through the carbon atom. Relative amplitudes of the atoms during the vibrations are shown.
Multiple Relaxation Times in Nonrigid Solute Molecules
Authors: Davies Mansel , Meakins R. J. 
Published: January 2005

This paper describes the first detailed investigation of the dielectric behavior of liquid solutions of large solute molecules possessing small polar groups capable of rotation about a chemical bond. Three hindered hydroxy-compounds are chosen as examples and their dielectric properties in Decalin solution are measured at frequencies up to 2.4×1010 cps which includes the region of maximum absorption. In each case two distinct absorption regions are obtained, in contrast to the results for the rigid molecule o-dichlorobenzene, which gives a Debye curve with a single relaxation time.
A comparison of the calculated and observed dipole moments supports the theory that in each case the lower frequency absorption is due to the rotation of the main part of the molecule and the higher frequency absorption is due mainly to the independent orientation of the hydroxyl group by rotation about the C–O bond.
The activation energies and frequency factors for the dielectric mechanisms are determined, where possible, from the displacement of the absorption with temperature. The activation energies for complete molecule rotation and for independent hydroxyl orientation are similar. The frequency factor for the hydroxyl mechanism is larger, however, and this accounts for the higher frequency of the absorption due to this mechanism.
Mechanism of the Gas Phase, Thermal Decomposition of Ozone
Authors: Benson Sidney W. , Axworthy Arthur E. 
Published: January 2005

The pyrolysis of ozone has been reinvestigated experimentally, and it is now shown that most of the known data are quantitatively explained on the basis of the simple mechanism, M+O3[open phi] lim 21M+O2+OO+O3→ lim 32 O2,where M may be O2, O3, CO2, N2, He, etc. There is no evidence for a direct bimolecular reaction of ozone to produce O2 nor is there any evidence for important surface effects or energy chains. On the other hand, the results at very fast rates of decomposition indicate an acceleration which can be accounted for in terms of temperature gradients in the system. This region is usually very close to the thermal explosion limit.
The values found for the rate constants are (for M equal to O3), k1=4.61±0.25×1012 exp(−24 000/RT) liter/mole−sec,k2=6.00±0.33×107exp(+600/RT) liter2/mole2−sec,k3=2.96±0.21×1010exp(−6000/RT) liter/mole−sec.
The relative efficiencies of O2, N2, CO2, and He in activating O3 (compared to O3 itself) are, respectively, 0.44, 0.41, 1.06, and 0.34.
As expected for energy transfer processes, k1 has an abnormally high pre-exponential factor, and k2 has correspondingly a negative energy of activation. It is further inferred that Reaction 3 which produces two O2 molecules with 99 kcal of excess energy between them does not produce more than one excited electronic state of O2 and that these hot O2 molecules are not very efficient in exciting O3 to decomposition. Calculations of the entropy of activation of Reaction 1 can be made and are shown to be in good agreement with this conclusion. From these findings it appears that the high quantum yields found in the photolysis of O3 at short wavelengths, if real, probably are attributable to metastable O atoms [1D] produced in the primary process which can generate chains in O3.
It can be shown that the homogeneous production of O atoms from O2 at high temperatures proceeds through two different paths having different activation energies, the lower energy path involving O3 as an intermediate.
Finally, possible mechanisms are considered for the chemical sensitization of the thermal explosion of O3 and its catalytic decomposition by H donors.
Photochemical Studies in Flash Photolysis. I. Photolysis of Acetone
Authors: Oster Gisela K. , Marcus R. A. 
Published: January 2005

The high-intensity flash photolysis of acetone was investigated using an exploding wire as a light source. Experiments were conducted with the unfiltered light of the flash, containing light in the near as well as in the far ultraviolet region of the spectrum. The results show that the C2H6/CO ratio in the reaction products is about 1.25 and is fairly insensitive to variation in acetone pressure. Addition of small amounts of biacetyl lowers the ratio still further. This is attributed to the deactivation of a long-lived excited acetone molecule formed in the ultraviolet region below 210 mμ. Addition of butane lowers the ratio far below unity.
The CH4/CO ratio has the constant value of 0.1 for various light intensities, acetone pressures, pressures of added butane or of carbon dioxide.
A convenient way of separating small amounts of ethane from very large amounts of carbon dioxide is described.
Infrared Spectrum of Trifluoroacetic Acid Vapor
Authors: Kagarise R. E. 
Published: January 2005

The infrared absorption of trifluoroacetic acid vapor in the region between 2 and 24 μ has been studied as a function of temperature. At room temperature both monomer and dimer molecules are present, while at 100°C the vapor is predominantly monomeric. On the basis of the resulting intensity changes it has been possible to conclusively identify the bands due to the two species. A partial assignment of the fundamental modes of vibration has been made using these data and the previously published spectrum of the deuterated acid.
The heat of dissociation (ΔH) for the dimer-monomer reaction has been determined from the temperature dependence of the OH stretching bands and found to be 13.7±0.4 kcal/mole.
Microwave Spectrum, Structure, Dipole Moment, and Quadrupole Coupling Constants of Formamide
Authors: Kurland Robert J. , Wilson E. Bright 
Published: January 2005

The microwave spectra of formamide, and the isotopic species 1, 2 N di-deutero formamide, 1 N mono-deutero formamide (cis) and (trans), have been investigated. The rotational constants obtained from the frequencies of assigned rotational transitions lead to the following effective structural parameters: for the bond distances, there results C–O = 1.243±0.007 A, C–N = 1.343±0.007 A, N–H = 0.995±0.007 A, and for the bond angles ∠HNH = 118.98±0.50°, ∠ NCO = 123.58±0.35°, ∠NCH = 103.9±1.2°. The molecule is planar. Stark effect measurements yield values for the dipole moment components which, when combined with assumed approximate bond moments and the structural parameters, give the magnitude and the direction of the dipole moment. The dipole moment is thus equal to 3.714±0.06 Debyes and makes an angle of 39.6° with the C–N bond. The quadrupole coupling constants, Xa = 1.9 mc, Xb = 1.7 mc, Xc = -3.6 mc, were calculated from the frequency shifts of the hyperfine splittings observed for several rotational transitions.
The structural parameters and quadrupole coupling constants are discussed in terms of the bonding characteristic of the N–C–O linkage in formamide and related compounds.
Diffusion Coefficients of the Systems Xe–Xe and A—Xe
Authors: Amdur I. , Schatzki T. F. 
Published: January 2005

The diffusion of radioargon, A37, and of radioxenon, Xe131m, through inert xenon was measured at —78, 0, 57, and 105°C. The apparatus, a Loschmidt cell in which saturation ionization currents were used as a measure of tracer concentrations, yielded diffusion coefficients which are estimated to have an accuracy of about one percent.
The intermolecular potentials of Xe–Xe, derived from the present results, agree with those obtained from thermal conductivity data in the same temperature range, but do not agree with potentials derived from second virial coefficients and crystal data. Nor do they agree with potentials derived from viscosity and thermal conductivity data at higher temperatures. It is shown that this lack of agreement is due to the inadequacy of the potential form. The potential well for the rare gases should be narrower than that given by the Lennard-Jones 12–6 potential.
Adsorption and Diffusion of Hydrogen on Nickel
Authors: Wortman R. , Gomer R. , Lundy R. 
Published: January 2005

The surface diffusion and adsorption of hydrogen on Ni field emitters has been investigated by a technique previously used for similar studies of H and O diffusion on W. It was found that diffusion occurs with an activation energy of 7±1 kcal in the chemisorbed layer, without the precipitation boundaries observed on W. This is believed to result from the inherent homogeneity of f.c.c. substrates, on which most adsorption sites seem equivalent. This is supported by the marked lack of emission anisotropy of hydrogen-covered Ni field emitters.
A field dependent transformation in the adsorbed film was found between 2° and 4°K and interpreted as a shift in the equilibrium between adsorbed H2 molecules and the terminal fraction of adsorbed H atoms. The implications of this result for the mechanism of H2–D2 exchange are discussed.
The activation energy of desorption at very low coverage is determined to be 46±4 kcal from the temperature dependence of desorption rates.
Series Expansion of Distribution Functions in Multicomponent Fluid Systems
Authors: Meeron Emmanuel 
Published: January 2005

The equations of Kirkwood and Salzburg for distribution functions are generalized to multicomponent systems. The generalized equations serve to derive a recurrence relation between the coefficients of powers of particle number densities in a Maclaurin expansion of the distribution functions. This recurrence relation is then used to derive the general term in the expansion of the distribution functions in terms of modified irreducible integrals in multicomponent systems, which includes the original one-component expansion of Mayer and Montroll as a special case.
The corresponding expansion of the potentials of average force is derived. The use of the new expansion is illustrated by a relatively simple derivation of the Fuchs expansion of the grand potential in multicomponent systems.
Possible applications to ionic solutions, impurities in solids and x-ray diffraction in solutions of several solutes are briefly discussed.
Some new formulas in the theory of cumulants (Thiele semi-invariants) are presented.
Structure of Gaseous Chloropicrin as Determined by Electron Diffraction
Authors: Barss W. M. 
Published: January 2005

The structure of chloropicrin was studied as a step in the investigation of several families of methane derivatives to determine variations in carbon bond angles and bond lengths in compounds having approximately tetrahedral carbon bonds. The results obtained showed the carbon-nitrogen bond to be longer in chloropicrin than in either nitromethane or tetranitromethane.
The electron diffraction patterns were obtained in a camera in which high background intensity gradients were corrected by means of a rotating shutter intercepting the scattered electrons. Intensity curves derived from microphotometer traces were subjected to Fourier analysis to obtain a radial distribution function. Intensity curves were synthesized for a series of molecular models to make a refined determination of the molecular parameters for chloropicrin.
Heat Capacity of Calcium from 1.8 to 4.2°K
Authors: Griffel Maurice , Vest R. W. , Smith J. F. 
Published: January 2005

The heat capacity of high-purity calcium has been measured over the temperature interval from 1.8 to 4.2°K. The electronic contribution is linear in T and the coefficient γ is 3.08±0.01 millijoules/(gram-atom) deg2 corresponding to a density of states at the Fermi level of 0.653 momentum state per electron volt per atom. A Debye temperature of 239±2°K was obtained.
For purposes of testing the calorimeter, the heat capacity of copper was determined. In agreement with other recent measurements, the value obtained for γ is 0.691±0.006 millijoule/(gram-atom) deg2 and θD is 342±2°K.
Thermoluminescence and Coloration of Lithium Fluoride Produced by Alpha Particles, Electrons, Gamma Rays, and Neutrons
Authors: Morehead Frederick F. , Daniels Farrington 
Published: January 2005

The coloration and thermoluminescence produced in LiF by 2 Mev alpha particles, by 2 Mev electrons, by 1 Mev gamma rays from Co60, and by thermal neutrons are described. The energy initially required to produce an F center varies. It is about 700 ev for alpha, 140 ev for beta, 65 ev for gamma rays, and 65 ev for thermal neutrons.
The amount of thermoluminescence light produced and the number of thermoluminescence peaks increased with the exposure to each of these radiations. The larger the radiation dosage, the greater is the fraction of thermoluminescence emitted at the higher temperatures. All of the thermoluminescence is related to the emptying of F centers, but only one photon is emitted as visible thermoluminescence for every 104 electrons removed from F centers.
The optical and thermal decolorizations are discussed.