bluuebunny/crossref_metadata_2025 huggingface dataset:
Refractive Index, Attenuation, Dielectric Constant, and Permeability for Waves in a Polarizable Medium
Authors: Vezzetti David J. , Keller Joseph B.
Published: January 2005

A new method is presented for calculating the refractive index, attenuation, dielectric constant, and permeability for electromagnetic waves in a medium of polarizable particles. It is similar to the method of Yvon and Kirkwood for finding the static dielectric constant. The main merit of the method is that it avoids the statistical hypotheses used in such calculations by Lorentz, Reiche, Hoek, Rosenfeld, and other authors. In addition, it permits the calculations to be continued to any degree of accuracy. We first use the method to obtain the dispersion equation as a power series in the molecular polarizability. The nth term in this series involves the distribution function of n + 1 particles. The terms of first and second degree are written out explicitly in terms of the two- and three-particle distribution functions. When terms of second and higher degree are omitted and the result specialized to particles with a scalar electric polarizability and zero magnetic polarizability, the dispersion equation agrees with that of Rosenfeld. When terms of second degree are retained and the static limit considered, the result reduces to that of Yvon. We next use the method to obtain the dispersion equation as a power series in the particle number density, which seems to be new. To obtain it we introduce ``pure'' n-particle scattering functions, which are analogous to the Ursell functions of statistical mechanics. This permits us to obtain the density expansion directly in a form simpler than is obtained by resumming the polarizability series.
Boundary-Value Problems for the Linearized and Weakly Nonlinear Boltzmann Equation
Authors: Pao Young-ping
Published: January 2005

The boundary-value problems of the linearized and nonlinear Boltzmann equations for a gas contained between two parallel plates are considered. First, the existence and uniqueness for the solution to the linear problem are proved for some function spaces which are convenient to the nonlinear analysis; the proof is based on a previous result due to Cercignani, who used a different function space. Then the existence and uniqueness for the solution to the nonlinear problem can be proved for small boundary data by using the implicit function theorem in functional analysis. With certain classes of boundary data, it is shown, for linear as well as nonlinear problems, that all the moments of the distribution function are continuous in the position variable. The solution to the linearized Boltzmann equation is shown to approximate the solution to the nonlinear Boltzmann equation in the limit of small boundary data. The results apply to hard-sphere molecules and hard-potential molecules, i.e., angle-cutoff power-law molecules with force exponents greater than 5.
The Polymerization of Ethylene Photosensitized by 51P1 Cadmium Atoms
Authors: Steacie E. W. R. , LeRoy D. J.
Published: January 2005

An investigation has been made of the reactions of ethylene photosensitized by 51P1 cadmium atoms, i.e., using the resonance line at 2288A. It is found that reaction occurs readily, in contrast to the action of 53P1 atoms, which have been previously shown to be ineffective. The products of the reaction are butene, hexene, and higher olefins, together with smaller amounts of acetylene and hydrogen. No pressure rise is detectable in the early stages of the reaction, and acetylene is a much less important product than is the case with mercury photosensitization. It is concluded that the primary step may be either Cd(1P1)+C2H4=Cd(1S0)+C2H3+Hor Cd(1P1)+C2H4=Cd(1S0)+C2H4*.Subsequent polymerization probably occurs by a free radical mechanism.
Counting of Free Alkyl Radicals. Application to the Photolysis of Acetone
Authors: Feldman Milton H. , Ricci John E. , Burton Milton
Published: January 2005

Long, heavy lead mirrors are deposited in a reaction tube, and metal is transported therefrom by free radicals according to the Paneth method. The lead alkyl is collected and the lead determined by a micro-method. Assuming that all the alkyl radicals are mirror-active and that all the lead is transported as PbR4, the number of radicals can be estimated. The method is applied to work on the photolysis of acetone at 2537A. It is shown that the difference in apparent half-lives of radicals produced at 45°C (1.1×10−2 sec.) and at 100°C (8×10−3 sec.) may be explained on the basis of the instability of free acetyl. The actual concentration of methyl radicals in the flowing gas in the experiments reported is estimated to be ∼2×10−3 mole percent or 1.7×10−12 mole per cc, immediately past the irradiated zone.
Contact Angles at Liquid-Liquid-Air Interfaces
Authors: Fox William
Published: January 2005

Angles at the points of contact of a number of liquid-liquid-air systems were measured. A new method of measuring the interfacial tension is presented. The work of adhesion between the phases is determined. A new theory of spreading is offered.
The Mercury Photosensitized Reactions of Ethylene at High Temperatures
Authors: LeRoy D. J. , Steacie E. W. R.
Published: January 2005

The mercury (3P1) photosensitized reactions of ethylene have been investigated over the temperature range 25°C to 350°C. In addition to those previously found at 25°C, the reaction Hg(3P1)+C2H4=C2H3+H+Hg(1S0) is shown to occur. There was a considerable increase in the quantum yield at high temperatures and this is attributed to the hydrogen atom and vinyl radical sensitized polymerization of ethylene. The reactions of ethylene with Na(2P), Cd(3P1), Zn(3P1), Hg(3P1), Cd(1P1), and Zn(1P1) atoms are summarized and the latter three are shown to be closely related.
The Differences in the Vapor Pressures, Heats of Vaporization, and Triple Points of Nitrogen (14) and Nitrogen (15) and of Ammonia and Trideuteroammonia
Authors: Kirshenbaum Isidor , Urey Harold C.
Published: January 2005

The differences in the vapor pressures of natural nitrogen and samples containing 34.6 percent nitrogen-15 were measured by a differential method and were found to be given by log P1/P2=(0.2474/T)−0.001994 where 1 refers to the natural nitrogen and 2 refers to the heavy sample. The difference in the heats of vaporization of the two samples was calculated to be 1.14 calories, that of the heavy sample being higher. The triple point pressures were measured and found to be 9.386 cm of Hg and 9.378 cm of Hg, respectively. From this the difference in the triple points was calculated to be 0.020°K. Assuming that Raoult's law may be used, the ratio of the vapor pressures and the difference in the heats of vaporization of the two pure isotopes, nitrogen-14 and nitrogen-15, were found to be log(P14/P15)=(0.7230/T)−0.005822ΔHvap 15−ΔHvap 14=3.33 calories.The triple point of the pure nitrogen-15 was found to be 0.058° higher than that of nitrogen-14 and the boiling point 0.052° higher. The differences in the vapor pressures of solid natural ammonia and of solid trideuteroammonia containing 98 percent deuterium were measured and found to be given by log (PNH3/PND3)=(49.69/T)−0.1305.The vapor pressures of the liquid ammonias were found to follow the equation log (PNH3/PND3)=(46.25/T)−0.14003.These two equations agree at the triple point. The difference in the heats of sublimation was calculated to be 227 calories, while the difference in the heats of vaporization is 212 calories, the values for the trideuteroammonia being higher than those for ammonia. The triple point pressures were found to be 4.557 cm of Hg for ammonia and 4.822 cm of Hg for the trideuteroammonia. This corresponds to triple point temperatures of 195.68°K and 198.79°K, respectively. The boiling point of the trideuteroammonia was found to be 2.37° higher than that of the ammonia.
Some Factors Affecting the Reduction of Silver Oxalate
Authors: James T. H.
Published: January 2005

(1) Silver oxalate precipitates age rapidly, and the process is not greatly impeded by adsorption of wool violet or 3,3′-diethyl-9-methylthiacarbocyanine. (2) Gelatin markedly decreases the rate of reaction between silver oxalate and hydroxylamine in slightly acid solution. A break is obtained in the rate-gelatin curve corresponding to a definite adsorption layer. The thickness of this layer is the same for silver oxalate, silver chloride, and silver thiocyanate. (3) The dye, 3,3′-diethyl-9-methylthiacarbocyanine, has a much smaller effect than gelatin upon the reaction rate. (4) The effect of bromide ion upon the gaseous products of the reaction between silver oxalate and hydroxylamine in alkaline solution is considerably smaller than in the corresponding reactions of silver chloride and thiocyanate.
Raman Spectra of Compounds in the Gaseous and Liquid States
Authors: Nielsen J. Rud , Ward Newton E.
Published: January 2005

An apparatus for exciting the Raman spectra of gases and liquids at temperatures up to 300°C is described. For phosphorus trichloride, methyl chloride, methyl bromide, methyl alcohol, methylene chloride, methylene bromide, chloroform, and carbon tetrachloride, the Raman spectra of the gas and the liquid at the same temperature have been photographed in juxtaposition with a liquid-prism spectrograph of speed f: 2.9 and linear dispersion 27A/mm at 4400A. The Raman spectra of gaseous n-pentane, n-hexane, and deuterium oxide have been photographed with 2537A excitation. The change in the Raman frequencies with the state of aggregation is different for different vibrations and varies greatly from compound to compound. In the absence of an adequate theory for this phenomenon, a search has been made for empirical regularities. The perpendicular bands of the symmetrical-top molecules are much less diffuse in the liquid than in the gas, showing that the intermolecular forces are effective in quenching the rotation of the molecules in the liquid. The other bands are about equally sharp in gas and liquid.
The Infra-Red Absorption Spectra of Ethylene and Tetra-Deutero-Ethylene under High Resolution
Authors: Gallaway W. S. , Barker E. F.
Published: January 2005

The fine structure of several infra-red absorption bands of C2H4 and C2D4 have been resolved. From the rotational constants so found, the C–C and C–H distances in this molecule were calculated to be 1.353 and 1.071A, and the H–C–H angle to be 119°55′. An assignment of fundamental frequencies has been made which is consistent with the observed data.
Solid Solutions of the Alkali Halides
Authors: Tobolsky Arthur V.
Published: January 2005

X-ray studies of solid solutions of alkali halide pairs with a common ion at room temperature and at 550°C show that these pairs can be divided into three groups depending on the percent deviation δ of their lattice parameters. For values of δ less than 6 percent miscibility is complete at room temperature. For values of δ between 6 and 13 percent miscibility is complete at 550°C. For values of δ larger than about 13 percent miscibility is not complete at 550°C. In terms of the Born theory of ionic lattices, the free energy of mixing, and Vegard's law, an approximate theory for the phase curve of these solid solutions is derived. For a typical alkali halide with an electrostatic energy of 180 kcal. at the absolute zero of temperature the equation of the phase curve is 9δ2/T(1–2x)+ln x−ln (1−x)=0,where x is the mole fraction of one component dissolved in the other. The temperature above which miscibility is complete is given by T=4.5δ2. The heat of mixing is approximately −9δ2 cal. The predictions of this theory are in good agreement with the above-mentioned experimental observations.
Frequency Spectrum of Crystalline Solids
Authors: Montroll Elliott W.
Published: January 2005

It is generally accepted that a normal crystalline solid can be pictured at absolute zero as an assembly of molecules arranged at periodically placed lattice points. Since at higher temperatures each molecule becomes a harmonic oscillator about its lattice point, in order to calculate thermodynamic properties of the crystal it is necessary to know the distribution of its internal normal modes of vibration. On the basis of the Born-von Kármán model these normal modes of vibration are roots of a secular determinant. In this paper it is shown that the 2nth moment of the distribution function of normal modes is proportional to the trace of the nth power of the matrix of the Born-von Kármán determinant. By expressing the distribution function as a linear combination of Legendre polynomials it is shown that the coefficient of each polynomial is a linear combination of the moments. The frequency distribution function of a two-dimensional simple cubic lattice is calculated by the above method and turns out to have two maxima. Usually the equation for a thermodynamic function F(T) involves the integral of the product of the frequency distribution function g(v) and a known function K(T, v). We show here that when F(T) is a known function of T an integral equation results with g(v) under the integral sign. This integral equation can be solved for g(v) by use of Fourier transforms.
The Third Law of Classical Thermodynamics
Authors: Cross Paul C. , Eckstrom Hartley C.
Published: January 2005

The third law, or law of limits as T→0°K, is expressed as: ``for any real phase Lim lim T→0(∂S∂xi)xj,n=0,and for any spontaneous isothermal process, Lim lim T→0Σiνi(∂S∂ni)T,y,nj≤0.''The equality sign applies to reversible processes and the inequality sign to irreversible processes. The n's represent composition variables, the x's (or T and the y's) a suitable set of state variables, and the v's the number of moles of the components entering into the reaction (positive for products, negative for reactants). Alternative statements of the third law are given and derived from the above statement. The completeness of this statement as a usable postulate for the further development of classical thermodynamics is briefly discussed.
Statistical Mechanics of Binary Mixtures
Authors: Alfrey T. , Mark H.
Published: January 2005

The configurations of a binary mixture are described by specification of the occupants of a reference set of lattice point pairs, rather than by specification of the occupants of each individual lattice point. If the total interaction energy can be expressed as the sum of terms due to nearest neighbor pairs, the configurational partition function can be derived directly.
The Crystal Structure of Hydrazinium Difluoride
Authors: Kronberg Marritt L. , Harker David
Published: January 2005

An x-ray analysis shows that crystalline hydrazinium difluoride is built upon a rhombohedral unit cell having a0=5.43A, α=38°10′, containing one molecular formula. The positions of the atoms have been determined and correspond to trans-hydrazinium ions which form linear hydrogen bonds to fluoride ions at the corners of an elongated octahedron. Each fluoride ion forms three hydrogen bonds to different hydrazinium ions, and condenses the octahedra into continuous layers. As a result of the packing of these layers to build up the structure, each nitrogen atom comes in contact with an ``extra'' fluoride ion and thereby assumes a coordination number of 5. Analysis of the N–N and N–H≡F distances of 1.42A and 2.62A, respectively, shows that each atom in the hydrazinium ion bears approximately ¼ of a unit of positive charge. The bearing of the structure of the ion on the adjacent charge rule is discussed. Some of the properties of the ion are interpreted in terms of the structure.
Ferromagnetic Gold-Iron Alloys
Authors: Pan S. T. , Kaufmann A. R. , Bitter F.
Published: January 2005

Magnetic measurements were made on a gold-iron alloy containing 37 atomic percent iron, both in the quenched and successively annealed states. It was found that the quenched supersaturated solid solution is ferromagnetic. When this supersaturated solid solution was gradually heated up, perceptible precipitation took place at about 450°C. Both the final gold-rich and iron-rich phases precipitated at 450°C were found to be magnetic at room temperatures. Magnetic measurements, checked by Debye-Scherrer patterns, indicate that the mechanism of precipitation in the alloy is mainly of the non-uniform type.
The Vibrational Spectra of Pyrrole and Some of Its Deuterium Derivatives
Authors: Lord R. C. , Miller Foil A.
Published: January 2005

The Raman spectra of pyrrole, pyrrole-N-d, symmetrical pyrrole-d4, and pyrrole-d5 have been studied with a high speed grating spectrograph. The infra-red absorption spectra of the same compounds have been investigated in the liquid state in the region 750–1900 cm−1. With the help of the selection principles and Teller's product rule, these spectra have been analyzed for a molecule of C2v symmetry. The analysis yields values for all but one of the twenty-four fundamental frequencies, and this one has been estimated. The spectra indicate clearly a C2v structure for pyrrole, although a Cs (non-planar) structure cannot yet be rigorously excluded.
Energy Levels and Thermodynamic Functions for Molecules with Internal Rotation I. Rigid Frame with Attached Tops
Authors: Pitzer Kenneth S. , Gwinn William D.
Published: January 2005

A general treatment of internal rotation is given for molecules whose moments of inertia for over-all rotation are independent of internal rotational coordinates. Tables are presented for the various thermodynamic functions which are accurate for molecules with one internal rotation and for the potential energy (V/2) (1 — cos nφ). The tables are shown to be a good approximation for molecules with several internal rotational coordinates, provided the potential energy can be expressed as a sum of terms of this type. Methods are suggested for treating problems where cross terms involving more than one internal coordinate are present in the potential energy. The energy level expressions are developed for the more general case with the potential energy expressed by a Fourier series. Although a few specific cases were worked out with different shape potential barriers, it appears that the simple form assumed above will be satisfactory for many purposes.
The Effect of Intermittent Light on a Chain Reaction with Bimolecular and Unimolecular Chain-Breaking Steps
Authors: Rice O. K.
Published: January 2005

The effect of intermittent light, as produced by a rotating sector, has been considered for a chain reaction having the following mechanism: A2+hν→2A,A+B→C+A,2A→stable products,A→stable products.It has been shown how to calculate the reaction rate as a function of the sector speed for different values of a certain parameter which depends on the individual rate constants and the light intensity and gives, essentially, the relative importance of the bimolecular and unimolecular chain-breaking steps. The relationships have been exhibited graphically for the case in which one-fourth of the sector passes the light beam. These relationships may be reversed, making it possible to obtain the rate constants of the intermediate reactions from measurements with intermittent light.
The Chain Photolysis of Acetaldehyde in Intermittent Light
Authors: Haden W. L. , Rice O. K.
Published: January 2005

(1) By comparison of the data on the photochemical decomposition and the azomethane-induced decomposition of acetaldehyde vapor, it has been concluded that the chain-carrying steps in the two cases are different. For the photolysis the following mechanism is suggested: (1)CH3CHO+hν→CH3+CHO,                 (2)CHO+CH3CHO→CH4+CO+CHO,            (3)CHO+CH3→stable products (chain−ending),(4)CHO→stable products (chain−ending).(There are possibly other chain-ending steps similar to reaction (3)). (2) Experiments have been performed using intermittent light at 200° and 300°. As a result of these experiments, estimates have been made for the individual rate constants, k2, k3, and k4, and it has been found that the activation energies are 2.6, 11.3, and 7.8 kcal., respectively. (3) It has been found that k2 and k3 check closely with the collision number multiplied by the appropriate Arrhenius factor. There is little or no evidence of necessity for mutual orientation of the molecules. The significance of this has been discussed. Reaction (4) probably takes place at the walls, and the value of k4 is of the same order of magnitude as the fraction of the molecules hitting the walls per second, times the appropriate Arrhenius factor. (4) The extent of and effect of diffusion of radicals beyond the illuminated region have been considered.
The Effect of Electrical Forces on the Stability of Colloidal Sols
Authors: Eversole W. G. , Hanson Allen L.
Published: January 2005

It is assumed that the stabilizing potential in a sol is not the potential at a distance t from the surface of the particle, (ζ), but the potential at a distance l, (λ). l is the distance from the solid surface at which a maximum in the potential energy curve determines the rate of coagulation, and λ is a constant for a given sol in states of equal stability. The quantities l—t and λ are evaluated from experimental data.
Statistical Thermodynamics of Rubber. II
Authors: Wall Frederick T.
Published: January 2005

The statistical theory of rubber elasticity is extended by postulating that the total volume of a piece of rubber remains constant during a stretching process. The modified theory is found to be in better agreement with observation than any previous molecular theory. In addition, it is shown theoretically that rubber should obey Hooke's law with respect to shear.
Gas Imperfections Determined from the Heat of Vaporization and Vapor Pressure
Authors: Curtiss Charles F. , Hirschfelder Joseph O.
Published: January 2005

The imperfections of many gases may be obtained by combining available heats of vaporization and vapor pressure data with the Clausius-Clapeyron equation. The accuracy of this method in some cases is comparable to that of good direct P.V.T. measurements and therefore may be useful in preliminary investigations. If P is the vapor pressure, T is the absolute temperature, ΔH is the heat of vaporization, V and Vl are the molal volumes of the vapor and liquid phases: PVRT=−ΔHR(1−Vl/V)[dlnP/d(1/T)]=1+βV.This equation determines the gas imperfection β. The value of β calculated in this manner is compared with experimental second virial coefficients for H2O, NH3, H2, O2, A, CH4, propane, n-butane, n-heptane, ethene, propene, CH3Cl, CCl3F, CH3OH, C6H6, and Hg. Values of β are determined for HI, HBr, HCl, CH3NH2, (CH3)2NH, HCN, isobutane, tetramethylmethane, 2,2,4, trimethylpentane, C2N2, COS, PH3, H2S, CH3Br, and C2H5OH. Evidence of hydrogen bond formation is shown for CH3OH, C2H5OH, CH3NH2, and (CH3)2NH. It is shown that HI and HCN contain a considerable fraction of instantaneously formed double molecules. The gas imperfection of benzene is perfectly normal. The number of instantaneously formed double molecules is estimated for all of the above molecular species.
A Practical Method for the Solution of Certain Problems in Quantum Mechanics by Successive Removal of Terms from the Hamiltonian by Contact Transformations of the Dynamical Variables Part II. Power Series in a Coordinate and Its Conjugate Momentum. The Anharmonic Oscillator by Perturbation Theory
Authors: Thomas L. H.
Published: January 2005

The non-commutative algebra of polynomials in a coordinate and its conjugate momentum is reduced to common algebra by Weyl's method, and tables are given for facilitating its use. It is shown how the problem of the anharmonic oscillator can be solved by contact transformations, and tables are given for removing terms up to the third degree in its coordinate and momentum and for finding the modified Hamiltonian up to the fourth degree, which is as far as is ordinarily required in molecular theory. To illustrate the power of the method, the energy is computed up to terms of the eighth degree for energy containing terms to that degree (in the coordinate only), obtaining Dunham's result together with the constant terms of that order not given by him.
Statistical Distribution Laws for Rate Processes
Authors: Longtin Bruce
Published: January 2005

A re-examination of the fundamental hypotheses of statistical mechanics shows that the principle of the most probable distribution may be interpreted in such a way as to be applicable as well to systems which are not at equilibrium. The general method of deriving distribution laws for systems not at equilibrium is outlined. The use of this method is illustrated by deriving a general distribution law for systems in which the velocities are required to be non-Maxwellian. The distribution of velocities of molecules in any group having a specified average velocity is Maxwellian relative to the group average velocity. The average total energy of such a system is shown to be the sum of the kinetic energies of mass motion of the several groups of molecules plus the Maxwellian average energy corresponding to the given volume and temperature.
Solvent Effects on the Kinetics of Ionic Reactions and the Choice of the Concentration Scale
Authors: Davis Hubert G. , LaMer Victor K.
Published: January 2005

The mole fraction scale gives simpler (i.e., more nearly linear) relations between the variables determining kinetics on changing solvents for the bromacetate-thiosulphate reaction than does the usual volume molar scale. The generality and basis of this finding is discussed from the viewpoint of Rabinowitch's cage model theory as well as from that of equilibrium theory. The quenching of fluorescence, which involves diffusion as a rate determining step, is a more nearly linear function of the fluidity when the data are expressed in mole fraction than in the volume molar scale. Experiments are in progress to determine, if possible, whether the cage model or a modified Smoluchowski diffusion treatment fits the facts better for low activation energy reactions like the quenching of fluorescence in solution.
The Specific Heat of Pure Iron at Low Temperatures
Authors: Kelley K. K.
Published: January 2005

Specific-heat measurements of iron of 99.94 percent purity were determined throughout the temperature range 52° to 298°K. These measurements were undertaken because of the five sets of determinations in this region previously recorded in the literature are in disagreement, with the exception of those of Eucken and Werth and of Simon and Swain, although even these differ on an average of 1.8 percent. Present results are considered accurate on the average to within 0.3 percent, and they confirm the work of the investigators just mentioned rather than that of Rodebush and Michalek and of Griffiths and Griffiths. The entropy of iron was computed as S298.16 = 6.49±0.03 cal./deg. (gram atom), of which only 4×10−4 is extrapolation below 1°K.
The Electron Affinity of Bromine and a Study of Its Decomposition on Hot Tungsten
Authors: Doty Paul M. , Mayer Joseph E.
Published: January 2005

The electron affinity of bromine has been measured by determining the ratio of ions to electrons leaving a hot tungsten surface in contact with bromine gas at low pressure. The value obtained is 80.5±0.4 kcal./mole. The measurements, which extend over a range of 700° in temperature and 80-fold in pressure, show no trend in the electron affinity and demonstrate that the decomposition of bromine under these conditions is a first-order reaction. The assumption of unit accommodation coefficient is shown to be correct.
Intensities of Electronic Transitions in Ammonia
Authors: Thompson Robert J. , Duncan A. B. F.
Published: January 2005

Absolute intensity measurements of the transitions in ammonia vapor with maxima at 52,500, 66,000, and 77,000 cm−1 are reported. Calculations are made of the intensities of the first and third transitions, using non-bonding nitrogen orbitals, of the form suggested by Slater. The calculated values are considerably lower than the measured values, but may be improved by variation of the effective nuclear charge. Similar calculations for the second transition are less conclusive, but seem to indicate that it also may originate from a nearly non-bonding nitrogen orbital. Some other possible origins of this transition are considered and rejected on the basis of either their energy or their intensity.
Bending Force Constants for Halogenated Ethylenes
Authors: Pitzer Kenneth S. , Freeman N. K.
Published: January 2005

Force constants have been calculated for the out-of-plane bending motions of the vinyl halides and for cis- and trans- 1,2-dichloroethylene. Published vibrational assignments have been followed for the most part, but several changes were found necessary. A generally consistent set of force constants was obtained in which the values are also similar to those for the methyl halides.
Notes on the Rate Process Theory of Flow
Authors: Bondi A.
Published: January 2005

This paper deals with the separation of the contributing terms of the energy and entropy of activation for viscous flow and the identification of some of the molecular constants entering into these terms, as a step toward the prediction of the viscosity of liquids from first principles. The energy of activation for hole formation ΔH‡h is found to be determined mainly by the magnitude of the dispersion energy and by the extent of displacement of the hole forming molecules from their equilibrium position. The latter, in the form of the viscosity-pressure coefficient ΔV‡, is, at present, not predictable from any molecular constant. The energy of activation for motion into the hole ΔH‡i was found for many substances to be numerically equal to the excess energy of vaporization ΔEvapi and is thus an additional measure of restricted external rotation. The cases in which ΔH‡i > ΔEvapi offer strong evidence for the requirement of deformation of the flowing molecule against internal potential energy barriers. The rotational, translational, and cooperative terms which contribute to the entropy of activation have been separated, but can so far be determined only from viscosity data. Numerical examples show that the stereometric arrangement of molecular structure determines the magnitude of ΔV‡ and ΔH‡i and thereby the viscosity of liquids to a far greater extent than chemical composition (except for OH groups). The existence of aliphatic fatty acids as double molecules in the liquid state over a wide range of temperatures is confirmed viscosimetrically, while the viscosity data of aliphatic alcohols suggest the presence of distinguishable multiple molecules only at very low temperatures but the existence of a continuous OH-bond network structure at ordinary temperatures. One of the important consequences of the rate process theory of flow is the recognition that the viscosity of a liquid is determined by the (very small) concentration of molecules in relatively shallow potential energy walls from which the activated molecules are preferentially recruited. Viscosity is therefore not a bulk property in the commonly accepted sense and depends only to a minor extent on the structure of a liquid, i.e., on its state of order.
The Use of Punched Cards in Molecular Structure Determinations I. Crystal Structure Calculations
Authors: Shaffer P. A. , Schomaker Verner , Pauling Linus
Published: January 2005

The application of punched cards and electrical accounting machines (of the International Business Machines Corporation) to crystal structure calculations is described. The machines may be used to evaluate Fourier series with greater accuracy, greater speed, and greater density of calculated points than is possible by the methods used heretofore. A method for the punched-card calculation of structure factors is also set forth, and the use of the machines for the reduction of observational equations to normal equations in least squares is discussed.
The Determination of Polymeric Molecular Weights by Light Scattering in Solvent-Precipitant Systems
Authors: Ewart R. H. , Roe C. P. , Debye P. , McCartney J. R.
Published: January 2005

The theory of scattering by an inhomogeneous dielectric medium has been extended so as to account for the turbidimetric behavior of polymer solutions in solvent-precipitant mixtures. It is predicted by this theory and verified by experiment that correct values of molecular weight are obtained by the usual interpretation of turbidity measurements if and only if the solvent and precipitant have the same refractive index. The practical utility of turbidimetry in high polymer solutions is shown to be greatly increased by the proper use of solvent-precipitant mixtures. If the solvent and precipitant have different refractive indices, scattering measurements give information about the extent of selective absorption of solvent by the polymer.
A Proposed Interpretation of the Zeta-Potential
Authors: Robinson Lawrence B.
Published: January 2005

The method used by Gurney and Fowler in explaining the interfacial potential at a metal-solution boundary is applied to the zeta-potential. This gives the ζ-potential as a straight line function of the logarithm of the concentration, in agreement with the shape of the curves as found experimentally. To obtain exact agreement between theory and experiment, it is proposed that the dielectric constant of the electrical double layer is about 0.6 that of the value for pure water. This assertion can be checked by accurate measurements on the surface conductance of solution of electrolytes.
Absorption of Water by Films of Cellophane and Polyvinyl Alcohol
Authors: Creutz E. , Wilson Robert R.
Published: January 2005

The absorption of water and dehydration of these films is found to obey a diffusion equation by means of which a diffusivity may be defined. This is not a constant but depends on the water concentration in the foils. A rapid change in water content immediately after changing the ambient conditions suggests the presence of adsorbed surface layers. The total absorption is found to increase faster than the relative humidity.
Near Ultraviolet Absorption of Pyridine Vapor
Authors: Sponer H. , Stücklen Hildegard
Published: January 2005

The absorption spectrum of pyridine at 3000–2500A has been studied in the first order of a 3-m grating spectrograph. The band system represents an electronic transition A1→B1 (using symmetry C2v for pyridine). Several progressions of totally symmetric vibrations are observed. The band 34769 cm−1 is taken as 0,0 band. Besides carbon ring vibrations the occurrence of hydrogen vibrations is established and discussed.
Classical Models and Many-Electron Atoms
Authors: Cook Melvin A.
Published: January 2005

Based on classical models including the interpretation of the deBroglie wave as an electromagnetic ``atmosphere'' which controls the orbit and the ``action'' of the classical electron, and postulating that the ``atmosphere'' of the electron suffers a permanent change only when the electron undergoes a change in its quantum state, an equation is derived for the He ground state iso-electronic sequence which agrees substantially with experiment. This view leads to the conclusion, moreover, that the binding energy in molecules formed without electronic transitions is caused entirely by a decrease in the average potential energy, the average kinetic energy of the molecule remaining the same as in the constituent atoms. This conclusion is verified in the systems H2 and H2+. Introducing the additional assumption that the resonance contribution to the total energy of a state, arising from an ``adiabatic'' orbital distortion, is proportional to the orbital frequency, equations are derived expressing the term values of a number of states of two-, three-, and four-electron atoms. The methods appear to apply quite generally.
Thermodynamic Properties of Gaseous 1,3-Butadiene and the Normal Butenes above 25°C Equilibria in the System 1,3-Butadiene, n-Butenes, and n-Butane
Authors: Aston John G. , Szasz George , Woolley Harold W. , Brickwedde Ferdinand G.
Published: January 2005

Tables of the thermodynamic functions Cp0, H0, S0, and F0 are given for 1,3-butadiene and the normal butenes for temperatures from 298.16°K to 1500°K for the substances in the ideal gas states at one atmosphere pressure. These have been prepared using reliable spectroscopic and molecular data, together with calorimetric entropies, gaseous specific heats, and heats of formation. Equilibrium constants are given for reactions in the system 1,3-butadiene, n-butenes, and n-butane. Available experimental data are compared with the calculations. The calorimetric data for 1,3-butadiene furnish strong evidence for the existence of two geometric (cis-trans) isomeric forms of 1,3-butadiene in appreciable concentrations at room temperatures. The two forms differ in energy by 2.3 kcal. mole−1, and are separated by a C–C rotational barrier 2.6 kcal. mole−1 above the lowest energy level of the cis, or higher, energy form.
Absorption Spectrum of Fluorbenzene in the Near Ultraviolet
Authors: Wollman S. H.
Published: January 2005

The absorption spectrum of C6H5F at 2750–2380A was photographed in the first order of a three-meter grating spectrograph. As in C6H5Cl the band system corresponds to an electronic transition A1, B1. This is an allowed transition and the 0,0 band is stronger than in C6H5Cl because of the greater perturbation by the fluorine. Several progressions of totally symmetric vibrations are observed. The vibration whose excitation brings the corresponding benzene spectrum into appearance, and which shows up relatively intensely in C6H5Cl, appears in C6H5F but is not particularly prominent. In contrast to C6H5Cl, transitions to the carbon-halogen vibration in the upper electronic state are quite strong.
A Note on the Theory of Diffusion Controlled Reactions with Application to the Quenching of Fluorescence
Authors: Montroll Elliott W.
Published: January 2005

The principles of Smoluchowski's collision theory of reactions in solution are outlined. This theory is applicable to reactions which occur immediately on the collision of two reactant particles; that is, diffusion controlled reactions. The rate of such reactions depends on the collision frequency of reactants. In this paper an expression for the collision frequency is derived as a function of time when initially there is a Boltzmann distribution of particles around any particular reactant molecule. Both the Brownian motion of and the forces between reactant molecules are considered in the calculation. The general results are applied to the theory of quenching of fluorescence. It is shown that the quenching constant, kQ, defined by (I0I−1)⧸nQ=kQ,(where I0 is the intensity of fluorescence in the absence of quencher and I the intensity in the presence of quencher of concentration nQ) can be expressed as a sum of two terms, one proportional to the reciprocal of the viscosity of the solvent and the other to the reciprocal of the square root of the viscosity.
The Electrical Potential at the Interface between Vitreous Silica and Solutions of Barium Chloride
Authors: Wood Lloyd A. , Robinson Lawrence B.
Published: January 2005

The zeta-potential of vitreous silica in contact with several solutions of barium chloride has been determined by the measurement of streaming potentials. Solutions of seven concentrations between 10−6 M and 10−2 M, inclusive, were studied, and the zeta-potential was found to decrease in a regular manner with increasing concentration. It is evident that there is no maximum in the curve of the zeta-potential vs. concentration, as most experimenters have reported.
Statistical Mechanics of Multimolecular Adsorption. I
Authors: Hill Terrell L.
Published: January 2005

Cassie's statistical treatment of multimolecular adsorption on a free surface, leading to the BET equation, is criticized and corrected. The method is generalized to include adsorption when the maximum number of layers of adsorbate is restricted. The isotherm equation obtained is the same as that found by Brunauer, Emmett, and Teller for this case, rather than the equation proposed by Pickett. The BET equation, though not completely satisfactory, is apparently the correct equation for the particular model used. Real improvements in the theory should follow from refinements in the model rather than from modifications in the treatment of the BET model. A more refined model is proposed and the general method of using it is discussed. The BET model is shown to be a crude special case of the model suggested here, but it has the advantage of presenting no mathematical difficulties. Preliminary results, based on improved models, indicate that a somewhat refined multimolecular adsorption theory is capable of predicting capillary condensation for suitable values of parameters, thus suggesting that the ideas of multimolecular adsorption and capillary condensation are not really in conflict, as is generally assumed. Further discussion is deferred to a subsequent paper.
The Scattering of Electrons by Hydrocarbon Films
Authors: Karle J.
Published: January 2005

Several formulae are derived expressing the intensity of electron scattering for a variety of orientations of hydrocarbon films on a solid surface. Intensity contour maps may be constructed from these formulae for arbitrarily chosen models. These maps are helpful for determining the structure of a film and are being prepared for future publication.
The Thermodynamic Properties and Potential Energy of Solid Argon. II
Authors: Rice O. K.
Published: January 2005

In the first paper with this title, a relation was derived from the available experimental data giving the Debye characteristic temperature of solid argon as a function of a (the interatomic distance) or V (the molal volume of the solid). This relation was not consistent with the usual Grüneisen assumption, which for a small range of volumes may be written approximately —Θ−1dΘ/dV=constant. In this paper it is shown that the Grüneisen assumption, with the constant set equal to 0.18 mole cc−1 is reasonably consistent with the experimental data. On this basis a new relation between the potential energy Ep of solid argon and a is derived. Most of the earlier conclusions are unaltered, but the present basis seems more reasonable, and, as will be shown in the following paper, avoids difficulties when application is made to liquid argon.
The Thermodynamic Properties of Liquid Argon
Authors: Rice O. K.
Published: January 2005

The thermodynamic properties and equation-of-state data of liquid argon are interpreted in terms of a partition function previously derived. This partition function has a part due to vibratory motion of the atoms in the liquid and a part due to translational motion. The vibratory part contains the Debye characteristic temperature Θ for the solid, evaluated for a certain interatomic distance a0 which appears as a parameter in the partition function. a0 is interpreted as the average interatomic distance between nearest neighbors in the liquid, and is a function of a, the latter being defined as (2½V/N)⅓, where V is the molal volume and N Avogadro's number. With V set equal to the molal volume of the liquid at its normal melting point, a0 is assigned a value which appears reasonable from the atomic distribution curves obtained by x-ray studies of the liquid. With this value of a0, the partition function for this fixed value of V gives reasonably good values of the entropy over a large range of temperatures. A small, entirely reasonable change in the partition function improves the agreement with the experimental data. The parameters in the partition function have been evaluated for other values of V by using equation-of-state data. This leads to a calculation of the specific heats of saturated liquid argon over a range of temperatures. The agreement with experimental data is not exceedingly close, but is probably within experimental error. A calculation is also made of the free energies of the solid and liquid phases along the melting curve. They are found to be equal to within reasonably close limits. The application to various values of V leads to the evaluation of a0 as a function of a. The experimental curve for (∂S/∂V)T plotted against V appears to show a change of slope near the value of V characteristic of the liquid at its normal melting point. There is also a change in slope of the curve for da0/da vs. a, at the corresponding value of a. These facts are interpreted in terms of the atomic distribution curves, which appear to indicate a change in structure of the liquid which starts near the same value of V or a. The liquid appears to change from a distorted face-centered structure to a distorted body-centered structure as the volume increases. Information about the potential energy of liquid argon is obtained from the experimental data by application of the partition function. It is found that the potential energy of the liquid can be rather effectively correlated with the potential energy of the solid. Finally, certain peculiarities of the equation-of-state data are believed to indicate a pre-freezing phenomenon, in which particles containing appreciable numbers of atoms and having the structure of the solid, appear in the liquid. A state of this sort can be stabilized by the entropy of mixing of the solid particles with the liquid.
Theory of the Non-Tetrahedral Carbon Atom
Authors: Duffey George H.
Published: January 2005

The hybridization of s and p orbitals to give non-tetrahedral orbitals is discussed. The results are applied to cyclic hydrocarbons. For cyclopentane the theory yields an H–C–H angle of 111° 1′, and for cyclobutane an H–C–H angle of 180°.
Notes on the Infra-Red Spectrum and Molecular Structure of Ozone
Authors: Adel Arthur , Dennison David M.
Published: January 2005

The nature of the fine structure of the band at 14.2μ in the absorption spectrum of ozone has been determined with prism and grating spectrometers. These data, together with the fine structure of the 9.57μ band (previously resolved in the solar spectrum) render possible an unambiguous choice between the divergent views currently held with regard to the structure of the ozone molecule. It is concluded that the form of the isoceles triangle is acute, with the apex angle in the neighborhood of 34°.
Studies on Glass. XVIII. The Heats of Solution of Crystalline and Glassy Glucose; the Heat of Mutarotation of α-Glucose
Authors: Rowe Robert D. , Parks George S.
Published: January 2005

A calorimeter has been developed for the rapid solution of a powdered solid in a suitable solvent and the accurate determination of the heat of solution during the process. This calorimeter has now been used to determine the heats of solution of two preparations of crystalline α-d-glucose in water, both with and without mutarotation, and also the heats of solution of two preparations of glucose glass. Relatively accurate thermodynamic data for the crystal-to-glass transformation have been computed from these solution heats. Also small, but significant, differences per mole in enthalpy (ΔH298=102±18 cal.), in entropy (ΔS298=0.24±0.06 cal./deg.), and in free energy (ΔF298°=31±10 cal.) have been found for these two glass preparations. A value of ΔH298=−175 (±5) calories has been obtained for the mutarotation of a mole of α-glucose, dissolved in water, to yield the equilibrium mixture of the alpha- and beta-forms.
Efficiency of the Electrolytic Separation of Potassium Isotopes
Authors: Hutchison Dwight A.
Published: January 2005

The electrolytic separation coefficient, α, has been determined for the potassium isotope separation in the electrolysis of aqueous solutions of potassium chloride at a flowing mercury cathode. Suspension of purified potassium chloride crystals in a liquid mixture of bromoform, n-pentanol, and n-hexanol served as the analytical procedure in determining the isotopic composition of samples. Densities of the liquid suspension mixture as a function of temperature were independently determined. The electrolytic separation factor for the potassium isotopes was found to be 1.0054±0.0005 for the temperature range of 15°—50°C, and, within the limits of error, was independent of temperature, of the fraction electrolyzed, of the concentration of the electrolytic solution, of the current density, and of the amount of back reaction at the cathode. An empirical relation between the electrolytic separation factors of elements thus far investigated and their atomic weights is presented.