bluuebunny/crossref_metadata_2025 huggingface dataset:
A Theory of the Linear Viscoelastic Properties of Dilute Solutions of Coiling Polymers
Authors: Rouse Prince E.
Published: January 2005

The necessary coordination of the motions of different parts of a polymer molecule is made the basis of a theory of the linear viscoelastic properties of dilute solutions of coiling polymers. This is accomplished by use of the concept of the submolecule, a portion of polymer chain long enough for the separation of its ends to approximate a Gaussian probability distribution. The configuration of a submolecule is specified in terms of the vector which corresponds to its end-to-end separation. The configuration of a molecule which contains N submolecules is described by the corresponding set of N vectors.

The action of a velocity gradient disturbs the distribution of configurations of the polymer molecules away from its equilibrium form, storing free energy in the system. The coordinated thermal motions of the segments cause the configurations to drift toward their equilibrium distribution. The coordination is taken into account by the mathematical requirement that motions of the atom which joins two submolecules change the configurations of both submolecules. By means of an orthogonal transformation of coordinates, the coordination of all the motions of the parts of a molecule is resolved into a series of modes. Each mode has a characteristic relaxation time. The theory produces equations by means of which the relaxation times, the components of the complex viscosity, and the components of the complex rigidity can be calculated from the steady flow viscosities of the solution and the solvent, the molecular weight and concentration of the polymer, and the absolute temperature.

Limitations of the theory may arise from the exclusion from consideration of (1) very rapid relaxation processes involving segments shorter than the submolecule and (2) the obstruction of the motion of a segment by other segments with which it happens to be in contact. Another possible cause of disagreement between the theory and experimental data is the polydispersity of any actual polymer; this factor is important because the calculated relaxation times increase rapidly with increasing molecular weight.
Solution of the Debye-Hückel Equations for a Polarized Electrode
Authors: Breyer B. , Gutmann F.
Published: January 2005

The Debye-Hückel equations are solved for the case of a polarized electrode, yielding, for the mean ionic concentration at a distance x from a plane cathode immersed into an aqueous solution of a uni-univalent electrolyte of concentration aN0 molecules/cm3, n1=aN0 cotanh2Kx/2,1/K being the Debye length. The mean local charge density and the mean local potential are calculated, and it is shown that the latter quantity is merely the thermodynamical potential resulting from the increased activity of the cations near the electrode, the system behaving as a concentration cell.
Diffusion in Binary Systems
Authors: Prager Stephen
Published: January 2005

The Onsager-Fuoss equation for the concentration dependence of the diffusion coefficient is derived from a kinetic picture, taking into account the asymmetry in the Brownian motion induced by concentration gradients. Mass flow is introduced by considering diffusion in the presence of a pressure gradient. Systems exhibiting volume changes on mixing are discussed, and a modification of the Matano procedure for calculating diffusion coefficients is suggested. It is shown that diffusion coefficients obtained from steady-state permeability measurements and those obtained from interdiffusion data differ by a factor of V̄2c2, the volume fraction of the nonpermeating component.
Thermal Diffusion in Binary Systems
Authors: Prager Stephen , Eyring Henry
Published: January 2005

Just as is the case with ordinary diffusion, thermal diffusion is accompanied by a mass flow, which does not vanish even after the steady state has been reached. As a result of this mass motion the thermal diffusion coefficients of both components in a binary mixture enter into the expression for the steady-state mole fraction gradient of either one, so that a knowledge of the latter is not sufficient, in general, to resolve the total heat of activation for diffusion into a heat of hole formation and a heat of activation for jumping. Mass flow should exist even in pure liquids in the presence of a temperature gradient, and this gives rise to the interesting possibility that the heat of activation for self-diffusion can be resolved into its components.
Rotation Vibration Bands of Some Symmetric Top Molecules Under High Resolution
Authors: Wiggins T. A. , Shull E. R. , Rank D. H.
Published: January 2005

The fine structure of some parallel bands of the symmetric top molecules CH3I, CD3Br, CHF3, and CHCl3 has been investigated in the 1.6 and 2.2μ regions. The double-pass plane grating spectrograph was capable of achieving a resolving power in excess of 100 000. For most of these bands the ``line'' nature of the sub-bands in the P, Q, and R branches was demonstrated. In the case of CH3I the resolution was complete enough to demonstrate conclusively the complicated fine structure of the P and R ``lines.'' Molecular constants have been derived from the bands of CH3I, CD3Br, and CHF3. The theoretically expected relationship between the zeta's has been shown to hold in perpendicular CH3I bands.
Cooperative Orientation in Solutions. The Accuracy of the Quasi-Chemical Approximation
Authors: Barker J. A.
Published: January 2005

The accuracy of the quasi-chemical approximation used in the theoretical treatment of a lattice model for solutions in which cooperative orientation of molecules takes place is examined. The quasi-chemical method of Guggenheim and the modified quasi-chemical method of Kikuchi are used to find higher approximations. It is found that the quasi-chemical approximation for pairs is satisfactory for lattices which are not closepacked, though it may be seriously in error for closepacked lattices.
Vibrational Spectra of Fluorinated Aromatics. III. 1,4-Difluorobenzene
Authors: Ferguson E. E. , Hudson R. L. , Nielsen J. Rud , Smith D. C.
Published: January 2005

The infrared absorption spectra of gaseous and liquid 1,4-difluorobenzene have been obtained in the regions 2–22μ and 2–38μ, respectively, with the aid of LiF, NaCl, KBr, and KRS−5 prisms. The Raman spectrum of the liquid phase has been photographed with a three-prism glass spectrograph of linear dispersion 15A/mm at 4358A. Depolarization ratios have been measured for the stronger Raman bands. A complete assignment of fundamental vibration frequencies has been made, and the spectra have been interpreted in detail. The nonplanar frequencies have been calculated with the aid of force constants determined for related molecules
The Interpretation of Infrared Dichroism in Fibrous Protein Structures
Authors: Fraser R. D. B.
Published: January 2005

The increasing use of infrared dichroism measurements in studying the molecular structure of fibrous proteins necessitates a critical examination of its interpretation. Relationships between transition moment direction and dichroic ratio are derived for perfectly and imperfectly oriented fibers, and the effects of reflection losses, form dichroism, and convergence are considered. Uncertainties in the assignment of the transition moment directions associated with the principal vibrations of the —CO·NH— group are discussed.
Bond Moments and Derivatives in CF4, SiF4, and SF6 from Infrared Intensities
Authors: Schatz P. N. , Hornig D. F.
Published: January 2005

The absolute intensities of the fundamental infrared absorption bands of SiF4, CF4, and SF6 were measured utilizing the pressure broadening technique. The effective bond moments, μ0, and bond moment derivatives, ∂u/∂r, are calculated as a function of the most general potential constants. Based on a valence force field plus repulsion between nonbonded atoms, the most probable values (first column) and the alternatives (second column) are as follows: μ0=2.3 d  3.3 dSiF4   ∂u/∂r=−7.49 d/A  3.66 d/A  μ0=1.12 d  2.36 dCF4∂u/∂r=4.88 d/A  3.35 d/A  μ0=2.65 d  0.65dSF6∂u/∂r=3.85 d/A−6.58 d/AThe results are discussed.
Equilibria Involving the CF(g) and CF2(g) Radicals at High Temperatures
Authors: Margrave John L. , Wieland Karl
Published: January 2005

The absorption spectrum of carbon tetrafluoride (CF4) gas thermally decomposed under equilibrium conditions in a graphite tube furnace shows the bands of CF2 at a temperature T≈1900°K and also the bands of CF at a temperature T≈2400°K. These results are in approximate agreement with thermodynamic calculations made by Potocki and Mann when the high value of 170 kcal/mole for the heat of sublimation of graphite and when f values of about 10−3 for both the CF2 and the CF bands are assumed.
Determination of the Potential Constants of Ozone from Centrifugal Distortion Effects
Authors: Pierce Louis
Published: January 2005

The microwave spectrum of O3 was reanalyzed to include the effect of centrifugal distortion. Using the Kivelson-Wilson energy expression for a semirigid rotor it was possible to fit eighteen rotational lines to within a mean deviation of ±1.4 Mc. The rotational constants determined in this manner are a=106 534.74 Mc, b=13 348.95 Mc, c=11 834.30 Mc. The four distortion constants predicted vibrational frequencies which differed by only four percent from the observed values.

A sensitive determination of the potential function was made by requiring it be compatible with both the observed infrared spectrum and the distortion frequency shifts derived from the direct analysis of the rotational spectrum. The resulting force constants are: fd=5.70×105 dyne cm−1, fα/d02=1.28×105 dyne cm−1, fdα/d0=0.332×105 dyne cm−1, fdd=1.52×105 dyne cm−1. The force constants were then used to calculate distortion constants for O16O18O16 and these in turn were used to analyze its rotational spectrum.
Infrared Spectrum of Hydrogen Sulfide from 2200–2800 cm−1
Authors: Allen Harry C. , Blaine L. R. , Plyer Earle K. , Cross Paul C.
Published: January 2005

The absorption of hydrogen sulfide from 2200 to 2800 cm−1 has been observed under high resolution. It can be accounted for by two bands having excited states (n1,n2,n3) = (0,2,0), and (1,0,0). A novel feature of this analysis is the assignment of the strong absorption in the high-frequency portion of this region as arising from the transition (0,0,0)→(1,0,0). The parameters giving the best fits to the observed absorption are: A*B*C*ν0(0,2,0)11.0999.4434.6102353.93 cm−1(1,0,0)10.2498.8314.6632614.56 cm−1.It was not possible to assign enough transitions in the (0,0,1) band to determine a unique set of parameters.
Thermoluminescence of Some Aromatic Hydrocarbons
Authors: Sharma J.
Published: January 2005

The thermoluminescence of diphenyl, solid benzene, toluene, and p-xylene has been studied after exciting them with cathode rays at liquid oxygen temperature. Also the decay rates of the afterglow have been measured. The thermoluminescence in each case consists of several peaks emitted at low temperature. The afterglow decay has been found to be exponential.
Influence of Fermi Resonance on the Centrifugal Stretching Constant of a Linear Molecule
Authors: Amat Gilbert , Goldsmith Mark , Nielsen Harald H.
Published: January 2005

A theory of the influence of Fermi resonance on the centrifugal distortion constant of a linear molecule has been developed and its predictions for CO2 compared with experiment. The theory of those bands which exhibit simultaneous Fermi resonance and l-type doubling is also discussed.
Interpretation of Infrared Dichroism in Fibrous Proteins —the 2μ Region
Authors: Fraser R. D. B.
Published: January 2005

The assignment of the overtone and combination bands which appear in the infrared spectra of fibrous proteins between 4200 and 5500 cm−1 is discussed on the basis of the normal vibrations of an isolated —CO.NH— group. Equations relating the degree of molecular orientation in a protein fibre with transition moment direction and dichroic ratio are derived and the assignment of the transition moment direction associated with certain vibrations is considered.
Kinetics of Strontium Oxide on Tungsten
Authors: Cape J. A. , Coomes E. A.
Published: January 2005

Field electron microscopy has been used to study the kinetics of strontium oxide on tungsten in the range 900–2200°K. Reactions take place on the {111} and {100} which have high concentrations of four nearest neighbor surface atoms. Below 1150°K there is some evidence for the dissociation of SrO and migration of Sr to the {110} edges where clusters of crystallites are formed. Two modifications of field emission patterns associated with the (Sr–O–W) complex within 1150–1550°K are tentatively identified with the basic and normal tungstate; apparently the first goes over to the second with an activation energy of ∼60 kcal as determined from desorption data. An unusually sharp decrease in Fowler-Nordheim work function occurs during this reaction. In the later stages of desorption above 1550°K patterns identifiable with an oxygen-tungsten surface are obtained. Desorption at this stage takes place with an activation energy of ∼140 kcal.
First-Order Stochastic Processes
Authors: Krieger Irvin M. , Gans Paul J.
Published: January 2005

A general class of ``first-order'' stochastic processes is defined as those for which the probability per unit time of a transition out of a state is proportional to the occupancy of that state. The solution to the differential-difference equation for the process, obtained earlier by Siegert [Phys. Rev. 76, 1708 (1949)], is obtained here using more elementary mathematics. The resultant solution is used to demonstrate that a system relaxing by first-order processes from one equilibrium state to another will maintain, at all times, a multinomial distribution.
Paramagnetic Resonance in Charred Dextrose
Authors: Pastor R. C. , Hoskins R. H.
Published: January 2005

The magnetic-resonance properties of charred dextrose outgassed in high vacuum were studied. Linewidth measurements in conjunction with elementary analyses for two series of chars provide some evidence of the effect of cyclization on the observed widths. Low-temperature measurements of T1 (c-w and direct pulse) have provided a better understanding of the nature of the distribution and saturation behavior of the spin systems.
Conditions Imposed by Gross Properties on the Intermolecular Potential
Authors: Frisch H. L. , Helfand E.
Published: January 2005

The conditions for, and implications of, the existence of a maximum in the second virial coefficient as a function of temperature are investigated. Brief comment is made on the use of the inversion of Laplace transforms, with respect to the reciprocal temperature, to obtain information about intermolecular potentials and cross sections from second virial coefficients and dilute gas transport coefficients.
Role of Thermal Diffusion in the Electrolytic Separation of Isotopes in Liquid Metals
Authors: Mangelsdorf Paul C.
Published: January 2005

From the principles of irreversible thermodynamics and the known properties of metals it is inferred that there is a contribution to the Haeffner effect isotope separations arising from the isothermal heat flux accompanying the current flow. The magnitude of this contribution is estimated to be a significant fraction of the observed effect, but of opposite sign.
Cluster Formation in Perfluoroheptane-i-Octane Systems near the Consolute Temperature
Authors: Brady George W.
Published: January 2005

Small-angle x-ray measurements on the system C7F16-i-C8H18 at temperatures near the consolute temperature show that a large degree of clustering takes place. Starting with pure i-C8H18, which exhibits no scattering, the scattered intensity increases with increasing C7F16 concentration in a manner which indicates that the clusters are increasing in size. The maximum size is attained at a volume fraction of ∼0.50, at which point the clusters are made up of ∼140 C7F16 molecules. With a further increase in concentration, interaction peaks first appear in the intensity curves, indicating an approach to close packing, and then the slope of the curves begins to decrease, indicating that a phase reversal has taken place giving rise to smaller clusters of hydrocarbon in perfluorocarbon.
Paramagnetic Resonance Absorption in Neptunium Hexafluoride
Authors: Hutchison Clyde A. , Weinstock Bernard
Published: January 2005

The paramagnetic resonance absorption of crystalline NpF6 has been studied at 3 cm wavelength and at the boiling point of liquid He. The data were fitted to the spin Hamiltonian, H=βH·g·S+I·A·S. The parameters are isotropic within the errors of the measurements, with g = −0.604 and | A/hc | = 0.1100 cm−1. These results are interpreted in terms of the configuration f1 perturbed by spin-orbit coupling and an octahedral molecular potential. The relationships of the present results to optical data and measurements of magnetic susceptibility for the same substance are discussed. Hyperfine structure due to F is observed and is anisotropic.
Vibrational Relaxation in Liquids
Authors: Fixman Marshall
Published: January 2005

Attempts have been made to apply the binary collision theory of vibrational deactivation to the liquid phase. The change of collision frequency with density was approximately accounted for, but the transition probability per collision was assumed independent of density. This latter assumption is investigated here by an addition, to the direct intermolecular force, of the frictional and random forces of Brownian motion theory. It is found that the frictional force has negligible effect, but the random force makes low-energy collisions much more effective in causing transitions than is predicted for an isolated binary collision by the semiclassical theory of Zener, Landau, and Teller. As a consequence, the isolated binary collision theory cannot be applied to liquids although it should be adequate for fairly dense gases. Probably the Brownian motion theory exaggerates the neighbor effects in liquids; the point is discussed.
Theory of Light Scattering by Thin Rodlike Macromolecules in a Liquid Subjected to Shear
Authors: Okano K. , Wada E.
Published: January 2005

The light scattering by thin rodlike particles in a liquid subjected to shear is calculated on the basis of the Rayleigh-Gans treatment. The calculations are made for both unidirectional laminary flow and for flow of periodically alternating direction. The calculation is carried out by two methods: the interference factor P is expressed in terms of a power series of G/D, where G and D are the rate of shear and the rotatory diffusion constant, respectively, of the rod rotating around its minor axis. This treatment is applicable to sufficiently low G/D values. The result for a very wide range of rate of shear is obtained by using the Peterlin distribution function of particle axis. Numerical calculation shows that both results agree in a region of G/D below about two if the axial ratio is large enough. The theoretical results appear to agree with the experimental ones.
Effect of Solvent and Solute Structure on Scintillator Pulse Heights. I. Correlation of Pulse Heights for Ring Substituted Styrene Plastic Scintillators with Hammett Substituent Constants
Authors: Sandler Stanley R. , Loshaek Samuel
Published: January 2005

A group of different ring substituted styrene plastic scintillators were prepared with a constant concentration of p-terphenyl as the fluor and POPOP as the waveshifter. The effect of this variation in the structure of the polymer phase on pulse-height response to β and γ radiation was determined. It was found that correlations exist between the relative pulse height and the Hammett (δ) and Taft (δI) substituent constants for the substituted polystyrenes. Pulse heights increase with an increase in the negative value of the substituent constant, i.e., with an increase in the electron-donating power of the ring substituent on the polystyrene. It was found that markedly lower relative pulse heights were obtained for a series of styrene plastics in which the α-hydrogen in the backbone chain was substituted by a methyl group. This suggests that an α-hydrogen in the backbone chain is required for an efficient plastic solvent.
Note on the Calculation of Saturation Effects in Magnetic Resonance
Authors: Stephen M. J.
Published: January 2005

A simple method using diagrams is described for calculating saturation parameters in spin systems. Results are derived for the multiresonance case. The lattice is regarded as inducing transitions among the various spin levels and the transition probabilities are assumed known. The method is particularly useful in complicated spin systems as are found in organic free radicals. For a free radical in solution with one odd electron and N equivalent nuclei under conditions where the intramolecular electron nuclear dipole-dipole interaction and g factor anisotropy contribute to the relaxation, the dependence of the saturation parameters of the electron resonance spectrum on the nuclear quantum number mJ is given by an expression of the form AmJ2+BmJ+C. Such behavior has been found experimentally.
X-Ray Diffraction Study of Lead Sulfide-Arsenic Sulfide Glasses
Authors: Petz John I. , Kruh R. F. , Amstutz G. C.
Published: January 2005

The structures of arsenic sulfide glass, two synthetic glasses, PbS·5As2S3 and 2PbS·5As2S3, and a natural glass, 5PbS·3As2S3, have been studied by x-ray diffraction. Arsenic is found to have three sulfur neighbors in the first three glasses, just as in crystalline arsenic sulfide. The natural glass and crystalline lead sulfide are similar in that lead is situated in octahedral holes among closely packed sulfurs. The increased ratio of sulfur to arsenic in the natural glass results in four sulfur neighbors for each arsenic. The lead-sulfur distance is about 3.1 A, and that for arsenic-sulfur is about 2.3 A.
A Closed General Solution of the Probability Distribution Function for Three-Dimensional Random Walk Processes
Authors: Hsiung Chi-hua , Hsiung Hsien-chih , Gordus Adon A.
Published: January 2005

A closed general solution of the probability distribution function for three-dimensional random walk processes is derived. In addition: (1) For the particular case of equal-length displacements, the exact solution is compared with the Gaussian approximation for n=3, 5, and 10 steps. (2) The general solution is utilized in calculating the probability distribution of gamma-ray energies resulting in the Cl35 (n, γ) Cl36 process. (3) For five unequal steps of fractional length: 0.582, 0.135, 0.131, 0.092, and 0.060 (which is somewhat characteristic of the fractional energies of gamma rays resulting from neutron capture), the exact solution is compared with a Gaussian, a modified Gaussian, and a five equal-step approximation. (4) There are presented the specific solutions for all possible unequal-length random displacements involving n=2, 3, and 4 steps.
Infrared Spectrum and Thermodynamic Properties of Ruthenium Tetroxide
Authors: Ortner M. H.
Published: January 2005

The infrared spectrum of liquid ruthenium tetroxide was determined over the range 300 to 5000 cm−1. Fundamental bands were observed at 330 and 913 cm−1, and were assigned to the infrared active ν3(F2) and ν4(F2) vibrations. A combination band [ν3+ν1](F2) at 1792 cm−1 permitted an assignment of the Raman-active ν1(A1) frequency in agreement with earlier work. The final ν2(E) Raman-active fundamental was calculated by the OVFF method, and the set of observed and calculated frequencies were utilized to calculate thermodynamic functions for the ideal gas from 298.16°K to 1000°K.
Molecular Association in Alkali Halide Vapors
Authors: Datz Sheldon , Smith William T. , Taylor Ellison H.
Published: January 2005

Molecular association equilibria in alkali halide vapors were studied by measuring the temperature dependence of the molecular weights of gaseous NaCl, NaBr, NaI, KCl, KI, RbCl, and CsCl. The molecular weights were determined by measurement of the absolute pressure exerted by a known weight of completely vaporized salt contained in an isothermal fused silica bulb of known volume. The pressure sensing element was a fused silica manometer containing molten gold. The apparatus was used in the temperature range of 1175° to 1430°K and pressures of from 10 to 40 mm were measured with a precision of ±0.05 mm. The temperature dependence of the equilibrium constants for the reaction (MX)2⇌2MX yielded dissociation energies (evaluated at 1300°K) ranging from 48.0 kcal mole−1 for NaCl to 34.7 for CsCl. The entropies of dissociation were found to fall within a small range, varying from 28.3 eu for NaCl to 25.0 for KI, and a statistical calculation of the entropy changes based on an ionic model was found to agree well with the experimental values. It is shown that these systems may be adequately described with an electrostatic model, although closer attention should be paid to the nature of polarization interactions.
Temperature Dependence of the Proton Spin-Lattice Relaxation Time in Liquid Butyl Alcohols
Authors: Bernheim Robert A. , Gutowsky H. S. , Lawrenson Ian J.
Published: January 2005

The proton T1 has been measured by rf pulse methods at 20 Mc for n-butyl, iso-butyl, sec-butyl, and tert-butyl alcohol over their liquid range. The observed temperature dependences of T1 correspond to activation energies of 3.9, 4.8, 5.2, and 7.3 kcal/mole, respectively, for the n, iso, sec, and tert alcohols. The T1 results and a comparison of them with known dielectric dispersion data indicate that the spin-lattice relaxation is produced by molecular motions which are restricted by hydrogen bonding and steric effects to reorientations mainly about the C–O and C–C bonds of the heavy atom skeleton.
Determination of Relative Electronic Transition Probabilities by Impact Methods
Authors: Dorman F. H. , Morrison J. D.
Published: January 2005

The possibility of obtaining relative electronic transition probabilities from ionization efficiency data is discussed. It is claimed that measurements of relative maximum ionization cross section lack much theoretical significance. It is shown that the factors determining the detailed form of the ionization efficiency curves need to be considered, and that when this is done it should be possible to calculate relative transition probabilities from the experimental data. An illustration is given of such a calculation for several states of excited and ionized krypton and xenon.
NMR Spectra of 1,1,4,4-Tetramethylcyclohexyl-cis and trans-2,6-diacetate
Authors: Musher J. I.
Published: January 2005

The high resolution NMR spectra of 1,1,4,4-tetramethylcyclohexyl-cis and trans-2,6-diacetate have been studied and provide a series of coupling constants which are then compared with values predicted by theory. Relative chemical shifts of equatorial and axial protons are also given.
Nuclear Quadrupole Coupling in the NH3 Molecule
Authors: Kato Yoshifumi
Published: January 2005

The electric field gradient q at the position of the nitrogen nucleus in the NH3 molecule is evaluated by using four representative molecular orbitals expressed as linear combinations of atomic orbitals. The integrals over atomic orbitals are carried out by the method of Barnett and Coulson. When the electric quadrupole moment Q(N14) of the nitrogen nucleus is determined from the experimental nuclear quadrupole coupling constant eQq, all Q(N14) values obtained by us fall into the range of values already found by several authors. The most reliable computed value of Q(N14) may be 0.94×10−26 cm2, which can be obtained from the wave function including configuration interaction given by Kaplan. The polarization effect of the inner shell pointed out by Sternheimer is also evaluated by the use of Slater atomic orbitals. There is some discussion about the bond equivalent orbitals of NH3.
Vibrational Relaxation of Carbon Monoxide in the Shock Tube
Authors: Matthews D. L.
Published: January 2005

The rate of approach to vibrational equilibrium of suddenly heated CO has been studied using a shock tube and interferometer in the temperature range 2200–4900° K. Care was taken to ensure purity of the gas, so that the effect of impurities could be considered negligible. The measured relaxation times, which ranged nearly exponentially from 50 μsec at 2200° to 2 μsec at 4900°, agree fairly well with the results of Windsor et al., who covered the range 1400°—3000° using a somewhat different method. Both sets of measurements show satisfactory agreement with Landau-Teller theory as refined by Herzfeld et al. Separate experiments were performed with CO to which was added about one percent of H2, N2, O2, CO2, and H2O, one at a time. CO2 produced a slight reduction and H2O a very marked reduction in the relaxation time; the others produced no observable effect.
Diffusion of Hydrogen through Palladium
Authors: Hurlbert R. C. , Konecny J. O.
Published: January 2005

Diffusion rates F (cm3 STP/cm2 min) of hydrogen from the upstream pressure P (atm) into vacuum through a palladium sheet of thickness L (microns) are represented by logF=3.70+0.68 logP−623/T−logL,except for very thin membranes. Explanations are suggested for the wide discordance of earlier results in the study of the diffusion of hydrogen through palladium.
Vacuum Ultraviolet Photolysis of Ethane: Molecular Detachment of Hydrogen
Authors: Okabe H. , McNesby J. R.
Published: January 2005

The primary process of direct ethane photolysis by Xe radiation (1470 A and 1295 A) was studied at room temperature. The hydrogen and methane isotopic compositions from a mixture of C2H6—C2D6 and from CH3CD3 were measured mass-spectrometrically. The results show that, contrary to the previously proposed mechanism, almost all (>95%) of the hydrogen is formed intramolecularly, and preferentially from the same carbon atom. Methane is also formed by a molecular process. Then the primary processes may be written as C2H6→CH3CH+H2C2H6→C2H4+H2C2H6→CH4+CH2.The absence of C2D6 in the products of the photolysis of CH3CD3 places an upper limit on [open phi]CD3/[open phi]CD3H+CH3D of about unity assuming all methyl radicals form ethane by recombination. The effect of the product ethylene on the composition of hydrogen isotopes from C2H6—C2D6 mixtures was examined, since any atomic hydrogen produced may be reacting rapidly with ethylene. The sample was purified and very low conversion (0.01%) was made. The result shows almost no change in the composition of the hydrogen isotopes in the products, indicating that the hydrogen forming step is largely molecular. It is suggested that higher hydrocarbons may be produced by the following reactions CH2+C2H6→C3H8CH3CH+C2H6→C4H10.
Microwave Spectrum of Isobutylene. Dipole Moment, Internal Barrier, Equilibrium Conformation, and Structure
Authors: Laurie Victor W.
Published: January 2005

The microwave spectra of isobutylene and isobutylene-d-3 have been studied in the region 17–36 kMc. Observed rotational constants (Mc) for isobutylene are a0=9133.32, b0=8381.75, c0=4615.99; for sym-isobutylene-d-3, a0=9132.59, b0=7788.98, c0=4431.05; for asym-isobutylene-d-3, a0=8819.46, b0=7981.08, c0=4469.59. The most likely structure compatible with these data is rc–c=1.507 A, rc=c=1.34 A, rCH(methyl)=1.085 A, rCH(ethylenic)=1.086 A, <Me—C—Me=115.9°, <HCH(methyl)=108°, <HCH(ethylenic)=117.5°. Measurements of the Stark effect show that the dipole moment μ=0.503±0.009 D. Fine structure leads to a barrier height hindering internal rotation of the methyl groups of 2.21 kcal/mole. The equilibrium conformation is C2v with two methyl hydrogens in the plane of the carbon atoms and the CH bonds pointing away from the symmetry axis. It is concluded that although CC single bonds are shortened when adjacent to a double bond, the double bond length is probably not much affected by the presence of an adjacent CH3 group.
Statistical Mechanics of Monatomic Systems in an External Periodic Potential Field. I. Introduction, Virial Expansion, and Classical Second Virial Coefficient
Authors: Hill Terrell L. , Greenschlag Samuel
Published: January 2005

In the first section a general research program is outlined which is concerned with the behavior of an equilibrium macroscopic system (gas, liquid, or solid) of monatomic molecules in an external periodic potential field. The problems of particular interest are: condensation theory; crystalline state and theory of fusion; ideal degenerate gases; distribution functions; virial expansion for a gas; and the very dilute gas. In the second section the virial expansion is discussed and the classical second virial coefficient for an adsorbed monolayer on a crystal surface is calculated as an illustration. This computation is compared with results obtained from the two conventional cases which are limiting forms of the present treatment: mobile and localized adsorption. The differences are considerable.
Difference of Intermolecular Potentials of CH3OH and CH3OD
Authors: Whalley E. , Falk M.
Published: January 2005

The intermolecular potentials of CH3OH and CH3OD have been examined using the difference of the heats of vaporization at 0°K obtained from thermal data, and the vibrational frequencies obtained from the preceding paper. They do not differ within the accuracy of the measurements. The intermolecular potential due to the change of the intramolecular zero-point energy is greater for CH3OH than for CH3OD, and so the other contributions to the intermolecular potential, viz., repulsive, dispersion, electrostatic, etc., energies, are greater by 459±∼260 joule mole−1 for the deuterium bond than for the hydrogen bond. This might be due mainly to a higher polarity of CH3OD than of CH3OH.
Second-Order Effects in Low-Field NMR for Ammonium Ion Solutions
Authors: Brown Robert J. S. , Thompson Don D.
Published: January 2005

Low-field free-precession signals from aqueous ammonium nitrate solutions show a complex beat pattern containing the 52.55 cps first-order spin-spin splitting observed at high fields and also a 1.35 cps second-order splitting when the proton precession frequency is 2137 cps. The T1 is slightly longer for the ammonium hydrogen than for the water hydrogen; T2 is shorter than T1 for the ammonium hydrogen and is shorter for the outer lines than for the central line.
Spin-Lattice Relaxation Time of F19 Nuclei in Ag2F
Authors: Choi Q. Won , Clark W. Gilbert
Published: January 2005

The spin-lattice relaxation time of F19 nuclei in Ag2F crystals has been measured at several temperatures. From the inverse proportionality constant of the relaxation time with respect to temperature in conjunction with the Korringa's theory, it is concluded that the relatively large paramagnetic shift observed is not due to the second-order paramagnetism but to the hyperfine interaction between conduction electrons and F19 nuclei.
Mass Spectrometer Investigation of Ionization of N2O by Electron Impact
Authors: Curran R. K. , Fox R. E.
Published: January 2005

The N2O molecule has been studied with a nearly monoenergetic electron beam. A result of the positive ion data is a value for D(N2–O) ≤ 1.34±0.2 ev and a value of D(N–NO) ≤ 4.50+0.10 ev. Measurements were made of the kinetic energies of the ions formed. N+ and N2+ are found to have zero kinetic energy at threshold. The production of an O− ion is observed with an appearance potential in the range 0 to 0.05 ev.
Proton Resonance Shifts in Alkali Halide Solutions
Authors: Fabricand Burton P. , Goldberg Sigmund
Published: January 2005

Proton magnetic resonance shifts in alkali halide solutions with respect to distilled water have been measured as a function of ionic charge, radius, and concentration. The shifts are linear with concentration up to a certain concentration depending on the salt. In this linear range, the shifts due to each ion are independent of one another and can be obtained by arbitrarily assuming the shift of the chloride ion to be zero. The ionic shifts so obtained are linear with the ionic crystal radius for anions and cations at a given salt concentration. Results are presented showing that the time-averaged packing of the ions is closer than if they were arranged on a cubic lattice and that the ionic effects on the proton shielding do not extend past nearest-neighbor water molecules.
Extraordinary Basic Functions in Valence Theory
Authors: Snyder Lawrence C. , Parr Robert G.
Published: January 2005

It is pointed out that, provided kinetic energies are properly computed, one may use functions which are continuous with piecewise continuous first derivatives as trial variation functions in quantum-mechanical calculations of molecular electronic wave functions. As a simple example, a function of the type A exp[−(Z<r<+Z>r>)]is shown to be a good alternative to the conventional Eckart function for the helium atom. A rather more detailed study of helium is carried out to illustrate the use of individual lobes of real hydrogenlike atomic orbitals as an extended basic set of functions for molecular calculations. Implications for the general problem of correlation energies in atoms and molecules are discussed, and it is shown that a rationalization of the lowered electronic repulsions employed in modern pi-electron theory is provided by the supposition that pi electrons tend to move in opposite rather than the same lobes of pi orbitals.
Isotropic and Anisotropic Hyperfine Interactions in Hydrazyl and Carbazyl
Authors: Lord N. W. , Blinder S. M.
Published: January 2005

This paper describes a detailed experimental and theoretical study of the hyperfine structure of diphenylpicrylhydrazyl (hydrazyl) and picrylaminocarbazyl (carbazyl). Both isotropic and anisotropic hyperfine interactions involving the α and β nitrogen atoms are considered. Experimentally, electron spin resonance spectra are observed for dilute solutions of each radical in both fluid and solid media. Concentrations of the order of 0.001 M are employed so as to minimize dipolar and exchange interactions among radicals. The fluid spectra yield, in straightforward fashion, the absolute values of the isotropic coupling constants | A1 | and | A2 |. These splitting parameters are chosen such that a synthesized line shape composed of Gaussians gives optimal reproduction of the observed resonance profile. For the solid solutions, Duco cement (with hydrazyl) and Lucite (with carbazyl) provide glassy trapping matrices. It is assumed that the radicals are frozen in an ensemble of random orientations in these solids. Appropriate theoretical line shapes, considering interactions with two magnetic nuclei, are derived, and values assigned to the anisotropic parameters B1 and B2 from comparison of experimental and theoretical resonance patterns. The isotropic constants are assumed to be unchanged in the transition from liquid to solid solution. It is found moreover that the inherent Gaussian half-width σ is approximately the same in both states. The parameters assigned through our analysis are Hydrazyl—A1=9.35±0.20 gauss; A2=7.85±0.20 gauss; B1=6.6±0.5 gauss; B2=5.8±0.5 gauss; σ=3.36±0.20 gauss. Carbazyl—A1=10.2±0.5 gauss; A2=5.8±0.5 gauss; B1=7.7±1.0 gauss; B2=4.1±1.0 gauss; σ=3.4±0.5 gauss. Resonance of the hydrazyl-Duco solution during incipient solidification was also observed. In this intermediate medium the anisotropic hyperfine interactions are only partially averaged out by molecular motions. It was found possible to characterize the rigidity of the medium by a parameter λ (0≤λ≤1) such that each anisotropic parameter is exhibited in the spectrum as if it were λ times its full value. Various implications of our results on the structure of hydrazyl and carbazyl are considered. One conclusion drawn is that both radicals are largely planar in configuration.
Radiolysis of Cyclohexane. III. Vapor Phase
Authors: Ramaradhya J. M. , Freeman G. R.
Published: January 2005

The radiolysis of cyclohexane vapor by Po210 α particles was investigated. The Po210 source was calibrated by ferrous-sulfate dosimetry, using G(Fe+++)=5.5. The product yields were studied as a function of dose. The initial yield for hydrogen was G(H2)i=8.0. The fraction volatile at −112°C, consisting of C2, C3, and C4 hydrocarbons, had an initial G value of 4.9±0.5. The poor agreement in material balance is tentatively ascribed to ion-molecule reactions, since ions formed during radiolysis have a life-time of the order of 10−3 sec. The value of the ratio G(cyclohexene)/(dicyclohexyl)=1.67 is similar to that found in liquid cyclohexane radiolysis. The G values for various types of cyclohexane fragmentation are also given.
Infrared Optical Constants of NaCl
Authors: Neuberger Jacob , Hatcher Robert D.
Published: January 2005

The infrared optical constants of NaCl are calculated by applying an extended form of the Born and Blackman anharmonic potential theory to the Kellerman model of the NaCl crystal. A damping factor is derived which depends on the amplitudes and frequencies of the characteristic modes as well as on the frequency of the incident radiation. By a numerical sampling of wave vector space, this damping factor and the resultant optical constants are calculated in the range 25μ—500μ. The theory predicts a subsidiary absorption maximum near 100μ which agrees with recent experimental measurements. The frequency distribution function of NaCl is also given here.
Delineation of the Problem of Soret Diffusion
Authors: Oriani R. A.
Published: January 2005

The phenomenological heat of transport is analyzed for the simple cases of self-diffusion via a vacancy mechanism and of diffusion of solutes in interstitial solid solutions. The heat of transport is shown to be equal to the sum of an energy-conversion term and an energy-transport term. The latter is a function of the details of the mechanism and is of kinetic character; a positive contribution is made to it by the localized normal modes about a solute atom. The energy-conversion term has a thermodynamic character once the diffusion mechanism is specified, and by its use one can decompose energies of solution or of vaporization into a part associated with the solute atom and another part associated with the solvent lattice.
Study of the N2O Molecule Using Electron Beams
Authors: Schulz G. J.
Published: January 2005

Inelastic processes and negative ion formation in N2O are measured using the trapped-electron method and conventional techniques, respectively. A large inelastic process is observed at 2.2 ev and is interpreted as the formation of vibrationally excited N2O via the formation of a temporary negative ion state. Negative ions O− are observed beginning at zero ev with peaks of the negative ion current occurring at 0.7 and 2.2 ev. The latter peak is attributed to the formation of the temporary negative ion with subsequent decay into a stable O− plus N2 in various states of vibrational excitation. Measurements of the kinetic energy of the negative ions confirm this hypothesis. A value of the dissociation energy of the N2–O bond in N2O is found from the appearance potential of O− extrapolated to zero kinetic energy. This value, D (N2–O) = 1.2±0.2 ev, agrees within experimental error with the value of 1.3±0.2 found independently by Curran and Fox, but disagrees with the thermochemical value of 1.66 ev.
Theoretical Investigations on the Light Scattering of Colloidal Spheres. XII. The Determination of Size Distribution Curves from Turbidity Spectra
Authors: Wallach Morton L. , Heller Wilfried , Stevenson Arthur F.
Published: January 2005

The theory of a method is outlined which gives size distribution curves in heterodisperse systems of non-absorbing colloidal and small microscopic spheres from measurements of turbidity spectra. The assumption is made that the distribution follows a function previously given which closely approximates that commonly found in emulsions. All the numerical data necessary for practical application of the method are provided for the relative refractive indices m=1.05 (0.05) 1.30. They were obtained from the Mie theory. The method may be used independently, but is particularly useful in conjunction with an alternate method described in a previous publication (XI).
NMR Measurement of Gas Compressibility
Authors: Lipsicas M. , Bloom M. , Muller B. H.
Published: January 2005

The nuclear magnetic resonance technique has been applied to measurement of the compressibility factors of gases. Some results are given for CH4 and compared with data available in the literature.
High Frequency Factors in Unimolecular Reactions
Authors: Steel Colin , Laidler Keith J.
Published: January 2005

High frequency factors are associated with two main classes of unimolecular reactions: (1) reactions in which two bonds are ruptured simultaneously, and (2) certain dissociation reactions in which only one bond is broken, such as the decomposition of ethane into two methyl radicals. These high values are related to the entropy increases occurring during the rupture of the bond or bonds, and a discussion is given of the way in which the entropy may change during the process. For the reactions of type (2) the data are consistent with the view that the entropy change occurs well before the bond is completely ruptured. For reactions of both types the rates at low pressures (i.e., the rates of energization) are probably not affected by such entropy increases, so that the pressures at which transition occurs from first to second order will be abnormally high for such reactions; this point of view is supported by detailed calculations for five reactions. The entropy changes during the course of reaction are interpreted as being due to a ``softening'' of molecular vibrations in the activated state.
Emission of Vacuum Ultraviolet Radiation from the Acetylene-Oxygen and the Methane-Oxygen Reactions in Shock Waves
Authors: Kistiakowsky G. B. , Richards L. Willard
Published: January 2005

The C2H2–O2 and CH4–O2 reactions were studied by observing the emission of vacuum ultraviolet radiation from shock waves in gas mixtures containing 85 to 99% Ar and with 2×10−6≤[O2]≤60×10−6 moles/l. In both reactions after an induction period of length ti, the emission intensity rises exponentially with a time constant τ and then decreases about as rapidly. For the C2H2–O2 reaction, emission predominantly in the wavelength range 1500<λ<1700 A was observed. It was estimated that one photon was emitted in this range per 3×104 C2H2 molecules passing through the reaction zone at 1840°K. The integrated emission intensity depends on the temperature as if the process producing it has an activation energy of 15 kcal/mole. In the range of conditions 0.65≤[O2]/[C2H2]≤3.6 and 1300≤T≤2200°K it was found that log10([O2]ti)  (mole  sec/l)=−10.57+17 100/4.58T. The data for τ from mixtures with 0.65≤[O2]/[C2H2]≤7.7 fit the expression log10([O2]τ)  (mole  sec/l)=−11.48+17 100/4.58T with a standard deviation of a factor of 1.4 in τ. In the first approximation the values of [O2]ti and [O2]τ are functions of temperature only. In lean mixtures, however, [O2]τ and especially [O2]ti are larger than the average. These results are explained in terms of a branching chain mechanism in which the reaction H+O2=OH+O plays the dominant role in controlling the rate.

The CH4–O2 reaction was studied in the range of conditions 0.5≤[O2]/[CH4]≤4.5 and 1800≤T≤2700°K. The emission intensities are an order of magnitude smaller and more strongly temperature dependent, τ is a factor of 2 or 3 larger, and ti is a factor of 20 larger at the low temperatures and a factor of 4 larger at the high temperatures than for the C2H2–O2 reaction. The kinetic implications of these findings are discussed.