bluuebunny/crossref_metadata_2025 huggingface dataset:
Transport Properties of Gases Obeying a Modified Buckingham (Exp-Six) Potential
Authors: Mason Edward A.
Published: April 2005

A large number of the Chapman and Cowling collision integrals have been calculated for gases obeying a modified Buckingham potential, [open phi](r)=ε1−6/α[6αeα(1−r/rm)−(rmr)6].The results are tabulated over a large temperature range, kT / ε from 0 to 200, and for four values of the parameter α, 12, 13, 14, and 15. The treatment was entirely classical, and no corrections for quantum effects were made. The results should be applicable to most simple, nonpolar gases, and may be used to obtain information about intermolecular forces from the observed temperature dependence of gaseous transport properties.

The second approximation to the thermal diffusion ratio and the third approximation to the coefficient of ordinary diffusion have been derived according to the method of Chapman and Cowling.

Evaluation of the potential parameters for specific substances and applications of the results will be published later.
The Electrical Conductivity of Supercritical Solutions of Sodium Chloride and Water
Authors: Fogo James K. , Benson Sidney W. , Copeland Charles S.
Published: April 2005

A description is given of the method used to measure the electrical conductivity of NaCl in steam at steam densities between 0.2 and 0.4 g/cc. Values of the specific and equivalent conductances are tabulated at 378, 383, 388, and 393°C for various NaCl concentrations at different steam densities. Sodium chloride behaves as a weak electrolyte at all steam densities used. Estimates of the ion-pair dissociation constant K, based on Shedlovsky's method, indicate that K decreases from about 9×10—3 to 6×10—7 as the steam density decreases from 0.4 to 0.2 g/cc. Preliminary results for cesium chloride and hydrogen chloride in steam indicate that cesium chloride is comparable in strength with sodium chloride, but that hydrogen chloride is a much weaker electrolyte.
Theory of Linear Flame Propagation. Part I. Existence, Uniqueness, and Stability of the Steady State
Authors: Layzer David
Published: April 2005

It is shown that the equations governing the steady, adiabatic, one-dimensional propagation of single-reaction flames admit an infinity of solutions, only one of which, however, can be realized physically. The steady state is shown to be stable against small perturbations, and the possibility of reconciling this result with apparently contradictory experimental data is discussed.
Theory of Linear Flame Propagation. Part II. Structure of the Steady State
Authors: Layzer David
Published: April 2005

A quantitative approximate theory of flame structure in the steady state, including formulas for the determination of flame speeds, is set forth. The theory predicts that in a first approximation, the sensitivity of a steady deflagration wave to external perturbations depends upon the shape of the temperature profile, but not upon the speed or width of the wave, or the pressure. It is shown that the sensitivity increases with increasing dilution of the explosive mixture, in agreement with the explanation of inflammability limits suggested in Part I.
The Thermodynamic Properties of Gaseous Titanium
Authors: Kolsky Harwood G. , Gilles Paul W.
Published: April 2005

Tables of the thermodynamics properties of titanium considered as an ideal monatomic gas were calculated using the Los Alamos Scientific Laboratory IBM 701 Computer for a temperature range 0 to 8000°K.
Critique of a Method of Treating the Effect of Excluded Volume in Polymer Chains
Authors: Rubin Robert J.
Published: April 2005

The nature of an implicit assumption in a recent Fokker-Planck treatment of the excluded volume problem is indicated. This assumption makes the results of the treatment conditional. It is shown that if one can verify the assumption, one can dispense with the use of a Fokker-Planck equation.
Examination of Methods for Detecting OH
Authors: Sanders T. M. , Schawlow A. L. , Dousmanis G. C. , Townes C. H.
Published: April 2005

The microwave spectrum of OH affords a new method of determining the abundance of OH in a low-pressure gas mixture. This method applied to the products of a discharge in H2O shows that certain previous methods for detecting the presence of OH radicals in fact are not sensitive to OH, but to some other reactive components of a discharge in H2O. OH radicals are obtained from a discharge in concentrations near 10 percent and with a lifetime of approximately 13 sec.
Adsorption Studies on Clay Minerals. IV. The System Montmorillonite-Cesium-Potassium
Authors: Faucher Joseph A. , Thomas Henry C.
Published: April 2005

The ion-exchange equilibria between a montmorillonite clay and potassium-cesium from chloride solutions have been studied by chromatographic and other methods. The results are summarized in terms of equilibrium constants and activity coefficients for the mixed clay phase. A tentative discussion is given of the rate of the exchange process, particularly as it affects the behavior of the chromatographic columns.
The Microwave Spectra, Structure, and Dipole Moment of Stable Pentaborane
Authors: Hrostowski Henry J. , Myers Rollie J.
Published: April 2005

The microwave spectra of several of the naturally occuring boron isotopic species of B5H9 and B5D9 have been observed. These data show that stable pentaborane consists of a tetragonal pyramid of boron atoms and has either C4 or C4v symmetry. The boron-boron distances are B1–B2=1.687±0.005 and B2–B2=1.800±0.003A. If C4v symmetry and B1–H1 and B2–H2 distances equal to 1.22A are assumed, the following boron-hydrogen parameters are obtained: B2–H3=1.35±0.02A, ∠B1–B2–H2=136°10′±30′ and ∠B1B2B2–B2B2H3=196±2°. Dipole moment values of 2.13±0.04 and 2.16±0.04 Debye units were measured for B5H9 and B5D9, respectively.
The Infrared and Raman Spectra of Formaldehyde-d1 Vapor
Authors: Davidson D. W. , Stoicheff B. P. , Bernstein H. J.
Published: April 2005

The infrared spectrum of HDCO vapor has been investigated in the region 2.5μ—25μ and all six fundamentals have been observed. Four of the fundamentals have also been observed in the Raman spectrum of the vapor.

The perpendicular component of an hybrid band at 3.5μ and the pure rotational Raman spectrum were resolved and analyzed. The rotational constant (A—B̄) for the symmetric top approximation was found to be 5.47±0.03 cm-1. This value, combined with the rotational constants of H2CO obtained by Dieke and Kistiakowsky, yields approximate molecular dimensions for the ground state of formaldehyde.
The Infrared Spectrum and Molecular Constants of DBr
Authors: Keller Fred L. , Nielsen Alvin H.
Published: April 2005

High-dispersion measurements have been made for the first time on the fundamental, first overtone, and second overtone infrared vibrational bands of DBr. Path lengths from 40 cm to 17 m were used with pressures ranging from 90 mm to 460 mm. The isotopic splitting of the rotation lines was measured and molecular constants determined for both isotopic species, DBr79 and DBr81. The principal constants for DBr79 are ωe=1885.33 K,xeωe=22.73 K,yeωe=−0.0106 K,Be=4.2908 K,αe=0.0839 K,De=9.64×10−5 K,β=−2·2×10−6 K. The principal constants for DBr81 are ωe=1884.75 K,xeωe=22.72 K,yeωe=−0.0106 K,Be=4.2876 K,αe=0.0838 K,De=9.59×10−5 K,β=−2·2×10−6 K .
The Vibrational Spectrum and the Specific Heat of Germanium and Silicon
Authors: Hsieh Yü-Chang
Published: April 2005

The vibrational spectra of Ge and Si have been constructed by computation of 174 characteristic frequencies in 29 directions by Born's lattice theory as elaborated by Smith. Two approximations have been considered, involving (a) the interaction between each atom and its first neighbors only, and (b) the interaction between the atom and its first neighbors, and the central force interaction between the atom and its second neighbors. The specific heats of Ge and of Si at low temperatures are calculated from the spectra. The theory indicates a minimum of the Debye characteristic temperature in qualitative agreement with the experiments, but fails to give quantitative agreement.
Diffusion Effects in the Photochemistry of Solid Films
Authors: Wilson Joseph E.
Published: April 2005

Little work has been done, either experimentally or theoretically, on the problem of photochemical reaction kinetics in the solid phase, although this field is of practical importance in connection with the weathering of polymeric films and sheets. Reaction kinetics in solid films are greatly influenced by diffusion phenomena. The Laplace transformation technique offers a convenient method of solving many problems concerning the interaction of diffusion behavior with reaction kinetics. The method is illustrated for the diffusion of a gaseous product from an irradiated film, with and without reaction rate dependence on product concentration, and for the diffusion of a gaseous reactant into an irradiated film, with and without reaction rate dependence on reactant concentration. In each case the expression for dissolved gas concentration across the thickness of the film is computed, and the quantum yield for the reaction involved is expressed as a function of film thickness, diffusion coefficient, rate of light absorption, and initial conditions. Equations for the effect of temperature variation and of intermittent light are derived in a few instances.
Magnetic Susceptibilities of Np+6, Np+5, and Np+4
Authors: Gruen Dieter M. , Hutchison Clyde A.
Published: April 2005

The magnetic susceptibilities of NaNpO2(CH3COO)2, NpO2C2O4H·H2O, and KNpF5 have been measured from 14°K to 320°K. The magnetic susceptibilities of the ions Np+6, Np+5, and Np+4 have been compared with those calculated for ions in electronic states of f-electron configurations in the presence of electric fields of specific forms and with various amounts of spin-orbit coupling.
Theory of Ignition Considered as a Thermal Reaction
Authors: Hicks Bruce L.
Published: April 2005

The history of a family of exothermally reactive solids is studied theoretically with the help of analytical and numerical calculations. The different members of this family of nonisothermal solids are obtained, by changing scales and values of parameters, from the basic model which describes a zero-order reaction of a semi-infinite slab of material subjected at its surface to heat transfer from a gas.

For low initial temperatures of the solid, the heat transfer rate determines the ignition time while for high initial temperatures, this heating parameter is less important than the initial temperature, which controls the adiabatic ignition time. For the model used, the ignition time is generally quite sensitive to the duration of the external heating. Within the solid, it is found that the inner boundary of the region in which the chemical heat production is negligible moves inward along a diffusional type of path x ∝ t½ but that the point of maximum temperature, which develops after interruption of the external heating, follows a much different path. An analytical, approximate method of estimating minimum ignition time was tested by making comparison with numerical integrations and is probably accurate to 25 percent in the ignition time.

The computational side of the theory presented here may be regarded as essentially complete for practical purposes until greater accuracy and detail are required by more critical applications than are now in prospect. Meaningful utilization of the computations in practical applications will not however be possible until reliable measurements have been made of certain of the parameters for the solid—namely, activation energy, frequency factor and thermal conductivity—and for the external heating— namely, gas temperature and heat transfer coefficient.

In the course of the computations, many mathematical questions arose which are fundamental to the investigation of this and more realistic models of ignition but which remain to be answered.
The Yield of Oxidation of Ferrous Sulfate in Acid Solution by High-Energy Cathode Rays
Authors: Saldick Jerome , Allen Augustine O.
Published: April 2005

An absolute determination of the yield of the ferrous sulfate radiation dosimeter has been made by delivering to the solution a measured charge of cathode rays at known energies of 1 or 2 Mev. Appropriate small corrections have been made for backscattering, window absorption and, bremsstrahlung. The result, G = 15.6±0.5, is in complete agreement with Hochanadel's calorimetric determination of the yield, but disagrees by 30 percent with the most widely used value obtained by cavity ion chamber comparison.
Rotation in Solid Mixtures of Neohexane and Cyclopentane from 20°K to Their Melting Points
Authors: Aston J. G. , Bolger Bouwe , Trambarulo Ralph , Segall H.
Published: April 2005

Studies of the broadening of the proton spin resonance line have been made for solid solutions of neohexane and cyclopentane.

A convenient apparatus for control of temperatures from 10°K to room temperature for such studies is described.

The ``complex'' of one mole of neohexane with two moles of cyclopentane rotates in the solid state down to 65°K. In solid solutions with cyclopentane in excess of the complex, the complex rotates independently of the cyclopentane down to 66°K. The complex has no effect on the lower rotational transition of the cyclopentane which apparently nucleates.
A Quantum-Mechanical Calculation of the Surface Energy of Crystalline Lithium Fluoride
Authors: van der Hoff B. M. E. , Benson G. C.
Published: April 2005

A quantum-mechanical model for calculating the surface energy of a LiF crystal is described. This work is an extension of previous papers on the energies of the LiF crystal and molecule. A simple form of distortion is permitted in the surface region. The value of the surface energy of a {100} face obtained from these computations is 557-erg cm—2 at 0°K and is appreciably higher than results based on classical considerations.
Nuclear Quadrupole Couplings in Solid Bromides and Iodides
Authors: Robinson Hugh , Dehmelt H. G. , Gordy Walter
Published: April 2005

From measurements of pure nuclear quadrupole transitions at 77°K the following coupling constants (in Mc/sec) and asymmetry parameters have been obtained: for I127|eQq| = 1765.846, ε2=0.00078 in CH3I; |eQq| = 1897.368, ε2=0.00736 in CH2I2; |eQq| = 2046.634, ε2=0.00033 in CHI3·3S8; |eQq| = 2130.33 for CI4; |eQq| = 2069.17 for CF3I; |eQq| = 1324.788 and 1333.313, ε2=0.000082 and ≤0.000010 for the two nonequivalent I's in unit cell of SiI4; |eQq| = 1484.339 and 1500.577, ε2=0.000087 and ≤0.000005 for the two nonequivalent I's in unit cell of GeI4; |eQq| = 1384.424 and 1394.190, ε2=0.000085 and ≤0.000016 for the two nonequivalent I's in unit cell of SnI4; |eQq| = 1517.07, ε2=0.00008 in AsI3·3S8; |eQq| = 1226.35, ε2=0.00101 in SbI3·3S8. The coupling values of Br are: |eQq(Br79)| = 437.27 and 441.15; |eQq(Br81)| = 365.272 and 368.514 for the two nonequivalent Br's in unit cell of PBr3 (T = 87±4°K); |eQq(Br79)| = 329.000 and 345.920; |eQq(Br81)| = 274.856 and 288.980 for the two nonequivalent Br's in unit cell of SbBr3. From these coupling values the number of unbalanced p electrons in the atoms was calculated. The latter quantity was found to be closely related to chemical bond properties such as ionic character, and was found to vary systematically with chemical constitution. A cross bonding mechanism involving d orbitals is proposed to account for the iodine coupling in certain solids.
The Microwave Spectrum of Vinyl Cyanide
Authors: Wilcox W. S. , Goldstein J. H. , Simmons J. W.
Published: April 2005

The rotational spectrum of the slightly asymmetric top, vinyl cyanide, has been investigated in a microwave spectrograph employing Stark effect modulation and in a direct absorption cell. The rotational constants a = 49 076.2 Mc/sec, b = 4971.33, and c = 4514.05 were computed from the observed frequencies of the J = 2→3 transitions. From measurements of the Stark effect, the components of the dipole moment were found to be μa = 3.68D, μb = 1.25, μ = 3.89. Partial resolution of the hyperfine structure of certain lines gave the value —3.0 Mc/sec for the ξaa component of quadrupole coupling.
The Infrared Spectra of Monochlorogermane and Monochlorogermane-d3
Authors: Lord R. C. , Steese C. M.
Published: April 2005

Infrared absorption spectra of GeH3Cl and GeD3Cl have been observed and the fundamentals located at 2121.2, 847.7, 422.6 cm—1 (parallel) and 2129.4, 874.6, 604.1 cm—1 (perpendicular) in GeH3Cl, and at 1522, 614, 421 cm—1 (parallel) and 1530, 630, 434 cm—1 (perpendicular) in GeD3Cl. Analysis of the rotational structure of the perpendicular bands in GeH3Cl leads to these values of the rotational constants: A″, 2.603 cm—1; ζ4, —0.059; ζ5, —0.124; ζ6, +0.209. Agreement with microwave A″ is satisfactory. Thermodynamic quantities are computed for GeH3Cl and GeD3Cl.
The Rate Constant of the Reaction between Hydrogen Peroxide and Ferrous Ions
Authors: Rigg Tyson , Taylor William , Weiss Joseph
Published: April 2005

The rate constant of the reaction between hydrogen peroxide and ferrous ions has been measured in sulfuric acid solutions, by direct spectrophotometric observations of the ferric salt produced at λ=304 mμ. It has been confirmed that the rate is independent of acidity (measurements were carried out from 0.05 N to 0.8 N H2SO4) and that the reaction is bimolecular within a wide range of the concentrations of the reactants; the hydrogen peroxide concentration was varied in the ratio 1:25 and the ferrous sulfate in the ratio 1:20. The rate constant, which has been measured within the temperature range of 15° to 40°C, can be represented by the equation k1=1.05×108×exp(−8460/RT)1 moles−1sec−1.
The Dielectric Properties of Some Long-Chain Fatty Acids and Their Methyl Esters in the Microwave Region
Authors: Buchanan T. J.
Published: April 2005

Measurements were made of the dielectric constant and loss of stearic, palmitic, and some other acids in the solid and liquid states between wavelengths of 1 and 50 cm. The loss was small in the solid state, and there was no absorption peak in the wavelength range covered; in the liquid state the loss was greater with evidence of a small absorption peak near 3 cm. The methyl esters show an absorption peak in the microwave region in both the solid and liquid states. The measurements on the liquid methyl esters indicate that resonance absorption is occurring at a frequency of about 6000 Mc/sec. Some ethyl esters were measured and were found to show a relaxation loss in the microwave region of the same order as the relaxation loss of the methyl esters but they showed no sign of resonance absorption loss. An attempt is made to explain both the relaxation loss and the resonance loss on the basis of a model which has already been used by Hoffman and Smyth.
The Onsager Thermodynamics of Galvanic Cells with Liquid-Liquid Junctions
Authors: Bearman Richard J.
Published: April 2005

The general theory of galvanic cells with liquid-liquid junctions, including gravitational effects, is discussed by means of the Onsager thermodynamics of irreversible processes.
Exchange Energy of Electrons in Metals and Ionic Crystals
Authors: Reitz John R.
Published: April 2005

The exchange energy of valence electrons in both monatomic and diatomic crystals is computed in the Bloch approximation for the case where the lowest electronic wave function in the band shows considerable spatial variation. Only ground-state wave functions which are spherically symmetric in each atomic cell are considered, but within this limitation two types of spatial variation are considered: radial variation in the unit cell, and the variation in a diatomic lattice due to the wave function being more concentrated on one of the atomic species than on the other. The results of the calculation show that, for a monatomic solid, deviations from uniformity in the wave function have a relatively small effect on the exchange energy; in highly ionic diatomic solids, however, the exchange energy may be increased up to 50 percent in magnitude over the free-electron value as a result of the electron density in anion cells being different from that of cation cells.
The Far Ultraviolet Absorption Spectra of the Isomeric Butenes
Authors: Gary Julia T. , Pickett Lucy W.
Published: April 2005

Measurements of the intensity and position of absorption from 45 000 to 64 000 cm—1 of butene-1, cis-butene-2, trans-butene-2, and 2-methylpropene were made on flowing vapors. All show a broad intense band which is most intense in the case of the cis-isomer, and superimposed systems of narrow bands, both at shorter and longer wavelengths. Whereas the position of the last named is dependent on the number of alkyl groups adjacent to the double bond, the broad band maximum is not similarly displaced but rather depends on the molecular shape and seems related to the dipole moment vector. The vibrational structure of the bands is consistent with infrared and Raman data.
Network Theory of the Gel Point and the ``Incestuous'' Polymerization of Diallyl Phthalate
Authors: Gordon Manfred
Published: April 2005

The status of the gel point equation, advanced by Flory, Stockmayer, and Walling for polyfunctional reactions, is briefly discussed. Two complicating factors in the chain polymerization of divinyl compounds, to which this equation has been applied, are reviewed: the admixture of a monovinyl compound of comparable reactivity, and the ``incestuous'' tendency for the two double bonds in a divinyl compound to enter the same polymerization chain. Contrary to the treatment by Simpson and co-workers, these two factors are found to demand different theoretical approaches. The progress of polymerization enriches the monomer mixture in the monovinyl compound, while the incestuous tendency remains constant. Kinetic derivations are given for the gel point condition in both cases. The gel point in the ``incestuous'' polymerization of diallyl phthalate is calculated to lie at conversions 40 percent higher than estimated by Simpson and co-workers, and much better agreement is thus achieved with their experimental measurements.

A simple network theory suffices to predict the gel point in two chain polymerization reactions. Substantial delays of the gel point, predicted by Walling's theory of diffusion control in such reactions, are not encountered.
The Crystal and Molecular Structure of B5H11
Authors: Lavine Louis R. , Lipscomb William N.
Published: April 2005

The molecular structure of B5H11 has been determined from 299 x-ray diffraction maxima which have been analyzed by three-dimensional Fourier and least-squares methods. There are four molecules in a monoclinic unit cell, in the space group P21/n, having parameters a=6.76, b=8.51, c=10.14A, and β=94.3°.

Although no molecular symmetry is demanded by the space group, the molecular dimensions indicate C8 symmetry for the isolated molecule. The boron skeleton is a fragment of the icosahedronlike arrangement in B10H14, and can also be derived from the tetragonal pyramid in B5H9 by opening up one of the basal B–B bonds. The apex boron BI is ``singly'' bonded to two hydrogens, one of which HVII, is very weakly bonded to the two outer borons BIII. Each BIII is ``singly'' bonded to two hydrogen atoms. Each of the remaining two borons BII is ``singly bonded'' to one hydrogen atom, and there are three bridge hydrogens, one bridging the BII–BII bond and two bridging the BII–BIII bonds. Molecular parameters are two BI–BIII=1.865, two BII–BIII=1.75, two BI–BII=1.72, one BII–BII=1.77A, seven B–H=1.07, six B–H (bridge) =1.24A, one BI–HVII=1.00 and two BIII–HVII=1.67A. The BIII–BI–BIII angle is 107°. Bond angles to hydrogen strongly resemble those in the other known boron hydrides.
Electron Affinity of Fluorine
Authors: Margrave John L.
Published: April 2005

Various theoretical and semi-empirical methods for determining electron affinities of atoms have been applied to fluorine. All results indicate a low value of the electron affinity consistent with recent experimental data, and with the value implied by the recently determined dissociation energy of the fluorine molecule. An extrapolation of the type suggested by Hellmann and Mamotenko appears to give the most reliable value and indicates EF=83.2±0.3 kcal/mole.
Further Studies on the Reaction of Cyclopentane with Mercury-6(3P1) Atoms
Authors: Beck P. W. , Kniebes D. V. , Gunning H. E.
Published: April 2005

A further investigation has been made of the reaction of cyclopentane with Hg6(3P1) atoms at 29.30±0.01°C, under static conditions. Analyses, using mass spectrometric techniques, confirm that the only direct products of the reaction are hydrogen, bicyclopentyl, and cyclopentene. No evidence was found for decomposition of the cyclopentane ring.

The kinetics of the reaction can be satisfactorily explained in terms of the following general mechanism:(1) cyclo CnH2n+Hg6(3P1)→cyclo CnH2n−1+H+Hg6(1S0),(2) H+cyclo CnH2n→H2+cyclo CnH2n−1,(3) 2(cyclo CnH2n−1)→cyclo CnH2n−2+cyclo CnH2n,(4) 2(cyclo CnH2n−1)→bicyclo C2nH4n−2,(5) H+cyclo CnH2n−2→cyclo CnH2n−1.Reaction (5) can be ignored at high substrate pressures or low extents of decomposition. The limiting high-pressure values for the quantum yields of cyclopentane disappearance, hydrogen formation, and cyclopentene formation are 0.90, 0.49, and 0.078, respectively.

From the steady-state treatment of the mechanism coupled with the quantum yield data, the ratio k4/k3, the ratio of the rates of recombination to disproportionation for cyclopentyl radicals, was determined to be 5.3.
Theory of Electromagnetophoresis. I. Magnetohydrodynamic Forces Experienced by Spherical and Symmetrically Oriented Cylindrical Particles
Authors: Leenov Daniel , Kolin Alexander
Published: April 2005

This paper is the first of a series dealing with the theory of the electromagnetokinetic effect. This effect consists of the exertion of a force upon a body submerged in a fluid which is traversed by an electric current and a transverse magnetic field. In this communication the conditions for equilibrium of an homogeneous fluid are established and forces upon particles suspended in the fluid are determined. The computations are carried out for spherical bodies and long cylindrical bodies oriented parallel to the magnetic field, to the electric current, and to the exerted force. It is shown that the effect could be observed with suspended particles which differ from the surrounding fluid in the value of their electrical conductivity or dielectric constant, and/or their magnetic permeability.
Calculation of the Moments of the Vibrational Frequency Distributions of Simple Crystals
Authors: Walnut Thomas H.
Published: April 2005

A method of obtaining moments of frequency distributions of vibrations of simple crystal lattices is demonstrated. The moments are obtained directly from corresponding powers of the dynamical matrices in terms of simple displacement coordinates.
Light Scattering by Tobacco Mosaic Virus Nucleic Acid
Authors: Northrop Theodore G. , Sinsheimer Robert L.
Published: April 2005

The molecular weight of ribonucleic acid separated from tobacco mosaic virus by heat denaturation of the protein has been measured by light-scattering techniques and found to correspond to the weight of all the nucleic acid in a virus rod. The nucleic acid disintegrated rapidly at room temperature, most probably by enzymatic action.
Structure of the Perrhenate Ion
Authors: Claassen Howard H. , Zielen A. J.
Published: April 2005

Raman and infrared spectra have been obtained for aqueous solutions of perrhenic acid and sodium perrhenate. The spectra are interpreted satisfactorily with the assumption that the perrhenate ion in dilute solutions is ReO4— and has tetrahedral symmetry.
Carbon-13 Isotope Effect in the Thermodecomposition of Nickel Carbonyl
Authors: Bernstein Richard B.
Published: April 2005

The C12–C13 fractionation factor in the decomposition of gaseous nickel carbonyl has been measured from 30—105°C, using samples of normal isotope abundance. Assuming that the rate-determining step is the rupture of a Ni–C bond, the rate constants are defined as follows: Ni(CO)4→ lim Ni(CO)3·    +CO  k1,Ni(CO)3C*O−|→Ni(CO)3·   +C*Ok2,→Ni(CO)2C*O·+COk3.The C12 enrichment of the first fraction of CO from decomposition gives, over the temperature range studied, k1/(k2+k3)=1.0222−6.7×10−5t(∘C).

The intramolecular and intermolecular isotope effects are defined as k3/3k2 and k1/4k2, respectively. The magnitude of the intramolecular effect was assumed to be given by the square root of the usual reduced mass ratio, with a value of 1.0345. Thus the intermolecular effect calculated from the data becomes, k1/4k2=1.0481−6.7×10−5t(∘C).

A theoretical estimate of the magnitude of the intermolecular effect was made using the method of Bigeleisen. Isotopic shifts in vibrational frequencies were computed, and the usual assumptions regarding the vibrations of the activated complex were made. The calculated isotope effect was somewhat smaller than that observed.
Eckart Conditions in Wilson's Treatment of Molecular Vibrations
Authors: Malhiot Robert J. , Ferigle Salvador M.
Published: April 2005

The consistency of Wilson's treatment of molecular vibrations with the Eckart conditions is discussed in detail. The necessary conditions for this consistency are written in vector form and the applicability of the equations, thus derived, to the calculation of s vectors is indicated.
Investigations of the ``Vapor Snake'' Phenomenon
Authors: Verschingel R. , Schiff H. I.
Published: April 2005

The ``vapor snake'' phenomenon, originally reported for cyclohexane, has been found to occur with some twenty compounds. The ease of occurrence increases with the triple point pressure of the compound. The tubule tip was always at the freezing point of the compound although the surrounding liquid may be above the freezing point. Although the presence of a crust on the surface of the liquid is not essential for the occurrence of the phenomenon, transport of heat by vapor to a cold portion of the sample must occur in order to produce a tubule sheath of the thickness observed.
Theory of Laminar Flame Stability. II. General Numerical Method and Application to Typical System
Authors: Rosen J. B.
Published: April 2005

The steady-state flame equations for a system which may include the effect of a free radical are obtained in dimensionless form and solved for a typical choice of parameter values. A general numerical method for determining the stability of such a system is described. This method is applied to the chosen steady-state solution which is shown to be unstable. The growth of the temperature, concentration, and mass-flow perturbations are shown, and the temperature perturbation is compared with that given by the corresponding approximate analytic solution obtained in Part I.
Vibrational Relaxation Times in Gases (Three-Dimensional Treatment)
Authors: Schwartz Robert N. , Herzfeld Karl F.
Published: April 2005

The calculations previously made by Schwartz, Slawsky, and Herzfeld are extended to three dimensions. As before, an exponential repulsion is fitted to the Lennard-Jones potential, with constants found from viscosity data. While the transition probability is determined directly by the short range repulsion forces, the attractive forces and the effect of the centrifugal quasi-potential modify the effective velocity of the colliding molecules. The agreement with experiment is fairly good, although high up on the repulsion curve (O2,N2) the Lennard-Jones 6—12 curve seems to be not quite steep enough.
Isotope Effect in Continuous Ultraviolet Absorption Spectra: Methyl Bromide-d3 and Chloroform-d
Authors: Gordus Adon A. , Bernstein Richard B.
Published: April 2005

A comparison of the continuous ultraviolet absorption spectra of CH3Br and CD3Br indicated a nearly constant shift of +280±50 cm—1 upon deuterium substitution. In the case of CHCl3 and CDCl3 the shift was less than the uncertainty of ±50 cm—1. These results are interpreted in terms of the Herzberg-Goodeve picture involving the carbon-halogen bond rupture.

The ultraviolet absorption spectra of CCl4, CFCl3, CH2Cl2, CF2Cl2, and CHFCl2 are also reported.
Flame Turbulence Measurements by the Method of Helium Diffusion
Authors: Westenberg Arthur A.
Published: April 2005

A technique is described for measuring transverse turbulence intensity in flames which makes use of the diffusion of helium. The latter is detected by a thermal conductivity method. The effects of various experimental parameters and the reliability of the technique are discussed. Results obtained in highly turbulent flames stabilized on various baffles in a 5 cm×20 cm duct are given, and compared with results obtained under comparable cold flow conditions. It appears that, under the conditions of these experiments, the amount of ``flame-generated'' turbulence detectable at a fixed point in the duct by this technique is probably small.
The Thermodynamics of Boron Nitride; Low-Temperature Heat Capacity and Entropy; Heats of Combustion and Formation
Authors: Dworkin A. S. , Sasmor D. J. , Van Artsdalen E. R.
Published: April 2005

The low-temperature heat capacity of microcrystalline boron nitride has been measured up to 300°K. It has been found that in the range from 20 to 65°K the heat capacity follows a T2 relationship rather than the usual Debye T3 law, and this has been explained as resulting from the layered, quasi-two-dimensional lattice of boron nitride. The Debye-type characteristic (two-dimensional) temperature is θ2=598°K. At 298.16°K Cp=4.783 cal/mole deg and S0=3.673 eu, of which 0.034 has been extrapolated below 20°K. Derived thermodynamic functions have been tabulated at 10° intervals between 20 and 300°K. The heat of combustion of boron nitride in a conventional bomb calorimeter to yield amorphous boric oxide and elemental nitrogen has been determined to be 90.2±0.5 kcal/mole. From this value and other established thermal data the heat of formation of boron nitride is exothermic 60.7±0.7 kcal/mole.
Equilibria in the Formation of Molybdenum and Thorium Iodides from the Elements
Authors: Allen Thomas L. , Yost Don M.
Published: April 2005

An investigation has been made of the reaction of molybdenum and iodine to form molybdenum diiodide in the temperature interval from 1086°K to 1914°K, and the reaction of thorium and iodine to form thorium tetraiodide in the temperature interval from 1395°K to 1706°K. Thermodynamic properties of molybdenum diiodide and thorium tetraiodide were determined from measurements of the equilibria in these reactions. For the reaction Mo(s)+2I(g)=MoI2(g) at 1200°K, ΔF0=—13.6 kcal/mole, ΔH0=—25.0 kcal/mole, and ΔS0=—9.5 cal/mole °K. For the reaction Th(s)+4I(g)=ThI4(g) at 1500°K, ΔF0=—83 kcal/mole. Using an estimated value for ΔS0 of —82 cal/mole °K, ΔH0=—206 kcal/mole. The average Mo–I bond energy in MoI2(g) and the average Th–I bond energy in ThI4(g) are both 89 kcal/mole.
Analysis of the Near Ultraviolet Absorption Spectrum of Acetylene
Authors: Innes K. Keith
Published: April 2005

The absorption spectrum of acetylene in the region 1970—2470A has been photographed in the fourth and fifth orders of a twenty-one-foot grating spectrograph with absorbing paths of 0.007 to 70 m-atmos.

It has been possible to extend the arguments which led King and Ingold to conclude that in the upper electronic state the molecule is bent and has C2h symmetry. The upper electronic state is Au or, possibly Ag.

The effective moment of inertia Ia of the excited state is small, causing sub-band separations of 50 to 150 cm—1. These sub-bands all have P, Q, and R branches, are well resolved, and have the appearance of bands of diatomic molecules. The following rotational constants of the upper state are derived: A0=12.94,  B0=1.1247,  C0=1.0297 cm−1. If the C–H distance is assumed to be between 1.070 and 1.090A, one finds rcc=1.388A,  [open phi]CCH=120∘. Ground-state combination differences are in agreement with precise values derived from infrared data. Some new lower state B values are obtained.

The O–O vibrational transition is shown to be at 42 197.69 cm—1. The sub-bands form ν4″ progressions and ν3′ progressions. Analysis gives two upper state vibrational frequencies ν3(CCH)=1047.70 cm−1  and  ν2(CC)=1389 cm−1. The following lower state vibrational constants are obtained: ω40=608.26,  x44=+3.29, g44=+0.17 cm−1. The fundamental frequency ν4″ is the sum of these constants, that is, 611.72 cm—1.
Thermodynamics of Equilibrium in the Ultracentrifuge
Authors: Young T. Fraser , Kraus Kurt A. , Johnson James S.
Published: April 2005

An exact equation has been derived which can be used for the determination of the ratio of the activity of substance i in a solution of molality mβ to the activity in a solution of molality mα. Here mβ and mα are the respective molalities observed at two positions xβ and xα within a two-component solution which has come to equilibrium in an ultracentrifuge. The calculation involves the densities of the solution at all positions between xβ and xα and the partial molal volumes of i for the two molalities mβ and mα. For each of these molalities partial volumes are required for the range of pressure between the equilibrium pressure acting on the solution of that molality and the pressure (ordinarily one atmosphere) of interest to the investigator. Some information concerning a solution containing more than two components can be derived from ultracentrifugal experiments if adequate density data are available.
Photon-Induced Diffusion in Thin Films and Single Crystals of Potassium Iodide
Authors: Delbecq C. J. , Yuster P. H.
Published: April 2005

Thin films of potassium iodide have been prepared at both room and liquid nitrogen temperatures. Absorption spectra are presented which show that films deposited at liquid nitrogen temperature are quite disordered, but after warming to room temperature are very similar to those films deposited at room temperature. Evidence is given which shows that in thin films and also in single crystals of potassium iodide diffusion is promoted by the absorption of light. It is proposed that diffusion is caused by point thermal spikes at the absorbing centers.
Photochemical Activity of Salts of Uranium in Solutions at the Temperature of Liquid Nitrogen
Authors: Freed Simon , Sancier Kenneth M.
Published: April 2005

Anhydrous chlorides of hexavalent (UO2++), quadrivalent, and trivalent uranium ions are photochemically active when in a solution fluid at 77°K. The solvent consisted of 10 percent n-propanol, 45 percent propane, and 45 percent propene. It was shown spectroscopically and also chemically that quadrivalent uranium was reduced to the trivalent form. There were indications that trivalent and hexavalent uranium were transformed photochemically to the tetravalent state.
The Bipyramidal XY3Z2 Molecular Model. Part I. Classical Vibration Problem
Authors: Ziomek Joseph S.
Published: April 2005

Symmetry coordinates are set up from the standpoint of group theory for describing the normal modes of oscillation of the XY3Z2 molecular model in such a manner that maximum factorization of the secular determinant is accomplished. The cubic and quartic portions of the anharmonic potential function are derived, and the components of vibrational angular momentum are set down. The complete valence-type potential function is discussed. Explicit relations are derived between the force constants occurring in the secular determinant and the physical valence force constants.
The Frequency of the Irradiating Light as a Determinant of the Joshi Effect in Oxygen under Silent Electric Discharge
Authors: Mohanty S. R.
Published: April 2005

Ceteris paribus, the negative Joshi effect —Δi in oxygen under electrical excitation increases linearly with the frequency v of the irradiating light: −Δi/iD=A(ν−νm),where iD is the rms current in dark, vm the minimum threshold frequency, and Λ a constant dependent upon the nature of the electrode surface, gas pressure, applied potential V, etc. vm decreases with increase in V because of the occurrence of the photoelectric analog of the Schottky effect. The increase in —Δi with v(>vm) is the consequence of a similar variation in the photoelectric yield. Superimposed on this are factors which tend to reduce —Δi: (1) the increase in photoelectron energy with v, which diminishes the probability of attachment, and (2) reduction in emission because of the negative space charge and the image force.
Temperature Dependence of the Ultraviolet Absorption Spectrum of Naphthalene in Solution
Authors: Passerini Riccardo , Ross Ian G.
Published: April 2005

The absorption spectrum of naphthalene solutions has been measured, in the region 3300—2400A, at temperatures between +60°C and —185°C. Particular attention was given to the long-wavelength vibrational bands of the first electronic transition (3200—2900A), in order to locate and establish the identity of the band origin. The band acquires most of its intensity through the participation of an active vibration, whose ground-state frequency measured from two observed vibrational bands, is 525±20 cm—1, in adequate agreement with the value 544±60 cm—1 found from the temperature dependence of intensity of the 0←1 band in this frequency. This is probably the Raman ag frequency 512 cm—1, which identification, in conjunction with previous polarization measurements, assigns the transition as B2u← Ag. Frequency and intensity data are given for 26 bands of this and the next transition (2900—2400A); the latter appears, vibrationally, to be allowed.
The Effect of Oxygen on the Photoconductivity of Anthracene. II
Authors: Chynoweth A. G.
Published: April 2005

The photoconductivity in the surface layers of crystalline anthracene has been found to increase considerably over its vacuum level when it is measured in the presence of oxygen or air. Replacing the oxygen by nitrogen or argon causes no such increase. The increased photoconductivity is attributed to the photooxidation of the surface, both the light and the oxygen being necessary to produce the effect. No reaction takes place in the dark. The oxide formed is fairly unstable and dissociates in the dark. Its rate of dissociation is considerably increased when the crystal is illuminated in the absence of oxygen. The experiments indicate that the peroxide is formed by a two-stage process, the highly unstable intermediate product being formed very rapidly while the final peroxide is formed much more slowly. The nature of the intermediate product is not known for certain. The end product is very likely the oxide formed by an oxygen bridge across the 9, 10 carbon atoms of the anthracene molecule. Apparently, both the oxidation products modulate the photocurrent solely by their effect on the mean free path of the carriers; the intermediate product producing a relatively large increase while the end product produces a smaller decrease in the mean free path.

It is suggested that the technique of photoconductivity measurements might prove to be useful in the study of the kinetics of certain photochemical reactions.
Symbolic Structural Formulas for Boron Hydrides
Authors: Platt John R.
Published: April 2005

A structural convention is proposed, intended to serve the same function for boron hydrides that the standard valence bond convention serves for organic compounds. It involves the auxiliary concept of the ``valence cone,'' which is the cone swept out by three tetrahedral orbitals rotating about the fourth as an axis. The known open boron hydrides BnHn+p then appear to be even-electron molecules with the boron atoms approximately in a close-packed equilateral-triangular network on the convex surface formed by their overlapping valence cones; with n single B–H bonds normal to this surface; and with p (even) added peripheral hydrogen in the surface located so that every boron atom has neighbors in all three sectors of its valence cone. As long as this network does not form a complete polyhedron, we may represent it on paper by a flat triangular network having the same topology.

This prescription gives uniquely and correctly the structures and formulas for the known B2, B4, B5, B6, and B10 hydrides and predicts other possible open compounds up to B11. It would be consistent with the existence of closed inert polyhedral hydrides BnHn up to B12H12 and with chains and lattices of such polyhedra.
Statistical Computation of Mean Dimensions of Macromolecules. I
Authors: Wall F. T. , Hiller L. A. , Wheeler D. J.
Published: April 2005

The configurations of flexible coiling type polymer molecules have been investigated statistically with a high-speed electronic digital computer by generation of large numbers of ``random walks.'' These walks were carried out subject to the excluded volume effect in simple cubic and tetrahedral lattices. It was found that the walk attrition obeys an exponential decay law with a half-walk of 6.7 steps in the cubic lattice and 17.3 steps for the tetrahedral. Mean square end-to-end separations, 〈rn2〉Av, were also obtained, and two distinct kinds of empirical formulas have been fitted to the data. So far, the statistical data are insufficient to establish unequivocally the nature of the functional dependence of 〈rn2〉Av for large values of n, the number of steps. A study was also made on the probabilities of ring closures for restricted random walks in the cubic system. It was found that for rings greater than 6 steps, the probability of formation varies inversely as the square of the ring size.
Substituted Methanes. XX. Potential Constants and Calculated Thermodynamic Properties for Some Dibromomethanes
Authors: Dowling Jerome M. , Meister Arnold G.
Published: April 2005

Using previous infrared and Raman data, a reasonable set of potential constants were obtained for CH2Br2 and CD2Br2, by means of the Wilson FG matrix method, with a potential energy function containing all possible second degree terms. Fundamental frequencies for CHDBr2 were then calculated using the potential constants found for CH2Br2 and CD2Br2. Finally the heat content, free energy, entropy, and heat capacity for the ideal gaseous state at 1 atmos pressure were calculated for these three molecules for twelve temperatures from 100°K to 1000°K with a rigid rotator harmonic oscillator approximation.
Theory of Concentration Quenching in Inorganic Phosphors
Authors: Dexter D. L. , Schulman James H.
Published: April 2005

A theory is presented for concentration quenching in solid systems, based on the migration of excitation energy from one activator center to another and eventually to an imperfection which may act as an energy sink. Calculations are made on the dependence of the fluorescence yield on concentration, and to indicate typical activator concentrations at which appreciable quenching may be expected to occur. If the transition in the activator is of the electric dipole or electric quadrupole type, appreciable quenching may arise when the activator concentration is 10-3 to 10-2; if it is a magnetic dipole transition, transfer will occur by exchange, rather than by overlapping of magnetic dipole fields, and the critical concentration will be of the order of a few percent. The implications of transfer phenomena upon the observed absence of luminescence in most ``pure'' inorganic crystals are discussed, and it is concluded that transfer rates are so high in strongly absorbing crystals that the energy can easily migrate to a very few sinks dispersed throughout the lattice.
The Reaction of Methyl Radicals with Aceto- and Propio-Nitrile
Authors: Wijnen M. H. J.
Published: April 2005

The reaction of CD3 radicals with aceto- and propio-nitrile has been studied over the temperature range 100 to 300°C at various intensities. The CD3 radicals were produced by photodecomposition of acetone-d6. As activation energies for the reactions CD3+CH3CN→CD3H+CH2CNand CD3+C2H5CN→CD3H+C2H4CN,we obtained E2=10±0.5 kcal and E3=8.5±0.5 kcal.
The Szilard-Chalmers Reaction in Aqueous Solutions of Tri- and Hexavalent Chromium
Authors: Fishman Lawrence M. , Harbottle Garman
Published: April 2005

Szilard-Chalmers (nuclear recoil) reactions have been observed in aqueous solutions of tri- and hexavalent chromium. The effects of pH, concentration, and a number of other variables have been examined, and the retention is found to depend on several of these factors. The results are interpreted in terms of thermal oxidation-reduction and exchange reactions of chromium V and/or IV.