bluuebunny/crossref_metadata_2025 huggingface dataset:
Static Space Charge and Capacitance for a Single Blocking Electrode
Authors: Macdonald J. Ross
Published: January 2005

Static space-charge distributions in materials having one charge blocking and one ohmic electrode are considered with special emphasis on the situation where charge carriers of only one sign are mobile but which may recombine bimolecularly with fixed charges of opposite sign. The dependence of potential, charge, and electric field on distance from the blocking electrode cannot be obtained exactly in closed form but various simple approximate relations are obtained and are compared with accurate digital computer solutions of the exact relation between potential and distance. Comparison is most significant when the distance scale is normalized by the effective Debye length, a quantity which is shown to depend on recombination ratio when charges of only one sign are mobile. The dependence of total space-charge and differential and static space-charge capacitance on applied potential and recombination is obtained in closed form, and it is shown that recombination can lead to peaks in the curves of static and differential capacitance versus applied potential. Observation of these peaks should afford a simple method of determining recombination ratio and other pertinent parameters of the material. Finally, the addition of a charge-free layer in series with the space-charge region is considered, and the effect of such addition on differential capacitance investigated. The combination of a charge-free layer and space-charge region represents a combination of Mott's and Schottky's theories of rectification insofar as capacitance effects are concerned and is therefore pertinent to measurements on barrier-layer rectifiers as well as to material with a completely blocking electrode.
Statistical Thermodynamics of the Sorption of Vapors by Solids
Authors: Dole Malcolm
Published: January 2005

The statistical method of treating the sorption of vapors, begun by Fowler and Guggenheim and extended to multilayer sorption by Cassie and Hill, is further generalized to include variable heats of sorption in different layers. It is shown under what conditions multilayer sorption can lead to a linear isotherm and to various modifications of the BET equation. The treatment is also extended to the case of interaction between sorbed molecules in the same layer.
Rotation-Vibration Spectra of Diatomic and Simple Polyatomic Molecules with Long Absorbing Paths. I. The Spectrum of Fluoroform (CHF3) from 2.4μ to 0.7μ
Authors: Bernstein H. J. , Herzberg G.
Published: January 2005

The spectrum of fluoroform has been investigated under high resolution (21-ft. grating) in the photographic infra-red with an absorbing path of up to 60 meters, obtained by multiple reflection according to the method of J. U. White. In addition, with the same path length the spectrum from 1.2 to 2.4μ was obtained under low resolution with a photoelectric infra-red spectrometer. A large number of overtone and combination bands, 47 in all, were found. Two parallel bands in the photographic region were well resolved and analyzed, yielding, for the moment of inertia about an axis perpendicular to the symmetry axis, IB[0]=81.08×10−40 g cm2From this value, assuming tetrahedral angles and a C–H distance as in methane, the C–F distance in fluoroform is found to be 1.329A, a value that is appreciably lower than that found in methyl fluoride, 1.380A. A provisional vibrational assignment of all the bands is given.
The Mercury Photosensitized Reactions of Ethylene Oxide
Authors: Phibbs M. K. , Darwent B. de B. , Steacie E. W. R.
Published: January 2005

The reactions of ethylene oxide with Hg(3P1) atoms have been investigated at 25°C at pressures between 10- and 600-mm Hg, and at 200°C and 300°C at 100-mm Hg. The principal products are H2, CO, CH3CHO and a polymer; smaller amounts of CH4, C2 hydrocarbons and formaldehyde are also formed. The nature of the products and the very small effect of pressure on the reaction are best explained by a mechanism based principally on the formation of the activated ethylene oxide molecule, with a minor portion of the reaction proceeding via a C–H split.
The Infra-Red Absorption Spectrum of Hexafluoroethane Gas
Authors: Nielsen J. Rud , Richards C. M. , McMurry H. L.
Published: January 2005

The infra-red absorption of gaseous hexafluoroethane between 2 and 25μ has been investigated with prism spectrometers of high resolution. On the basis of normal vibration calculations and the known Raman frequencies it has been possible to interpret all but 3 of the 51 observed absorption maxima. Only combination bands permitted for both the staggered (D3d) and the eclipsed (D3h) model were used in the assignment of bands. Five fundamental frequencies have been determined in addition to the six obtained from the Raman spectrum. No combination band involving the remaining frequency, associated with the torsional oscillation of one CF3 group relative to the other, could be identified. An attempt to determine the moments of inertia of the C2F6 molecule from the envelope of the strongest parallel band gave unsatisfactory results.
Physical Adsorption on Non-Uniform Surfaces
Authors: Halsey George
Published: January 2005

Analysis of adsorption on a uniform surface using the quasi-chemical theory of interaction shows that the hypotheses of the BET theory lead to substantially no adsorption beyond the first layer if E2 = EL, and stepwise isotherms if E1>E2>E3>···>EL. For the monolayer adsorption of gases on silver, platinum, and steel, the heterogeneous nature of the adsorbing surface is clearly indicated. Cooperative adsorption on the non-uniform surface is treated, and the cooperative analog of the Freundlich equation derived. The typical multi-layer isotherm is shown to be composed of three regions: non-cooperative adsorption on a strongly heterogeneous surface; cooperative adsorption on a still heterogeneous surface; and cooperative multi-layer adsorption induced by small van der Waals perturbations some distance from the surface.

The isotherm p/p0=exp{—a/θr} is derived and shown to be a good representation of adsorption data that conform to the BET Type I, II, or III shapes.
On the Thermochemistry of Organic Compounds
Authors: Valatin J. G.
Published: January 2005

A discussion of different arguments on the dissociation energy of CO and on the role of the 5S state of carbon is given. The consistency of the 169.735 kcal./mole value of the heat of sublimation of carbon into 5S carbon atoms given by Gerö in spite of some arguments of Long and Norrish is shown. The energy required to rupture ethane into two methyl radicals results to be {C–C}ethane=82.78 kcal./mole, in excellent agreement with the value which can be obtained by a cycle proposed by Van Artsdalen without the use of the heat of sublimation value of carbon. The difference of the mean C–C bond energies in diamond and in the higher members of the paraffin series is 2.04 kcal./mole. The energy required to rupture the double bond in 1-heptene, {C=C}1-heptene=145.43 kcal./mole, in 2-methyl−1-butene {C=C}2-methyl−1-butene=148.70 kcal./mole. In the acetylene hydrocarbons {C≡C}1-pentyne=198.67 kcal./mole, {C≡C}acetylene=194.28 kcal./mole.
The Vibrational Spectra of Molecules and Complex Ions in Crystals. I. General Theory
Authors: Hornig Donald F.
Published: January 2005

It is shown that if a crystal is approximated as a harmonic oscillator, only a very small number of vibrational modes may be active in the infra-red or Raman spectra. These modes are all totally symmetric with respect to translation. They must also have proper symmetry with respect to the factor group of the space group which we have called the unit cell group. The active frequencies may be calculated from a single unit cell. It is shown further that the number and symmetry type of vibrational modes may be correctly calculated from the local symmetry (site group) of the center of gravity of each kind of molecule. In the harmonic approximation the spectrum should consist of very sharp lines. The wide bands obtained experimentally are probably due to combination lines with lattice vibrations and indicate anharmonic coupling between molecular and lattice modes. Such combinations may cause apparent violations of selection rules for internal vibrations. The symmetry basis for obtaining selection rules in this case is given. The importance of obtaining spectra over a wide temperature range and particularly at very low temperatures is emphasized. In cases where all internal modes have a frequency great compared to the frequency of lattice modes the problem is examined from the point of view of the Born-Oppenheimer approximation. It is shown that for some symmetries perturbations linear in the lattice displacement may occur. In these cases considerable splitting of degenerate molecular vibration modes is possible. Groups for which first-order splitting is not expected are listed. Symmetry species of other groups are classified into those which may and which may not be split in this approximation, and the lattice modes responsible for splitting are classified as rotations or translations and by symmetry type.
Entropy, Enthalpy, and Free Energy of the Electrical Double Layer at an Ideal Polarized Electrode. Part I. Thermodynamic Theory
Authors: Grahame David C.
Published: January 2005

There are several kinds of entropy, enthalpy, and free energy changes associated with the electrical double layer. Definitions of the thermodynamically significant quantities are given, together with equations for their evaluation. It is shown that the ideal polarized electrode may be regarded as one electrode in a galvanic cell and that the usual thermodynamic treatment of cells may be applied. The electrochemical process occurring in such a cell is identified, and a method of evaluating a new property, the transference number of the ions of the double layer, is given. The relationship between electrocapillary properties of metals and the thermodynamic properties of colloids is indicated. The thermodynamics of gas adsorption on solids is presented as an aid to the interpretation of the above.
Electronic States of Organic Molecules
Authors: Simpson William T.
Published: January 2005

The spectra of three simple dye-like molecules, and of benzene and naphthalene, are treated in a semiquantitative fashion. The methods employed are the bond orbital, the molecular orbital (somewhat modified), the antisymmetrized molecular orbital, and two models, one related to the bond orbital, the other to the molecular orbital. The positions of main and second-order bands, and intensities, are calculated. Extension of the calculations to complex cases is indicated.
The Mercury Photosensitized Reactions of Isobutene
Authors: Allen G. A. , Gunning H. E.
Published: January 2005

An investigation has been made of the reaction of isobutene with mercury (3P1) atoms at 30°C. Acetylene and propylene have been shown not to be among the main products of the reaction. The over-all rate of consumption of isobutene and the rate of pressure decrease both decrease with increasing initial pressure in the complete quenching region. These rates approach constant values for initial pressures of 180 mm and higher The results of this investigation show that isobutene behaves similarly to the other olefins in reacting with mercury (3P1) atoms at 30°C, in that the reactions can be explained by the following initial steps for the mechanism: i−C4H8+Hg(3P1)→i−C4H8*+Hg(1S0)i−C4H8*+i−C4H8→2i−C4H8,accompanied by the decomposition of the activated isobutene molecule into reaction-initiating fragments.

The discrepancies between the results of this investigation and those of the earlier work of Gunning and Steacie may be due to the effect of impurities in the original isobutene, since it is shown that small amounts of added propylene or acetylene change the rate of reaction markedly.
The C–H Bond Energy in Toluene and Xylenes
Authors: Szwarc M.
Published: January 2005

The pyrolysis of toluene and the xylenes was investigated by a new technique, which made it possible to study these reactions for degree of decomposition ranging from 0.01 percent up to a few percent. It was shown that these reactions are homogeneous, unimolecular reactions. It was found that the weakest bond in these molecules is the C–H bond in the methyl group. The bond energy of that C–H bond was found to be 77.5 kcal. for toluene and meta-xylene, 75 kcal. for para-xylene and 74 kcal. for ortho-xylene. These data indicate that the resonance energy of the benzyl radical is 24.5 kcal. and that the hyper-conjugation in para-xylene decreases the C–H bond energy in the methyl group of this molecule by 2.5–3 kcal.
The Raman Spectrum and Structure of Nickel Carbonyl
Authors: Crawford Bryce L. , Horwitz William
Published: January 2005

A redetermination of the depolarization factors of the Raman lines of nickel carbonyl shows the presence of only two polarized lines instead of three, as previously reported by other investigators. The data obtained not only eliminate the only evidence against the tetrahedral structure for this molecule but supply additional evidence in its favor.
Target Chemistry of Cesium; Isolation of Ba133, 134
Authors: Kurbatov M. H. , Yu Fu-Chun , Kurbatov J. D.
Published: January 2005

Barium (Ba133, 134) obtained by dn and d2n reactions of spectroscopically pure cesium chloride was separated in quantities of <1×10−9 gram without addition of common barium. The procedure studied involves adsorption of barium on hydrous ferric oxide under conditions at which cesium ions remain in solution. The effect of (a) pH of solution and (b) varying quantities of ferric hydrous oxide on the fraction of Ba adsorbed from solution containing <10−9 g Ba, keeping other factors constant, showed that the fraction of Ba adsorbed, y=k[Z(X — X0)]λ, Z being the quantity of adsorbent (from 1×10−5 to 3×10−4 g atom Fe); X, the OH− concentration in solution (from 3×10−9 to 3×10−6); X0, the critical concentration of OH− necessary to maintain the adsorbent in the solid state. When pH was kept constant the value of λ for y=k′Zλ was found to be 0.35, and when the quantity of adsorbent was constant the λ for y=k″(X — X0)λ was 0.33. The fact that the two experimental slopes were so nearly the same in spite of certain variations in experimental conditions is taken as support for two assumptions made in the derivation of the expression viz., (1) the fraction of barium adsorbed from a very dilute solution depends on the quantity of adsorptive centers in the solid phase and (2) the quantity of adsorptive centers in the solid phase available for barium adsorption is proportional to the OH− concentration in solution, other factors being constant. Adsorption procedure is described.
The Molecular Structure of Dimethyltrisulfide, (CH3)2S3
Authors: Donohue Jerry , Schomaker Verner
Published: January 2005

Dimethyltrisulfide (CH3)2S3 has been investigated by the electron diffraction method. The molecule was found to have the chain configuration, with the following interatomic distances and angles: C–H=1.09A (assumed), C–S=1.78±0.04A, S–S=2.04A, ±0.02A, ∠H–C–S=112° (assumed), ∠S–S–S=104°±5°, and ∠C–S–S=104°±5°. The results also suggest that the C–S bonds oscillate with rather large amplitude about a mean position approximately 106° out of the plane of the three sulfur atoms.
The Effect of Trapping Centers on Dielectric Breakdown in Alkali Halides
Authors: Meyer Charles F. , Herman Robert C.
Published: January 2005

The Seeger-Teller theory of dielectric breakdown for the alkali halides has been extended to account for the effect of trapping at low temperatures. The cross section of ionized F-centers has been estimated classically, as well as from recent experiments of Domanic on the photoelectric yield of F′-centers, to be about 3×10−13 cm2 near liquid air temperatures. The increase in the breakdown field for NaCl is given as a function of the concentration of vacant halogen ion sites. An observable increase, of about 10 percent, in breakdown voltage is predicted at a concentration of 2×1018 centers per cm3.
Statistical Mechanics of Multimolecular Adsorption. IV. The Statistical Analog of the BET Constant a1b2/b1a2. Hindered Rotation of a Symmetrical Diatomic Molecule Near a Surface
Authors: Hill Terrell L.
Published: January 2005

An approximate study is made of the restricted rotation of a symmetrical diatomic molecule near a surface. This makes possible some calculations concerning the BET constant C=R exp(ε1—Λ)/kT, and especially the factor R (which is customarily set equal to unity). Cassie has pointed out that if this factor is set equal not to unity but to about 1/50 or even less, the low values of the heat of adsorption usually found on putting R=1 in the analysis of data are accounted for. The results obtained here indicate, unfortunately, that this factor is of the order of, say, 5–10, and that another explanation of the low heats of adsorption mentioned above will have to be found. An alternative method of estimating the area occupied per molecule in a completely filled monolayer is mentioned in an appendix.

The temperature dependence of the quantity R is of some experimental interest, and a brief discussion of this dependence as predicted by the present approximate treatment is included.
Poisoning of Platinum Catalysts at High Temperatures
Authors: Savage Robert H.
Published: January 2005

Poisoning films of exceptional thermal stability are formed on a platinum catalyst when heated in a silicone vapor (hexamethyldisiloxane) at pressures of the order 10−3 mm. These films prevent the combination of hydrogen and oxygen at low pressures and are not removed until heated to about 1440 K in the presence of hydrogen (or to higher temperatures in oxygen). It is suggested that the film may consist of a silicon oxide oriented with the silicon atoms attached directly to the platinum and presenting an outer layer of oxygen atoms, effectively shielding the catalyst.
Structure of the Hydrogen Fluoride Dimer
Authors: Evans George E. , Glockler George
Published: January 2005

Classical electrostatics were employed to study the configuration and potential energy of the (hypothetical) (HF)2 molecule in the gaseous state. Of the planar models studied, a Z-shaped structure of C2h symmetry with both F–F–H angles equal to 32.5 degrees had a minimum potential energy.
Dielectric Measurement of Liquids at Microwave Frequencies
Authors: Crouch G. E.
Published: January 2005

A method of measuring the dielectric properties of medium and high loss liquids at microwave frequencies is described. In this method the liquid sample is placed in an open circuit-terminated section of wave-guide and standing wave-ratios are measured at intervals as the length of the dielectric liquid column in the wave guide is changed. The method of measuring the wave-length of the radiation in the liquid-filled wave guide is indicated. A simple procedure for calculating the dielectric properties from these measurements is presented. Some dielectric properties of liquids measured with this method at 3-cm wave-length are given.
Steric Effects. I. Van der Waals Potential Energy Curves
Authors: Hill Terrell L.
Published: January 2005

Reliable van der Waals potential energy functions are available in only a limited number of cases. An approximate semi-empirical method is presented for estimating these curves in other cases, based on an extrapolation from the nature of the curves that are known. The relation of the above method to calculations of the type discussed by Westheimer and Mayer on the activation energy for racemization of substituted symmetrical diphenyls is considered.
Ionization and Dissociation of Paraffin Hydrocarbons by Electron Bombardment
Authors: Koffel Marilyn B. , Lad Robert A.
Published: January 2005

Appearance potential values are reported for fragments resulting from electron bombardment of the paraffin hydrocarbons through the hexanes, and for n-heptane and 2,2,3-trimethylbutane. The values for methane, ethane, propane, and the butanes are compared with previously published values.
A Theory of Vapor Pressures of Liquids Based on van der Waals' Equation of State
Authors: Wall Frederick T.
Published: January 2005

An expression is derived for the vapor pressure of a liquid assuming the validity of van der Waals' equation of state. The theory involves the use of an appropriate mathematical expression for the volume of a van der Waals liquid and does not require recourse to any empirical relationships. The vapor pressure equation so obtained can be put into a reduced form, which is of a universal nature. The laws of Guldberg-Guye and of Trouton are shown to be compatible with the theory with constants of the correct order of magnitude.
The Solubility of Water in Hydrocarbons
Authors: Black Cline , Joris George G. , Taylor Hugh S.
Published: January 2005

The method in which tritium oxide acts as a tracer in the determination of water solubility in hydrocarbons has been used for the measurement of the solubility of water in a number of paraffinic, olefinic, and diolefinic hydrocarbons. The effect of temperature, pressure, size of hydrocarbon molecule, and the constitutive factors have been studied. Solubilities were determined in the temperature range from 5° to 30°C at pressures from 1 to 6 atmospheres.
The Intrinsic Viscosities and Diffusion Constants of Flexible Macromolecules in Solution
Authors: Kirkwood John G. , Riseman Jacob
Published: January 2005

A theory of the intrinsic viscosities and translational diffusion constants of flexible macromolecules is developed on the basis of the random coil model with hindered internal rotation. Proper account is taken of the hydrodynamic interaction of the monomer units of the molecule and of inhibited flow through the chain. The theory leads to results qualitatively similar to those obtained by Debye on the basis of a molecular model consisting of a sphere containing a uniform distribution of resisting points. However, significant quantitative differences between the two theories are found.
Kinetics of Emulsion Polymerization
Authors: Smith Wendell V. , Ewart Roswell H.
Published: January 2005

As a basis for understanding emulsion polymerization, the kinetics of free radical reactions in isolated loci is discussed subject to the condition that the free radicals are supplied to the loci from an external source. Three cases of interest are considered: that in which the average number of free radicals per locus is small compared with unity, that in which this number approximates one-half, and that in which the number is large. Of these three possibilities, the second, in which the free radicals per locus approximate one-half, is by far the most interesting as it explains in a satisfactory manner the characteristic features of styrene emulsion polymerization. For this case the average rate of reaction per locus is independent of the size of the locus, since this rate is simply one-half the rate of polymerization of a single free radical. Thus the rate of emulsion polymerization, the concentration of monomer in the loci, and the number of loci present provide the information needed for calculating the chain propagation constant for the monomer.

A simplified treatment is given for approximating the number of reaction loci (polymer particles) produced in emulsion polymerization when the rate of polymerization per locus is constant (see case 2 above). The law obtained indicates that the number of particles should increase with the soap concentration (3/5ths power) and with the rate of formation of free radicals (2/5ths power), but should decrease with increasing rate of growth of the free radicals (−2/5ths power).
Heats of Dissociation of the N2 Molecule and the NH Radical
Authors: Glockler G.
Published: January 2005

A comparison made between certain radicals and molecules would indicate that the heat of dissociation of nitrogen molecules (D(N2)) is 9.764 ev and the heat of dissociation of NH radicals (D(NH)) into atoms is 3.74 ev.
Ultraviolet Absorption Spectrum of Toxicarol and Dehydrotoxicarol
Authors: Shang-yi Ch'en , Feng-chuan Chao
Published: January 2005

The ultraviolet absorption spectra of toxicarol and dehydrotoxicarol in ethyl alcohol solution were studied with a Hilger E−316 quartz spectrograph and a Hilger H−16 sector-photometer. The curve of toxicarol shows a maximum at λ2741 with a molecular extinction coefficient 23,000. The curve drops down vertically at a wave-length λ2801 covering an extinction range from 19,000 to 24,000. The absorption curve of dehydrotoxicarol has two maxima, one being at λ2780 with molecular extinction coefficient 20,250, the other at λ3304 with molecular extinction coefficient 7180. One minimum occurs at λ3114 with coefficient at 5320.
The Stark Effect for a Rigid Asymmetric Rotor
Authors: Golden S. , Wilson E. Bright
Published: January 2005

The Stark effect, arising from the interaction of a uniform electric field with a permanent electric dipole that is arbitrarily oriented within a rigid asymmetric rotor, and with a dipole induced in the rotor by the field, has been evaluated by perturbation methods. Tables are given for the perturbation of the energy levels so that, for J≤2, the rotational energies of an asymmetric molecule in an electric field may be readily approximated to terms quadratic in the electric field.

The effect of accidental degeneracy upon the Stark effect and line intensities has been considered. A qualitative discussion of certain features of Stark patterns is given that may be useful in the identification of rotational spectral lines.
Fine Structure of Raman Lines Due to Chlorine Isotopes
Authors: Rank D. H. , Sheppard N. , Szasz G. J.
Published: January 2005

In continuation of previous work the isotopic fine structures of polarized lines in the Raman spectra of trichloroethylene, tetrachloroethylene, 1,2-dichloroethane, methyl chloroform, 1,1,2-trichloroethane, and 1,1,2,2-tetrachloroethane have been studied. Observed and computed contours are compared. In the majority of cases the results are according to theoretical expectations based on the number of chlorine atoms in the molecule, and the relative abundance of the two isotopes. The fine structure pattern obtained for the ``trans'' form of 1,1,2,2-tetrachloroethane is anomalous. It is possible that this anomaly is caused by weak mechanical coupling between the motions of the two —CCl2 groups in this molecule, or by the presence of a weak combination band that distorts the contour. Experimental methods of checking these explanations are discussed.
Spectroscopic Studies of Rotational Isomerism. I. Liquid n-Butane and the Assignment of the Normal Modes of Vibration
Authors: Szasz G. J. , Sheppard N. , Rank D. H.
Published: January 2005

The Raman spectrum of n-butane has been investigated over the temperature range 147°K to 305°K. The results clearly show the presence of two rotational isomers in the liquid. These are the planar, trans-form (symmetry C2h) and probably the gauche form obtained by a rotation of 120° about the central C–C bond (symmetry C2). The photoelectric spectrograph was used for quantitative intensity measurements on the line pair at 432 cm−1 and 325 cm−1 over the temperature range studied. These lines belong to the two rotational isomers and the results were used to give a value of 770±90 cal. mole−1 for the energy difference, —ΔH, between the two forms of n-butane in the liquid phase. This result is shown to be in good agreement with a value assumed by Pitzer in his treatment of long chain paraffins. A detailed assignment has been made of the vibrational spectrum of the trans-rotational isomer.
General Theory of the Formation of Liquid Films
Authors: Robinson Lawrence Baylor
Published: January 2005

Langmuir's theory of the formation of liquid films in narrow capillaries is developed for the general case of any electrolyte. The determination of the thicknesses of such films involves hyperelliptic integrals. By suitable transformations one can represent the integrand as the the product of binomial series and Legendre's series. No attempt is made to evaluate the thicknesses of the film numerically, because of the complexity of the necessary computations.
Frequency Dependence of the Capacity of a Diffuse Double Layer
Authors: Ferry John D.
Published: January 2005

The capacity of a diffuse double layer is calculated to be inversely proportional to the square root of the frequency at frequencies high compared with the reciprocal of the relaxation time of the ionic atmosphere. This dependence is observed experimentally with inert electrodes in very dilute solutions, but at considerably lower frequencies. The observed capacity is probably concerned with phenomena at the immediate vicinity of the electrode rather than the diffuse double layer.
Dielectric Behavior of Solutions of Electrolytes in Solvents of Low Dielectric Constant. III. The Influence of Constitution on Dielectric Absorption
Authors: Strobel H. A. , Eckstrom H. C.
Published: January 2005

Using a calorimetric method, a study of the influence of constitutional factors on the dielectric absorption of a variety of long chain salts in benzene solution has been made. In a series of octadecyltributylammonium salts, absorption at a given concentration proved dependent on the constitution of the anion and increased for the following anions in the order of their naming: formate, nitrate, chloride, iodide, and thiocyanate. Two salt series in which the chloride and thiocyanate anions were combined with different cations showed a marked dependence of absorption and of calculated aggregate dimensions on the size of the positive ions. All salt solutions below about 0.005 molar behaved as monodisperse systems; at about 0.01 molar additional varieties of ion clusters appeared to become stable and the systems were highly polydispersed; at somewhat higher concentrations there was evidence that a few types of aggregates were predominating and that the complexity was being reduced. On the basis of Debye theory, critical frequencies, average aggregate radii, and dipole moments have been evaluated wherever feasible. The results are in good agreement with such polarization and conductance data as are available.
Contributions to the Theoretical Treatment of Ammonium. I
Authors: Horváth J. I.
Published: January 2005

In this paper we determine the electron distribution, the binding energy, and the ionic radius of the positive ammonium molecule ion. The general idea of our method is that the molecule is divided by a spherical surface which contains the protons and it is supposed, in our first approximation, that the charge of protons is distributed uniformly on this surface. Now, we we have inside our sphere a nitrogen nucleus, the charge of which is over compensated by ten electrons and so a N3− ion is formed. The whole formation can be regarded from the outside of the sphere as similar to the Na+ ion, because the charge of the four protons has been added to the charge of the N nucleus. In a second approximation we pay attention to the fact that the protons are not exactly uniformly distributed on the spherical surface but on the points of a tetrahedron. We have taken into consideration the inhomogeneous field of protons by using the perturbation calculation. The ionic radius of our molecule ion is determined as usual in the statistical theory of atoms. Finally, we check our result with a cycle process. We do not use semi-empirical parameters.
Internal Motion and Molecular Structure Studies by Electron Diffraction
Authors: Karle Isabella Lugoski , Karle Jerome
Published: January 2005

A procedure has been developed for the determination of molecular structure by electron diffraction which yields accurate intensity data and obviates the necessity for visual examination of the diffraction photographs. The theory for computing radial distribution curves has been extended to permit accurate curves to be obtained from scattering data covering only a restricted range of angle. From this method, it is possible to obtain not only equilibrium distances but also the probability distributions for the vibrational motion between pairs of atoms in a molecule. The procedure has been applied to CCl4 and CO2 and when comparisons may be made with spectroscopic results, satisfactory agreement is obtained.
The Microwave Spectrum of Chloroacetylene and Deuterochloroacetylene
Authors: Westenberg A. A. , Goldstein J. H. , Wilson E. Bright
Published: January 2005

The J=1→2 pure rotational transitions in the linear molecules HCCCl35, HCCCl37, DCCCl35, and DCCCl37 have been observed using a Stark modulation microwave spectrograph. The expected quadrupole hyperfine structure has been observed and analyzed in the usual manner, yielding values for the nuclear quadrupole coupling constants of −79.67, −62.75, −79.66, and −63.12 (mc) respectively. The observed Stark effect is in good agreement with that calculated for a linear molecule with a single quadrupolar nucleus using the previously reported value of 0.44 Delsye unit for the dipole moment. The dipole moment calculated from the Stark Effect data is 0.44±0.01 D. Bond distances calculated are H–C=1.052±0.001A, C≡C=1.211±0.001A, and C–Cl=1.632±0.001A.
Ultrasonic Measurements in Metallic Beryllium at Low Temperatures
Authors: Overton W. C.
Published: January 2005

Using the ultrasonic pulse method, the velocity of longitudinal waves in metallic beryllium has been measured from 300°K to 23°K, and transverse waves from 300°K to 3°K. The adiabatic moduli and compressibility have been computed from the velocities. A new technique for affixing the quartz transducer to the solid for ultrasonic measurements, in suitable solids, below 100°K, has been successfully employed for the measurements in beryllium.
The Vibrational Frequencies of Ethylene
Authors: Arnett Raymond L. , Crawford Bryce L.
Published: January 2005

The infra-red spectrum of a mixture of deuterated ethylenes has been obtained, and the non-planar fundamentals analyzed. The assignment establishes the twisting frequency as 1027 cm−1 (C2H4). This result leads to a new and more satisfactory assignment of the fundamental vibrational frequencies of ethylene.
Classical Thermodynamics and Reaction Rates Close to Equilibrium
Authors: Manes Milton , Hofer L. J. E. , Weller Sol
Published: January 2005

For reversible reactions close to equilibrium the net reaction rate (rf—rb) is shown to be proportional to ΔX, where X is any one of the thermodynamic functions, e.g., the Gibbs free energy, F, governing equilibrium under the conditions of the reaction, e.g., (rf—rb)=rf·—ΔF /RT. The derived relationships are independent of the manner in which small displacements from equilibrium may be brought about. Equations are derived by which the magnitude of the forward (or backward) reaction rate at equilibrium may be determined with the aid of observations of the net reaction rate close to equilibrium. Since the magnitude of the former is a function of the kinetics of the reaction, measurements of the net reaction rate near equilibrium over a range of conditions may be used within specified limits to determine the kinetics of reversible reactions.
Some Studies in Molecular Orbital Theory II. Ionization Constants in Heteroaromatic Amines and Related Compounds
Authors: Longuet-Higgins H. C.
Published: January 2005

The relative basicities of a series of mono-aza-aromatic amines are calculated by a very simple application of LCAO molecular orbital theory. Rough quantitative agreement between theory and experiment is obtained if the heterocyclic nitrogen atom is supposed to take up the proton; on the other hand, if the amine group is assumed to add the proton in the first ionization, the observed basicities are negatively correlated with theory.

It is also shown how the qualitative differences in reactivity between methyl-aza-hydrocarbons and between heteroaromatic phenols may be understood in similar very simple terms.
The Vibrational Spectra of Molecules and Complex Ions in Crystals IV. Ammonium Bromide and Deutero-Ammonium Bromide
Authors: Wagner E. L. , Hornig D. F.
Published: January 2005

The infra-red spectra of thin non-scattering films of NH4Br and ND4Br were obtained at 28°C, −78°C and −190°C. The spectra of both compounds in Phase III are in agreement with the x-ray symmetry, D4h7. The torsional oscillation frequencies occur at 319 cm−1 and 230 cm−1 in NH4Br and ND4Br, respectively. The spectra of Phase II are similar to those of the chloride and indicate a structure in which the NH4+ ions are disordered in their equilibrium orientations. There is no evidence of free rotation at any temperature studied. The spectra support x-ray evidence for a further transition at −100°C in ND4Br to Phase IV which has symmetry Td1 as in NH4Cl.
Specific Magnetic Susceptibilities and Related Properties of Manganese-Activated Zinc Fluoride
Authors: Johnson Peter D. , Williams Ferd E.
Published: January 2005

The specific magnetic susceptibilities of manganese-activated zinc fluoride phosphors of diverse activator concentration, and prepared by various crystallization procedures, have been measured from −60°C to 200°C. A trivial Weiss constant, except for phosphors of inordinately high manganese concentration, demonstrates the absence of appreciable exchange demagnetization of adjacent paramagnetic activator ions and suggests that there exists negligible departure from a random distribution of manganese ions over cation sites. Utilizing this distribution, and recognizing that only manganese ions not having other manganese ions at any of the nearest cation sites are capable of luminescence, an expression for the dependence of luminescent efficiency on activator concentration is derived and found to be in quantitative agreement with experiment.
The Repulsive Potential of Normal Helium Atoms
Authors: Rosen Philip
Published: January 2005

The repulsive potential between two normal helium atoms is calculated using the bond eigenfunction method. It is found that Slater's potential, V(R)=770 exp(−2.43R/a0)×10−12 ergs, must be multiplied by a factor of 2.1 in the region of the minimum of the total potential. By extrapolating to R=0, the energy of beryllium in the ground state is found to be −29.4 Rhc units.
Dielectric Constants of Non-Polar Fluids. I. Theory
Authors: Brown William Fuller
Published: January 2005

The dielectric constant of a classical fluid, composed of spherically symmetric molecules with dipole-dipole interactions, is calculated by a method that leads to formulas previously derived by Yvon but is more direct and yields additional results. The relations of the formulas of Lorentz, Yvon, Kirkwood, and Böttcher to one another are clarified. An accurate calculation of the deviation from the Clausius-Mosotti formula requires knowledge of molecular distribution functions of various orders, but an approximate calculation is possible on the basis of the radial distribution function alone. It is shown that the success of Böttcher's approximation is partly the result of an approximate cancellation of errors, and that a practically equivalent formula can be obtained by another method that lends itself more readily to improvement. The distinctive feature of the present calculation is the introduction of quantities pi(h), the mean moment of molecule i when the positions of it and of h−1 other molecules are specified; Lorentz's formula corresponds to the approximation p1(2)=p1(1), and other formulas to various approximate evaluations of the difference p1(2)—p1(1).
Motions of Molecules in Condensed Systems. VIII. Infra-Red Spectra for Ammonium Nitrate, Thallous Nitrate, and Plumbous Nitrate at −160° and 25°C
Authors: Newman Roger , Halford Ralph S.
Published: January 2005

Envelope structure in the spectra of these substances is shown to depend upon temperature in a way that indicates the presence of both additive and subtractive combinations of lattice modes with molecular modes. At −160°C there are no less than seven distinct satellites on the high frequency side of one band in thallous nitrate with damped out counterparts on the low frequency side. The possibility is considered that a second-order phase transition, as well as a first-order one, may be influencing envelope structure in ammonium nitrate. The spectra for plumbous nitrate contain several features of interest.
Estimated Bond Energies in Carbon, Nitrogen, Oxygen, and Hydrogen Compounds
Authors: Glockler George
Published: January 2005

Estimates of bond energies of CC, CN, CO, NO, OO, NN, CH, NH, and OH bonds are made on the basis of the heat of sublimation of carbon (L(C)) being 7.36 ev and the heat of dissociation of nitrogen (D(N2) = 11.80 ev).
The Use of Single-Crystal Neutron Diffraction Data for Crystal Structure Determination
Authors: Peterson S. W. , Levy Henri A.
Published: January 2005

Intensities of neutron reflections from single crystal specimens of several substances have yielded structure factors in close agreement with calculation and with those measured by the usual powder method. Specimens whose dimensions were in the millimeter range were used. Three materials yielded low results, probably because of extinction in the single crystal specimens. The use of single crystal neutron reflections for crystal structure determination appears practical in many cases.
Excited Triplet States of Some Polyatomic Molecules. I
Authors: McClure Donald S.
Published: January 2005

Molecules in their metastable triplet state are obtained by intense ultraviolet excitation, and the absorption spectrum of the excited molecules is then measured. The conditions needed to obtain the required concentration of excited molecules are shown, and a method for determining this concentration is developed. This enables one to determine the extinction coefficient for the triplet-triplet transition and is an aid in characterizing the new state. The methods are applied to a number of compounds having long-lived triplet states.
The Properties of the Interstitial Compounds of Graphite. I. The Electronic Structure of Graphite Bisulfate
Authors: Hennig Gerhart
Published: January 2005

1. The electrical resistance, its temperature dependence, and the Hall coefficients of graphite bisulfate compounds have been determined at various oxidation stages. The measurements have indicated that the oxidation removes electrons from a nearly full conduction band.

2. Reduction of the lamellar bisulfate compounds produces residue compounds which retain about a third of the bisulfate ions and half the sulfuric acid originally present in the lamellar compounds. The formula of the residue compounds is approximated by Cn·HSO4·4H2SO4.

3. The model of a hypothetical graphite which has lost electrons from its conduction band, is approximated closely by these residue compounds, since the impurities are distributed in a state of high disorder. The lamellar compounds, on the other hand, may distort the band structure of graphite because they form a superlattice.
The Microwave Spectra and Molecular Structures of Trifluorosilane Derivatives
Authors: Sheridan John , Gordy Walter
Published: January 2005

Pure rotational spectra have been measured for the molecules Si28F3H, Si29F3H, Si30F3H, Si28F3Cl35, Si28F3Cl37, Si28F3Br79, Si28F3Br81, and Si28F3CH3. Values of B0 and moments of inertia, IB, are tabulated. The nuclear quadrupole couplings of Cl35, Br79, and Br81 in these molecules have been determined from their hyperfine structures as −43, 440, and 370 Mc/sec, respectively. Molecular dimensions, calculated by assuming the first parameter mentioned to be within the stated limits, are, for SiF3H, dSiH=1.55±0.05A, dSiF=1.561∓0.005A, ∠FSiF=108°6′∓30′; for SiF3Cl, ∠FSiF=108°30′±1°, dSiF=1.560∓0.005A, dSiCl=1.989±0.018A; for SiF3Br, ∠FSiF=108°30′±1°, dSiF=1.560∓0.005A, dSiBr=2.153±0.018A. The special shortness of silicon-halogen bonds is discussed and shown to be related to the electronic structure of silicon. The spectrum of SiF3CH3 shows lines caused by molecules in excited torsional vibrational states, which show additional splitting caused by the doubling of the torsional vibrational levels. From relative intensities the height of the barrier opposing free rotation about the SiC bond is estimated as 1200 cal/mole. From the variations of B0 with torsional vibration, the separations of the doublets in the ground, first, and second torsional vibration levels are estimated as 0.1 cm−1, 1.4 cm−1, and 12 cm−, respectively.
Note on the Theory of Critical Phenomena
Authors: Mayer Joseph E.
Published: January 2005

Zimm's theoretical considerations of the preceding paper are compared with the earlier conclusion of this author. Some of the consequences which must be drawn if one is not to accept Zimm's conclusions are pointed out. It appears that Zimm's conclusions are at least as plausible as this author's earlier hypotheses.
Molecular Orbital Theory of Spectra of Cr3+ Ions in Crystals
Authors: Lohr L. L. , Lipscomb William N.
Published: January 2005

A semiempirical LCAO molecular orbital computer program is used to study optical and magnetic properties of Cr3+ ions in noncubic sites in various host crystals. In particular, it is found that the principal contribution to the zero-field splitting of the 4A2 ground term of t23 in a trigonal field arises primarily from the 2T2 term of t23 and not from the 4T2 term of t23e, as is usually presumed.
Electrical Conductivities of Molten Bi–BiI3 Solutions
Authors: Grantham L. F. , Yosim S. J.
Published: January 2005

The electrical conductivities of Bi–BiI3 solutions were measured above the consolute temperature over the entire composition range. The specific conductance increases continuously and monotonically with increasing metal composition; e.g., at 500°C the increase is from 0.32 for pure BiI3 to 7170 (Ω cm)−1 for the metal. The temperature coefficients of the specific conductance are positive for all compositions except those greater than 80 mole % bismuth. Both a positive and negative temperature coefficient were observed at 80%. The results are discussed in terms of various mechanisms of conductance.
Luminescence Phenomena in Gamma-Irradiated Pure Alkanes at 77°K
Authors: Janssen Onno , Funabashi Koichi
Published: January 2005

Previous reports from this laboratory described the characteristic luminescence of γ-irradiated, pure 3-methylpentane glass and the influence of preirradiation standing time at 77°K on the luminescence intensity (annealing effect: decrease in intensity). In this paper it is shown: (a) that cracks in the annealed glasses are not necessarily required for the annealing effect to be observed, although they apparently accelerate the glass relaxation markedly, and (b) that the luminescence spectra of isopentane are different for the glassy and polycrystalline states. It is also shown, using a simple model, that the lowest charge-separated state can be stationary and lower in energy than the first excited state of the molecule; consequently, the charge-separated state can be the luminescent state for pure alkanes.
Kinetics of CO Formation Studied by Far-uv Flash Photolysis of CO2
Authors: Clerc Michel , Barat Francois
Published: January 2005

A simple, low-energy (100–200 J), short-duration (3-μsec) flash-photolysis apparatus for the vacuum ultraviolet down to the transparency limit of lithium fluoride (1100 Å) is described.

The photolysis of CO2 has been studied. Recombination rate of CO+O(1D) is 2×109 liters mole−1·sec−1 in the presence of a large excess of nonphotolyzed CO2 which may act as a third body. From kinetic considerations, the average lifetime of O(1D) was estimated to be of the order of 50 μsec under these experimental conditions. The fact that O(1D) plays a role is supported by the observation at 1152±0.5 Å of an absorption which could be attributed to the (2p41D−3s11D°) transition known in emission.