bluuebunny/crossref_metadata_2025 huggingface dataset:
Electron Spin Resonance Spectra of Cyclic Ketyls and Ortho-Semiquinones
Authors: Dehl Ronald , Fraenkel George K.
Published: January 2005

Electron spin resonance spectra are reported for the radical anions of fluorenone, 2,7-difluorofluorenone, 4,5-phenanthrylene ketone, 0-phenanthrenequinone, acenaphthenequinone, and benzil. The radicals were generated electrolytically in dimethylformamide solution. Electrolytic reduction of the hydrocarbons fluorene, 4,5-methylenephenanthrene, and 9,10-dihydrophenanthrene resulted in the oxidation of the methylene groups to carbonyl groups. Presumably this oxidation was caused by trace amounts of oxygen in the system. Approximate self-consistent configuration-interaction molecular orbital calculations of the McLachlan type were performed to obtain the spin densities in the radical anions. Good agreement between calculated spin densities and experiment for the planar radicals was obtained by increasing the carbonyl-ring resonance integral above the usual values, and in some cases further improvement resulted from a small decrease in the inter-ring resonance integral.
Electron Mobility in Crystals
Authors: Fixman Marshall
Published: January 2005

A perturbation expansion of the mobility of independent electrons is given and is examined in detail for weak scattering by impurities or intracellular vibrations, and for strong scattering by intracellular vibrations. In the latter case, if the lattice coordinates have a Gaussian distribution, a cell-to-cell random tunneling picture is shown valid for very strong scattering. For weak impurity scattering by random centers of concentration n̄, the correction to the Boltzmann—Bloch mobility is of order n̄lnn̄. The transition between the weak scattering limit, where the Boltzmann equation holds, and the random tunneling limit, where the Boltzmann equation is invalid, is correctly given by the first approximation in which scattering events do not interfere. The perturbations vanish at both extremes.
Nuclear Magnetic Resonance and Molecular Motion in the Benzene—Silver Perchlorate Complex
Authors: Gilson D. F. R. , McDowell C. A.
Published: January 2005

Nuclear magnetic resonance measurements have been carried out on the benzene—silver perchlorate complex at 77° and 298°K. The results show that at the lower temperature the benzene molecule in the complex is more or less rigidly held in the crystal lattice, whereas at room temperature it is rotating more or less freely about the sixfold molecular symmetry axis.
Transition Probabilities in a Dipole-Coupled System of Protons and Delocalized Electrons
Authors: Poindexter Edward H.
Published: January 2005

General expressions are derived for relaxation transition probabilities in a dipole-coupled electron—proton system when the electron cannot be considered as a point-dipole. It is shown that the transition rates always maintain the same ratios to each other, regardless of the distribution of the electron wavefunction. Thus the double-resonance enhancement of the proton NMR signal is not directly affected by the delocalization of the electron. Specific expressions are given for the transition rates in four cases: the electron wavefunction concentrated at one point, equally divided between two points, uniformly distributed over a ring, and uniformly distributed over a disk.
Vibration—Rotation Spectrum of the Perpendicular Bending Modes of CH2N2
Authors: Moore C. Bradley
Published: January 2005

The perpendicular bending fundamentals of CH2N2 have been examined under medium resolution. A new fundamental mode has been identified at 564.0 cm—1 and band centers at 1109.0, 421.2, and 406.0 cm—1 have been located. The assignment of the individual Q branches shows that the three lowest frequency fundamentals are strongly Coriolis coupled. An analysis of the spectrum yields band centers, Coriolis coupling constants, and rotational constants. An improved estimate of the A moment of inertia has been made, giving the HCH angle (126.0°) and the C–H bond length (1.075 Å).
Structure of Molten Oxides. I. Viscosity of GeO2, and Binary Germanates Containing Li2O, Na2O, K2O, and Rb2O
Authors: Riebling E. F.
Published: January 2005

An improved counterbalanced sphere viscometer was used to determine the viscosity of pure molten GeO2 at temperatures from 1470° to 1720°C. This data agrees with the Kurkjian and Douglas data obtained below 1500°C. Activation energy and entropy calculations suggest a gradual thermal breakdown of molten GeO2 compared to SiO2.

Viscosity information was obtained at temperatures between 1000° and 1500°C for binary alkali germanate melts containing up to 32 mole % Li2O, Na2O, K2O, and Rb2O. Viscosity isotherms, activation energies, and activation entropies suggest gross similarities between the viscous flow mechanisms of binary alkali germanate and silicate melts. However, differences of detail imply divergent modes of network alteration with the addition of a given amount of alkali oxide.
Short-Range Interactions of Aqueous Ions
Authors: Magnusson L. B.
Published: January 2005

Data on the 1–1 fluoride complex ion with noble-gas-type cations are examined for information on short-range ion—ion and water—ion interactions. A four-term numerical correlation of the standard free energies with the size and charge of the ion is developed based on the approach that electric saturation is not directly important to the complex formation. Deviations from the classical point charge Coulomb energy are expressed by a term independent of temperature and the dielectric medium, exponential in the separation distance, and containing only fundamental quantities which suggest wave-mechanical interaction between cation and anion. The total standard entropy change separates into three terms; the temperature dependence of the macroscopic dielectric constant, the removal of coordinated water, and the cratic term for the change in the number of solute particles. A screened charge model of the hydrated ion is proposed in which hydration is the loss of the quantum-mechanical free energy of the gaseous ions by the formation of covalent bonds with the water. The ion charge is delocalized, spreading out to the coordinated water. The degree of hydration depends on the free energy of the water, with the free energy for coordination of the last water molecule being less than 1 kcal.
Catalytic Effects in the Transformation of Graphite to Diamond
Authors: Strong H. M.
Published: January 2005

The transformation graphite to diamond is catalyzed by the Group VIII metals, manganese and chromium. The fact that these metals are good solvents for carbon tends to obscure their catalytic role in this transformation. It was found that copper-rich copper—nickel alloys capable of dissolving less than 0.06 at. % carbon catalyzed the formation of diamond whereas lead and antimony having about equal solvent capacity did not. The diamond nucleation rate increased exponentially with nickel concentration in the copper-rich alloys. Hence, on the basis of the theory that nucleation catalysts provide surfaces of low interfacial energy, one important role of the nickel in these alloys may be interpreted as that of reducing the interfacial energy between diamond and alloy.
Enhanced Oxidation of Platinum in Activated Oxygen
Authors: Fryburg George C.
Published: January 2005

An enhanced oxidation of platinum has been observed in moist activated oxygen, and the cause of this enhancement has been investigated. The surface oxidation was examined at 1000°C and 0.50 mm Hg pressure of oxygen, and the rate was found to be markedly increased by the oxygen atoms. The reaction was found to obey a linear law of the form ω= (k+k2n0)t, where n0 is the number of oxygen atoms striking unit area of the platinum per second. Oxygen atoms were shown to be at least 400 times more reactive than oxygen molecules.
Solution of a Characteristic Value Problem from the Theory of Chain Molecules
Authors: Zimm Bruno H. , Roe Glenn M. , Epstein Leo F.
Published: January 2005

An eigenvalue problem encountered in the dynamical theory of chain molecules is ∫ −11α′′(s)(|r−s|)−12ds=−λα(r),α′(±1)=0.This is solved by three methods: use of a Fourier series for α, expansion of α in associated Legendre polynomials Pm2, and by a variation method. The eight smallest eigenvalues are calculated explicitly and an approximate formula is found for the remaining ones. Formulas are found also for the eigenfunctions.
Thomas-Fermi Model of Compressed Atoms
Authors: Latter Richard
Published: January 2005

Solutions of the zero-temperature Thomas-Fermi equation for an atomic system have been obtained by numerical integration with the aid of the IBM 701 Defense Calculator. The complete range of atomic volumes of physical interest has been covered in sufficient detail to permit accurate interpolation to intermediate regions. Tables of the potential distributions are given as well as of the important physical properties.
Mass Spectrometric Investigation of the Hydrogen-Oxygen and Methyl-Oxygen Reactions
Authors: Ingold K. U. , Bryce W. A.
Published: January 2005

The reactions of hydrogen and of methyl radicals with oxygen have been studied by means of a mass spectrometer designed to detect free radicals. The reactants were present at low pressures in a stream of helium. Radicals detected were OH and HO2 in the hydrogen-oxygen reaction, and CH3O, CH3O2, OH, HO2, CH2, and probably CHO in the methyl-oxygen reaction. A rough value of 10—3 to 10—4 was obtained for the collision efficiency of the oxygen+methyl radical reaction.
Statistical Mechanical Theory of Transport Processes. IX. Contribution to the Theory of Brownian Motion
Authors: Ross John
Published: January 2005

The equations of Brownian motion are derived from Liouville's equation in a treatment which parallels Kirkwood's statistical mechanical analysis but which is based upon the theory of phase space transformation functions. The transformation function obeys Liouville's equation and thus expresses the equations of motion; it is obtained as a solution of that equation by a consistent method of successive approximations which treats the forces as perturbations. Retention of first-order terms only in this solution leads to the Chandrasekhar equation and yields a tractable relation between the friction constant and the intermolecular forces. The restrictions imposed by the present derivation on the molecular interpretation of the equations of Brownian motion are discussed.
Infrared Study of the B2D6–B5H9 Exchange Reaction
Authors: Kaufman Joyce J. , Koski W. S.
Published: January 2005

An infrared spectroscopic study of partially deuterated pentaborane samples prepared by exchanging deuterium between diborane and pentaborane has been made. A comparison of these data with corresponding mass spectroscopic measurements shows that when this exchange takes place at 80°C only the nonbridge hydrogen positions in the pentaborane are involved.
Vibrational Spectra of Fluorinated Aromatics. X. p-Fluorochloro-, p-Fluorobromo-, and p-Fluoroiodobenzene
Authors: Narasimham N. A. , El-Sabban M. Z. , Nielsen J. Rud
Published: January 2005

The infrared absorption spectra of liquid p-fluorochloro-, p-fluorobromo-, and p-fluoroiodobenzene, and the stronger bands of the first two compounds in the gaseous state, have been obtained in the region 2—38μ with NaCl and CsBr prisms. The Raman spectra of the compounds in the liquid state have been photographed with a 3-prism glass spectrograph of linear dispersion 15 A/mm at 4358 A, and depolarization ratios have been measured for the stronger Raman bands of p-fluorochloro- and p-fluorobromobenzene. Complete assignments of the fundamental vibrational frequencies have been made, and the spectra are interpreted in detail.
Electronegativities of the Elements
Authors: Gordy Walter , Thomas W. J. Orville
Published: January 2005

Electronegativity values derived from various methods are compared, and a complete electronegativity scale is arranged for all the elements. A chart is given which shows a systematic relation of electronegativity to the periodic system of the elements. A linear relationship is found between electronegativity and the work function of metals.
Surface Area and Particle Size of Evaporated Lead Sulfide Films
Authors: Harada Roy H.
Published: January 2005

Physical adsorption isotherms of lead sulfide films evaporated in vacuum and through oxygen were measured in order to determine their surface area and particle size. The surface areas of fresh and of annealed vacuum evaporated films were found to increase linearly with film thickness. Annealing the films in vacuum decreased the surface area considerably. The average specific surfaces of the fresh and annealed films were 63 m2/g and 6 m2/g, corresponding to particle sizes of 0.013μ and 0.13μ, respectively. The surface area of fresh films evaporated through oxygen depended upon the rate of evaporation. The average specific surface of the fresh slowly evaporated films was 66 m2/g; for those evaporated faster, it was 118 m2/g. The corresponding particle sizes were 0.012μ and 0.0068μ. When these films were annealed in a closed vacuum system, the specific surface became 12 m2/g and 14 m2/g, corresponding to particle sizes of 0.067μ and 0.056μ, respectively.

For films evaporated through oxygen, the oxygen is chemisorbed on the surface of the film during evaporation. When such a film is annealed sulfur dioxide is evolved and sulfate is formed.
Refinement of the Lennard-Jones and Devonshire Theory of Liquids and Dense Gases
Authors: Taylor William J.
Published: January 2005

The Lennard-Jones and Devonshire (LJD) theory of liquids represents an advance over the early free-volume theories, in that each molecule is assumed to move in a potential field generated by its neighbors. However, this potential is the static field computed with each neighbor at its equilibrium position (cell center), so that the LJD theory does not take account of the correlation of the motion of neighboring molecules. This correlation problem is treated in the present paper by recasting the exact classical partition function in a form in which the LJD potentials appear in the principal terms, while certain correlation potentials appear in correction terms. The resulting integrals are analogous to those appearing in the conventional theory of an imperfect gas, but with the correlation potential playing the role of the usual intermolecular potential, and the range of integration of each molecule limited to its own cell (where it is also subject to the static LJD potential). A practical method of evaluation of the integrals is developed, based on power series expansions of the factors containing the correlation potentials.

The limitation of each molecule to a single cell (single occupancy) is not an essential feature of the theory. The allowance for multiple occupancy of the cells leads to the communal entropy correction, which has been treated by Pople and others. The present correction for correlation of neighboring molecules is applicable even for single occupancy, and is thus an addition to the communal entropy correction.

The method is compared with Kirkwood's self-consistent field modification of the LJD theory, which takes some account of correlation, but only in an average sense. Comparison is also made with the recent cell-cluster theory of de Boer, which was in fact antedated by the present work (see footnote). The two theories are basically equivalent, in spite of their different formulations. It is felt that the present method puts the integrals in a form more practical for calculation.
Molecular Orbital Treatment of Conjugation in Vinyl Chloride, with Inclusion of Overlap
Authors: Goldstein J. H.
Published: January 2005

Simple molecular orbital theory, with inclusion of all overlap effects, has been applied to the problem of conjugation in vinyl chloride. Using the value of —2.45 ev for the carbon-chlorine exchange integral, —10.64 ev for αC1 as calculated from atomic ionization potentials, and other parameters assumed equal to the ethylene values, values of 9.99 ev and 0.063 are calculated for the ionization potential and chlorine py-electron defect resulting from conjugation. These results are in good agreement with the experimental values, 9.95 ev and 0.06, respectively. A convenient distribution matrix treatment is described and some of the effects of neglect of overlap are discussed.
Quantum-Mechanical Study of the Inductive Effect
Authors: Cahill Joseph M. , Mueller Charles R.
Published: January 2005

The inductive effect of a carbonyl group on an adjacent carbon-carbon bond is investigated by means of the semilocalized orbital method. The electronic structure of the isolated bonds is calculated and then the result of their interaction is investigated. The inductive effect is found to be of sizeable magnitude and to originate largely from the field of the oxygen atom. Propagation of the inductive effect by means of successive distortion of valence orbitals, through the bond, appears to be less important.
Electronic Structures of NH, NH2, and NH3
Authors: Higuchi Jiro
Published: January 2005

LCAO MOs have been calculated for the ground states of NH, NH2, and NH3 at various bond angles, using the LCAO—SCF method. Interactions between all electrons have been considered, but the orthogonality relationship between the 1s orbitals of nitrogen and hydrogen has been assumed. The MOs and the orbital energies disclose strong parallelisms between the a1 and the σ sets and between the b2 and the e sets, but the s-p hybridization increases with the number of hydrogen atoms. The MOs have also been investigated by a unitary transformation to the localized symmetry orbitals, and the binding energies of orbitals have been compared with Walsh's MO energy diagram. The dipole moments evaluated without configuration interaction have been discussed in comparison with the contributions of lone-pair electrons. Lower electronic states have also been calculated using the same MOs. The results obtained are in relatively good agreement with observations, but the first excited state of NH3 cannot conclusively be determined because of the disregard of the 3s orbital of nitrogen.
Asymmetric Rotor. Convergence in the Continued-Fraction Expansion of the Reduced Energies
Authors: Posener D. W.
Published: January 2005

Computation of the energy levels of the asymmetric rotor often involves the use of successive approximations which may converge slowly to the required result. The theory of convergence in the continued-fraction expansion of the reduced energies is here discussed and used to derive corrections which, where necessary, materially reduce the computational effort involved in obtaining solutions.
Spectroscopic Properties of Organic Photoconductors. II. Specular Reflection Spectra of Cationic Dye Films
Authors: Weigl John W.
Published: January 2005

The specular reflectivity of solid dye films has been measured at 12° incidence, by means of a new device attached to the Beckman Quartz Spectrophotometer. The observed spectra are in general agreement with the results of dispersion theory.
Some Vibration-Rotation Bands of Ketene
Authors: Arendale William F. , Fletcher William H.
Published: January 2005

Several vibration-rotation bands of ketene have been resolved with a grating spectrometer and the rotational constants obtained from the subsequent analysis. Parallel bands of CH2CO and CD2CO yield B0 values of 0.3403 and 0.2952 cm—1, respectively. Strong and apparently complicated interactions prevent a satisfactory analysis of the perpendicular bands, but the methylene rocking and wagging bands appear to have origins at 978 cm—1 and 788 cm—1, respectively. The low frequency perpendicular bands have been re-examined with a prism instrument, but with increased resolution. Analysis gives 588 cm—1 and 528 cm—1 for the band origins.
Monolayers of Linear Macromolecules
Authors: Frisch H. L. , Simha Robert
Published: January 2005

A model is proposed for monolayers composed of linear macromolecules, particularly at an oil/water interface. If the polymer at the interface is sufficiently flexible, the layer will consist of anchored portions connected by bridges of segments lying out of the plane in which the anchored segments are deposited. An equation of state for the monolayer is derived and its limiting form is compared with those due to Singer and Bull. The limiting form of our equation of state seems to be in satisfactory agreement with some published experimental data. These results suggest the possibility of obtaining rough indications of the shape and mean dimensions of the macromolecule at the interface from film studies at both the air/water and oil/water interface. Finally the application of this model to explain the apparent dissociation of protein monolayers is indicated.
Microwave Determination of the Structure of Pyrrole
Authors: Bak Bo/rge , Christensen Daniel , Hansen Lise , Rastrup-Andersen John
Published: January 2005

A number of deuterated pyrroles have been prepared and their microwave spectra recorded. For each isotopic species the two 1→2 transitions observable around 20 000 MHz were localized together with a number of Q-lines in the 17 400—26 000 MHz region scanned. For all isotopic molecules rotational constants were calculated. In this way seven mutually independent numerical data were obtained which is insufficient for a direct calculation of the nine geometrical parameters of pyrrole. Additional assumptions as to the length of the two C, H bonds lead to definite models for pyrrole.
Relative Rates of Isomerization of Cyclopropane and Cyclopropane-t1
Authors: Lindquist R. H. , Rollefson G. K.
Published: January 2005

The relative rates of isomerization of cyclopropane and monotritiated cyclopropane have been determined in the temperature range of 447° to 555°C. The ratio of the rate constants for the two reactions can be fitted by the equation: k/k′=0.63±0.02 exp(825±60/RT).

The marked increase in the temperature-independent term upon tritium substitution is discussed in terms of Slater's unimolecular reaction rate theory and Eyring's absolute reaction rate theory. The possibility of classical vibration coupling causing the observed effect is suggested.
Proton Conductance and the Existence of the H3O· Ion
Authors: Conway B. E. , Bockris J. O'M. , Linton Hedda
Published: January 2005

Measurements of the conductance of HCl in water, methanol, ethanol, n-propanol, ethylene glycol, glycerol, 1:4 dioxane, acetone, formic, and acetic acids and the respective aqueous-nonaqueous systems have been made as a function of concentration of water and HCl. The degree of anomalous proton conductance decreases with increasing n in CnH2n+1OH, and conductance minima occur in aqueous alcoholic HCl solutions of low H2O content.

Former theories of proton conductance have permitted no quantitative distinction to be made between the rates of classical proton transfer, quantum-mechanical tunneling transfer, and water rotation as rate determining stages. If resonance in H3O· is set up sufficiently quickly after arrival of a given proton at a water molecule, rotation of H3O· cannot be a rate determining step.

Detailed calculations of the rates of classical proton transfer, tunnel transfer, and the rate of rotation of water are made. Classical transfer is much slower and tunnel transfer much faster than corresponds to the observed proton mobility; rotation of hydrogen bonded water molecules near the H3O· ion is the rate determining reaction (preceded and succeeded by fast tunneling of protons). This conclusion is quantitatively consistent with the OH′ mobility in water, and the H·/D· mobility ratio and qualitatively consistent with pressure and temperature effects and with the absence of abnormal mobility of NH4· and NH2′ in liquid NH3. A detailed interpretation of the dependence of abnormal conductance upon chain length in ROH gives fair quantitative agreement with experiment. The conductance minima observed in aqueous alcoholic HCl are quasi-quantitatively predicted by the theory.

The proton spends about 1% of its time undergoing tunnel transfers; the effective existence of the H3O· ion is thus confirmed.
Photolysis of Ethane at 1470 A
Authors: Wijnen M. H. J.
Published: January 2005

The photolysis of ethane at 1470 A has been investigated in the temperature range 25° to 240°C and over a wide range of initial ethane pressures. As reaction products were found mainly H2, CH4, C3H3, and C4H10. Traces of ethylene and, not identified, higher hydrocarbons were also detected. The results indicate that the primary step in the photolysis of ethane is C2H6+hν→C2H5+H.The amounts and ratios of products, formed during the photolysis, indicate that the reaction mechanism of the photolysis is similar to that of the Hg photosensitized decomposition of ethane.

A few experiments on the photolysis of CO2 at 1470 A indicate that[open phi]CO increases with increasing temperatures.
Evaporation of Perfect Crystals
Authors: Sears Gerald W.
Published: January 2005

Evaporation from a perfect face of a paratoluidine crystal does not occur until a critical undersaturation is reached. The vaporization kinetics may be rationalized by postulating that the evaporation rate is limited by two-dimensional nucleation of monolayer holes.
Flame Zone Studies. II. Applicability of One-Dimensional Models to Three-Dimensional Laminar Bunsen Flame Fronts
Authors: Fristrom Robert M.
Published: January 2005

The applicability of one-dimensional models in flame theories has been investigated experimentally in the case of a lean quarter-atmosphere propane air flame. Studies of flow patterns through the flame fronts were made using particle track techniques. From this time-position information, normal gas velocity, stream tube area, and gas density were calculated throughout the flame front. If the density is a single valued measure of the state of the gas, then one-dimensional models can be tested for Bunsen flames. Unidimensionality was verified for this and several other propane-air flames under a number of conditions. In the reaction region preceding the luminous zone it was also found that the velocity and density profiles were invariant with respect to changes in flame geometry, gas flow, and burner diameter. Therefore, it is a good approximation to speak of single reaction path for this flame, which is a function only of the initial state of the gas.

The measurements indicate that one-dimensional flame theories should be modified to include the effects of area expansion during the course of the reaction. Continuity, diffusion, and heat conduction equations should also be generalized to include the effect of expansion. It was noted that the hydrocarbon flame reaction consists of two regions: a fast propagating reaction associated with the luminous regions and the major portion of the heat release and a slow secondary reaction associated with the post luminous mantel of the flame. Flow in the primary region is a function only of the initial state of gas and independent of external influences such as gas velocity and flame geometry. Flow in the secondary region could be varied over wide limits with no measureable effect on the propagation of the flame.

Burning velocity was found to be independent of gas velocity, flame geometry, and radius of curvature of flame front, and a function only of the initial state of the gas, providing it was defined as the minimum normal gas velocity ahead of the flame front. A discussion is given of the errors introduced by measuring burning velocity by flow measurements in the throat of the burner.
Zeeman Quadrupole Spectra of p-Chloroaniline and p-Chlorobenzylchloride
Authors: Meal Harlan C.
Published: January 2005

Analysis of the Zeeman quadrupole spectra of Cl35 in single crystals of p-chloroaniline and p-chlorobenzylchloride yields the following information: There are two sets of chlorine atoms in the p-chloroaniline crystal with differently oriented electrical field gradients. The angle between the field gradient z-axes is 79°±1°; the y-axes are parallel. Both field gradients have the same asymmetry, η=0.06±0.03. In p-chlorobenzylchloride there are four sets of chlorines (attached directly to the ring) which have differently oriented field gradients. The z-axes are parallel to the edges of a rectangular pyramid with apex angles of 8° and 67°, both ±1°. All four have the same asymmetry, η=0.07±0.02.

The bond between the chlorine and the ring is calculated to have 2.0±1.0% double bond, 79±10% single bond and 19±10% ionic character in p-chloroaniline; 2.4±0.7% double bond, 80±10% single bond and 17±10% ionic character in p-chlorobenzylchloride. The large uncertainty in the single bond and ionic characters results from the uncertainty in the hybridization of the chlorine bonding orbital.
Infrared Spectra of Gaseous and Solid Digermane
Authors: Dows David A. , Hexter R. M.
Published: January 2005

The infrared spectra of gaseous and solid Ge2H6 have been studied in the spectral region 400—4000 cm—1. The infrared-active fundamental frequencies are as follows: A2u: 2078, 755; Eu: 2114, 898, and 407 cm—1. Assignment of combination bands gives the remaining fundamentals: A1g: 2070, 765, 229; A1u: 144; Eg: 2150, 875, and 417 cm—1. From the torsional frequency, a cosine barrier to internal rotation is 1200 cal. The structure of the perpendicular band at 898 cm—1 has been resolved, giving information connecting the Coriolis constant for this vibration with the molecular structure parameters.

The spectrum of the solid, obtained at 90°K, shows only those fundamentals active in the gas phase. Small splittings or satellites are observed, and possible crystal symmetries are suggested.
On the Second Virial Coefficients for Assemblies of Nonspherical Molecules
Authors: Castle Barbara J. , Jansen Laurens , Dawson John M.
Published: January 2005

A method of calculating the second virial coefficients for nonspherical molecules is presented which differs from the usual procedure in the following ways:

(a) The long-range directional forces between molecules are generally represented by a multipole expansion of the Coulomb interaction; this expansion is not valid for small intermolecular distances. However, these forces are usually extended into the region of small separations between molecular centers in the calculation of the second virial coefficients. The magnitude of the error introduced by this extension is investigated and found to be appreciable. The customary method is modified in such a way that the long-range orientational forces are cut off inside the molecular diameter r0.

(b) Effects resulting from anisotropy in the London forces are taken into account. It is shown that this component of the directional field is usually predominant, even for molecules with large quadrupole moments.

(c) Induction forces are considered, especially those resulting from permanent quadrupole moments. It is found that the effect of these forces is, in general, not negligible.

The results are applied to an evaluation of the second virial coefficients for carbon dioxide, nitrous oxide, nitrogen, carbon monoxide, ethane, and ethylene. A comparison is made between the effects of the long-range directional forces on the physical properties of nitrogen, carbon monoxide, and carbon dioxide in the gaseous state and in the crystal.
On the Theory of Oxidation-Reduction Reactions Involving Electron Transfer. I
Authors: Marcus R. A.
Published: January 2005

A mechanism for electron transfer reactions is described, in which there is very little spatial overlap of the electronic orbitals of the two reacting molecules in the activated complex. Assuming such a mechanism, a quantitative theory of the rates of oxidation-reduction reactions involving electron transfer in solution is presented. The assumption of ``slight-overlap'' is shown to lead to a reaction path which involves an intermediate state X* in which the electrical polarization of the solvent does not have the usual value appropriate for the given ionic charges (i.e., it does not have an equilibrium value). Using an equation developed elsewhere for the electrostatic free energy of nonequilibrium states, the free energy of all possible intermediate states is calculated. The characteristics of the most probable state are then determined with the aid of the calculus of variations by minimizing its free energy subject to certain restraints. A simple expression for the electrostatic contribution to the free energy of formation of the intermediate state from the reactants, ΔF*, is thereby obtained in terms of known quantities, such as ionic radii, charges, and the standard free energy of reaction.

This intermediate state X* can either disappear to reform the reactants, or by an electronic jump mechanism to form a state X in which the ions are characteristic of the products. When the latter process is more probable than the former, the over-all reaction rate is shown to be simply the rate of formation of the intermediate state, namely the collision number in solution multiplied by exp(—ΔF*/kT). Evidence in favor of this is cited. In a detailed quantitative comparison, given elsewhere, with the kinetic data, no arbitrary parameters are needed to obtain reasonable agreement of calculated and experimental results.
Vibration—Rotation Interaction in Polyatomic Molecules. I. The Zeta Matrices
Authors: Meal Janet Hawkins , Polo S. R.
Published: January 2005

Some properties of the zeta matrices which simplify the analytical treatment of vibration-rotation interaction are given. Methods of obtaining relationships among the zeta elements which depend only on the atomic masses and geometry of the molecule are outlined and some examples are discussed. Symmetry arguments are introduced to simplify the results further.
Electronic and Vibrational States of Tetracene (Naphthacene)
Authors: Sidman Jerome W.
Published: January 2005

The absorption and fluorescence spectra of tetracene have been studied in substitutional solid solutions in naphthalene and in anthracene at 20°K. In agreement with theoretical predictions, the lowest excited singlet state at 20 246 cm—1 is 1B2u, 1La, since the transition with the ground state is polarized along the short molecular axis. Vibrational frequencies of tetracene are compared in ground and excited electronic states, and are compared with the vibrations of anthracene and naphthalene.
Influence of Adsorbed Films on Crystal Growth Kinetics
Authors: Sears Gerald W.
Published: January 2005

The growth kinetics of crystals are appreciably altered by strongly adsorbed films. The growth steps are inoperative or poisoned below a critical supersaturation. Since this supersaturation for poisoning is much less than the supersaturation level for two-dimensional nucleation, the effect should only be observable for the growth of imperfect crystals.
Nuclear Magnetic Resonance : Structure of the Amino Group. II
Authors: Moulton W. G. , Kromhout R. A.
Published: January 2005

The nuclear magnetic resonance spectra of powder samples of hydroxylamine hydrochloride and oxamide have been obtained. N–H bond distances were calculated to be 1.036±0.025 A in formamide, and 1.039±0.013 A in oxamide, assuming a 120° bond angle and a planar structure in each case. An attempt is made to correlate the N–H bond lengths with the hydrogen bond length by a modification of Lippincott's theory of the linear O≡O hydrogen bond.

The rigid lattice second moment of cyanamide was also measured. The result is not consistent with the assumption of an ammonia-like N–H bond structure, but requires a larger H–H separation.
Charge Distribution in the Pentaboranes
Authors: Lipscomb William N.
Published: January 2005

A study of free electron distributions in a hemispherical box and a hemispherical shell, and a study of simplified LCAO models for B5H9 and B5H11, indicates the general nature of the charge distribution in these highly unsymmetrical molecules.
Spectroscopic Studies of Reactive Molecules by the Matrix Isolation Method
Authors: Becker Edwin D. , Pimentel George C.
Published: January 2005

The matrix isolation method for the study of reactive molecules is described. The properties that should be possessed by a material suitable for use as a matrix are discussed with particular reference to spectroscopic investigations. Tests of the method have been conducted with infrared spectroscopic techniques using the free radical NO2 and the hydrogen bonding molecules HBr, HCN, HN3, NH3, and H2O. Xenon, nitrogen, and argon are effective as matrices in isolating these molecules at 20°K with a mole ratio of matrix to active material in the range 100:1 to 500:1. The vibrational frequencies of these molecules isolated in a matrix are nearly the same as the frequencies in the gas phase.
Phosphorescence Spectra of the β-Halonaphthalenes
Authors: Sidman Jerome W.
Published: January 2005

The 3La→1A phosphorescence spectra of the β-halonaphthalenes have been studied at 20°K in crystals and in dilute solid solutions in naphthalene and in each other. No phosphorescence was observed at 300°K or at 77°K in the pure or mixed crystals. The phosphorescence spectra at 20°K are sharp in the solid solution in naphthalene, whereas the spectra of the pure crystals or of the solid solutions in the β-halonaphthalenes are broad. The spectra are similar in energy and vibrational structure. The vibrational frequencies which appear in the spectrum can be related to those of naphthalene. From the vibrational analysis, it is concluded that the molecule possesses the same elements of symmetry in both ground and triplet states.

Quenching by impurities in the purest obtainable crystals of naphthalene made it impossible to observe the naphthalene phosphorescence.

The causes for broadening in low-temperature electronic spectra are discussed.
Near Infrared Spectra of Diborane, Pentaborane, and Decaborane
Authors: Pondy P. R. , Beachell H. C.
Published: January 2005

Spectra of diborane, pentaborane, and decaborane have been examined in the near ir at high resolution. Assignment of the observed frequencies for diborane have been made. Pentaborane has been subjected to group theoretical reduction considerations to ascertain which overtone frequencies are ir active for this molecule. On the basis of the data obtained, bond energies, bond distances, and force constants have been calculated for the B–H bond in each of these molecules. Spectral structure comparisons of diborane, ethane, and ethylene have been made.
Space-Charge Formation in Small PbS Particles
Authors: Minden Henry T.
Published: January 2005

A theoretical model is discussed for the effect of oxygen on the electrical properties of PbS thin films. The films are assumed to be composed of very small n-type microcrystals, on the surface of which oxygen is adsorbed. The adsorbed atoms are singly ionized by electrons from the interior of the microcrystals. The appropriate Poisson-Boltzmann equation is solved for particles of radius 5×10—8 m and 5√10×10—8 m, and for donor concentrations of 1023 m—3 and 1024 m—3. The potential distribution is given as a function of the surface acceptor concentration required for the conservation of charge.

Models for the electron and hole conductivities are given, and the results of calculations based on these models are compared with experiment. This theory is contrasted with the earlier bulk diffusion theory of the effect of oxygen. The free energy of adsorption is roughly calculated. Implications of this theory are discussed—on the general character of conduction in PbS films, on the temperature coefficient of conduction, and on the nature of photoconduction.
Nuclear Magnetic Interactions in the HF Molecule
Authors: Solomon I. , Bloembergen N.
Published: January 2005

Magnetic relaxation times of hydrogen and fluorine in anhydrous hydrofluoric acid cannot be accounted for on the assumption of a pure dipole-dipole interaction between the hydrogen and the fluorine nuclei in the same molecule. However, the introduction, in the Hamiltonian, of a scalar term AI·S resulting from the indirect electron-coupled interaction between the two nuclei removes all the discrepancies between the calculated and observed decay times. Although the splitting due to this scalar term is smeared out by the rapid chemical exchange of the protons with the traces of water present in the acid, the nuclear Overhauser effect provides the extra parameter required to separate the dipole-dipole interaction from the scalar interaction and to calculate separately the scalar splitting and the exchange rate of the protons. The value obtained for the splitting is A/h=615 cps.

The same method has been applied to investigate the structure of the HF molecule in solutions. The experimental results can be explained qualitatively by the following picture: (a) The fluorine nuclei form long chains that move more slowly than the Larmor frequency of fluorine. (b) The chemical exchange with the relatively large quantity of water present makes the motion of the hydrogen nuclei fast with respect to the hydrogen Larmor frequency. The results are: Long relaxation times for hydrogen with T1 and T2 equal, relatively short relaxation times for fluorine resonance, with T2 shorter than T1.

Solutions of salts of hydrofluoric acid (KF) show the same character as solutions of the acid.
Treatment of the Equations of Classical Diffusion in Homogeneous Isotropic Media
Authors: O'Sullivan D. G.
Published: January 2005

A method is described which utilizes a generalized convolution to produce simplification of the equations of a wide range of classical diffusion processes. The resulting transformation expresses the solutions to these equations in terms of solutions for much simpler problems, many of the latter being already available in textbooks. Demonstrations are given of the use of this method in the facile development of the required concentration mappings for certain systems.
Photochemical Oxygen-Hydrogen Reaction at 1849 A
Authors: Volman David H.
Published: January 2005

The photochemical reaction between oxygen and hydrogen was studied at atmospheric pressure in a flowing system using the 1849.6 A mercury resonance line as a light source. The yields of hydrogen peroxide, water and ozone were determined. The results obtained in this work above the convergence limit of the oxygen molecule absorption spectrum are in agreement with those obtained in other studies below the convergence limit. The predissociation of oxygen molecules to form oxygen atoms as the primary process following light absorption is shown to be the only reaction of optically excited oxygen. The mechanisms used to explain the formation of products, ozone, hydrogen peroxide and water, are compatible with well-known reactions in various oxygen-hydrogen systems.
Physical Basis of the Free-Electron Gas Model of Branched Molecules
Authors: Kuhn Hans
Published: January 2005

The postulatory nature of the electron gas model is discussed. It is pointed out that the one-dimensional waves introduced in the model are not wave functions in the strict quantum-mechanical sense, since they are not solutions of a clear-cut quantum-mechanical problem. Rather, the free electron model is to be viewed as a device which, similar to the vector model of atomic spectral terms, predicts on the basis of simple calculations the result of rigorous quantum-mechanical treatments. The value of the postulates of the free-electron model is indicated by how well the one-dimensional waves imitate the results of the strict treatment. It is shown that a recently given alternate postulate regarding the treatment of branch points leads, in this respect, to an improvement of the model.
Thermal Diffusion in Krypton and Argon
Authors: Corbett J. W. , Watson W. W.
Published: January 2005

The mathematical description of a two-bulb thermal diffusion experiment is extended to the case of multicomponents isotopic mixtures. A self-consistent method of comparing two-bulb data to theoretical predictions is developed and applied to the argon data of Stier. The best fit for the modified Buckingham exp-six, α=14, intermolecular potential model is obtained for a force constant, ε/k=110°K. Measurements of the thermal diffusion factor of krypton versus temperature are presented and compared to the Lennard-Jones (9,5) and (13,7) and the modified Buckingham exp-six, α=14 models, yielding the force constant values, ε/k=169, 395, and 470°K, respectively.
Microwave Absorption and Molecular Structure in Liquids. XIII. The Critical Wavelengths of Some Aliphatic Ethers and Long-Chain Ketones
Authors: Rathmann G. B. , Curtis A. J. , McGeer P. L. , Smyth C. P.
Published: January 2005

The dielectric constants and losses of ethyl ether, n-decyl ether, n-heptanone-2, n-pentadecanone-8, n-heptadecanone-9, and benzophenone, and of solutions of benzophenone in heptane and in a 50–50 mixture of heptane and benzene have been measured at wavelengths of 1.25, 3.22, and 10.0 cm at temperatures between 4 and 85°. The arc plots constructed from these data and the measured low-frequency dielectric constants have been used to calculate the critical wavelengths at which the loss is a maximum. Several molecules of similar sizes and shapes are shown to possess similar viscosities and critical wavelengths. For the pure polar liquids, a rough proportionality between the critical wavelengths or dielectric relaxation times and the viscosities is observed.
Self-Diffusion in Liquid Argon
Authors: Corbett J. W. , Wang J. H.
Published: January 2005

The self-diffusion coefficient of liquid argon was measured by the capillary technique. The average value of D at 84.31∓0.13°K and 658∓12 mm of Hg is (2.07∓0.06)×10—5 cm2/sec.
On the Burning Rate of Carbon Monoxide
Authors: Friedman Raymond , Cyphers Joseph A.
Published: January 2005

Burning velocity measurements of the CO–O2–N2–H2O system were made with the flat-flame burner technique. The plan of experimentation was to vary the H2O content, the equivalence ratio, and the pressure, while holding the flame temperature constant by controlling the proportion of N2 in the mixture. The results could be represented empirically by the relation: vu2=3.8×106(CO)u(H2O)u0.5(P/Patmos)−0.24e−11 130/Tb,where vu is burning velocity (cm/sec), (CO)u and (H2O)u are mole fractions in the unburned gas, P is pressure, and Tb is burned-gas temperature. The Zeldovich, Frank-Kamenetsky, and Semenov equation was used to obtain an ``over-all'' activation energy (20 kcal) and frequency factor for the process, and the CO oxidation rate in this type of flame was then compared with the rate at which the CO forming as an intermediate in a lean hydrocarbon-air flame is oxidized in the downstream portion of such a flame. The comparison showed that, at comparable conditions, the CO oxidized 5.6 times as fast in the CO flame as in the hydrocarbon flame. Temperature traverses in hydrocarbon-air flames to which large proportions of H2O have been added showed the rate of CO oxidation to be slightly increased thereby.

Equilibrium concentrations of the species H, OH, and O in the burned gases were calculated for a variety of CO–O2–N2–H2O mixtures, all at the same flame temperature, and correlations with burning velocity were sought. The square of the burning velocity was found to be directly proportional to (OH)b(CO)b0.72; alternatively, the group (H)b(O2)b0.136 gave equally good correlation. A third successful grouping was [(H)b+0.15(OH)b]½. The writers are not convinced that correlations of this type reveal the burning mechanism.