bluuebunny/crossref_metadata_2025 huggingface dataset:
On the Theory of Oxidation-Reduction Reactions Involving Electron Transfer. II. Applications to Data on the Rates of Isotopic Exchange Reactions
Authors: Marcus R. A.
Published: January 2005

The rates of some homogeneous isotopic exchange reactions in solution are considered in the light of a recently developed quantitative theory of redox processes (Part I). The relative importance of several factors influencing the rates of these reactions is discussed. These factors include the Coulombic repulsion between the ionic reactants and the extent of solvation of the ions. Free energies and entropies of activation of various reactions are calculated from the theory without the use of any adjustable parameters. The agreement with the experimental data is considered to be satisfactory.

On the basis of the theory and of earlier experiments in heavy water an experimental method is tentatively suggested for distinguishing electron and atom transfer mechanisms. This method applies to halide-catalyzed exchange reactions of metal aquo-ions, and to other anion-catalyzed reactions of this type not involving breakable OH bonds.
On the Theory of Oxidation-Reduction Reactions Involving Electron Transfer. III. Applications to Data on the Rates of Organic Redox Reactions
Authors: Marcus R. A.
Published: January 2005

A recently developed theory of oxidation-reduction reactions (Part I) is used to calculate the rates of organic redox reactions whose mechanism involves the transfer of an electron from one reactant to the other. The theory can be used to discuss factors affecting the rates of these reactions. These factors include a standard free energy of reaction, the Coulombic interaction of the ionic charges of the reactants, and the solvation of the charged reactants. Attention is focused on the relation between the rate of the redox step in the over-all process and the standard free energy change, ΔF0, of this step, rather than on the more usual but less fundamental one between the corresponding quantities of the over-all process itself.

An approximate method is described for applying the theory to a molecule whose charge is not located at its center. Essentially all organic molecules lie in this category.

As an example of these considerations, several typical reactions are discussed. These reactions involve the oxidation of a series of hydroquinones by ferric ions and of a series of leucoindophenols by dissolved oxygen. They are assumed to possess electron transfer, rather than atom transfer, mechanisms. Free energies and entropies of activation of the redox step are calculated using the theoretical equation. The calculated results are considered to be in reasonable agreement with the experimental data, no adjustable parameters being employed.
Selective Solvation and Dielectric Saturation as Related to Electron Exchange Reactions
Authors: Amis Edward S.
Published: January 2005

The Np(V)—Np(VI) electron exchange reaction has been found to be independent of the composition and of the gross properties, dielectric constant, refractive index, viscosity, etc., of two mixed solvents. To account for these phenomena, the critical complex is assumed to consist of a region containing the reactant ions and the solvent component of highest dielectric constant. This component preferentially solvates the ionic reactants. In this region, complete dielectric saturation is also assumed.
Theoretical Investigations on the Light Scattering of Colloidal Spheres. II. Accurate Interpolations of Theoretical Turbidity-Data
Authors: Heller Wilfried
Published: January 2005

The quantity log[(τ/c)0λ] is found to vary linearily with log(m—1) if α is kept constant. The relationship is valid as long as α does not exceed about 2/3 of that value at which the first turbidity maximum is attained. This relationship can be used for precise and accurate interpolations of theoretical (τ/c)0 data, derived from the Mie theory, for any intermediate m values. To a limited extent, extrapolations to m values pertinent to aerosols are also possible. The α and m range of practical usefulness of the graphical or numerical method of interpolation or extrapolation is quantitatively defined.
Theory of Radiation Chemistry. IV. Chemical Reactions in the General Track Composed of N Particles
Authors: Monchick L. , Magee J. L. , Samuel A. H.
Published: January 2005

The chemical reactions which occur in particle tracks are diffusion-controlled. In this paper a set of partial differential equations is presented which describes the dissipation of a track composed of N particles. These equations involve functions which can be interpreted as correlation functions for the relative distribution of the particles. A superposition approximation is introduced which greatly simplifies the equations and a method for obtaining the correlation functions is presented.

As an example of application of these equations a model for the action of ionizing radiation on water is discussed. It is shown that the radiation chemistry of water is adequately described for reasonable values of the parameters of the model.
Diffusion and Exchange of Zinc in Crystalline Zinc Oxide
Authors: Secco Etalo A. , Moore Walter J.
Published: January 2005

The exchange of zinc vapor with crystals of zinc oxide has been measured between 900 and 1025°. The ZnO crystals, incorporating radioactive Zn65, were prepared by the reaction of zinc vapor and atmospheric oxygen. A sample of the crystals was weighed into a small quartz bucket suspended in a cylindrical quartz vessel. After addition of enough pure zinc to give the requisite vapor pressure, the vessel was evacuated and sealed. The ZnO sample contained about 1000 acicular crystals, with a mean diameter of 0.01 mm and a selected narrow distribution of diameters. At different times the bucket was withdrawn, and the residual radioactivity of the ZnO was determined. Except for the initial stages, the exchange reaction appeared to be controlled by the diffusion of Zn in ZnO. The diffusion coefficient D was calculated at 1 atmos zinc pressure as D = 4.8 exp(—73.0 kcal/RT) cm2 sec—1. Variation of zinc pressure from 0.2 to 2.0 atmos showed that D varies as PZn0.65, suggesting that the diffusing species is the singly dissociated interstitial zinc ion, Zni+. These results are consistent with observations on the rate of solution of zinc in zinc oxide, if D = fiDi where fi is the concentration of interstitial zinc and Di is its mobility, but the possibility that the exchange rate is not diffusion controlled cannot be rigorously excluded.
Emission Band Spectra of Nitrogen. Kaplan's First and Second Systems
Authors: Lofthus Alf , Mulliken Robert S.
Published: January 2005

Seven bands of Kaplan's first system and eleven bands of Kaplan's second system have been photographed under high resolution. The two systems are definitely y1Π−a′1 Σ and y 1Π−w1Δ. It is very probable that they are y 1Πg−a′1Σu− and y 1Πg−w 1Δu and that the two lower states belong, along with A 3Σu+ and b′1Σu+, to the N2 configuration ··· πu3σg2πg. A clear breaking-off of the branches coming from the Π+ levels of the y 1Πg state above v′=0,J′=10 was observed. This is interpreted as an allowed predissociation by a Σg+1 state dissociating to two 2D atoms. Consequently lower limits probably close to the term values for the x, y, w, and a′ states could be determined; this locates the a′ and w states respectively probably about 2.2 and 2.7 ev above state A, in good agreement with theoretical expectations. Perturbation of the remaining Π— levels was also observed. Rotational and vibrational constants and term values of the various states are presented. The transitions a′↔a and w↔a should give rise to bands in the (mostly far) infrared.

It is noted that the constants of both the x and y states are close to those of the N2+ state ··· πu3σg2, and it is proposed that x1Σg— and y1Πg are respectively derived from the latter by the addition of an electron in a 3pπu and a σu (4pσu ?) Rydberg orbital. It is then proposed that the DΣu+3 and p′ Σu+1 states of N2, whose constants are close to those of the ground state ··· πu4σg of N2+, are derived from the latter by addition of an electron in the same σu Rydberg orbital as in the y state. The states p′ and e are the first two members of Worley's first Rydberg series.
Magnetic Dipole Effects in Ferrites
Authors: Johnson Richard A. , Healy Daniel W.
Published: January 2005

This paper presents an analysis of the role which classical magnetic dipole-dipole interactions may play in the physical behavior of ferrites with particular attention to magnetic anisotropy. Included is an evaluation of these effects in magnetite and lithium ferrite where an ordered arrangement of dipoles can exist and a study and calculation of some statistical effects which exist in other ferrites where this ordering is absent. The results obtained from this analysis are then compared with the pertinent experimental data.
Microwave Spectrum and Barrier to Internal Rotation in CH3BF2
Authors: Naylor Robert E. , Wilson E. Bright
Published: January 2005

The microwave spectrum of CH3BF2 has been observed in the frequency range 12–33 kmc. The identifiable lines are explained in terms of a model consisting of a symmetric top (CH3) rotating with respect to an asymmetric framework (BF2) with the top axis coinciding with the (least) principal inertial axis of the molecule. The value of the barrier to internal rotation was determined to be 13.77±0.03 cal. Three moments of inertia were also obtained from the analysis: A = 10586.73 (BF2 group only), B = 8329.01, C = 4650.52 Mc. These are insufficient to determine the molecular structure, but are consistent with the structure reported from electron diffraction. Stark effect measurements yield a dipole moment of 1.67±0.02 D.
Dipole Moment of Lithium Hydride
Authors: Hurst R. P. , Miller James , Matsen F. A.
Published: January 2005

A dipole moment of 6.04D, with hydrogen negative, has been computed for the LiH molecule. Electronegativity scales, x-ray crystal studies, and electrolysis of LiH give indirect support for this result.
Pure Rotational Spectra of the Partially Deuterated Ammonias in the Far Infrared Spectral Region
Authors: Palik E. D. , Bell Ely E.
Published: January 2005

Rotational spectra of NH2D and NHD2 have been measured in the spectral range from 30 to 200 cm—1. The inversion splitting of the NH2D lines has been observed. The spectra have been analyzed to obtain term values for many of the low J rotational levels of the ground states of those molecules. The effects of centrifugal distortion on the energy levels is discussed. Molecular constants and dimensions are obtained.
Raman Spectra, Vibrational Assignments, and Force Constants for BH3CO and BD3CO
Authors: Taylor Robert Cooper
Published: January 2005

Raman spectra of BH3CO and BD3CO have been obtained for the liquid state at —80°C, and a complete assignment of the sixteen fundamentals of the two molecules has been made with the help of the Teller-Redlich product rule and a normal coordinate treatment. The calculations were carried out using the FG method of Wilson, ten symmetry force constants being required to produce a fit with a standard deviation of 0.3% from the observed fundamentals. Extension of the calculations to include the isotopic B10 molecules gave results in agreement with the data available.
Vibrational Spectra of Normal and Isotopically Labeled Boric Acid
Authors: Servoss R. R. , Clark H. M.
Published: January 2005

Infrared spectra over the NaCl and KBr spectral regions have been obtained for H3BO3, H3B10O3, and D3BO3 as the solid contained in pressed plates of KBr. Raman spectra have been studied for solutions of boric acid in water, methanol, and methyl borate. Frequency assignments for the normal vibrations are given.
Iodine Complexes in Inert Solvents. VI. Solvation Processes in Solutions of Oxygenated Solvents and Iodine, Bromine, or Sulfur Dioxide
Authors: de Maine P. A. D.
Published: January 2005

A survey of recent literature on systems containing halogens or sulfur dioxide in aliphatic oxygenated solvents or inert solvents is given. It is shown that the classical concepts of solvation processes do not apply to these systems. It is concluded that the results are best understood with the new ``liquid-lattice penetration complex'' theory, if it is assumed that the stabilizing energy of the heterogeneous aggregates is provided by Mulliken's ``charge-transfer'' forces.

A new interpretation of the term ``activity coefficient'' is given. These coefficients are shown to arise from the neglect of lattice factors.
Interchange of Charge between Gaseous Molecules in Resonant and Near-Resonant Processes
Authors: Gurnee E. F. , Magee J. L.
Published: January 2005

Interchange of charge between monatomic and diatomic ions and molecules in gaseous systems is considered theoretically by an ``impact parameter'' method. Formulas for charge transfer cross sections for resonant and near-resonant cases are developed, and comparisons are made between experimental and theoretical results. The validity of the impact parameter method is considered by comparison with the more rigorous method of scattered waves.
Use of Gaussian Wave Functions in Molecular Calculations
Authors: Kimball G. E. , Neumark G. F.
Published: January 2005

Gaussian functions have been used in a simple variational approach to calculate the energy of a number of two-electron systems, namely the hydrogen molecule, the negatively charged hydrogen ion, and the (1s)2 1S, (1s) (2s) 3S, and (1s) (2p) 3P states of helium. The last two were included in order to test two different 2s and a 2p function. The error in the total energies varied from 14% to 33%, showing that these functions can give ``fairly good'' energy values. This, and some other evidence, seems to indicate that in such variational calculations the specific form of the starting wave function may not be too important.

Calculations were also carried out on one single electron system in order to further compare the two different 2s functions. Both here and in the case of the triplet helium both functions gave almost identical energies.
Ultraviolet Absorption Spectra and the Chemical Mechanism of CS2–O2 Explosions
Authors: Myerson Albert L. , Taylor Francis R. , Hanst Philip L.
Published: January 2005

Ultraviolet absorption spectra have been obtained at various times during and after homogeneous explosions of carbon disulfide-oxygen mixtures thermally initiated at temperatures of 190 to 300°C. This has been accomplished by triggering a flash source of continuum by means of the early chemiluminescence of the explosion. These photographically recorded spectra show the presence, and the absorption intensity as a function of time, of CS, SO, SO2, S2O2, S2, CS2 and a species which absorbs in a continuum, to which has been assigned the structure of a sulfur superoxide, SOO. Numerous conclusions have been reached from these data concerning the elementary chemical reactions that are involved in these experiments. A direct bimolecular reaction is postulated for the initiation process which produces the superoxide, and eventually free radicals. In the very early stages of the explosion, propagation proceeds via a slowly branching primary chain which involves an attack on the reactants by sulfur and oxygen atoms. As the branching reaction proceeds and the temperature increases, the mechanism undergoes a number of changes including an increase in the importance of a nonfree radical, bimolecular process. The explosion is especially interesting in that one of the final products, sulfur dioxide, does not appear in more than minor concentrations, almost characteristic of an intermediate, until the explosion is over. This is explained in terms of the reactions postulated.
Effect of Pressure on the Isotope Effect in a Unimolecular Gaseous Reaction : Tritium and Carbon-13 Effects in the Isomerization of Cyclopropane
Authors: Weston Ralph E.
Published: January 2005

As a new means of studying the effect of pressure on unimolecular gaseous reaction kinetics, the tritium isotope effect in the isomerization of cyclopropane to propylene has been measured. At a pressure of 200 mm, the ratio of rate constants for unlabeled and singly-labeled species is given by k/k′ = (0.86±0.06) exp (385±95/RT). The temperature range was 406–492°C. As the pressure decreases, the isotope effect is lowered and, within experimental error, disappears at 1 mm. Upon the addition of inert gas to cyclopropane at this pressure, the isotope effect is increased to a value corresponding to a higher pressure of reactant. The relation between these results and the calculations of N. B. Slater on the kinetics of this reaction is discussed.

The carbon-13 isotope effect was measured at 1 atmos and 492°, and was found to be k/k′=1.0072±0.0006. This may be explained on the basis of a change in either a carbon-carbon or a carbon-hydrogen bond in the transition state.
Pairing Energies in the Actinide Series
Authors: Griffith J. S. , Orgel L. E.
Published: January 2005

The authors' previous calculations of pairing energies for dn configurations are extended to fn configurations. The ground state of f2, as in PuF6, is shown to be nondegenerate whether the spins are paired or not. However, detailed calculations show the magnetic properties to favor the view that the spins are in fact paired. This assumption is also found to accord with the observed variation of vibrational frequencies for UF6, NpF6, and PuF6.
Magnetic Moment of Iron Ions
Authors: Broersma S.
Published: January 2005

Proton magnetic relaxation rates were measured in solutions of ferric perchlorate with stoichiometric concentrations ranging from 10—1 to 4×10—5 molar, at pH's between 0 and 12. It is found that the magnetic moments of Fe(OH)2(+1) and Fe(OH)(+2) are equal to that of Fe(+3) (5.9 Bohr magnetons), while Fe2 (OH)2 (+4) is diamagnetic. The experimental results suggest that the equilibrium constant for the formation of Fe2 (OH)2 (+4) from Fe (+3) is 1×10—2 moles/l at 20°C.
Interaction of Rare Gases with Graphite
Authors: Crowell A. D.
Published: January 2005

The interaction energies and frequencies of vibration of neon, argon, krypton, and xenon atoms over the surface of a basal plane of graphite have been calculated, assuming a (6–12) potential between the gas atoms and carbon atoms in the graphite lattice. The graphite lattice is approximated by a set of planes of uniform distribution of matter. The significance of the results is discussed briefly.
Susceptibility and Curie Point of Magnetically Dilute Crystals
Authors: Behringer Robert E.
Published: January 2005

The Opechowski calculation of the apparent Curie point, TC, is extended to the case of magnetically dilute f.c.c. crystals. To first order in temperature the result is equivalent to a molecular field treatment. The calculation is carried to fourth order in temperature and a plot is made of TC vs p, the fractional concentration of magnetic atoms. The theoretical result is compared to some existing experimental data and values of the exchange interaction, J, are estimated.

The above calculation is found to be useful only for 0.8≤p≤1.0. For low concentrations a crude calculation is made based on clusters of magnetic atoms. To first order in temperature, a linear relationship is found between apparent Curie point and concentration.
Preparation and Proton Magnetic Resonance Studies of Anhydrous Ammonia
Authors: Ogg Richard A. , Ray James D.
Published: January 2005

Comparison of high-resolution proton magnetic resonance spectra of anhydrous N14H3 and N15H3 (99.8% N15) leads to the conclusion that the line width in N14H3 is due to quadrupole relaxation. A new method of preparation of anhydrous, sodium-free ammonia is described. The natural abundance of N15H3 in N14H3 is shown to be observable by magnetic resonance technique.
Electronic Structure of Sodium-Ammonia Solutions by Nuclear Magnetic Resonance
Authors: McConnell Harden M. , Holm C. H.
Published: January 2005

Knight shifts (ΔH) of the N14 and Na23 nuclear magnetic resonances have been observed in liquid sodium-ammonia solutions at 7000 gauss as a function of the mole ratio R=(moles NH3)/(moles Na) for 10⪝R ⪝1000. The Knight shifts decrease with increasing R and for R≈10, ΔH(N14)≈4, ΔH(Na23)≈1 gauss. The experimental results in these variable composition solutions are conveniently discussed in terms of P(N14) and P(Na23), the average hyperfine contact densities of N14 and Na23 nuclei at an unpaired electron. P(N14) and P(Na23) were estimated from K–NH3 paramagnetic susceptibility data and the ΔH's. For 50<R<400, P(Na23)=5–3×10—3 P0(Na23) where P0(Na23) is the contact density in an isolated sodium atom. In this concentration range we conclude the odd electrons move in highly expanded orbitals about Na+ ions similar to those appropriate to tetrahedrally bonded P+ ions in P-doped silicon where a similar reduction in the contact hyperfine density is found. Marked electron condensation on Na+ ions occurs at R⪝50 where P(Na23) and the electrical conductivity increase rapidly. P(N14)≈0.1 P0(N14) and is independent of R. H1Knight shifts were too small to detect.
Entropy of Chemisorbed Hydrogen
Authors: Takaishi Tetsuo , Kobayashi Akio
Published: January 2005

The vibrational entropy of chemisorbed hydrogen is analyzed and the frequencies of its vibration parallel to the surface are obtained as to hydrogen on reduced nickel, reduced copper, and platinum-black. The activation energies for migration are estimated from these frequencies. They are of the right order for nickel and copper but not for platinum-black. The latter fact proves that the active centers for adsorption are sparsely distributed over the surface of platinum-black. This method of investigation of vibrational state is complementary to that by infrared spectroscopy.
Infrared Spectra and Force Constants of Cyanoacetylene
Authors: Turrell George C. , Jones Walter D. , Maki Arthur
Published: January 2005

The infrared spectra of gaseous, liquid, and solid cyanoacetylene, H–C≡C–C≡N, have been observed in the region from 450 cm—1 to 3400 cm—1. Six of the seven fundamental vibrational frequencies expected for cyanoacetylene on the basis of a linear structure have been assigned and the remaining frequency has been estimated from observed combination bands. A force constant calculation has been carried out using a simple valence potential function.
On the Electroreduction of Anions
Authors: Frumkin A. N. , Nikolajeva N. V.
Published: January 2005

The electroreduction of anions is often strongly influenced by the electronic charge on the surface of the metallic electrode, and this influence can be traced to the influence of the charge on the composition of the electrical double layer. Experiments cited by others as tending to disprove this supposition are shown to be in fact compatible with it. Neutral molecules containing coordinated chlorine behave with respect to electroreduction much like anions because the chlorine assists in the adsorption of the molecule, and this adsorption is charge sensitive. In all cases the difference in the mechanism of the electroreduction of anions or of neutral particles with anionic groups at different potentials can be interpreted as determined by differences in the conditions of adsorption of the reacting particles.
Vibrational Spectra and Molecular Structure of Some Halogenated Methyl Cyanides
Authors: Wait Samuel C. , Janz George J.
Published: January 2005

The series of halogenated methyl cyanides: CCl3CN, CCl2FCN, CClF2CN, and CF3CN, presents the interesting case where the substituent, X, in the CX3 group is progressively replaced by an atom of greater electronegativity. The present communication reports the infrared and Raman spectra and vibrational assignments for the fundamental bands of the molecules in this series. Comparison of the results clearly shows regularities in certain fundamentals (C≡N stretch, C–C≡N symmetric and antisymmetric bends, C–F symmetric and antisymmetric stretches) which may be attributed to the changes in the force field caused by increasing electronegativity of the CX3 group. Force constants are calculated for CX3CN molecules belonging to the C3v point group by the Wilson FG matrix method, the potential function containing all possible second degree terms. The limits of the invariancy of the force constants are examined in this series.
Electronic Spectrum and Dissociation Energy of Fluorine
Authors: Rees A. L. G.
Published: January 2005

The continuous absorption spectrum of molecular fluorine and the Raman displacement for the 0→1 vibrational transition have been used to compute the potential energy curve for the repulsive 1Πu state dissociating to two normal fluorine atoms. This curve is consistent with a value of 37.1±0.85 kcal mole—1 for the dissociation energy of the ground state. A weak absorption, attributed, on the grounds of location and intensity, to 3Π0+u←1Σg+, has been shown to occur in the long wavelength region of the main absorption and a segment of the potential energy curve for 3Π0+u has been deduced. Absorption curves, calculated from the potential energy curves and the ground-state anharmonic eigenfunctions, fit the observed data satisfactorily.
Relationship between Relaxation Time and Viscosity for Water
Authors: Grant E. H.
Published: January 2005

The Debye relationship connecting relaxation time, viscosity, molecular size, and absolute temperature appears to hold almost exactly in the case of water. The Debye equation was formulated on the basic assumption that each molecule can be considered as turning in a viscous continuum as it rotates in dielectric relaxation, and it is well known that this molecular picture is inapplicable to water.

It is shown that a similar relationship can be deduced directly from equations based on the hydrogen bonded structure of the liquid.
Microwave Spectrum of Ethyl Chloride
Authors: Wagner Roselin S. , Dailey B. P.
Published: January 2005

The microwave spectrum of ethyl chloride has been investigated and accurate values for the rotational constants B and C for several isotopic species have been obtained. For C2H5Cl35, B=5493.8 Mc, C=4962.3 Mc, and for C2H5Cl37, B=5379.1 Mc and C=4867.1 Mc. Two deuterated species have been studied. For trans CH2DCH2Cl35, B=5098.8 Mc and C=4637.5 Mc. The rotational constants for gauche CH2DCH2Cl35 are B=5297.6 Mc and C=4784.9 Mc. The following model reproduces these constants to within 4 Mc: d C–C=1.5495 A, d C–H=1.101 A, d C–D=1.090 A, ≰ HCH=110° 00′, ≰ CCCl=110° 30′, d C–Cl=1.7785 A. From the structural data obtained for the deuterated ethyl chlorides it has been possible to establish the staggered configuration as the equilibrium configuration. The quadrupole analysis shows that eqQ along the C–Cl bond axis is —70.07 Mc for Cl35 and —55.03 Mc, for Cl37, indicating an ionicity of 25%. The torsional frequency has been estimated to be 236 cm—1 and the barrier height is 3.4 kcal/mole.
Bond Energies of Transition Metal Halides
Authors: Allen Thomas L.
Published: January 2005

Bond energies of transition metal halides of the type MXn have been calculated from existing thermodynamic data. It has been found that the Pauling equation for the bond energies of polar bonds, in conjunction with Eley's method of calculating metal-metal bond energies, is applicable to these molecules.
Medium Effects in Nuclear Magnetic Resonance Spectra of Liquids. II. Simple Aliphatic Molecules
Authors: Bothner-By Aksel A. , Glick Richard E.
Published: January 2005

The positions of resonance lines in the proton magnetic resonance spectra of many simple aliphatic compounds in liquid media are given as a function of medium susceptibility by the equation H=siHi0(1−2.6K)1. This behavior is compared with that theoretically expected and some possible explanations for the non-agreement are discussed.
High-Field Stark Effect in Linear Rotors
Authors: Peter Martin , Strandberg M. W. P.
Published: January 2005

Stationary perturbation theory has been used to calculate the Stark effect in the linear rigid rotor for the case in which the electric energy is large compared with the rotational energy. The method has been checked against the exact energy values, which were calculated for this purpose. Extension of the method to the Stark effect in the general rotor is possible.
Vibrational Spectrum and Force Constants of Diboron Tetrachloride
Authors: Mann D. E. , Fano Lilla
Published: January 2005

The infrared spectrum of gaseous diboron tetrachloride (B2Cl4) and the Raman spectrum of the liquid are analyzed. The molecular symmetry is shown to be Vd, in accord with the electron diffraction result for the vapor. A complete vibrational assignment is given. The fundamentals are (in cm—1): 1131, 401, 225 in a1; 730, 291 in b2; 917, 617, 180 in e. A normal coordinate analysis, based on a Urey-Bradley potential function and a least-squares method of force constant adjustment, is used to establish the assignment. With the aid of the third-law entropy, the barrier restricting internal rotation about the B–B single bond is fixed at 1700± 600 cal/mole.
Derivation of an Internuclear Potential Function from a Quantum-Mechanical Model
Authors: Lippincott Ellis R.
Published: January 2005

A simple quantum-mechanical model of bond formation is presented which allows the derivation of an internuclear potential function of the form V=−Deexp(−nΔR2/2R),where n=keRe/De. The method makes use of a delta-function model whereby bond formation is described by the shifting of atomic delta functions into molecular delta functions. The predicted results for H2+ are nearly exact for all bond properties while the results for H2 are more accurate than those for all but the most elaborate methods used previously. The model has also been used to calculate values of Re, De, ωe, and ωexe for a large number of stable excited states of H2 with good results. Advantages of the method are that the same form for the internuclear potential function is obtained for multi-electronic bonds as for one and two electron bonds, and that multi-electronic bond systems can be handled by one-dimensional methods. Theoretical values for the parameter, n, for multi-electronic bonds are calculated which agree well with values obtained from experimental data. A disadvantage of the method is that the problem of bond formation has been oversimplified by using arbitrary assumptions.
Optical Spectra of Hydrated Ions of the Transition Metals
Authors: Holmes Owen G. , McClure Donald S.
Published: January 2005

The absorption spectra of crystalline hydrates of the first transition group ions have been measured with polarized light at room temperature, and with unpolarized light at a series of lower temperatures. Some new data on solution spectra have also been obtained. The values of Dq for these compounds are obtained, and are used to explain irregularities in the heats of hydration of the ions. The temperature dependence of the spectra shows that the transitions are vibration-induced electric-dipole transitions for the most part. The dichroism has been used to resolve some of the bands and to determine the effect of noncubic components of the crystal field.
Study of the Electronic Ground State of the Ammonia Molecule
Authors: Kaplan Harvey
Published: January 2005

The electronic structure of the ground state of the ammonia molecule has been calculated in the SCF LCAO MO approximation for two sets of internuclear separations: the experimentally observed values and a symmetric planar arrangement. The effect of limited configuration interaction on these results has also been investigated. The atomic orbitals used include 1s, 2s, and 2p nitrogen orbitals and 1s hydrogen orbitals, the nitrogen orbitals being the Hartree and Hartree solutions of the Hartree-Fock problem for the neutral nitrogen atom and the hydrogen orbitals being the standard free atom functions. All integrals were calculated using the method of Barnett and Coulson and Lundqvist and Löwdin, the only approximation involved being the mathematical one of terminating infinite series.

The significance of the results is discussed, and calculations of the binding energy, the dipole moment, and other molecular properties are compared with experiment.
Quadrupole Interaction of Nuclei with Conduction Electrons
Authors: Mitchell A. H.
Published: January 2005

The nuclear spin-lattice relaxation time in metals is calculated taking into account the following three interactions between the nuclei and the conductions electrons: (1) the usual contact part of the hyperfine interaction, which is the dominant mechanism; (2) the noncontact part of the hyperfine interaction; (3) the quadrupole interaction for nuclei of spin I≥1. It is found that the latter two interactions are of the same order of magnitude. If the electronic wave function at the Fermi surface has a p-wave component comparable with its s-wave component, these two mechanisms may appreciably shorten the relaxation time as calculated using only the contact part of the hyperfine interaction.
Statistical Computation of Mean Dimensions of Polymer Molecules. IV
Authors: Wall F. T. , Hiller L. A. , Atchison W. F.
Published: January 2005

In a further investigation of the nonintersecting random walk problem, two new types of random walks have been examined to determine the effect of the magnitude of the ``excluded volume'' on the limiting behavior of the ratio, 〈rn2〉n, where 〈rn2〉 is the mean square length of nonintersecting random walks of n steps. In two dimensions, 〈rn2〉/n normally diverges, but for walks in a right-left two-choice 90° lattice, for which exclusions are counted on odd steps only, the ``excluded area'' is reduced to such an extent that convergence of 〈rn2〉Av/n may occur. In three dimensions, 〈rn2〉/n may converge, but if random walks in a three-choice tetrahedral lattice are generated subject to the condition that walks cannot return to lattice points within unit distances from previously occupied sites, the ``excluded volume'' is sufficiently increased so that 〈rn2〉/n certainly diverges as n→∞.

In addition to the above, our process for selecting the random numbers used to generate random walks has been re-examined more fully and has been found to be satisfactory. We have also examined values for mean square lengths of failures which might result from backward steps. These distances agree with an empirical relationship found to hold for the other types of failures, thus providing further justification for an earlier theoretical interpretation of the nonintersecting random walk problem.
Internal Barrier of Propylene Oxide from the Microwave Spectrum. I
Authors: Swalen Jerome D. , Herschbach Dudley R.
Published: January 2005

In order to study the effects of hindered internal rotation of a methyl group for a high barrier case, the microwave spectrum of propylene oxide has been observed. Rotational transitions have been assigned up to J=30 in the ground torsional state and to J=10 in the first excited torsional state. The structure of the molecule was partially determined by combining the rotational constants derived from the spectrum with the known structure of ethylene oxide. From Stark effect measurements, the dipole moment was determined to be 2.00±0.02 debye.

The theory of the interaction of internal rotation with over-all rotation is discussed, including the necessary extension of the theory of Wilson, Lin, and Lide for a molecule having no symmetry. Because the tunnel effect splits each torsional state into two levels, the rotational lines appear as doublets. The threefold barrier hindering internal rotation of the methyl group is fitted to the doublet separations. For the ground state, the splitting of the lines was observed only for high J rotational transitions. A barrier of 2710 cal/mole was obtained. For the first excited torsional state, the splittings are about fifty times larger, and are observable for low J transitions. These yield a barrier of 2560 cal/mole. The causes of this apparent difference in barrier height and the errors in the method are discussed.
Molecular Orbital Study of the Porphyrins
Authors: Seely Gilbert R.
Published: January 2005

An LCAO molecular orbital calculation has been carried out for models of porphin and its hydrogenated derivatives, chlorin, α and β tetrahydroporphin, and hexahydroporphin. Application of the results to the spectra of these compounds has provided a consistent interpretation in terms of relative energies of the two highest filled molecular orbitals. Comparison is made largely with the observed spectra of zinc tetraphenylporphyrins. The calculation confirms the proposed structural assignments for α and β tetrahydroporphins. The use of Tschebycheff polynomials in solving secular equations is described.
Tentative Phase Diagram for Solid H2S
Authors: Stevenson Richard
Published: January 2005

The solid phases of hydrogen sulfide under high pressures have been studied by the volume discontinuity method. Evidently two new solid phases have been observed. The natures of the freezing transition and the higher temperature solid-solid transition are discussed, and the results are compared with the analogous case of water.
Photoconductivity of Anthracene. III
Authors: Compton D. M. J. , Schneider W. G. , Waddington T. C.
Published: January 2005

The photoconductivity of anthracene has been studied using three types of crystals: large scintillation crystals, crystals grown from dimethylformamide, and sublimation flakes. The existence of a true bulk conductivity as well as a surface conductivity has been demonstrated. This bulk conductivity is not affected by oxygen. The space charge found by previous workers has been shown to be located at the electrodes and to be due to poor contacts. The dependence of both the surface and the bulk photocurrent on temperature, voltage, and wavelength and intensity of light, have been studied and found to be markedly different from each other. The surface photocurrent shows a non-ohmic voltage dependence.

It is concluded that the formation of charge carriers is not a primary process of light absorption, but a secondary process, competing with fluorescence and thermal degradation of the absorbed light energy, which is free to move through the crystal in the form of excitons. A mechanism for the migration of charge carriers has been put forward to explain the main features of the photoconduction. A much higher effective carrier mobility on the surface than in the bulk of the crystal is postulated. The behavior of the surface photocurrent is interpreted in terms of the formation of carriers in the bulk, those that diffuse to the surface playing the greater part in carrying the current. The bulk current is considered as a recombination-limited photocurrent. In agreement with previous workers, it is concluded that most of the current is carried by positive holes.
Improved Statistical Method for Computing Mean Dimensions of Polymer Molecules
Authors: Wall F. T. , Rubin R. J. , Isaacson L. M.
Published: January 2005

Further work on the dimensions of coiling type polymer molecules has been carried out with an electronic digital computer using nonintersecting random walks as molecular models. A modified method has been devised which significantly reduces the serious attrition of samples. The procedure, applied to walks in the two-choice square lattice, consists of adding strides of four steps instead of adding single steps one by one. The strides are so chosen that a valid statistical sample can be attained while eliminating most of the attrition attributable to closures of four-membered rings. The method shows promise of being applicable to problems of a more general nature.
Crystal and Molecular Structure of B9H15
Authors: Dickerson Richard E. , Wheatley Peter J. , Howell Peter A. , Lipscomb William N.
Published: January 2005

With only the information that B and H alone are present, and that the melting point is —20°, the molecular structure of B9H15, a new boron hydride, has been determined from single crystals by x-ray diffraction methods. There are four molecules in the unit cell, space group P21/n, with a=11.80 A, b=6.94 A, c=11.25 A, and β=109° 9′. The boron skeleton, solved by three-dimensional Patterson and trial and error methods, and refined by least squares methods, is a fragment of the icosahedron formed by removing three connected borons not forming an equilateral triangle. Hydrogen atoms, located from three-dimensional difference maps, agree with those expected from previously known boron hydrides. The over-all agreement factor is R=Σ∥F0| — |Fc∥/Σ|F0|=0.155.

Computations on the UNIVAC Scientific 1103 Computer are described briefly, with emphasis on the use of fractional shifts of parameters in the least squares method. A least squares normalized weighted sum of squares of residuals is proposed as a better criterion of agreement than R.
Least Squares Refinements of B10H14, B4H10, and B5H11
Authors: Moore Emmett B. , Dickerson Richard E. , Lipscomb William N.
Published: January 2005

New interatomic distances in B10H14, B4H10, and B5H11 indicate that the B–B distances which are more strongly bound in the simplified valence theory are slightly shorter than other B–B distances. The position of the unique hydrogen atom in B5H11 is now somewhat more satisfactory in relation to the plane of symmetry of the isolated molecule. The improvement of agreement of observed and calculated x-ray intensities suggests that least squares refinements as usually applied are not carried through enough iterations.
Semitopological Approach to Boron-Hydride Structures
Authors: Dickerson Richard E. , Lipscomb William N.
Published: January 2005

A semitopological approach to the structures of boron hydrides is discussed in detail, as an extension of the equations of orbital and electron balance derived by Eberhardt, Crawford, and Lipscomb. This consistent set of principles gives the presently known boron hydrides whose frameworks are icosahedral fragments, and predicts (1) the hydrogen arrangement in B6H10, (2) that a stable B8 hydride will probably be either B8H12 or B8H14, (3) B9H13 should not exist, and (4) that no B7 hydride should exist.
Nonideality of Liquid Ortho-Parahydrogen Solutions
Authors: Friedman Harold L.
Published: January 2005

The thermodynamic properties of liquid ortho-parahydrogen solutions are calculated from the total pressure measurements of Woolley, Scott, and Brickwedde [J. Research Natl. Bur. Standards 41, 379 (1948)] by a method which is applicable to systems in which the fugacity coefficients of the vapors are independent of composition at given T and P, and in which the liquid solution obeys the law, Gex/x(1—x) =constant.

For ortho-parahydrogen solutions at 20°K, Hex=3.07x(1—x) cal/mole and Sex=0.097x(1—x) cal/mole deg. The asymmetry of the pair-wise intermolecular potentials noted by Woolley, Scott, and Brickwedde is confirmed.
Theory of Dilute Polymer Solutions
Authors: Koyama Ryuzo
Published: January 2005

Assuming the pearl necklace model for a chain polymer molecule in a solution, the theoretical expressions for the mean intermolecular potential and the radial distribution function of polymer molecules are derived. The methods in the theory of Born and Green, which is based on the superposition approximation, are conveniently applied to the case of solution.

The results show that the mean intermolecular potential is nearly approximated by the Gaussian function, and it depends on the molecular weight and the temperature; the radial distribution function is also dependent on the molecular weight as well as on the temperature. At critical temperature where the second virial coefficient vanishes, the mean intermolecular potential vanishes and the radial distribution function assumes the constant value which is equal to unity. Theoretical expressions for the second and third virial coefficients are also given.
Vibration Spectrum of Graphite and Boron Nitride. II. The Three-Dimensional Spectrum
Authors: Newell Gordon F.
Published: January 2005

A detailed analysis of the spectrum of graphite and boron nitride that began in Part I with a description of the two-dimensional spectrum neglecting the interaction between layers is completed here with the inclusion of the coupling between layers. Of particular interest is the low-frequency end of the spectrum which is distorted by the coupling in such a way as to cause a significant change in the thermodynamic behavior of the system at sufficiently low temperatures. Although most of the qualitative features of the spectrum have been described elsewhere, it is shown here that it is actually possible to find analytic approximations to the Born-von Kármán spectrum within well-defined limits of accuracy. The lack of experimental measurements of the elastic constants and other relevant data, however, makes any quantitative calculation of specific heat very difficult although it is apparent that the model is capable of explaining qualitatively the peculiar properties of these highly anisotropic crystals.
Infrared and Raman Spectra of Fluorinated Ethylenes. VIII. 1,1-Difluoro-2-bromoethylene
Authors: Theimer Rose , Nielsen J. Rud
Published: January 2005

The infrared absorption spectrum of gaseous CF2:CHBr has been obtained with a Perkin-Elmer double-pass spectrometer equipped with LiF, NaCl, and CsBr prisms. The Raman spectra of the compound in the gaseous and liquid states have been photographed with a 3-prism glass spectrograph of linear dispersion 15 A/mm at 4358 A. The 12 fundamental vibrational wave numbers have been assigned, as follows: Species a′ : 3135, 1732, 1317, 1172, 957, 768, 568, 366, and 164 cm-1; species a″ : 741, 583, and 227 cm-1. Except for the lowest a′ fundamental, all are for the gaseous state. The observed spectra have been interpreted in detail. Thermodynamic properties for the ideal-gaseous state at 1 atmos have been calculated for 6 temperatures.
Dispersion of Soluble Matter in Flow through Granular Media
Authors: Beran Mark Jay
Published: January 2005

This paper treats the problem of dispersion of soluble matter within a one dimensional tube filled with granular media. It is supposed that the solvent is flowing slowly through the tube with mean velocity v̄, and it is desired to find the future concentration pattern of the soluble matter. It is found that after a long time an initially thin slug of soluble matter is normally distributed about the position v̄t and that its standard deviation is proportional to t½. It is further shown when this effect need not be considered in Ion Exchange problems.
Free Diffusion : Diffusion Coefficient Varying Exponentially with Concentration
Authors: Clarke David M.
Published: January 2005

An approximate solution to the Fick equation for free diffusion is derived in terms of the error integral and its first derivative for the case when the diffusion coefficient shows exponential variation with the concentration of the diffusing species. The results are discussed with reference to the skewed character of the concentration gradient.
Dielectric Dispersion in Viscous Polar Liquids
Authors: Winslow J. W. , Good R. J. , Berghausen P. E.
Published: January 2005

The dielectric dispersion has been studied over the range 50 cycles to 100 kilocycles for the following liquids: tolyl xylyl sulfone, pentachlorobiphenyl, hexachlorobiphenyl, and solutions of tolyl xylyl sulfone in supercooled o-terphenyl. The results in all three cases conformed to the unsymmetrical dispersion equation of Davidson and Cole. A possible explanation for the deviation from Debye-type behavior is discussed.
Induced Polarization and Dielectric Constant of Polar Liquids
Authors: Cole Robert H.
Published: January 2005

The role of induced polarization in statistical theory of the dielectric constant of polar molecules is examined using the classical harmonic oscillator model of induced displacements by external and intermolecular fields. In the absence of translational fluctuations and anisotropy of polarizability, the theory leads to the results of Kirkwood and Onsager. Reasons for different results obtained by other developments are discussed.