bluuebunny/crossref_metadata_2025 huggingface dataset:
Vapor Pressure, Mass, and Infrared Spectra of Hexaborane
Authors: Gibbins Sidney G. , Shapiro I.
Published: January 2005

The vapor pressure for hexaborane over the temperature range —40°C to 16°C can be expressed by the equation log10Pmm=5.2124— (1566.3/T) +0.005841 T. The melting point is —63.2°C; the extrapolated boiling point equals 82.2°C. The vapor pressure at 0°C is 11.85 mm instead of the published literature value of 7.2 mm. The purification of the hexaborane has been followed by infrared and mass spectra. A discussion of these spectra is given.
Structure of Silico-Tungstic Acid in Aqueous Solution
Authors: Levy H. A. , Agron P. A. , Danford M. D.
Published: January 2005

The structure of 12-silico-tungstic acid, H4SiW12O40, in aqueous solution has been investigated by x-ray diffraction. The results indicate that 12 tungsten atoms are contained in a monodisperse species with arrangement similar to that found in the crystalline acid. Each tungsten atom has two near tungsten neighbors at each of the distances 3.36 A and 3.71 A.
Vibrational Spectrum of 4,4-Dimethylcyclopentene
Authors: Lauer James L. , Jones William H. , Beachell Harold C.
Published: January 2005

The vibrational analysis of 4,4-dimethylcyclopentene has been carried out by a normal coordinate calculation based on the Wilson FG matrix method. Assignments of the infrared and Raman bands were made with the help of the calculated fundamentals. The model used in the calculation was assumed to be planar and to possess C2v symmetry. The good agreement between calculated and observed frequencies justified this assumption.

A matrix iteration program was used on an IBM—650 digital calculator to find the roots of the secular determinant. It worked very well considering the large number of modes caused by the low symmetry of the molecule.
Ionic Models and the Vibrational Spectra of Molecules
Authors: Pearson Ralph G.
Published: January 2005

It is shown that an ionic model with polarization terms gives reasonable values for the vibrational frequencies of linear symmetric MX2 molecules. The potential function of such a model is indistinguishable from the valence force potential with interaction terms and this result is general for all molecules. Contrary to the literature, even a central force potential will give a nonzero bending frequency for a linear symmetric molecule.
NMR Study of the Protolysis Kinetics in Methanol and Ethanol
Authors: Luz Z. , Gill D. , Meiboom S.
Published: January 2005

Measurements by the nuclear magnetic resonance technique of the hydrogen exchange kinetics in methanol and ethanol are reported. The exchange reaction is both acid and base catalyzed. The observed kinetics can be interpreted as a simple proton transfer between a neutral alcohol molecule and an alcoxonium, or alcoxyde ion, respectively. In methanol a third mechanism, not involving ions, was also observed. In ethanol this reaction is presumably too slow for detection by the NMR technique. The hydrogen exchange was also studied in alcohol-water mixtures. Possible exchange mechanisms are discussed and values for their respective rate constants are given.
Density of Electronic Energy Levels for a One-Dimensional Liquid
Authors: Ford Joseph
Published: January 2005

Preliminary to a three-dimensional calculation, the density of one-electron energy levels for a one-dimensional array of square wells whose positions are Gaussianly distributed independent random variables has been calculated. The Hamiltonian matrix elements are calculated using the tight-binding approximation and the Montroll moment-trace method is used to compute the first six moments of the density of states curve. Hermite and Legendre polynomial expansions are then used to obtain the density of states curve itself. This method is, of course, valid independent of dimension. The integrated density of states curve as here obtained agrees nicely with the computer solution given by Landauer and Helland.
Dipole Moment Function of Diatomic Molecules
Authors: Trischka John , Salwen Harold
Published: January 2005

The connection between the dipole moment function (dipole moment as a function of internuclear distance), M(u), and its matrix elements has been studied for the one-dimensional model of a diatomic molecule. It is shown that M(u) is completely determined by a single row or column of the matrix 〈v | M(u) | v′〉, but that the diagonal matrix elements do not completely determine M(u). Attention is given to the problem of approximating M(u) when a finite number of matrix elements are known. The usual method (called by us the ``polynomial approximation'') is compared with a new approximation scheme which we call the ``wave function approximation.'' These methods are equivalent for a harmonic oscillator, but not in general. Estimates of the errors of the two methods are obtained in the case where the anharmonicity of the potential is small. The ``wave-function expansion'' of M(u) which is developed and used to carry out the calculations is a new way of relating matrix elements to M(u) which makes it much easier to calculate the dipole moment function from its matrix elements. This method has been used to obtain explicit formulas relating the dipole moment function to its matrix elements for the harmonic oscillator and for the Morse oscillator.
Vibrational Spectrum of Cyanate Ion in Various Alkali Halide Lattices
Authors: Maki Arthur , Decius J. C.
Published: January 2005

The infrared absorption spectra of dilute solid solutions of cyanate ion in KI, KBr, KCl, and NaCl single crystals have been examined between 600 and 5000 cm—1 at temperatures ranging from 150 to 480°K. Over fifty distinct maxima have been observed and assigned (including numerous isotopic, combination, and hot bands) in the most concentrated sample, for which KBr was the solvent. A strong Fermi resonance between 2ω2 and ω1 occurs. The vibrational energy has been expressed in terms of the eleven fundamental frequency and anharmonicity constants appropriate to a linear, unsymmetric triatomic molecule. Force constants in the KI solvent lattice are fNC=15.51, fCO=11.03, f′=1.35, and (fα/l1l2)=0.506 mdyne/A, a result which shows very clearly that the NC bond is of higher order than the CO bond in the cyanate ion, and that the latter bond is notably weaker in cyanate ion than in CO2, where its force constant is 16.0.

In general, the fundamental frequencies increase as the lattice constant decreases. Fairly detailed calculations show that although the induction energy term arising from the dipoles induced in the solvent by the vibrating cyanate ion is not negligible, the observed variation of frequency cannot be explained by the induction term alone and must involve the short-range, repulsive forces.
Electron Impact Study of Nitric Oxide Using a Modified Retarding Potential Difference Method
Authors: Cloutier G. G. , Schiff H. I.
Published: January 2005

An electron impact study of NO was made using the retarding potential difference method for producing the effect of a monoenergetic electron beam. In this modification of the method the electron retarding potential is provided by the potential minimum which exists between the anode and cathode of a space-charge limited diode.

The ionization potential of NO was found to be 9.25±0.02 ev and the ionization efficiency curve for NO+ to be nonlinear near the onset. This curvature can be attributed to the difference in the equilibrium internuclear distances of NO and NO+. Appearance potentials were obtained for the formation of N+, O+, and O- ions from a number of processes. With the exception of O- ions formed by electron capture, it was not necessary to postulate that any of the ions are formed with excess kinetic energy. The appearance potentials of all the processes are consistent, within experimental error, with a value of 6.50 ev for the dissociation energy of NO. The shape of the resonance capture curve for O- formation was used to construct part of the potential energy diagram for the NO- ion.
Ethane Carbon-Carbon Distance Obtained from Infrared Spectra
Authors: Allen Harry C. , Plyler E. K.
Published: January 2005

The parallel band of ethane at 2753 cm—1 and the parallel band of ethane-d6 at 2816 cm—1 have been observed and analyzed. The resultant values of B for C2H6 and C2D6 are 0.6637 cm—1 and 0.4598 cm—1, respectively. From these B values the C–C distance is found to be 1.534 A and the quantity (rCC/2+rCHcosθ)2+rCH/22sin2θ=1.866 A where θ=180−∠HCC.If the rCH value of methane (1.093 A) is assumed, the ∠HCC is 109° 45′.
Monochromatically Excited Fluorescence in Rare Earth Salts
Authors: Varsanyi F. , Dieke G. H.
Published: January 2005

Monochromatic excitation, continuously variable in wavelength, makes it possible to analyze in detail the excitation of the fluorescence spectra of rare earth salts. This is a very sensitive method for studying the coupling of the electronic levels with the lattice vibrations. When a crystal contains several kinds of rare earth ions their fluorescence spectra are excited independently of each other.
Local Steric Hindrances and Configurations of Linear Macromolecules in Solutions. I. Formulation
Authors: Nagai Kazuo
Published: January 2005

The previous theory treating the analogous problem is developed to include rigorously the interactions between the atomic groups whose relative spatial configurations are determined by the rotational angles of two neighboring skeletal bonds. The mean-square end-to-end distances and/or the electric moments are calculated for isotactic- and syndyotactic-vinylic macromolecules as well as a few other macromolecules with similar structures. As a model for linear macromolecules is adopted, the discrete one whose each C–C bond is assumed to take only three rotational configurations (e.g., trans, gauche, and another gauche). In such a model the problem of taking all of the interactions between neighboring bonds into account is equivalent to that of a one-dimensional cooperative system. While the partition function of this system can be obtained easily, some techniques are required to find the mean quantities under consideration. Results obtained involve the task of evaluating the trace of a certain matrix of nine degrees. Numerical calculations by a computer and discussions of the results will be given in part II of this series.
Molecular Ions
Authors: Varney Robert N.
Published: January 2005

Physico-chemical analysis of data concerning drift velocities of ions in nitrogen discloses that N4+ ions are the stable ones at low temperature and E/p0 and that the ions dissociate into N2+ and N2 at higher E/p0, higher temperature, or lower pressure. The dissociation behaves identically with thermal dissociation of molecular gases. The analysis yields the following numerical data: N4+ binding energy against dissociation into N2+ and N2, 0.50 ev; Ion temperature in °K as a function of E/p0 in volts per cm per mm Hg, θ=12.5 E/p0.
Atomic Distributions in Liquid, Plastic, and Crystalline Sulfur
Authors: Tompson C. W. , Gingrich N. S.
Published: January 2005

X-ray diffraction patterns were obtained, using improved technique, for liquid sulfur at 80°C (supercooled), 120°C, 165°C, 200°C, 240°C, and 300°C; and for amorphous sulfur at 4°C and for powdered crystalline orthorhombic sulfur at 23°C, confirming reported new details at small angles and extending observations to nearly twice the range of (sinθ)/λ heretofore reported. Atomic distribution curves are presented for all these cases. Nearest neighbor distances and numbers remain constant throughout at 2.07 A and 2 atoms, respectively, but other features of the distribution curves change with temperature. New results with neutron diffraction at 120°C are compared with these x-ray results.
Electrical Properties of Poly-Copper Phthalocyanine
Authors: Epstein A. , Wildi Bernard S.
Published: January 2005

Hall effect and electrical resistivity measurements as a function of temperature to ∼450°C have been carried out on a polymer of copper phthalocyanine. From the Hall effect data it is concluded that intrinsically the polymer of copper phthalocyanine is P type. Two states of this polymer have been determined, one has an activation energy of 0.26 ev and a carrier density ∼1016/cm3 (the carrier concentration varying with temperature), a second, a heat-treated polymer, also shows P type conductivity but the carrier density is ∼1018/cm3 and is constant in the range of temperature measured. The mobility in the heat-treated polymer is found to increase with increasing temperature. N type conductivity observed on the first structure is believed to be a consequence of impurities.
Energy Transfer in Molecular Complexes. II. The Anthracene-sym-Trinitrobenzene Complex
Authors: McGlynn S. P. , Boggus J. D. , Elder E.
Published: January 2005

The emission spectrum of the anthracene-sym-trinitrobenzene complex has been investigated in a solid solution in a diethylether-isopentane (EP) glass at 77°K. The observed luminescence consists of two distinct electronic transitions: one transition is the reverse of the charge-transfer E←N absorption of the complex; the other transition is a phosphorescence very similar to the T→S emission of anthracene in EP, but blurred somewhat in vibrational structure, blue shifted by 113 cm—1, decreased in lifetime by a factor of about 2 and showing decreases in the ground state vibrational frequencies of a few percent. These results, as opposed to previous conclusions (vide infra), would suggest that the phosphorescence is truly a T→S process of the complex which is largely localized on the anthracene component.

Vibrational analyses of T→S spectra of anthracene in EPA and in EP and of the T→S and E→N spectra of the complex in EP at 77°K are given.
Short-Range Interaction between a Hydrogen Molecule and a Hydrogen Atom. II
Authors: Jameson William J. , Aroeste Henry
Published: January 2005

Computations of the interaction between a hydrogen atom and a hydrogen molecule, where one of the three atoms is in a two-quantum electronic state, have been made using a modified Heitler-London procedure. The calculated interaction energies of the system including a degenerate state for which the magnetic quantum number is m=0 are about 5 ev lower than the previous Heitler-London results in which no excited state were considered. The results are compared with experimentally determined energies, and a possible explanation of the discrepancy between theoretical and experimental values is presented. Calculations are also presented for cases where m=1.
Threshold Law for the Probability of Excitation by Electron Impact
Authors: Dorman F. H. , Morrison J. D. , Nicholson A. J. C.
Published: January 2005

The threshold law for processes of excitation is difficult to measure directly and lack of experimental evidence has prevented a choice being made between different theoretical treatments. The ionization efficiency curves for the ion-pair processes, I+ from I2, O+ from O2, and C+ from CO, and for what is here claimed to be auto-ionization in N2+ and O2+ have been measured. It is shown that these curves measure excitation probabilities and that the threshold law is in all cases a step function of the energy. The implications of this with regard to the assignment of dissociation products and the measurement of appearance potentials are discussed.
Threshold Ionization of HCl by Electron Impact
Authors: Fox R. E.
Published: January 2005

The ionization of HCl by electron impact is studied in a mass spectrometer with a pseudomonoenergetic electron beam. The ionization potential of HCl is determined as 12.56±0.1 ev. The ionization curve at threshold exhibits excessive curvature which is attributed to the 2Πi doublet ground states of the ion estimated to be separated by 0.3 ev. A sharp change in slope of the ionization curve at 1.6 ev above threshold is attributed to the onset of ionization of the A2Σ+ excited state of HCl+.
Nuclear Quadrupole Coupling in Chlorite Ion
Authors: Ragle J. L.
Published: January 2005

Chlorine pure quadrupole spectra have been observed in silver chlorite and sodium chlorite at room temperature. The observed coupling constant of 108.16 mcps for silver chlorite is discussed in terms of a simple model of the electronic structure, in which the magnitude of the apparent coupling constant may be understood as resulting from a highly asymmetric field gradient ellipsoid and from residual positive charge on the chlorine atom.
Electron Spin Resonance Studies of the Potassium Salt of m-Dinitrobenzene Negative Ion
Authors: Ward Raymond L.
Published: January 2005

A detailed analysis of the electron spin resonance spectrum for the potassium salt of m-dinitrobenzene negative ion in DME is presented. Isotopic substitution has been performed in various positions in the molecule. m-Dinitrobenzene negative ion exhibits only one nitrogen hyperfine interaction of 9.0 gauss, and possesses proton hyperfine interactions of 4.6 gauss for the number 2, 4, and 6 protons and 1.2 gauss for the number 5 proton. The hyperfine spectrum is different for each of the alkali metals, Li, Na, K, Rb, and Cs, but still retains only one nitrogen hyperfine interaction. An enriched Li6 metal salt of m-dinitrobenzene indicates no alkali metal hyperfine interaction.
Nature of the Free Electron Model. The Simple Case of the Symmetric Polymethines
Authors: Kuhn H. , Huber W. , Handschig G. , Martin H. , Schäfer F. , Bär F.
Published: January 2005

In the case of the polymethines H2C=CH(CH=CH)j−1CH2⊕and H2C=CH(CH=CH)j−1CH2⊖the wave functions and energy levels of the π electrons given by the one-dimensional free electron model are compared with those given by more elaborate methods in which the π electrons are treated as electrons in a one- or two-dimensional core potential obtained from nuclear charge and shielding considerations. The results of the three treatments are in good agreement, and thus the reliability of the simple free electron model is justified.
Nature of the Free Electron Model. The Case of the Polyenes and Polyacetylenes
Authors: Bär F. , Huber W. , Handschig G. , Martin H. , Kuhn H.
Published: January 2005

The wave functions and energy levels of the polyenes and polyacetylenes found on the basis of the simple sine curve potential model are compared with those given by more refined methods in which the π electrons are treated as electrons in a one-, two-, or three-dimensional core potential obtained from nuclear charge and shielding considerations. The results of the four treatments are in good agreement, and by considering the electron density distribution along the chain each treatment leads to the same conclusion, that each single bond and each double (or triple) bond in a long-chain polyene (or polyacetylene) must have, respectively, the same length as the single bond and double (or triple) bond in butadiene (or diacetylene). The values of the absorption maxima given by the four models are in good agreement with the experimental values.
Bond and Molecular Polarizability Tensors. I. Mathematical Treatment of Bond Tensor Additivity
Authors: Smith Richard P. , Mortensen Earl M.
Published: January 2005

A general equation is obtained for the polarizability tensor of a molecule, considering the molecular tensor to be constructed from bond tensors. Bond-by-bond transformations of the bond tensors are used, so that the general equation involves bond angles and angles describing internal rotations. For tetrahedral hydrocarbons and their derivatives, the general equation reduces to simple forms. It is shown that the theory provides a simple method for the calculation of molecular anisotropy.
Bond and Molecular Polarizability Tensors. II. Discussion of Values of Polarizability Parameters for Some Single Bond Involving Carbon
Authors: Smith Richard P. , Mortensen Earl M.
Published: January 2005

It is pointed out that for C–C, C–H, C–O, and C—halogen bonds, the experimental data on molecular polarizability tensors (light depolarization data, Kerr constants, etc.) do not permit evaluation of longitudinal and transverse bond polarizabilities. Only certain linear combinations of these quantities, involving parameters for more than one type of bond, are determinable. The data pertaining to these bonds are discussed in this light. Denbigh's longitudinal and transverse polarizabilities1 for C—halogen bonds probably are essentially correct, but his C–C and C–H polarizabilities are not meaningful.
Crystal Spectra of Metal Coordination Compounds. II. Violet Form of CoPy2Cl2 and CoCl2·6H2O
Authors: Ferguson J.
Published: January 2005

A microspectrophotometric study of the visible polarized crystal spectra of the violet form of cobalt dipyridine dichloride and cobalt chloride hexahydrate is reported. An analysis of the band structure of the former is made in terms of noninteracting, complex units, but in the latter, interaction between a cobalt ion and the chloride ions on next nearest neighbor complexes, in addition to the ligands, is needed for a successful analysis of the spectrum.
Far Infrared Spectra of Some Symmetric Top Molecules
Authors: Robinson Dean W. , McQuarrie Donald A.
Published: January 2005

Pure rotational spectra out to 30 cm—1 are presented of the gaseous molecules CH3CN, CH3CCH, HCF3, and (CH3)3N. These spectra are interpreted in view of the rotational constants previously determined from microwave data. The heretofore undetermined value of DJ for CH3CN has been estimated to be 1.45×10—7 cm—1, the value of DJK for (CH3)3N is shown to be positive, and the intensity distribution in the high-J subbands of the oblate top, HCF3, has been estimated to have its center at K=17.
Simultaneous Electronic and Vibrational Transitions in the Spectra of Hydrated Nickel(II) Ion
Authors: Piper T. S. , Koertge Noretta
Published: January 2005

A series of weak bands at about 19 000 cm—1 was found in the visible spectra of the hydrated nickel(II) ion in several crystals. These bands are assigned to simultaneous electronic and vibrational transitions involving the H–O stretching vibration. This assignment was confirmed by observation of an isotopic shift upon deuteration.
Vibrational Intensities of Benzene in the Liquid Phase
Authors: Hisatsune I. C. , Jayadevappa E. S.
Published: January 2005

The intensities of the four fundamental absorption bands in liquid benzene have been measured by using the Wilson-Wells method. In addition, the intensity of the 15-μ CH bond out-of-plane bending mode absorption band has been measured in cyclohexane, isooctane, methyl formate, and ethyl propionate solutions at five different concentrations. The solution values were in all cases larger than the pure liquid result. The effect of iodine in the most dilute solution of each solvent was also investigated, but no apparent difference from the simple solution was observed. The variations in the intensity, the band width, and the peak frequency with concentration found here suggest the existence of pronounced intermolecular interactions in liquid benzene.
Dipole Moment Function for HD
Authors: Blinder S. M.
Published: January 2005

The wave-function method of Trischka and Salwen for computing dipole moment functions is applied to the HD molecule. From data on relative intensities of the weak rotation-vibration transitions, several possible dipole functions are constructed. The one having a maximum coincident with the vibrational potential minimum is believed to be the most reasonable.
Ion-Molecule Charge Transfer Reactions in the Alpha Radiolysis of Various Hydrocarbons in a Mass Spectrometer
Authors: Rudolph P. S. , Melton C. E.
Published: January 2005

The new alpha-particle mass spectrometer proves to be a powerful tool for the study of charge transfer between gaseous ions and molecules. Energetically possible charge-transfer reactions have been differentiated into probable and improbable reactions by employing binary mixtures of hydrocarbon gases in this instrument.

The alpha-particle induced charge-transfer reaction, C2H2++C6H6→C2H2+C6H6+, is shown to be very efficient. In contrast, the charge-transfer reaction, C2H2++C2H4→C2H2+C2H4+, is shown to be inefficient. This inefficiency is discussed in terms of the competing chemical reaction, C2H2++C2H4→C3H3+ +CH3.
Paramagnetic Resonance of Ti3+, Cr3+, and Fe3+ in AlCl3·6H2O
Authors: Wong Eugene Y.
Published: January 2005

Magnetic resonance of single crystals of TiCl3·6H2O, CrCl3·6H2O, and FeCl3·6H2O diluted with AlCl3·6H2O was observed. The results in each case were fitted to a spin Hamiltonian.
Detonation Pressure of Liquid TNT
Authors: Garn W. B.
Published: January 2005

The plane steady-state detonation pressure behind the reaction zone of liquid TNT is reported. This pressure of 171.8 kilobars was established by measuring free-surface velocity as a function of plate thickness for 2024 aluminum plates placed in contact with the detonating explosive. The zero thickness metal shock pressure, obtained by extrapolating the free-surface velocity data, is corrected to the corresponding detonation pressure by an impedance matching calculation. Recording was done by a sweeping-image camera technique.
Note on the Paramagnetic Resonance of Iron in Glass
Authors: Castner Theodore , Newell George S. , Holton W. C. , Slichter C. P.
Published: January 2005

Fe+ + + and Fe+ + ions in glass have been studied by means of paramagnetic resonance. The correlation of the Fe+ + + concentration with an intense resonance at g=4.27 shows the resonance is due to Fe+ + +. A theory is proposed explaining the observed g value and the implications for the atomic surroundings of Fe+ + + are discussed. It is also proposed that the g=6 resonance observed in glass by Sands is due to Fe+ + +.
Potential Energy Curves of Hydrogen Fluoride
Authors: Fallon Robert J. , Vanderslice Joseph T. , Mason Edward A.
Published: January 2005

Potential energy curves for the X 1Σ+ and V 1Σ+ states of HF and DF have been calculated by the Rydberg-Klein-Rees method. The results calculated from the different sets of data for HF and DF are found to be in very good agreement. The theoretical results of Karo are compared to the experimental results obtained here.
New Emission Bands of Forbidden Systems of Nitrogen in the Vacuum Ultraviolet Region
Authors: Ogawa M. , Tanaka Y.
Published: January 2005

Using a 2-m vacuum spectrograph and an ordinary transformer discharge through mixtures of N2 with argon and xenon, we observed two new systems of N2 emission bands, one for each mixture, in the region between 1550 and 2250 A. According to the vibrational analysis, the bands, which were excited in the mixture of (N2+A), are due to the transition (a′1Σu−−X 1Σg+), and the bands, which were excited in the mixture of (N2+Xe), are due to the transition (3Σu−−X 1Σg+). The present results are in good agreement with those of Wilkinson and Mulliken whose observations were made for the same systems of bands in absorption.
Atomic Polarization. I. Vibrational Polarization of Gases
Authors: Illinger Karl H. , Smyth Charles P.
Published: January 2005

A derivation is given for the vibrational polarization and the vibrational polarizability of a molecule in several degrees of approximation. From the expressions derived, the vibrational polarization is calculated for a large number of molecules. A discussion, within the framework of the present derivation, is given of the atomic polarization, and a detailed comparison with previous theories is made.
Structure of Isobutylene
Authors: Bartell L. S. , Bonham R. A.
Published: January 2005

The molecular structure of gaseous isobutylene has been investigated by the sector-microphotometer method of electron diffraction. The major internuclear distances found, in terms of center of gravity parameters, rg, were C–H (methyl)=1.113±0.003 A (assumes ethylenic hydrogens have ethylene values), C=C=1.331±0.003 A, C–C=1.505±0.003 A, and (C···C)Av=2.498±0.005 A. Angles were C–C–H (methyl) =110.4° and Me—C—Me∼112°. Amplitudes of vibration were determined.
Unperturbed Chain Dimensions of Polymeric Chains
Authors: Hoeve C. A. J.
Published: January 2005

Methods are given for the calculation of polymer chain dimensions unperturbed by excluded volume effects but dependent on restricted rotation around the chain bonds as a result of interactions between substituents on neighboring chain atoms. The matrix methods used by most previous investigators are valid only for cases where the rotations, or pairs of neighboring rotations, are noninteracting. The methods recently developed by Lifson to account for interactions between any two consecutive rotations in chains of the type (CR2)i are extended to chains of the type (CH2–CR2)i and isotactic chains of the type (CH2–CHR)i.

As an illustration the chain dimensions of polyisobutylene are calculated by using parameters from x-ray data in the crystalline state and results from stress-temperature measurements on amorphous networks. Reasonable agreement is obtained with experimental data on dilute solutions of polyisobutylene.
Infrared Dispersion Measurements and Integrated Absorption Coefficients for Pure Liquid Benzene
Authors: Schatz Paul N.
Published: January 2005

The refractive index of pure liquid benzene has been measured in the 2-to 21-μ region to an accuracy of about ±0.003 using an interferometric technique developed by Kagarise and Mayfield. A general relation is derived between the refractive index and integrated absorption coefficients of a pure liquid. The relation is used to determine the absolute intensities of the fundamental vibrations of pure liquid benzene from the dispersion data. A comparison is made with the same intensities determined in the direct absorption measurements of Hisatsune and Jayadevappa. The dispersion values appear to be higher than the absorption results, the difference being about 40% for the 14.8 μ fundamental where the most accurate comparison is possible. A comparison between pure liquid and gas intensities is also made.

A brief discussion is given of the advantages and limitations of the dispersion method in determining integrated intensities in liquids.
Volumes of Activation. II. Pressure Dependence of Activation Parameters
Authors: Keyes Robert W.
Published: January 2005

The relation between activation volume and activation energy of diffusive processes which was previously proposed is integrated to show how the activation free energy depends on the volume of the solid. The result is shown to be in agreement with the data of Nachtrieb et al. on the pressure dependence of the diffusion constant of sodium.
Ground State Electronic Wave Function of Methane
Authors: Nesbet R. K.
Published: January 2005

An approximate electronic wave function for the ground state of CH4, in the equilibrium nuclear configuration, has been obtained by a variational calculation. Approximate Hartree-Fock molecular orbitals are expanded as linear combinations of a set of basis orbitals of the form f(x, y, z) exp(—ar2) centered on carbon and hydrogen. Five independent s orbitals and two p orbitals on carbon are combined with one simple Gaussian orbital on each hydrogen nucleus. The parameters specifying these orbitals were obtained by preliminary variational calculations on the carbon atom. Correlation effects due to all possible Slater determinants constructed from these orbitals are calculated by a perturbation method. Parallel calculations with the same orbitals were carried out on the 3P ground state of carbon. Calculated ionization potential and dissociation energy are compared with experimental values.
Calculation of the Dissociation Energy of NH by a Semiempirical Interpolative Method
Authors: Companion Audrey L. , Ellison Frank O.
Published: January 2005

Simple valence bond wave functions (using hybridized orbitals) are constructed for the CH, NH, and OH molecules. The intraatomic energy is evaluated by Moffitt's atoms-in-molecules method. The interatomic energy is approximated by: (1) replacing heavy-atom 1s electrons by point charges at their nuclei; (2) restricting exchange energy contribution to permutation of bonding electrons; (3) using Mulliken approximation to reduce exchange and hybrid integrals to Coulomb and overlap types; (4) evaluating one-center integrals by the Pariser approximation and by a new method which utilizes the virial theorem; and (5) expressing two-center integrals by simplified expressions which give correct semiempirical values at R=0 limit and which contain two arbitrary parameters. The latter are adjusted so as to yield correct dissociation energies of CH and OH. The dissociation energy of NH is then found to be 3.61 ev, which lies within the uncertainty of the best experimental result 3.7±0.5 ev. Calculated degrees of hybridization agree well with previous estimates.
Structure of Glass Forming Halides. I. Liquid Beryllium Fluoride
Authors: Mackenzie J. D.
Published: January 2005

Viscosity and electric conductivity measurements have been made on liquid beryllium fluoride over the temperature range 700–950°C. The high specific resistance and viscosity and the magnitude of the corresponding energies of activation indicate that the classical random network structure for glasses is applicable. Liquid BeF2, similar to liquid GeO2 and SiO2, is highly associated even at elevated temperatures. At a temperature 200° above the melting point, the energy of activation for viscous flow is greater than the heat of vaporization. The ease of glass formation is attributed to the network structure of the liquid.
Application of a High-Speed Electronic Computer in Diffusion Kinetics. II. Depletion Effect in the Spherical One-Radical One-Solute Model
Authors: Fricke Hugo , Phillips David L.
Published: January 2005

The earlier computations [D. A. Flanders and H. Fricke, J. Chem. Phys. 28, 1126 (1958)] on the Spherical One-Radical One-Solute model were extended by taking account of the transient dilution of the solute which occurs during the reaction. Although the drop in concentration of the solute near the center of the reaction zone may be considerable, its effect on the fraction of radicals combining with the solute is only of the order of one percent under the most unfavorable conditions likely to be encountered when the model is applied to γ-irradiated aqueous solutions.
On the Nature of Solvent Effects in the Proton Resonance Spectra of Unsaturated Ring Compounds. II. Heterocyclic Compounds
Authors: Schaefer T. , Schneider W. G.
Published: January 2005

In unsaturated heterocyclic compounds, the relative chemical shifts of the protons bonded to the ring are strongly dependent on solvent and concentration. In 6-membered ring compounds, as for example 4-picoline, the β hydrogens show a pronounced shift to low field in acetone solutions and to high field in benzene solutions. This behavior is similar to the behavior found for p-substituted toluenes (preceding paper). In the 5-membered heterocyclic compounds, for example pyrrole, the behavior of α and β hydrogens is reversed, the proton signals of α hydrogens being displaced selectively in acetone and benzene. The results can be interpreted in terms of a preferential hydrogen bonding of the α protons with the donor solvent molecules.
Absolute Infrared Intensities of the Ammonium Ion in Crystals
Authors: Ferriso C. C. , Hornig D. F.
Published: January 2005

The absolute intensities of the two infrared active fundamentals of the ammonium ion, ν3 and ν4, have been studied in several environments. Dilute solid solutions of NH4+ ions in KCl, KI, CsCl, and CsI were studied and compared with pure NH4I. After separating the effect of the net charge, the apparent bond moments ranged from 0.63 d to 0.80 d (av 0.71) and the bond dipole derivatives, ∂μ/∂r, from 2.06 d/A to 3.59 d/A (av 2.80 d/A). The bond moment is substantially the same as in NH3.
Matrix Effects on the Electron Spin Resonance Spectra of Trapped Hydrogen Atoms
Authors: Adrian F. J.
Published: January 2005

A study is made of the matrix effects on the electron spin resonance (ESR) spectra of hydrogen atoms stabilized in nonpolar matrices. It is assumed that the perturbing effect of the matrix consists of van der Waals interactions and the overlap or Pauli exclusion forces. These two effects are treated separately and the results added to get the net result. The van der Waals effect, which is treated by perturbation theory, leads to a reduction in the hfs splitting. The overlap effect, which is treated by requiring that the hydrogen atom wave function be orthogonal to the wave functions of the matrix particles, leads to an increase in the hfs splitting. In addition, the exclusion effect tends to introduce a small amount of the unpaired electron charge density onto the matrix particles. This can lead to a change in the electronic g factor, and also to hyperfine interactions with the nuclei of the matrix particles. The theory gives a good qualitative picture of the various matrix effects and their dependence on various properties of the matrix atoms and molecules.
Transferability of Urey-Bradley Force Constants. I. Calculation of Force Constants on a Digital Computer
Authors: Overend John , Scherer J. R.
Published: January 2005

An algorithm for the systematic calculation of Urey-Bradley force constants has been programed for a digital computer (the Datatron 204). The secular equation is set up and solved in internal coordinates, the potential energy being transformed from Urey-Bradley space to internal-coordinate space by a matrix Z. This same matrix is also used to transform the Jacobian of λ with respect to the force constants from internal-coordinate to Urey-Bradley space, thereby allowing the direct determination of Urey-Bradley force constants. A method is described whereby the Z matrix and Wilson's G matrix may be set up by the computer from the geometrical parameters of the molecule.
Dislocation Etchings
Authors: Sears Gerald W.
Published: January 2005

The theory of preferential etching at dislocations has been presented by Cabrera. In the present report the theory is reviewed and compared to empirical observations on the dissolution of lithium fluoride. The observed dissolution behavior is consistent with Cabrera's theory as modified by the effect of dissolution poisons.
Calculation of the Coupling Terms Neglected in Performing the Born-Oppenheimer Separation for the Hydrogen Molecule Ion
Authors: Jepsen Donald W. , Hirschfelder Joseph O.
Published: January 2005

A method is given for calculating the coupling between the nuclear and electronic motion in the hydrogen molecule ion using the exact wave functions. Calculations are carried out for the transition 1sσ—2sσ and compared with values obtained from simple approximate methods. Estimates are made of the cross sections for excitation and capture into the 2s state during a proton-hydrogen atom collision, using approximate H2+ wave functions to describe the state during collision. Finally, it is shown that a Born-Oppenheimer separation carried out in relative coordinates should be slightly more accurate than the usual treatment using fixed space coordinates. Two different types of relative coordinates suggest themselves for use at different ranges of internuclear separation.
Extended Theory of Sputtering
Authors: Harrison Don E.
Published: January 2005

The author's earlier theory of sputtering has been simplified to a form from which direct computations are possible without extended numerical analysis. A considerable analytic simplification is obtained by a new choice of boundary conditions, and certain mathematical expressions have been modified by physical considerations where a detailed analysis is not justified by the present state of experimental information. The special cases of very high and very low energy sputtering are examined in some detail. The (lnE0)/E0 high-energy results of Goldman and Simon are shown to be fortuitous but still significant. Low energy results are of the form reported by Wehner.
Intermolecular Coupling of Vibrations in Molecular Crystals
Authors: Dows David A.
Published: January 2005

The connection between intermolecular potential energies and the unit cell vibrational frequencies in molecular crystals is summarized in Sec. I. Details of the treatment of potentials which can be written as functions of intermolecular atom-atom distances are developed. The frequencies of vibration of methyl chloride in the crystal are treated by the methods discussed in Sec. II. Dipole-dipole interactions are insufficient to explain the observed splittings. For vibrations which are primarily hydrogen motions, an intermolecular hydrogen-hydrogen repulsion potential accounts satisfactorily for the observed effects.
Electron Capture by Neutral Molecules
Authors: Stanton R. E.
Published: January 2005

The problem of calculating the probability of electron capture by neutral molecules is analyzed. It is shown that capture is possible only through the breakdown of the separation of nuclear and electronic motion in the Schrödinger equation, and that this is equivalent to the use of the nuclear kinetic energy as a perturbation operator. For diatomic molecules, it is found that capture is improbable except for those states of the negative ion whose major configuration contains at least as many MSO's of a given spin-symmetry type as the neutral molecule. Experimental verification of this result is found in the case of hydrogen.
Effect of Pressure on the Spectra of Color Centers
Authors: Eppler R. A. , Drickamer H. G.
Published: January 2005

The effect of pressure on the spectra of certain color centers produced in the alkali halides by x irradiation has been measured to pressures as high as 166 000 atm.

For the F center a shift to higher energies with increasing pressure is observed. The slope of the shift versus density is at least twice the value that would be predicted from Ivey's relation at low pressure, and decreases with increasing pressure. This indicates that the compressibility in the neighborhood of the F center is greater than in the bulk crystal, particularly at low pressure.

For the M center in LiCl a shift to higher energy with increasing pressure is observed, about one-fifth as great as the shift observed for the F center.
Equilibrium and Transport Properties of the Carbon Tetrachloride-Methylene Chloride System
Authors: Mueller Charles R. , Ignatowski Albert J.
Published: January 2005

Liquid densities of solutions of CCl4 and CH2Cl2 have been measured at 20°C, and the excess volume has been obtained. Liquid-vapor equilibrium studies have been made at 30°, 35°, and 39°C, and the excess free energy of mixing has been deduced. Liquid viscosities have been measured at 20°C. The excess free energy of activation for viscous flow has been calculated. Vapor viscosity measurements have been made on the same system at 20°, 80°, and 140°C, as an adjunct to the theory to calculate the parameters in the Lennard-Jones potential.
Electronic Interaction in the Free-Electron Network Model for Conjugated Systems. III. Spectra of Hydrocarbons Other Than Even Alternants
Authors: Ham Norman S.
Published: January 2005

The effects on spectral calculations of including interaction between the ground and lower excited states are investigated by the free-electron model for some hydrocarbons in which such interaction should occur in principle, viz., phenanthrene, perinaphthenylium cation, and azulene. The resultant lowering of the ground state energy is less than 150 cm—1 when the ground and excited states have equal charge densities. For azulene, with unequal charge densities, the interaction is about 4000 cm—1, and the agreement with experiment for the two lower singlet levels is considerably improved. The free-electron calculations for the nonalternant ions C5H5; and C7H7+ are also reported.
Potential Energy Curves for Lithium Hydride
Authors: Fallon Robert J. , Vanderslice Joseph T. , Mason Edward A.
Published: January 2005

Potential energy curves for the X 1Σ+, A 1Σ+, and B 1π states of LiH have been calculated by the Rydberg-Klein-Rees method. The results are in agreement with curves previously obtained by Crawford and Jorgensen and by Rosenbaum using different methods. As a check, the somewhat peculiar curve for the A 1Σ+ state has also been calculated for LiD, and agrees with the LiH curve to about one percent. The curves obtained theoretically by Karo and Olson for the X 1Σ+ and A 1Σ+ states are only in fair agreement with the experimental results.
Nonresonant Absorption in Symmetric-Top Gases: Dependence of Relaxation Frequency on Temperature
Authors: Maryott A. A. , Estin A. , Birnbaum G.
Published: January 2005

The nonresonant absorption spectra of CHF3, CH3F, and CClF3 were obtained in the gaseous state at various temperatures in the range 230° to 360°K. In all cases the maximum value of the dielectric loss per unit pressure varies as T—2, in accordance with the Debye equation. The variation of relaxation frequency (line width) with pressure and temperature is represented by Δν∞pT—m, where m has the following values: 1.59±0.03 for CHF3, 1.60±0.02 for CH3F, and 1.27±0.02 for CClF3, Since CHF3 and CH3F have rather large dipole moments, the predominant interaction should be of the first-order dipole-dipole type. On this basis Anderson's theory predicts m = 1. Closer agreement with the experimental data is obtained with an expression derived essentially from dimensional considerations of a torque-impulse model, which gives m = 1.5. In the case of CClF3, which has a comparatively small dipole moment, the data indicate that molecular reorientation is governed primarily by forces of shorter range.
Polarized Octahedra in Barium Tetratitanate
Authors: Templeton David H. , Dauben Carol H.
Published: January 2005

Single-crystal x-ray diffraction studies show that BaTi4O9 is orthorhombic, space group Pmmn, with a = 14.53±0.02, b = 3.79±0.01, and c = 6.29±0.01 A, with two formula units per unit cell and calculated density 4.54 g cm—3. Each barium atom has four oxygen neighbors at 2.81 A, two at 2.96, and four at 3.09, at the corners of a pentagonal prism. Titanium atoms are in distorted octahedra of oxygen atoms. The Ti–O distances range from 1.77 to 2.32 A, with standard deviations of 0.03 A or less. Titanium atoms occur at points 0.30 and 0.21 A from the centers of gravity of the oxygen atoms of the two kinds of octahedra. This polarization of the two octahedra is similar to or greater in magnitude than that observed in the ferroelectric phases of BaTiO3 and PbTiO3.
Some Properties of First Order Density Matrices with Special Application to Many-Electron Atoms
Authors: Bingel Werner A.
Published: January 2005

Properties of the first order density matrix γ(x′ | x) of an N-electron system are discussed, including the relation between γ(x′ | x) and the spinless first order density matrix γ(r′ | r) and those symmetry properties of the total electronic charge density γ(r) ≡ γ(r | r) which result from the corresponding properties of the total wave function with special reference to many-electron atoms. General formulas are given for the evaluation of γ(r) of many-electron atoms in the orbital approximation and for its decomposition into terms of different angular symmetry. These formulas are applied to all terms of the electron configurations snpm and the results collected in tables.
Sputtering of Silver by Light Ions with Energies from 2 to 12 kev
Authors: Grønlund Finn , Moore Walter J.
Published: January 2005

Electromagnetically analyzed ionic beams from a radio-frequency source were used to study the sputtering yield S (atoms per ion) for light ions normally incident on silver targets at energies from 2 to 12 kev. The yields displayed broad maxima with energy in the range studied. At 5 kev the following values of S were found: H+, 0.035; D+, 0.090; H2+, 0.077; D2+, 0.21; H3+, 0.11; D3+, 0.33; He+, 0.48; N+, 4.0; O+, 4.4; Ne+, 5.5. The angular distribution of sputtered silver followed a cosine dependence about the normal to the target surface even when the beam hit the target at oblique incidence.