bluuebunny/crossref_metadata_2025 huggingface dataset:
Formulas for Thermal Conductivity of Ternary Gas Mixtures
Authors: Srivastava B. N. , Saxena S. C.
Published: January 2005

The thermal conductivities of ternary mixtures of neon, argon, and krypton have been recently reported by the authors. In the present paper these values have been compared with those calculated from the two simple generalized expressions for the thermal conductivity of a ternary mixture, one of which is obtained from an extension of the Enskog's expression for the binary thermal conductivity while the other from the Lindsay-Bromley formula. It is found that the latter generalization yields values which are in better agreement with the experiment, provided the two constants of the Lindsay-Bromley formula are determined experimentally from binary conductivity.
Dielectric Properties of Polyethylene Glycols at Microwave Frequencies
Authors: Koizumi Naokazu
Published: January 2005

The complex dielectric constants of ethylene, diethylene, triethylene, tetraethylene, and hexaethylene glycols in the liquid state have been measured at frequencies of 1.43, 9.73, and 18.7 kmc/sec at temperatures from 5 to 50°C. The parameters of dielectric relaxation for these polyethylene glycols have been calculated from the complex dielectric constants and the static dielectric constants by the circular arc rule of Cole and Cole. It has been found that the dielectric relaxation times obtained do not vary much with the homolog of this polyethylene glycol series, being of the order of 10—10 sec at 20°C. The value of relaxation time is the largest for diethylene glycol, decreasing slightly with higher homologs of this series. This striking feature is discussed in terms of flexibility of the polyoxyethylene chain due to internal rotation around the C–O bonds of the chain skeleton, which would make more possible a partial and independent orientation of the hydroxyl groups at the ends of the molecular chain in the case of higher polyethylene glycols.
Isotopic Exchange Reactions. The Halogen Exchange between SiCl4 and HCl
Authors: Herber Rolfe H.
Published: January 2005

The kinetics of the isotopic chlorine exchange between SiCl4 and HCl have been measured using the tracer Cl36. The reaction is first order in HCl and second order in SiCl4. E‡ and S‡ are 22.4 K cal mole—1 and —17.6 cal deg—1 mole—1, respectively. A mechanism for the exchange is proposed.
Solid Methane—Changes in Phase under Pressure
Authors: Stevenson Richard
Published: January 2005

The solid phases of ordinary methane were studied under pressure at low temperatures by the volume discontinuity method. The phase diagram of the solid is presented. A new phase was observed, and the ``missing'' phase (by analogy to CD4 and CD3D) evidently appears only under pressure at liquid helium temperatures. Observations indicate another phase at high pressures in the low-temperature region. Indications of correlations among the phase diagrams of CH4, CH3D, and CD4 are shown.
Vibrational Spectrum and Structure of Metal-Cyanide Complexes in the Solid State. III. Hg(CN)2
Authors: Jones Llewellyn H.
Published: January 2005

The infrared spectra of solid Hg(CN)2 and the mono- and di-substituted C13 and N15 species have been observed. The polarized spectrum of a single crystal of the normal species was also observed. The seven fundamental vibrations of the linear, symmetric Hg(CN)2 molecule have been assigned at 2192, 415, 2193.5, 442, 276, 341, and ca 100 cm—1.

From the observed frequencies of the normal and isotopic species, force constants were calculated for two possible structures: N–C–Hg–C–N and C–N–Hg–N–C. It is shown that the latter structure gives unreasonably large values for the CN stretching force constant (> 20 md/A) and the CN, HgN interaction constant (∼2.4 md/A), while the former structure yields quite reasonable force constants, namely: Fcn=17.6, Fhgc=2.61, Fcn, c′n′=—0.1, Fhgc, hgc′=0.1, and Fhgc, cn=0.1 md/A. These results are presented as strong evidence that the cyanides are bound to the mercury through carbon atoms.
Compressions and Solid Phases of CO2, CS2, COS, O2, and CO
Authors: Stevenson Richard
Published: January 2005

Compressions and phase diagrams for solid CO2, CS2, COS, O2, and CO are presented for pressures up to 10 000 atmos at low temperatures. A new modification of COS was observed under pressure.
Study of the Wurtzite-Type Binary Compounds. II. Macroscopic Theory of the Distortion and Polarization
Authors: Keffer F. , Portis A. M.
Published: January 2005

The slight departure of wurtzite-type binary compounds from ideal c/a ratio and ideal sublattice displacement parameter u is accounted for by the forces arising from partial polar binding. These long-range forces are calculated in terms of a postulated charge ±fe per ion and certain lattice sums which we evaluate. When balanced against the elastic, piezoelectric, and dielectric constants of the crystal, the forces account for both the direction and the order of magnitude of the distortion. The compounds AlN, BeO, and ZnO are considered in detail. An experimental value of 8.5 is given for the dielectric constant of AlN, but in the absence of precise values for elastic and piezoelectric constants only an order of magnitude check of the theory can be made at this time. Some remarks are appended on the general problem of finite lattice sums in complex lattices which have dipole and/or quadrupole moments in the unit cell.
Statistical Mechanics of Flexible High Polymers at Surfaces
Authors: Frisch H. L. , Simha Robert
Published: January 2005

The isotherm corresponding to monolayer adsorption and the equation of state of a monolayer at a liquid interface are derived. As previously, we replace the number of segments per chain actually deposited, by an average value, which is proportional to t½ (t total number of segments) and depends on chain flexibility. This introduces a considerable simplification. However, a previous overcounting of configurations on the surface is eliminated. This affects primarily the results at low surface coverage and leads to the anticipated limiting laws. The isotherms differ considerably, although not as much as for rigid macromolecules of equal chain length, from the Langmuir type. The change in surface tension in solution as a function of bulk concentration, molecular weight, and solvent power is calculated.
Simple Molecular Orbital Theory of Conjugation in Vinyl Bromide and Bromobenzene
Authors: Howe John A. , Goldstein J. H.
Published: January 2005

Quadrupole coupling constants for vinyl bromide, supplemented by other data of spectroscopic origin, have been utilized to obtain a value for the resonance integral, βCBr, in simple molecular orbital theory with inclusion of overlap. Using this parameter, resonance dipole moments were calculated for vinyl bromide and bromobenzene, in reasonable agreement with experiment. Assumptions and approximations involved in the method are reviewed, and the properties of carbon-halogen bonds are discussed in the light of the results of this and similar previous studies.
Range of Validity of Higashi's Equation for a Quick Determination of Dipole Moment in Solution
Authors: Krishna Bal , Srivastava K. K.
Published: January 2005

The present authors have discussed the range of validity of Higashi's equation for determining the electric dipole moment of a substance in a nonpolar solvent. Mathematical analysis shows that Higashi's equation is valid for the straight part of the curve showing the variation of the dielectric constant of the solution with the mole fraction of the solute. With the six organic solutes examined the above conclusion is found to be valid for four, viz., chlorobenzene, ortho-dichlorobenzene, nitrobenzene, and methylene chloride. Ethylene dichloride and ethylene dibromide whose molecules are subject to restricted rotation, show anomalous results. It is likely that Higashi's equation may not be applicable to such molecules. Benzene was used as a solvent throughout.
Vibrational Intensities in Halogenated Methanes. III. The Interpretation of Solution Data
Authors: Mallard William C. , Straley Joseph W.
Published: January 2005

Using solution samples, the absolute infrared absorption intensities of five fundamental bands of CH2Cl2 were measured by an extrapolation technique and by approximate methods suggested by Ramsay. These determinations were used to test a classical relationship, proposed by Polo and Wilson, between corresponding liquid and vapor absorption band intensities. Qualitative agreement with published vapor intensity measurements was obtained.
Infrared and Raman Spectra of Fluorinated Ethanes. X. 1,1,1-Trifluoro-2-bromoethane
Authors: Nielsen J. Rud , Theimer Rose
Published: January 2005

The infrared absorption spectrum of gaseous CF3–CH2Br has been obtained with a 1 m cell and a Perkin-Elmer double-pass spectrometer equipped with CsBr, NaCl, and LiF prisms. The Raman spectrum of the liquid phase has been photographed with a 3-prism glass spectrograph of reciprocal linear dispersion 15 A/mm at 4358 A, and depolarization ratios have been measured for all but 2 of the Raman bands. The 18 vibrational fundamentals have been assigned as follows: Species a′ : 3000, 1311, 1251, 1083, 850, 844, 725, 634, 526, 312, and 158 cm—1; species a″ : 3052, 1437, 1282, 1143, 539, 352, and 104 cm—1. The spectra have been interpreted in detail. Thermodynamic functions have been calculated.
Evaluation of Molecular Quadrupole Moments from Microwave Line Breadths. II. Experimental
Authors: Feeny Harold , Madigosky Walter , Winters B.
Published: January 2005

An improved microwave spectroscope has been used to determine the effect of O2, N2, CO2, and H2 in broadening the J=3→3 inversion line of ammonia. An accurate evaluation of the molecular quadrupole moments of these gases was obtained from the measured collision diameters of 4.32, 5.64, 7.45, and 3.28 A units, respectively.
Organic Ions in the Gas Phase. IV. C7H7+ and C5H5+ Ions from Alkylbenzenes and Cycloheptatriene
Authors: Meyerson Seymour , Rylander Paul N.
Published: January 2005

Electron-impact studies have led to the proposal that the C7H7+ ion derived from toluene is not benzyl but tropylium. The mass spectra of toluene-α-C13 and cycloheptatriene confirm this proposal. Energy considerations indicate that toluene and related aromatic hydrocarbons yield the same kind of C7H7+ ion as cycloheptatriene, and that formation of this ion from toluene and cycloheptatriene proceeds through the same intermediate. A metastable peak, labeling, and correlations indicate that C5H5+ ions from n-alkylbenzenes are derived in part from a C7H8+ precursor, and not exclusively from C7H7+.
Spectroscopic Study of Electronic Flame Temperatures and Energy Distributions
Authors: Broida Herbert P. , Shuler Kurt E.
Published: January 2005

A spectroscopic study has been made of electronic temperatures and electronic excitation in flames from an analysis of the intensity distribution of selected parts of the iron spectrum. The iron was added to the flames in the form of ferrocene to serve as a temperature and excitation ``indicator.'' The flames investigated were the stoichiometric H2–O2 and C2H2–O2 flames at atmospheric pressure, a stoichiometric C2H2–O2 flame at low pressure (2.1 mm) and a N+CO atomic flame (3.7 mm). This study shows that the iron spectrum can be used as a spectroscopic ``thermometer'' to determine electronic temperatures in good agreement with adiabatic flame temperatures and OH rotational temperatures in flame regions at thermal equilibrium. The reaction zones of the C2H2–O2 and N+CO flames showed a marked departure from equilibrium as indicated by the nonthermal excitation of the added iron, the observed iron spectrum resembling that of an iron arc. This nonthermal excitation of the iron spectrum, which is readily evidenced by the appearance of iron lines originating from high-energy levels (En′≥50 000 cm—1), can serve as a very sensitive indicator of the departure from equilibrium in a high-temperature reaction system. A brief discussion is given of the possible chemical and energy exchange mechanisms which may give rise to the abnormal excitation of iron in various reaction systems.
Inelastic Molecular Collisions with a Maxwellian Interaction Energy
Authors: Widom B.
Published: January 2005

The radial Schrödinger equation for arbitrary values of the angular momentum is solved exactly with a repulsive R—4 potential energy, the solutions being Mathieu functions whose arguments are linear functions of logR. These solutions are then applied to the problem of vibrational relaxation in the distorted wave approximation. Emphasis is given to the case in which the energy which is exchanged in the inelastic collision, ε0, is very much greater than the smaller of the energies of the incident and emergent waves. It is found that in this case the energy exchange probability per collision is proportional to a sinusoidal factor which may have a value anywhere between 0 and 1, depending on the precise magnitude of ε0; to a factor which decreases as the exponential of ε0¼; and to a factor which depends on the angular momentum quantum number, l, and on the smaller of the incident and emergent wave numbers, k. This last factor is evaluated for fixed l with k—1 much less than the effective range of molecular interaction; for fixed l with k—1 much greater than the effective range; and for l large with k fixed. The relaxation time is obtained and both its magnitude and temperature dependence are discussed. Over an appropriate range of temperature it is found to decrease as the exponential of —T⅓, which is not the same as the Landau-Teller exponential of T—⅓. The temperature dependence found in the present work is in much better agreement with the observed high-temperature vibrational relaxation of oxygen, and still better agreement is obtained when the present approximation methods are applied with an exponential interaction energy. The magnitude of the relaxation time, however, is not predicted nearly so well as is its temperature dependence.
Modifications of the Rb Emission Spectrum due to Atomic Interactions
Authors: Jefimenko Oleg , Curtis Waldo
Published: January 2005

Emission spectra of Rb-rare gas mixtures (Rb–He, Rb–Ne, Rb–A, Rb–Kr, and Rb–Xe) were investigated in search of diffuse bands recently observed in the absorption spectra of Cs and Rb in the presence of foreign gases. In addition to the bands accompanying principal series lines observed in absorption, a number of new bands (interaction satellites) were found on the long wavelength side of the Rb lines belonging to the sharp and the diffuse series. The bands accompanying sharp series lines are very narrow and intense and have the appearance of somewhat broadened spectral lines. The bands at diffuse series lines are less intense but much wider, and are separated from the atomic lines considerably more than the bands at the sharp series lines. The bands on the short wavelength side of the atomic lines were found only at the principal series lines. Extensive continua were observed on the long wavelength side of the resonance lines and the second doublet of the principal series. At the resonance lines these continua show fluctuations of intensity differing for the various mixtures and cover distances of several hundred wave numbers. The red bands, the violet bands, and the continua may appear simultaneously and do not require different operating conditions for their observation.
Evaluation of Force Constants of Tetrahedral Hydrides from Raman and Infrared Data
Authors: Pistorius C. W. F. T.
Published: January 2005

The force constants of 4 molecules and 4 ions of the type XH4 belonging to the Td symmetry have been calculated by Wilson's F–G matrix method, using Raman and infrared data. Using a modified Urey-Bradley field, the force constants between nonbonded atoms were calculated separately and substituted in the main equations. Anharmonicity was not taken into account.
Vibrational Spectra of Molecules and Complex Ions in Crystals. X. H2S and D2S
Authors: Reding F. P. , Hornig D. F.
Published: January 2005

The infrared spectra of H2S in phases III, II, and I were studied at 66, 112, and 140°K, respectively. That of D2S was studied in phase III at 66°K. The spectra of phase III consist of extremely sharp lines and the structure must be ordered, probably with eight molecules in a primitive unit cell of symmetry D4h. The stretching bands in the spectra of phases II and I are broader and indicate a disordered arrangement of the hydrogen atoms. The structure of the crystal in phase III is discussed. The crystal spectra indicate that the fundamental frequencies in gaseous D2S must be very nearly ν2=855 cm—1 and ν3=1910 cm—1.
Thermal Exchange of Iodine with Methyl Iodide and with Hydrogen Iodide in the Gas Phase
Authors: Schmied Henry , Fink Richard W.
Published: January 2005

The thermal exchange of iodine with CH3I and with HI has been studied in the gas phase between 60° and 140°C. The exchange is strongly surface sensitive and follows the rate law: R=k1(CH3I)(I2)+k2(CH3I). The exchange proceeds by means of two competing mechanisms, one of which is independent of iodine concentration and possibly involves the formation of CH3· free radicals on the surface which then react with I2. This heterogeneous reaction may be eliminated by preheating the reaction vessel overnight at 550°C, which reduces the reaction to a simple bimolecular exchange following the rate law: R=(CH3I)(I2)(2.5×106)exp(−9000/RT) moles−cm−3−sec−1which was obtained specifically for a surface/volume ratio of 1.19 cm—1.

The formation of a complex between CH3I and I2 was studied spectrophotometrically in dry n-heptane. The heat of formation of the complex was found to be —4.5 kcal mole—1, and the entropy of formation was found to be —25.8 cal deg—1 mole—1 for a standard state of 1 mole-liter—1. The formation of a complex between HI and I2 also was established in dry n-heptane.

The gaseous exchange of HI with I2 was found to be so fast that kinetic data could not be obtained. A theoretical estimate of the exchange half-life assuming an atomic iodine mechanism shows that the reaction would be rapid; however, experimental evidence is presented which suggests that a bimolecular mechanism is more likely.
Raman and Infrared Intensities in the Vibrational Spectra of Hydrocarbons. II. The CH Vibrations of Straight n-Paraffins
Authors: Theimer O.
Published: January 2005

The Raman and infrared intensities of the CH vibrations of solid n-paraffins are analyzed theoretically. The dependence of the relative intensity I of bands on the number N of C atoms is investigated experimentally. An empirical relation of the form I = ANp+BF(N), where A»BF(N), p=0 for factor group modes, p=—1 for terminal modes, and —3<p<—1 for ``inactive'' modes, is found and confirmed by the theory. The intensities of 5 infrared-active factor group modes are calculated from 3 independent parameters only, in agreement with experiment. One of the parameters is the permanent CH-bond moment whose magnitude is found to be 0.085±0.02 debye. The relative intensities of the Raman-active twisting, wagging, and rocking modes are determined theoretically; one finds approximately: Itw:Iw:Ir=6:3:1. This supports previous assignments.
Vibrational Relaxation Times in Nitrogen
Authors: Lukasik S. J. , Young J. E.
Published: January 2005

By means of a technique involving an acoustical resonant cavity, the vibrational relaxation time in nitrogen has been measured at 1186, 1020, 778°K. The lifetime of an excited vibrational level in nitrogen at the above temperatures is found to be 2.29×106, 4.55×106, 6.55×106 collisions, respectively. These results are in good agreement with shock-tube measurements of Blackman in the temperature range of 3500–5600°K. The effect of water vapor on the relaxation time is discussed. Previous measurements by Huber and Kantrowitz are shown to have been affected by water vapor impurities; the present measurements are believed to be relatively free from this effect since the concentration of water vapor was at most 0.005%.
On the Rotatory Dispersion of Protein and DNA
Authors: Murakami Hideo
Published: January 2005

From the viewpoint of Kirkwood's theory, the general formula of rotatory dispersion is presented. This formula is then applied to the rotatory dispersion of protein. Under reasonable assumptions, the behavior of the critical wavelength λC, which seems to be a measure of denaturation, may well be interpreted. The rotatory dispersion of DNA is also explained as the sensitive reflection of the structural characteristics of this molecule. In the case of the latter substance, special attention is focused on Condon's one-electron effect.
MO-Theoretical Approach to the Mechanism of Charge Transfer in the Process of Aromatic Substitutions
Authors: Fukui Kenichi , Yonezawa Teijiro , Nagata Chikayoshi
Published: January 2005

An MO-theoretical investigation on the mechanism of aromatic substitution is made. Supposing that the approaching reagent and the atom to be replaced can be treated as an atom (pseudoatom) which has a π-type orbital in the course of reaction, an important role of hyperconjugation taking place between the pseudoatom and the aromatic compound is remarked. Since the electron density at the pseudoatom relates to the amount of charge transfer through this hyperconjugation and varies as the reaction proceeds, the proceeding of the reaction can be measured by this electron density. Then, the electron density is expressed, in the form of a contour diagram, in terms of the Coulomb integral of the pseudoatom and the resonance integral between the pseudoatom and carbon atom to be attacked. Thus, a reaction path can be represented by a locus plotted on this diagram. The discriminating property of frontier orbitals can be observed in this diagram. It has been confirmed that an electrophilic, or a nucleophilic, substitution takes place only when a certain condition is satisfied with respect to the energy of the reagent. By determining the transition state which corresponds to the end point of the locus, several reactivity indices, i.e., frontier electron density, superdelocalizability, its one-term approximation and a generalized reactivity index are derived from the hyperconjugation energy at the transition state, which is also available as a generalized reactivity index. Correlation between these and the existing indices is examined.
Ionization and Dissociation of Oxygen Difluoride by Electron Impact
Authors: Dibeler Vernon H. , Reese Robert M. , Franklin J. L.
Published: January 2005

The mass spectrum of OF2 includes the ions OF2+, OF+, O+, and F—. The ionization potential of the molecule and appearance potentials and excess kinetic energy are measured for the OF+ and F— ions. The known heat of formation of OF2 and the appearance potential of the F— ion permit calculation of the bond dissociation energies D(FO–F) and D(O–F) and an estimate of the ionization potential, I(OF). Dissociation energies estimated for the OF2+ ion are consistent with those of the neutral molecule.
Paramagnetic Resonance in Trivalent Transition Metal Complexes
Authors: Jarrett H. S.
Published: January 2005

Paramagnetic-resonance absorption has been observed in complexes of acetylacetone with the trivalent transition metals titanium, chromium, iron, molybdenum, and ruthenium. The symmetry of the field perturbing the metal ion is predominantly axial. For the complexes of Ti+3 and of Ru+3, the axial potential is negative. Energy-level splittings by the ligand field and g factors were obtained for the various complexes. Resonance was also observed in complexes of trifluoroacetylacetone with chromium and iron and in the complex chromium (III) hexafluoroacetylacetonate. Resonance could not be detected in the complexes vanadium (III) acetylacetonate, manganese (III) acetylacetonate and ferric (III) hexafluoroacetylacetonate, although magnetic-susceptibility measurements on the last two compounds indicated that they were paramagnetic.
Argon Adsorbed on a Graphitic Surface. The Heat of Adsorption from Lattice Liquid Theory
Authors: Pace E. L.
Published: January 2005

A model is proposed to account for the differential or isosteric heat of adsorption which has been observed for argon on graphon at concentrations between 0.5 and 2.0 monolayers for temperatures in the neighborhood of the normal boiling point of argon.

The energy of a molecule on the surface is considered to be the sum of two contributions: (1) a site energy for the isolated molecule and (2) an interaction energy with neighbors in the same layer. The site energy for a molecule is calculated assuming atoms and molecules in lower layers fixed with respect to both a configuration in a hexagonally packed planar lattice and the distance between layers. The interaction energy is calculated assuming the behavior in any layer is represented by a two dimensional lattice liquid model utilizing the so-called Ono approximation for the variation of the generalized free volume with vacancies in the lattice. The distribution of adsorbed molecules in any layer is considered to be completely random.

On the basis of this model, an interpretation is made of the two maxima in the isosteric heat which have been observed experimentally.
Halogen-Catalyzed Decomposition of N2O and the Role of the Hypohalite Radical
Authors: Benson Sidney W. , Buss Jerry H.
Published: January 2005

It is shown that the Cl2 catalyzed decomposition of N2O cannot be explained by a nonchain reaction but is consistent with a Cl atom chain in which Cl atoms are regenerated by the reactions, 2ClO→ lim 4′Cl–O–O+Cland by ClO–N2O→N2+Cl–O–Ofollowed by Cl–O–O+M→Cl+O2+MIt is proposed that the peroxy radical Cl–O–O is the unstable intermediate responsible for the high efficiency observed for O2 in catalyzing the recombination of Cl atoms. It is also proposed that at low temperatures O2 should be an efficient catalyst for the generation of Cl atoms via the reaction O2+Cl2→ O—O—Cl+Cl. The peroxy ClOO species is shown to be a reasonable one to account for the high-rate constant observed for reaction 4′ and for the chain decompositions of Cl2O and OClO. Its thermodynamic properties are estimated as ΔHf0=21±2 kcal, Sf0=61 cal/mole—°K, with a bond-dissociation energy, D(Cl—OO)=8±2 kcal.
Calculation of Atomic Valence State Energies
Authors: Companion Audrey L. , Ellison Frank O.
Published: January 2005

Given a molecular valence-bond wave function (constructed according to the approximation of perfect pairing), the general theory is presented for calculating either (1) the energy following complete nonadiabatic dissociation of the atoms (hence, the promotional energy) or (2) the intra-atomic energy of the molecule for equilibrium positions of the nuclei. It is found that existent methods and tables are generally sufficient for treating only molecules having less than two unpaired electrons and, if hybridization is admitted, only molecules having less than two bonds. Tables are here given which serve the needs with respect to all possible structures involving s- and p-valence electrons. Promotional energies for the CH and CH2 molecules are derived for illustration.
Statistical Mechanics of Transport Processes. XI. Equations of Transport in Multicomponent Systems
Authors: Bearman Richard J. , Kirkwood John G.
Published: January 2005

The equations of hydrodynamics including the equations of continuity, equations of motion of the individual components as well as the over-all equation of motion, and the energy transport equation are derived from statistical mechanics. Introduction of perturbations to the singlet and pair space distribution functions linearized in the temperature gradient, diffusion velocities, and the local rate of shear leads in the stationary case to the linear relations of irreversible thermodynamics between the gradients of temperature and chemical potential and the fluxes of heat and matter.
Nuclear Quadrupole Coupling in the Li2 Molecule
Authors: Mannari Isao , Arai Tadashi
Published: January 2005

The method of deformed atoms in molecules is applied to calculate the electric field gradient q at a nucleus in Li2, using the molecular wave function obtained by Arai and Sakamoto. The field gradient is composed of nuclear and electronic terms which almost cancel each other, so that its magnitude and even its sign are seriously affected by accuracy of wave functions used. It is nevertheless expected that the A. S. wave function, which gives a dissociation energy of 0.96 ev compared with the experimental value of 1.05 ev, is sufficiently accurate. Neglecting the shielding effect induced in the 1s shell by the nuclear quadrupole moment Q, the result obtained is q/2e=q′=—0.0034 au at an internuclear distance of 4.93 au. The nuclear quadrupole coupling constant eqQ found experimentally is positive (+0.060 Mc/sec). A negative value of the quadrupole moment Q(Li7) thus is obtained, in agreement with the prediction of the nuclear shell model.
Molecular and Crystal Structure of B6H10
Authors: Hirshfeld F. L. , Eriks K. , Dickerson R. E. , Lippert E. L. , Lipscomb William N.
Published: January 2005

The approximately pentagonal pyamidal arrangement for boron atoms in B6H10 has been shown to be attached to a hydrogen arrangement resulting in Cs-m molecular symmetry. There are four bridge hydrogens and no BH2 groups in the molecule. The boron framework is bonded, to a very rough approximation, by two electron-pair bonds and two three-center bonds. The electron-pair bond perpendicular to the molecular symmetry plane is usually short (1.60 A). Comparison with other boron hydrides leads to some tentative conclusions about factors governing the relative stabilities of these compounds.
Fragmentation of Methane by Electron Impact, and the Latent Heat of Sublimation of Carbon
Authors: Morrison J. D. , Stanton H. E.
Published: January 2005

The ions produced in the fragmentation of methane by electron impact have been found to be formed with initial kinetic energy. Taking this energy into account, the electron impact data on methane are shown to be compatible with the spectroscopically acceptable value of 171 kcal/mole for the latent heat of sublimation of carbon in agreement with the value obtained by direct measurement.
Configuration Interaction Study of the Electronic Structure of the OH Radical by the Atomic and Molecular Orbital Methods
Authors: Freeman A. J.
Published: January 2005

The role played in configuration interaction calculations by the particular form of the orbitals selected as basis is explored by a direct application on the electronic structure of the ground state of the OH molecule. Two configuration interaction studies have been carried out using different sets of one-particle functions: (1) the set natural to the isolated atoms (called AO's) and (2) the orbitals belonging to the molecule (MO's).

In (1), using the Hartree-Fock 1s, 2s, and 2p functions for atomic oxygen and the 1s state for hydrogen, and keeping the 1s oxygen state doubly occupied, all Slater determinants of the appropriate ground state symmetry (2π) were found. The dissociation energy and the expansion coefficients of the determinants were determined by a variational procedure which minimized the energy of the system. The nonorthogonality of the basic AO's was treated without approximation by the method of Löwdin. The necessary integrals were calculated on Whirlwind I, the M.I.T. high-speed digital computer; all two-center integrals were computed by expanding the hydrogen orbital about the oxygen center (analogously to the methods of Barnett and Coulson, Coolidge, Löwdin, etc.).

In (2), the molecular orbitals (MO's) were found as linear combinations of the above AO's, with coefficients determined by a modified self-consistent field (Roothaan) procedure, in which the energy of a single Slater determinant was made stationary at three values of the internuclear separation. A configuration interaction calculation was then made using these ``best'' MO's as the basic set of one-particle functions. Also included are a calculation of the dipole moment and Mulliken's electron distribution analysis.

The results of these studies are discussed and comparison is made to experiment and other theoretical calculations.
Interaction Energy and Scattering Cross Sections of H— Ions in Helium
Authors: Mason Edward A. , Vanderslice Joseph T.
Published: January 2005

An approximate quantum-mechanical calculation is made of the energy of interaction of H— and He. The results are not of high accuracy, but serve to indicate the general nature of the interaction. This knowledge makes it possible to calculate more accurate values of the interaction from measured elastic scattering cross sections. The resultant interaction is combined with the previously known interaction of H and He to give an approximation to the inelastic (electron detachment) cross section, which is shown to be in reasonable agreement with experiment. The calculations emphasize the importance of the repulsion forces rather than the attraction forces. The accuracy of a correction for the finite width of the ion beam is also examined in some detail.
Application of the Pariser and Parr Method to Dye Ions with Amidinium Resonance
Authors: McGlynn Sean P. , Simpson William T.
Published: January 2005

The transition energies and transition probabilities for the family of dye ions Me2N–(CH=CH)n−1–CH=N lim +Me2are calculated using the method of Pariser and Parr. The nitrogens are taken into account by a perturbation method. Configuration interaction considering single excitations from the ground configuration is employed, though in the comparison with experiment it is judged better to use the diagonal matrix elements for the transition energies.
Infrared Spectra of HCl–HBr Mixed Crystals
Authors: Hiebert G. L. , Hornig D. F.
Published: January 2005

The infrared spectra of HBr–HCl mixed crystals consist of a band characteristic of chains of similar molecules plus a line caused by the end molecule in any chain, this structure being repeated in the HCl and HBr regions. The frequency of HBr when hydrogen bonded to HCl is higher than when bonded to another HBr; that of HCl is lower when bonded to HBr than when bonded to another HCl.
Liquid-Gas Infrared Intensities, Pressure-Induced Absorption, and the Temperature Dependence of Infrared Intensities in Liquids
Authors: Person Willis B.
Published: January 2005

The recent paper by Polo and Wilson eliminates the apparent discrepancy between the equations given for the relationship between intensities of a compound in the gas phase and the intensities in the liquid phase. However, the experimental tests of this equation have not been conclusive. This paper applies their equation to the pressure-induced absorption of methane, and to the temperature dependence of the integrated intensities of liquid cyclohexanone and liquid benzene. The treatment of Polo and Wilson is extended to give an equation which is valid for solutions. In all cases, qualitative agreement is obtained between experiment and calculation and it would seem that the effect of index of refraction on the intensity accounts for a significant part of the changes observed. The agreement for benzene and for the pressure-induced absorption of methane is excellent.
Infrared Spectrum of Methyl Chloride near 6000 cm—1
Authors: Brown Robert G. , Edwards T. Harvey
Published: January 2005

The rotational fine structure of the parallel component of 2v4 of methyl chloride has been resolved. The Q branches of the sub-bands, and the P and R branch lines of the K = 3 sub-band have been identified and analyzed. The molecular constants obtained are (in cm—1): v0 = 6015.56, B′ = 0.4439, B″ = 0.4436, B′ — B″ = 0.00044, and (A′ — B′) — (A″ — B″) = —0.0481.
Surface Ionization Phenomena on Polycrystalline Tungsten
Authors: Zemel Jay
Published: January 2005

By assuming the existence of patches of different work functions on the surface of tungsten filaments, the ratio of ions to atoms emitted from the total surface has been computed by applying the Langmuir-Saha equation to each patch. From a suitable choice of the fraction of the surface covered by patches of work function [open phi]n, a good fit to published data is obtained. The significance of these patches in the interpretation of surface ionization data is discussed.
Ion Exchange Kinetics. A Nonlinear Diffusion Problem
Authors: Helfferich F. , Plesset M. S.
Published: January 2005

Ideal limiting laws are calculated for the kinetics of particle diffusion controlled ion exchange processes involving ions of different mobilities between spherical ion exchanger beads of uniform size and a well-stirred solution. The calculations are based on the nonlinear Nernst-Planck equations of ionic motion, which take into account the effect of the electric forces (diffusion potential) within the system. Numerical results for counter ions of equal valence and six different mobility ratios are presented. They were obtained by use of a digital computer. This approach contains the well-known solution to the corresponding linear problem as a limiting case. An explicit empirical formula approximating the numerical results is given.
Delta-Function Model for Short-Range Intermolecular Forces. I. Rare Gases
Authors: Mason Edward A. , Vanderslice Joseph T.
Published: January 2005

A delta-function model is proposed for the calculation of short-range intermolecular forces. The features which must be incorporated into such a model to make it yield quantitative results for repulsion energies are investigated by considering first the repulsion interaction of two hydrogen atoms with parallel electron spins. Extension to the rare gas atom interactions is then made by replacing their many electrons by an effective charge distribution. This procedure permits the simple treatment developed for hydrogen atoms to be taken over formally for rare gas atoms. Interactions between unlike atoms are also considered. As finally formulated, there are no disposable parameters and the interaction energy is directly related to known properties of the isolated atoms. The properties needed are the atomic number, the first ionization potential, and the average radius of the largest electronic orbit. Agreement with experiment is good in all cases, and is almost always superior to that achieved by conventional valence bond or molecular orbital methods.
Chemical Bond. II. A One-Dimensional Approach to the Energetics and Ionic Character
Authors: Barrow Gordon M.
Published: January 2005

One-dimensional counterparts of atomic bonding orbitals are given which allow, in the LCAO method, calculation of binding energies and electronic distributions for single bonds between atoms of various electronegativities. The bond energies and ionic characters so calculated are shown to be in satisfactory agreement with the values observed for a number of bonds. Predictions are then made of the ionic character of a bond as a function of electronegativity difference and bond length.

The potential usefulness of the approach is stressed in terms of the simplicity of the model and of the calculations and the essential correctness of the theoretical results.
Photoconductivity of Anthracene. IV. Bulk Photoconduction in Single Crystals
Authors: Kommandeur J. , Schneider W. G.
Published: January 2005

Bulk photoconduction of anthracene single crystals has been measured using monochromatic light. The intensity and voltage dependences are found to depend on the field direction and the wavelength of the exciting light. The spectral response of photoconduction depends on the field direction. A model is proposed to account for these observations and for the space charge effects that are found to occur. This model rests mainly on the assumptions of a higher mobility for the positive charge carriers and the nonreplenishment of charge carriers at the evaporated silver electrodes. Recombination of carriers is deduced, and a quantitative relationship between spectral response and extinction coefficient is found.
Photoconductivity of Anthracene. V. Effect of Imperfections on the Bulk Photocurrent
Authors: Kommandeur J. , Schneider W. G.
Published: January 2005

Bulk photocurrents of anthracene have been measured on crystals of high purity, scintillation crystals, and crystals irradiated with thermal neutrons. It is found that the source and treatment of the crystals strongly affects the spectral response and the voltage and intensity dependence of the bulk photocurrent. This can be related to the density of the imperfections in the crystals. Direct evidence for the existence of traps was furnished by the electrical analog of the thermoluminescent glow curves and by the increase of the photocurrents with red radiation.
Ligand Field Theory of Ni(II) Complexes. I. Electronic Energies and Singlet Ground-State Conditions of Ni(II) Complexes of Different Symmetries
Authors: Maki Gilda
Published: January 2005

A parametric method of calculating the electronic energies of an ion of configuration 3d8 (3d2 positrons) when placed in a ligand field of point charges or dipoles is described. The method is applicable with a change of sign of the energy matrix elements to ions with a 3d2 electronic configuration. By use of the experimentally determined free ion term energies for the Ni(II) ion the calculations are made specific. The final energy eigenvalues obtained here are for the Ni(II) ion in four and six coordinated complexes of tetragonal, octahedral, cis-, and trans-planar symmetries. All free ion states of the same multiplicity and symmetry arising from the ground-state configuration were allowed to interact. An effective interelectron distance, dipole moment, and point charge were used as parameters. Some of the numerical results for specific values of the parameters are given as examples. The remainder of the energy calculations are tabulated in the dissertation. Minimum field strength conditions necessary for a four coordinated complex to become diamagnetic are determined using the calculated energies. The relative ease of conversion to a singlet ground state in the different symmetries is noted and the effect of an axial field on the change in multiplicity is obtained from the results of the calculations for the six-coordinated complexes. The results will also be used subsequently to assign the low intensity electronic spectra obtained for a series of Ni(II) chelates of appropriate symmetries and to explain the effect of solvent on the spectra and magnetic moments of these chelates.
Microwave Spectrum of Methyl Difluorosilane
Authors: Swalen J. D. , Stoicheff B. P.
Published: January 2005

The microwave spectra of five isotopic species of methyl difluorosilane (CH3SiHF2) have been observed. From the rotational constants, the following structural parameters were determined rFF=2.541±0.001 ArSiC=1.833±0.002 A∠FSiF=106∘44′±30′rSiF=1.583±0.002 A∠;CSiH=116∘10′±1∘rSiH=rSiD=1.474±0.005 A∠FSiC=109∘52′±30′rCH=1.09 A (assumed)∠HCH=108∘ (assumed).A dipole moment of 2.11 debye was obtained from Stark effect measurements.

The hindered internal rotation of the methyl group splits some of the rotational lines into doublets with spacings from 0.5 to 2.9 Mc. An analysis of the doublet splitting in three of the isotopic species gives a barrier height of 439 cm—1 (1255 cal/mole) hindering internal rotation.
Internuclear Distance and l-Type Doubling in Carbon Disulfide
Authors: Guenther A. H. , Wiggins T. A. , Rank D. H.
Published: January 2005

The 003–000 and 0113–0110 bands of CS2 have been measured with high precision. It has been possible to derive a very precise value of the CS distance, re=1.5532±0.0005 A. The values obtained for the molecular constants were B000=0.109099±0.000023, α2=—0.000256, α3=+0.000711, all quantities expressed in cm—1. The mean measured value of q was found to be 6.6×10—5 cm—1 which can be compared to a theoretically predicted value of 7.8×10—5 cm—1.
Elastic and Inelastic Scattering of Low-Velocity Ions: He+ in Ne, Ne+ in He, and Ne+ in Ne
Authors: Cramer W. H.
Published: January 2005

Experimental results are presented for collisions in the energy range 4 to 400 electron volts of He+ ions in neon and of Ne+ ions in helium and in neon. Charge exchange was observed only in the case of Ne+ in neon. Empirical potential functions for the interactions are tabulated and discussed. It is concluded that the HeNe+ ion, if formed, would probably separate if subjected to impact at thermal energies.
Chemical Equilibrium in Complex Mixtures
Authors: White W. B. , Johnson S. M. , Dantzig G. B.
Published: January 2005

A new method for the determination of the equilibrium composition of complex mixtures is described. The general method, which is based on the minimization of free energy, states the problem with unusual simplicity, avoiding many of the usual difficulties of description and computation. Two specific computation procedures are shown, one using a steepest descent technique applied to a quadratic fit, the other making use of linear programing.
Chain Configurations of Polymers and Polyelectrolytes
Authors: Fisher Michael E.
Published: January 2005

On the basis of a rigorous statistical mechanical approach it is shown that the treatments of the configuration of a polyelectrolyte molecule given by Katchalsky and Lifson and by Krieger are equivalent to retaining only the first-order term of the high temperature expansion of the free energy. Katchalsky's and Lifson's more accurate calculation is exact in the limit of a ``continuous'' chain but the neglected correction terms are shown to be significant. Krieger's approximate expression for the first-order term is only valid for highly stretched chains and it predicts incorrect results when the interaction potential is appreciable near the origin.
Characteristic Frequencies of Triethylborane
Authors: Lehmann Walter J. , Wilson Charles O. , Shapiro I.
Published: January 2005

The infrared spectra of isotopically normal and triethylborane b10 are reported, and the major bands are assigned to the characteristic bond vibrations of the molecules. Analogous to trimethylborane, the asymmetric B–C stretching frequency is placed at ca 1120 cm—1. In view of the complexity of the molecule a more complete assignment is not feasible at this time.
Theory of Dilute Polymer Solution. I. Excluded Volume Effect
Authors: Kurata Michio , Yamakawa Hiromi , Teramoto Ei
Published: January 2005

A statistical theory of the excluded volume effect in a polymer molecule is developed, making use of a pearl necklace model with a continuous medium approximation. For the mean square end-to-end distance 〈R2〉 and the mean square radius of gyration 〈S2〉, the theory leads to the same expressions as Zimm, Stockmayer, and Fixman's. Taking solutions of polystyrene in cyclohexane as an example, it is illustrated that, in the vicinity of the Flory temperature, the expression for 〈S2〉 enables to give a complete quantitative interpretation to light scattering data. The distribution function for distance Rkl between segments k and l, its 2mth moment 〈Rkl2m〉, and the mean square distance 〈Sk2〉 between segment k and the center of molecular mass are also calculated to make clear the nature of the excluded volume effect. Finally, the influence of the volume effect upon light scattering measurement is discussed somewhat in detail.
Floating Wave Functions for H2+ and H2
Authors: Shull Harrison , Ebbing Darrell D.
Published: January 2005

Floating wave functions using ordinary 1s orbitals are reexamined for both H2+ and H2. Results previously reported in the literature are found to be in error. The newly obtained energies are disappointingly high. It is conjectured that these relatively poor energies are largely the result of the inability of this kind of approximation to give a good representation of the discontinuities in the wave function in the vicinity of the nuclei.
On the Virial Coefficients for a Lennard-Jones Gas
Authors: Nosanow L. H. , Mayer J. E.
Published: January 2005

Simpler methods for computing the second and third virial coefficients for a Lennard-Jones gas are given. The second virial coefficient is found to obey a second-order linear homogeneous differential equation in the temperature. The use of these methods is discussed.