bluuebunny/crossref_metadata_2025 huggingface dataset:
Dispersion of the Electro-Optic Kerr Effect in the Infrared Region
Authors: Charney Elliot , Halford Ralph S.
Published: January 2005

The infrared dispersion of electro-optic anisotropy has been investigated theoretically and experimentally. Anomalies of the refractive index in the neighborhood of resonant absorptions are accompanied by anomalous dispersion in the electro-optic Kerr effect. A theoretical analysis of the effect of molecular structure on the form of the anomalous behavior demonstrates that the relative orientation of the permanent molecular dipole and the radiation-induced dipole determines the sign of the deviation of the dispersive behavior from normal. The dependence on the applied electrostatic field strength is predicted to be the same in resonant and nonresonant regions.

Experimental examination of the electro-optic anisotropy of nitrobenzene at field strengths of 28 000 v/cm to 48 000 v/cm in the overtone region (1.5–5.6 μ) of the infrared spectrum confirms these theoretical conclusions.
Cleanup of Atomic Hydrogen
Authors: Blodgett Katharine B.
Published: January 2005

When hydrogen is dissociated by an incandescent tungsten filament in a glass tube, some of it is cleaned up if the tube is cooled in liquid air. The amount cleaned up can be greatly increased by coating the inner wall with mercury or copper. In one experiment the amount cleaned up in cold mercury was equivalent to 14 monolayers of atomic hydrogen. The cleanup proceeded at a diminishing rate until the pressure fell to the value at which hydrogen left the mercury as fast as it entered. When hydrogen was cleaned up in a very thin coating of mercury there were 1.5 to 1.8 atoms of mercury per atom of hydrogen. All the cleaned-up gas was recovered when the tube was brought to room temperature. After cleanup in copper there was little recovery until the temperature rose above —150°K.
Theoretical Investigations on the Light Scattering of Colloidal Spheres. IV. Specific Turbidities in the Lower Microscopic Range and Fine Structure Phenomena
Authors: Heller Wilfried , McCarty H. James
Published: January 2005

Additional calculations were carried out on the scattering cross sections of spheres and the specific turbidities of their dispersed systems using again the Mie theory. The parameters considered were α=7.0 (0.2) 25.6 and m=1.05 (0.05) 1.30. The close spacing of the α values allowed the detection of a fine structure of regular period in the (τ/c)0(α) curves and related curves. The fine structure is explained as the result of interferences of secondary magnitude.
Neighbor Interactions and Internal Rotations in Polymer Molecules. II. Polyelectrolytes
Authors: Lifson Shneior
Published: January 2005

The influence of the interaction between neighboring ionizable groups of a polyelectrolyte molecule on the internal rotations around its skeletal bonds is considered. It is found that the repulsion between neighboring groups tends to contract the molecule by twisting the molecular chain, and acts therefore against other forces which tend to extend the molecular dimensions.

The quantitative analysis is based on calculating a grand partition function of the polyelectrolyte molecule, in which both the energy of interactions within each bond and the energy of interaction between neighboring ionizable groups are expressed as functions of the internal rotation angles. The grand partition function is used in obtaining the various averages of the trigonometric functions of the internal rotation angles which determine 〈h2〉 according to the results of the previous paper (Part I). These averages are given as functions of the degree of ionization of the macromolecule.

The effect of the internal rotation of the skeletal bonds on the potentiometric titration and buffering capacity of polyelectrolyte solutions is discussed.
Statistical Computation of Reaction Probabilities
Authors: Wall F. T. , Hiller L. A. , Mazur J.
Published: January 2005

Calculations have been carried out on a high-speed electronic digital computer to determine statistically the transition probability for a simple chemical reaction. Using the London-Eyring-Polanyi form for the potential energy of the colinear system, H+H2, we have solved the classical equations of motion for the system under a great variety of conditions. Collisions of a hydrogen atom and a hydrogen molecule, with and without initial molecular vibration, were studied as a function of the total kinetic energy. By carrying out numerous calculations for a sufficiently large number of different initial conditions, we obtained an average behavior of the system, which we believe provides a satisfactory approximation to the quantum mechanical average. It was found that the reaction probability was greatest when the energy was just slightly above the activation energy. Moreover, it was observed that, if the molecule was initially vibrating, only a part of the energy of vibration was available for reducing the kinetic energy of translation required for activation. It was also found that the conversion of energy between vibration and translation was relatively improbable.
Application of Schwarz's Inequality to Perturbation Theory
Authors: Gray B. F.
Published: January 2005

It is shown by use of the variation theorem, that under fairly general conditions the energy given to an odd order of approximation by perturbation theory is an upper bound to the correct energy. Under less general conditions it is shown that for a positive definite perturbation the energy given by an even-order approximation is a lower bound and for a negative definitive perturbation it is again an upper bound. Some applications are discussed.
Studies in Nonequilibrium Rate Processes. IV. The Rotational and Vibrational Relaxation of a System of Rotating Oscillators
Authors: Herman Robert , Shuler Kurt E.
Published: January 2005

In continuation of previous papers in this series a theoretical study has been made of the rotational and vibrational relaxation of a system of rotating oscillators, represented by a rigid rotator-harmonic oscillator model, in their interaction with a constant temperature heat bath. The relevant relaxation equations for this system have been derived and both numerical solutions, computed with an IBM 704 electronic computer, and approximate analytical solutions have been obtained for the mode and rate of change of the rotational-vibrational level population with time. The results show that, owing to the large order of magnitude difference in the efficiency of translational-rotational and translational-vibrational energy transfer, there is very little coupling between the vibrational and rotational relaxation and the system of rotating oscillators relaxes essentially as if composed of two independent and noninteracting systems of harmonic oscillators and rigid rotators. A calculation of the rotational relaxation time, t(relax), using the adiabatic transition probabilities given by Brout and by Takayanagi and the concomitant selection rules ΔJ=±1 (for heteronuclear molecules) gives values for t(relax) which are greater by a factor of several orders of magnitude (∼102) than the experimental relaxation times found from shock wave studies. This indicates clearly that rotational relaxation does not take place via a stepwise ``ladder process'' involving only transitions between neighboring rotational levels.
Microwave Spectrum, Internal Barrier, Structure, Equilibrium Configuration, and Dipole Moment of Methyl Monofluorosilane
Authors: Pierce Louis
Published: January 2005

The microwave spectrum of methyl monofluorosilane has been investigated in the region 18 to 38 kmc. Several transitions of the isotopic species CH3SiH2F and CH3SiD2F are split into doublets because of coupling of internal and over-all rotation. These splittings give a barrier to internal rotation of 1559±30 cal/mole. The form of the potential barrier was assumed to be V=12V3(1−cos3α). A few transitions belonging to the first excited torsional state were observed and assigned. The splittings in the excited state are consistent with the barrier as determined from ground state observations.

Rotational constants of CH3SiH2F, CH3SiD2F, C13H3SiH2F, CD3SiH2F, and CH3SiDHF have been determined and were used to calculate the structure of the molecule.

The structural parameters are: SiC1.848 ACSiF109∘ 13′SiF1.600HCH107∘ 52′SiH1.473CSiH109∘ 28′ (assumed)CH1.090HSiH109∘ 28′ (assumed).

A study of CH2DSiH2F proves conclusively that methyl monofluorosilane in its equilibrium configuration has the methyl group staggered with respect to the SiH2F group.

The dipole moment was found to be 1.71D.
Absolute Infrared Intensities of the Fundamental Vibrations of NF3
Authors: Schatz Paul N. , Levin Ira W.
Published: January 2005

The absolute infrared intensities of the fundamental vibrations of NF3 have been measured. The results have been interpreted in terms of the N–F bond moment (μ), its derivative (∂μ/∂r), and the unshared pair moment on the N atom (μu.p.). The bond moment obtained from the A1 bending mode is found to be in the vicinity of 1 D. μu.p. is in the vicinity of either 1.2 D or 1.7 D depending upon the sign assumed for the molecular dipole moment. The bond moment calculated from the E mode is quite sensitive to the potential function. Since this function is not known with high accuracy, one is not able to determine whether the bond moments from the two different symmetry species are in agreement.

There is a striking difference in the values of ∂μ/∂r from the two symmetry species with ∂μ/∂r (A1) in the range of 1.5 to 2 D/A and ∂μ/∂r (E) in the vicinity of 4.5 D/A. A qualitative explanation for this difference is offered.
Gaseous Detonations. XI. Double Waves
Authors: Cher Mark , Kistiakowsky G. B.
Published: January 2005

Photographic studies of detonations of benzene-oxygen mixtures with the slit and rotating drum camera arrangement have shown under well defined conditions the occurrence of a sharp luminous front receding at a constant rate (ca 73m/sec) from the detonation wave front. The same phenomenon has been observed in several other hydrocarbon-oxygen mixtures but not in mixtures of hydrogen and oxygen. Measurements of gas densities by the method of x-ray absorption gave confirmatory evidence that the secondary fronts are shock waves in the domain of the rarefaction wave. A qualitative theory of the secondary wave is developed by analogy with the steady supersonic gas flow through convergent-divergent nozzles. It is concluded that the secondary wave is due to entropy increase in the rarefaction wave, caused by a spontaneous reaction. Detonation velocity measurements of benzene-oxygen mixtures and thermodynamic velocity calculations show indeed that thermodynamic equilibrium is not attained in the C-J state of the detonation wave, but the nature of the lagging chemical reaction cannot be established.
Electroconvectional Heat Transfer in Gases
Authors: Arajs Sigurds , Legvold Sam
Published: January 2005

Electroconvectional heat transfers have been measured in gaseous N2, CO2, NH3, SO2, and CCl3F. The results are interpreted and correlated according to the theories of Kronig and of Senftleben and Bültmann. The theoretical predictions of Senftleben and Bültmann concerning the dependence of the electroconvectional heat transfer on the pressure of the gas and the magnitude of the electric field are found to fit the experimental results.
Number of Single, Double, and Triple Clusters in a System Containing Two Types of Atoms
Authors: Behringer Robert E.
Published: January 2005

A set of graphs are presented from which one can read directly the probability that, in a lattice containing two types of atoms A and B randomly distributed over the lattice sites, a type A atom will be in a cluster of one, two, or three A atoms. Results are presented as a function of concentration for simple cubic, body-centered cubic, face-centered cubic, and hexagonal close-packed lattices.
Size Effect in Heterogeneous Nucleation
Authors: Fletcher N. H.
Published: January 2005

Assuming a spherical nucleating particle, the effect of particle size and surface properties upon nucleation efficiency is investigated. A general result is derived which is then applied to the condensation, sublimation, and freezing of water on foreign nuclei. The size effect is found to become important in the range 100–1000 A of particle radius. For particles larger than this, nucleation efficiency is substantially independent of size, while for smaller particles the efficiency is very greatly reduced.
Vibrational Energy Exchange between Diatomic Molecules and a Surface
Authors: Herman Robert , Rubin Robert J.
Published: January 2005

The problem of the steady-state vibrational energy distribution of diatomic molecules that temporarily reside on a surface during exposure to a molecular beam is examined according to the rate equations proposed by Klemperer and Herschbach. It is shown that it is possible to obtain explicitly the steady-state vibrational energy distribution for different vibrational energy distributions in the incident beam and that the vibrational energy accommodation coefficient suitably defined is of a very simple form.
Structure of Liquid Germanium Dioxide
Authors: Mackenzie J. D.
Published: January 2005

Viscosity and electric conductivity measurements have been made on liquid germanium dioxide over the temperature range 1250–1550°C. The relationship between log viscosity and 1/T is not linear and the energy and entropy of activation for viscous flow decreases with increasing temperature. Electric conduction obeys the empirical Arrhenius relationship, the energy of activation for conduction being 46.5 kcal/mole. From electronegativity considerations the energy of the Ge–O bond is estimated to be 104±8 kcal. Liquid GeO2, similar to liquid SiO2 is highly associated, the classical network structure for solid glasses being applicable. A mechanism for viscous flow is postulated.
Normal Vibrations of N-Methylacetamide
Authors: Miyazawa Tatsuo , Shimanouchi Takehiko , Mizushima San-ichiro
Published: January 2005

The in-plane normal vibrations of N-methylacetamide and its deuterated compound were calculated as a six-body problem. The force constants were transferred from diformylhydrazine and other molecules with similar structures. The normal modes as well as the distributions of the potential energy among symmetry coordinates were also calculated. The result of these calculations allows quantitative discussions concerning the nature of the amide I, II, II′, III, III′, and IV vibrations and other normal vibrations of N-methylacetamide.
Recalculation of the Latimer, Pitzer, and Slansky Absolute Electrode Potential— A Discussion of Its Operational Significance
Authors: deBethune Andre J.
Published: January 2005

The Latimer, Pitzer, and Slansky (LPS) calculation of the absolute electrode potential of the standard calomel electrode (StdCE) involves a sequence of processes in which the metals Hg and Na appear. Let Hg be the ``first'' metal and Na the ``second'' metal. The substitution of 21 other metals M for Na as the second metal leads to an array of remarkably self-consistent values. With 16 uni- and divalent second metals M, the LPS potential of the StdCE falls in the range of +0.523 v to +0.693 v (with the Gibbs-Stockholm sign convention) with a mean of +0.599 v and a standard deviation of 0.043 v. The constancy of these values is shown to be thermodynamically reasonable. The LPS method is then generalized to obtain the absolute electrode potentials of 22 other standard electrodes (SMeE) by substituting 22 other ``first'' metals Me for Hg. The generalized LPS absolute potentials of the 22 SMeE's can be converted to that of the StdCE by (1) a simplest, (2) a more refined calculation procedure. The simplest generalized LPS potential of the StdCE is strongly dependent on the choice of the first metal Me, the more refined potential is independent of this choice and agrees with the values obtained above with Hg as first metal.

A conceptual experiment is set up by which it is shown that the LPS potential or any of the generalized LPS potentials of the StdCE can be interpreted operationally as linear combinations of conceptually observable potentials differences, all potentials being taken in ``pieces of the same kind of metal'' (to use Gibbs' phrase). This experiment suggests that the LPS potential of the StdCE is equivalent to the measurable outer or volta potential difference in a free space gap between mercury and electrolyte, when the two phases are in electrical contact. The discrepancy between the LPS calculated value and Klein and Lange's experimental value for this volta PD is discussed, and an experimental value of —98.3 kcal obtained for the standard free energy of hydration of the sodium ion.
On the Vibrations of a Generalized Diatomic Lattice
Authors: Maradudin Alexei , Weiss George H.
Published: January 2005

In this paper we present some results for regular diatomic chains whose unit cells contain more than two atoms. Using the transfer matrix method and certain theorems due to Hoffman and Mazur we show the band structure of the frequency spectra for chains whose unit cells contain three and four atoms. Finally we derive the constant term in the frequency spectrum of a disordered diatomic lattice.
On the Theory of Electronic-Vibrational Interaction for Rare Earth and Actinide Series Ions in Crystals. II. Octahedral Complexes
Authors: Satten Robert A.
Published: January 2005

A method is presented for obtaining the selection rules for transitions between shielded 4fn or 5fn states of rare earth and actinide ions coupled to lattice modes in crystals. This extends our previous work which was limited to rigid vibrational motion of complexes in crystalline fields. The method is illustrated for ions in octahedral complexes at sites of either Oh or D3d symmetry. It is clear from the examples how to apply to other complexes or to include interactions beyond the complex and thereby to obtain the effect of coupling lattice modes involving particles external to the complex. The method is contrasted with that applicable in the case of strong vibration-electronic interaction, i.e., to unshielded electronic states.
Higher Order Rotation-Vibration Energies of Polyatomic Molecules. IV
Authors: Amat Gilbert , Nielsen Harald H.
Published: January 2005

In three previous papers of this series, the rotation-vibration Hamiltonian has been expanded in orders of magnitude and then subjected to two contact transformations. These contact transformations, carried out thus far through the third order of approximation, are now extended through the fourth order of approximation.
Interrelations Involving Solutions of Equations of Equalizing Processes and Oscillating Processes
Authors: O'Sullivan D. G.
Published: January 2005

Assessment of the velocity of a fast chemical reaction can be made by studying the way the reaction interferes with other rapid processes. Both equalizing processes, such as diffusion, and oscillating processes, such as the passage of sound waves, can be employed. Solution of the differential equations of these processes, under a variety of conditions, is a necessary part of the background investigation of these methods and is also of importance in the study of many other physical and chemical problems. This paper shows how a wide range of these solutions can easily be obtained from simpler existing solutions. Among other results, complete resolutions of the ``age equation'' ∂v(r,t)/∂t=D(r)·∇2v(r,t)+A(r,t)+B(t)·v(r,t) and the vibration equation ∂2ξ(r,τ)/∂τ2+b∂ξ(r,τ)/∂τ=κ(r)·∇2ξ(r,τ)+A(r,τ)+B(r)·ξ(r,τ) have been effected for arbitrary initial conditions and a range of important boundary conditions (including those of Dirichlet and Neumann as special cases).
Application of Charge-Transfer Theory to the Heats of Adsorption of the Inert Gases on Charcoal
Authors: Tuck D. G.
Published: January 2005

The adsorption of the inert gases on charcoal is considered from the viewpoint of charge-transfer no-bond complex formation, and interaction integrals are calculated from the heats of adsorption at effectively zero coverage. The numerical values obtained in this way are compatible with similar data in the literature. It is shown that the linear relationship previously reported between the heat of adsorption of the inert gases on charcoal and the polarizabilities of the gases can be satisfactorily derived on the basis of this theory, and arises to a large extent from the comparatively high ionization potentials of these elements.
Study of the Compressions of Several High Molecular Weight Hydrocarbons
Authors: Cutler W. G. , McMickle R. H. , Webb W. , Schiessler R. W.
Published: January 2005

Isothermal compressions were measured for thirteen high-purity liquid hydrocarbons and two binary mixtures of liquid hydrocarbons. These hydrocarbons have a molecular weight range of 170 to 351 and included normal paraffins, cycloparaffins, aromatics, and fused ring compounds. The pressure range for these measurements was from atmospheric to as high as 10 000 bars, being limited to lower values for some compounds to avoid possible solidification of the liquid. The volume changes due to pressure were measured at six temperatures spaced about equally in the range 37.8°C to 135.0°C. The volume changes and pressures were measured by methods similar to those of P. W. Bridgman.

Pressure-volume isotherms can be described adequately by the Tait equation, v0—v=C log(1+P/B), or for pressures above a certain minimum, whose value depends on the compound, by the Hudleston equation log[v2/3P/(v01/3−v1/3)]=A+B(v01/3−v1/3).For the Tait equation the parameter C can be predicted for hydrocarbon liquids from the relation C=0.2058 v0.

Compressibility for a given hydrocarbon decreases with increasing pressure at constant temperature and increases with increasing temperature at constant pressure. The compression, and the compressibility, of liquid hydrocarbons are strongly dependent on molecular structure. Cyclization introduces a rigidity of molecular shape which decreases the compressibility markedly. Furthermore, fused ring cyclization as exemplified by naphthyl and decalyl structures has a considerably greater effect in decreasing compressibility than cyclization to nonfused rings such as cyclopentyl, cyclohexyl, or phenyl, even at equivalent carbon atom in ring percentages.

Isobars and isochores were drawn and studied over the full range of temperature and pressure. The coefficient of thermal expansion, (1/v0) (δv/δT) P, for a given hydrocarbon, decreases with increasing pressure at constant temperature. (δ2v/δT2) P undergoes a sign change at a certain pressure, whose value depends on the compound; (δv/δT) P increases with increasing temperature below this pressure and decreases with increasing temperature above this pressure. The pressure coefficient, (δP/δT) v, is not a function of volume alone but is also dependent on the temperature and pressure. (δE/δv) T and (δE/δP) T go to zero and then reverse sign for compounds that can be studied to sufficiently high pressures.
On the T1/T2 Ratio for Protons in Aqueous Mn++ Solutions
Authors: King James , Davidson Norman
Published: January 2005

The T1≠T2 anomaly for water protons in solutions containing Mn++ has been investigated. At 40 Mc (proton frequency), T1/T2=9.5(±0.5) for Mn++ solutions. When the Mn++ is complexed by the hexadentate ligand, ethylenediaminetetraacetate (MnY—2), or by the tetradentate ligand, nitrilotriacetate (MnX—1), T1 is increased slightly and T2 is increased markedly, so that T1=T2 and the anomaly disappears. For MnX—1, there are probably still 2 H2O molecules complexed to Mn++. EPR studies show that the paramagnetic relaxation time is reduced by complexing (from 3×10—9 sec for Mn++ to 3×10—10 sec for MnX—1). The results therefore support the suggestion by Bloembergen that the anomalous T2 broadening is caused by an AI·S coupling between the electron spin, S, of Mn++ and the proton spins, I, in the coordination sphere plus a long paramagnetic relaxation time. All features of the variation of T1 and T2 with frequency are explained rather well by consideration of the combined effects of the I·S interaction and the dipole interaction.

The experimental results are   Mn++  MnY−2  MnX−1MnX2−4NT1 M sec1.6×10−43.05×10−42.35×10−4NT2 M sec1.65×10−52.6×10−42.25×10−47.4×10−4T1/T29.5(±0.5)1.15(±0.12)1.05(±0.15)
Molecular Composition of Alkali Fluoride Vapors
Authors: Eisenstadt M. , Rothberg G. M. , Kusch P.
Published: January 2005

The abundances of polymeric species of the alkali fluorides in the vapor phase and their dissociation energies have been determined by use of the method of Miller and Kusch. For LiF, NaF, KF, RbF, and CsF, the dissociation energies of the dimer are 58.9, 54.3, 47.6, 42.0, and 37.8 kcal/M, respectively. For LiF the trimer was also observed, with a dissociation energy of 38.3 kcal/M. When the salt is in equilibrium with its vapor at a temperature where the vapor pressure is 10—2 mm of Hg, the abundance of the dimer decreases in the sequence from LiF to CsF. The heats of sublimation for the various species were also found.
Spin Exchange and Spin-Lattice Relaxation Induced by Mechanical Rotation of Solids
Authors: Woessner D. E. , Gutowsky H. S.
Published: January 2005

Measurements with spin-echo apparatus have shown that mechanical rotation of a sample in the static magnetic field decreases the proton T1 in solid chlorobenzenes for particular proton magnetic resonance frequencies within the range 23.2–41 Mc/sec. The results are explained by the following model: magnetic coupling between protons and lattice is weak while the quadrupolar coupling of chlorine nuclei with the lattice is strong. Upon rotation of the sample, the angular dependence of the Zeeman splitting of the chlorine quadrupole levels enables the chlorine resonance frequencies to be brought into coincidence with that of the protons. The resulting spin exchange and energy transfer between protons and chlorine nuclei provides an indirect but nonetheless effective thermal contact of protons with the lattice, thereby reducing the proton T1. The general question of anomalies in the dependence of T1 upon resonance frequency is discussed briefly.
Thermal Conductivity of Liquid Ozone
Authors: Waterman Thomas E. , Kirsh Donald P. , Brabets Robert I.
Published: January 2005

The thermal conductivity of liquid ozone has been determined experimentally. A value of 5.31×10—4 cal/(sec)(cm2)(°C/cm) at —183°C is reported. This value and values measured at three other temperatures are compared with published data for the thermal conductivity of liquid oxygen.
Statistical Mechanics of Irreversible Processes in Polymer Solutions
Authors: Erpenbeck Jerome J. , Kirkwood John G.
Published: January 2005

The Kirkwood theory of irreversible processes in polymer solutions has been reformulated so as to include all contributions to the frictional forces exerted on the monomer units. The generalized diffusion equation for the nonequilibrium distribution function derived on this basis contains a new perturbation term, dependent upon the external field of force. The solution of this equation may be expressed by a perturbation expansion analogous to that given previously.

The general theory has been applied to the intrinsic viscosity problem. Although the general theory reverts to the previous one, new techniques have been applied which enable the intrinsic viscosity and rigidity to be expressed in terms of the eigenfunctions and eigenvalues of the Oseen interaction tensor and the generalized diffusion operator. Moreover, a second formulation of the viscosity has been devised in which the result appears in terms of appropriate time correlation functions.
Microwave Spectra of Molecules Exhibiting Internal Rotation. IV. Isobutane, Tertiary Butyl Fluoride, and Trimethylphospine
Authors: Lide David R. , Mann D. E.
Published: January 2005

Several microwave transitions of (CH3)3CH, (CH3)3CF, and (CH3)3P have been measured and assigned. Rotational constants B0 for the three molecules are 7789.45, 4712.15, and 5816.24 Mc, respectively. Molecular structures and dipole moments have been determined. The (CH3)3CF structure indicates an unusually long CF bond. The prominent satellite lines have been assigned to excited vibrational states; the l-type doubling pattern of transitions in degenerate states has been fitted to theory. Vibrational frequencies determined from relative intensity measurements agree with infrared and Raman results but indicate an incorrect species assignment in (CH3)3P. Frequencies of the torsional vibrations have been used to derive information of the potential function for internal rotation. The leading Fourier coefficient in this function is 3900, 4300, and 2600 cal/mole, respectively, for (CH3)3CH, (CH3)3CF, and (CH3)3P. The terms representing interactions among the CH3 groups are much smaller.
Vibrational Spectrum of Disilyl Sulfide
Authors: Linton H. Richard , Nixon Eugene R.
Published: January 2005

The infrared and Raman spectra of both SiH3SSiH3 and SiD3SSiD3 are reported. Interpretation of the gas and liquid spectra indicates a value of about 100° for the SiSSi angle. The low-temperature infrared spectra suggest a C2v symmetry for the molecule in the crystal.
NMR and Hyperfine Interactions in Paramagnetic Solutions
Authors: Shulman R. G.
Published: January 2005

It is shown how indirect hyperfine interactions affect NMR properties in a variety of paramagnetic solutions. In particular the resonances are shifted from the normal resonance field of ψ/γN by hyperfine interactions arising from complex formation with the magnetic ions. These concepts explain the resonance shifts and are useful in understanding the kinetic behavior, equilibrium constants, and chemical bonding of paramagnetic complexes.
Thermodynamic Study of SiC Utilizing a Mass Spectrometer
Authors: Drowart J. , De Maria G. , Inghram Mark G.
Published: January 2005

The sublimation of hexagonal SiC has been studied under equilibrium conditions. The predominant gaseous species above SiC are Si, SiC2, and Si2C. By combining the heat of formation of gaseous Si from solid SiC and the known standard heat of formation of SiC, a value of 113 kcal/g atom is obtained for the heat of sublimation of Si at 298°K. From the measured partial pressures, using estimated free energy functions, dissociation energies for Si2, Si3, SiC, SiC2, Si2C, Si2C2, Si2C3, and Si3C are calculated and compared with previously known dissociation energies for group IV B molecules.
Hydrogen →Deuterium Exchange Reaction in Fibrous Proteins. I
Authors: Fraser R. D. B. , MacRae T. P.
Published: January 2005

Measurements of infrared spectra obtained with polarized radiation are reported for nylon, silk fibroin, feather rachis, stretched wool, and kangaroo tail tendon before and after reaction with deuterium oxide. In every case except tendon replacement of hydrogen by deuterium in the peptide linkage occurs preferentially in the less well oriented regions of the specimen. A residual absorption band between 4600 and 4650 cm—1 is evident in the partially deuterated protein specimens and it is suggested that this may be assigned to a combination of CH and CO stretching modes.
Absorption Spectra in Molten Salt Solutions
Authors: Greenberg Jacob , Sundheim Benson R.
Published: January 2005

The absorption spectra of solutions of alkali halides and of halogen gases in alkali halide eutectic melts are described. The spectra of the halides are interpreted as charge transfers from the anion. The halogens are shown to dissolve in these solvents to form trihalide ions.
Study of Molecular Patterns in the Field Emission Microscope
Authors: Melmed Allan J. , Müller Erwin W.
Published: January 2005

Field emission patterns of organic dye molecules such as phthalocyanine or flavanthrene show improved stability when the tip temperature is lowered. No prior contamination or buildup is necessary for the production of typical quadruplet or doublet patterns. Upon heating or ion bombardment the molecule patterns may disappear in several distinct steps of size and intensity. On the average 13 phthalocyanine or 2 flavanthrene molecules must strike the tip to produce one pattern. These observations suggest that the substances studied here evaporate and arrive at the tip as polymerized units consisting of two to six molecules. A mechanism for image formation is proposed.
Ion Exchange Kinetics. A Nonlinear Diffusion Problem. II. Particle Diffusion Controlled Exchange of Univalent and Bivalent Ions
Authors: Plesset M. S. , Helfferich F. , Franklin J. N.
Published: January 2005

The differential equation derived previously which describes the particle diffusion controlled ion exchange between spherical beads of uniform size and a well-stirred solution is solved numerically for the exchange of monovalent ions for bivalent ions, and of bivalent ions for monovalent ions. The approach is based on the Nernst-Planck equations of ionic motion. Numerical results for six different mobility ratios are presented and discussed. They were obtained by use of a digital computer. An explicit equation approximating the numerical data is given.
Small Perturbations in Solution Theory
Authors: Buff Frank P. , Schindler Fred M.
Published: January 2005

A general perturbation theory is developed for the solution properties of systems with comparable intermolecular interactions. By employing our earlier general statistical mechanical theory of solutions as a starting point, the dominant contribution to the excess chemical potential is developed rigorously to first and second orders in the perturbation parameters. The very small first-order terms are in agreement with those originally found by Longuet-Higgins and the second-order results may be exhibited in alternative forms. One of these, with use of a physically plausible approximation for the solute-solvent radial distribution function, evaluated in the pure solvent, leads to formulas identical with those of the Prigogine-Scott two-fluid model. Alternatively, this distribution function may be expressed exactly in terms of the pair and triplet correlation function of the solvent. Numerical calculations on the latter, based on liquid argon as reference fluid, provide additional support for the successful two-fluid model.
Calculation of the Radial Distribution Function from the Cell Theory of Liquids
Authors: Dahler John S.
Published: January 2005

A method is given for determining the radial distribution function from the cell theory of liquids. The application of the scheme is demonstrated for two simple choices of the cell distribution function. This technique should prove useful in correlating the observed structure of the radial distribution function with molecular ordering in liquids and in establishing the limitations of the cell model.
On the Statistical Mechanical Theory of Solutions
Authors: Mazo R. M.
Published: January 2005

A perturbation expansion of the excess free energy of a binary mixture based on the theory of composition fluctuations in an open system is presented. The theory is applied to classical mixtures and quantum mechanical isotope mixtures, and comparisons with conformal solution theory and Chester's theory of isotope mixtures are made. The advantage of the present theory is that it contains in summed form, in each order of perturbation, terms which in the direct expansion of the partition function would be considered to be higher order.
Semiempirical Calculation on the Electronic Structure of the Nitrogen-Containing Heterocyclic Molecules. I. General Theory
Authors: Anno Tosinobu
Published: January 2005

A semiempirical theory for n — π and π — π spectra of nitrogen heterocycles is proposed. The theory is an extension of the semiempirical molecular-orbital method of Pariser and Parr, and the nonbonding electrons localized at the nitrogen atoms as well as π electrons are considered explicitly into the interaction term in the Hamiltonian. The orbitals in which nonbonding electrons are contained may be any 2s—2p hybrids. The differential overlap between atomic orbitals are formally neglected. One-center electronic-interaction integrals are obtained from atomic spectral data and two-center integrals at moderate internuclear distances are extrapolated, using corresponding one-center integrals obtained from atomic spectral data together with the theoretical value of the two-center integrals at larger internuclear distances. On account of the hybrid nature of the nonbonding AO's (AO's from which nonbonding MO's are constructed), various kinds of two-center integrals as well as one-center ones appear. The method of obtaining these integrals is described systematically. The method of obtaining the valence-state ionization potential for nonbonding electrons in hybrid orbitals is also described.

Finally, as an example of the application of the present scheme, the energy levels of the pyrazine molecule are calculated, assuming that the s character of the nonbonding AO at the nitrogen atom is one third and taking account only of interactions among the ground and the singly-excited configurations. Only the singlet levels are considered in this paper. Although the calculated Ag1→B3u1(π−π) transition energy agrees fairly well with experiment, it is found for Ag1→B1u1,B3g1(n−π) transitions that the calculated values are considerably higher than the observed values. This is probably due either to the neglect of the doubly excited configurations or to the invalid assumption concerning the hybridization parameter of the nitrogen nonbonding AO. This point will be discussed in Part II of this series.
Growth of Potassium Chloride Crystals from Aqueous Solution
Authors: Sears Gerald W.
Published: January 2005

It is shown that the growth behavior of potassium chloride crystals from aqueous solution is consistent with the Frank growth mechanism. The growth behavior is altered by the presence of a few parts per million of lead chloride. It is imputed that the rate of growth at unit steps is inhibited and that the rate of two-dimensional nucleation is markedly increased by the presence of lead chloride. The effects are consistent with complete line adsorption of a complex lead containing ion at growth steps.
Entropies and Energies of Dimerization of Alkali Metal Halides
Authors: Bauer S. H. , Diner R. M. , Porter Richard F.
Published: January 2005

Calculated entropies of dimerization for a number of gaseous alkali metal halides, assuming the rhombic planar model for the dimer, fall in the range —31.0±1.5 entropy units. Entropies of dimerization deduced from experimental data for several species diverge appreciably from the calculated values. The differences can be attributed to uncertainties in the graphical determination of dimerization energies. Energies of dimerization recalculated by combining experimental values of ΔF° (dimerization) with theoretical values of ΔS° (dimerization) correlate well with the interionic separations in the dimers.
Quantum-Mechanical Calculation of One-Electron Properties. I. General Formulation
Authors: Karplus Martin , Kuppermann Aron , Isaacson Leonard M.
Published: January 2005

For a one-electron operator, general formulas for weighted transition functions, weighted density functions, and their integrals are introduced. A detailed treatment is given of the expressions that are obtained from these formulas when they are applied to a system whose wave functions are expanded in a series of determinants of one-electron spin orbitals. Explicit consideration is given to the nonorthogonality problem and a method for the exact inclusion of overlap terms is formulated. The simplifications resulting from the use of the single determinant approximation and orthonormal functions are discussed. A brief evaluation of the suitability of the formulation for digital computer calculation is given.
On the Approximate Calculation of Eigenfunctions
Authors: Gray B. F.
Published: January 2005

A method is given for determining the variable parameters in a trial wave function which is independent of the minimum energy criterion. The energy is given as the root of a secular equation, but the value obtained may be above or below the true value. It is shown that the results of the method approach those of the standard one as the trial function becomes a better approximation to the true one, by applying it to the series of two-electron ions.
Infrared Spectra of Partially Deuterated Diboranes
Authors: Lehmann Walter J. , Ditter Jerome F. , Shapiro I.
Published: January 2005

Infrared spectra, in the 2 to 15 μ range, of equilibrium mixtures of various proportions of B2H6 and B2D6 are reported. These mixtures contain twenty-one different species (represented by seven molecular formulas ranging from B2H6 to B2D6), which exist in equilibrium with one another and cannot be separated by chemical or physical means. However, the spectra of the individual formula groups B2D5H and B2H5D were obtained by spectroscopically compensating for other species present in the equilibrium mixtures. An assignment of the observed and unobserved fundamental frequencies of the four molecules represented by the two formulas is made with the help of previously published data on B2H6 and B2D6 and by application of the noncrossing rule and the product and sum rules. Comparisons with published spectra of partially deuterated ethylenes and dimethylaminodiborane support these assignments.
Theory of Orientational Effects and Related Phenomena in Dielectric Liquids
Authors: Piekara A. , Kielich S.
Published: January 2005

Formulas are developed for the molar constants of five nonlinear effects of molecular orientation in liquids; namely, the dielectric saturation in electric, magnetic, or optical fields and the electric as well as the magnetic birefringence. No assumption is made concerning the nature of the intermolecular forces, and no special model of molecular interaction is introduced. If the molecules may be considered to possess axial symmetry, four correlation factors RP, RCM, RK, and RS can be derived. These factors appear in the formulas of the molar constants of the Cotton-Mouton and Kerr effects, and of the effect of dielectric saturation in an electric, magnetic, or optical field. The correlation factors have been calculated as functions of θ(pq), the angle between the axes of symmetry of the pth and qth molecules, in the absence of a biasing field. The theory makes it possible to predict the value of the magnetodielectric saturation effect in diamagnetic liquids, as well as the photodielectric saturation, relating these phenomena to magnetic or electric birefringence. Moreover, the meaning of this theory consists in the fact that it gives a quantitative explanation of the inverse saturation effect appearing in some polar liquids and increasing their dielectric constant. Satisfactory results have been obtained by applying this theory to such phenomena as light scattering in liquids or the lowering of the freezing point, in which the orientationally dependent intermolecular forces play an important part.
Composition of Nitrogen Oxide Equilibria
Authors: van Beek-Visser Eleonora
Published: January 2005

The nitrogen oxide equilibrium is recalculated on the basis of the new spectroscopic value for the dissociation energy of nitrogen. Complete tables of the composition are given in the temperature range 2–5000°K. The maximum amount of fixed nitrogen (at 1 atmos pressure and a nitrogen oxygen ratio as in natural air) is ∼5 mole percent and occurs at a temperature of ∼3500°K. The influence of the N/O ratio is indicated.
Zeeman Quadrupole Spectrum of Cyanuric Chloride
Authors: Adrian F. J.
Published: January 2005

Zeeman splitting studies of the Cl35 pure quadrupole resonances in cyanuric chloride have been carried out. Location of the principal electric field gradient axes demonstrated that cyanuric chloride is a planar molecule, with a threefold rotation axis perpendicular to the molecular plane. The planar molecules all lie in the (1, 0, 1) planes of the monoclinic crystal. It seems likely that the molecules are oriented within these planes so that each molecule has a carbon-chlorine bond lying along the b crystallographic axis. The field gradient asymmetry parameter is 0.24 for all the Cl atoms. This result is interpreted in terms of the effect of the ring nitrogens on the double-bond character of the carbon-chlorine bond.
Molecular Structure and Vibrational Spectra of Alkali Halide Dimers
Authors: Berkowitz Joseph
Published: January 2005

The molecular structure and infrared-active vibrational frequencies of alkali-halide dimer molecules have been calculated, assuming an ionic model similar to that used for alkali halide diatomic molecules and crystals. The results of the calculation provide further evidence for the presence of large concentrations of lithium halide dimers. The previous identification of infrared bands with monomeric alkali halides is verified and several alternatives are then suggested for the absence of dimer bands. Some inconsistencies in the dimerization energies obtained from molecular beam studies also become apparent by this treatment.
Influence of Oxygen on the Transfer Efficiency and Fluorescent Yield of Organic Solutions
Authors: Bar V. , Weinreb A.
Published: January 2005

The quenching action of oxygen on the transfer efficiency and fluorescent yield of organic solutions is investigated in systems in which the transferring solvent is undiluted and in systems in which it is diluted by an inert solvent. It is shown that quenching by oxygen is a process competing with energy transfer from the solvent to the solute, with emission of solute fluorescence, and with self-quenching of the solute. Experimental evidence for the assumption that transfer of energy takes place by a direct interaction between excited solvent molecules and accepting solute molecules is augmented.
Dielectric Properties of Aqueous Ionic Solutions. Parts I and II
Authors: Hasted J. B. , Ritson D. M. , Collie C. H.
Published: January 2005

The dielectric constants and loss angles of a series of concentrated aqueous ionic solutions have been measured at wave-lengths of 10 cm, 3 cm, and 1.25 cm. From these results the values of the static dielectric constant and relaxation time for these solutions have been calculated on the basis of the Debye formula, which appears to hold accurately. All salts show a lowering of the dielectric constant and a shift in the relaxation time of water. It is found that the dielectric constant ε can be represented by a formula ε=εω+2δ̄c, where εω is the dielectric constant of water, c is the concentration in moles per liter, and δ has values between −7 and −15 for various salts in concentrations of up to 2 M.

In Part I the measurements are described and the results discussed in relation to the structure of ionic solutions. In Part II the validity of the Debye-Sack saturation theory of the dielectric constant and the effects of the fall of dielectric constant on the electrolytic properties of concentrated solutions are discussed.
Discussion of the Absolute Reaction Rate of Unimolecular Decompositions
Authors: Hirschfelder Joseph O.
Published: January 2005

In the usual theory of absolute reaction rates it is assumed that the molecules in the activated complex are in statistical equilibrium with the molecules in the initial state. This assumption is not justified in the case of unimolecular decompositions because the molecules in the initial state must gain the energy of activation by a stepwise process, usually by the transfer of quanta of vibrational energy from one normal mode to another. The size of these energy jumps and their frequency inevitably affect the over-all reaction rate. The problem is considered in considerable detail for a rough idealized mode. In this case, the actual reaction rate should be smaller by a factor of 0.5 to 0.387 than the value computed from the usual theory of absolute rates. A rigorous development would require further development of the original Ramsperger-Rice-Kassel treatment.
The Use of Tritium in the Determination of the Solubility of Water in Solvents. The Solubility of Water in Benzene
Authors: Joris G. G. , Taylor H. S.
Published: January 2005

A new method for determination of the solubility of water in hydrocarbons is based on the use of radioactive hydrogen isotope, tritium, as tracer for the dissolved water. This method is applicable to the determination of the solubility of water in compounds in which it is sparingly soluble.