bluuebunny/crossref_metadata_2025 huggingface dataset:
Mobility and Adsorption of Hydrogen on Tungsten
Authors: Gomer R. , Wortman R. , Lundy R.
Published: January 2005

The surface diffusion of hydrogen on W field emitters has been investigated by making use of the low vapor pressure and high sticking coefficient of H2 at liquid helium temperature to obtain unilateral contamination. Average values of the energy of desorption of H2 have also been obtained. It is found that spreading occurs in three distinct phases. At very high initial coverages a moving boundary migration occurs below 20°K, corresponding to migration of physically adsorbed H2 on top of the chemisorbed layer, precipitation at its edge, and further migration over the newly covered region. For initial deposits corresponding to ∼1 monolayer spreading sets in at ∼180°K with a boundary moving radially outward from the close-packed 110 faces. The activation energy of this process is ∼6 kcal and corresponds to migration over the smooth (close-packed) regions of the tip followed by precipitation of chemisorbate at trap sites on the rough regions. At coverages too low to permit saturation of traps diffusion out of the latter becomes rate controlling so that boundary free diffusion with E≈9.5 kcal and at even lower coverages with E∼16 kcal is observed. The heat of adsorption of H2 at extremely low coverage is found to be 64 kcal, but drops rapidly with increasing coverage. These results lead to the conclusion that surface heterogeneity is largely the result of surface topography and is inherent on all but the close-packed faces of W. The activation energies for diffusion are found to be 10 to 20% of the binding energy, depending on the nature of the sites. It is also seen from the low-temperature spreading that ∼75% of the chemisorbed layer can be formed below 20°K with effectively zero activation energy, and a large probability factor. The bearing of these results on the mechanism of some catalytic reactions is discussed.
Bonding in Copper(II) Chelates: Solvent Effects in Their Visible Absorption Spectra
Authors: Belford R. Linn , Calvin M. , Belford Geneva
Published: January 2005

Absorption spectra, in the visible red and near infrared, are reported for solutions of bis-acetylacetono-Cu (II) and its 3-ethyl variant in various media. The spectra could arise from a set of three Gaussian components whose positions and intensities are shown to depend primarily upon solvent basicity. These component bands are identified with three 3d1—3d1 transitions predicted from crystal field and molecular orbital theories. The behavior of these bands upon alteration of solvent and of chelate ring substituents appears consistent with the postulate that pi-bonding changes are energetically of less importance than changes in crystal field splitting and in sigma bonding.
Kinetics of Slow Fractures in Glass
Authors: Levengood W. C. , Johnston W. H.
Published: January 2005

Fractures in plate glass, originating at a cutter mark and progressing slowly parallel to the surface, were observed under controlled conditions. The rates of spread of such fractures, immediately after the glass is cut and for several hours afterward, were determined by viewing microscopically the movement of interference fringes produced in monochromatic light. Effects of external atmosphere, and of various included gases introduced during melting, are described. A theory of the kinetics of slow fracture rates is offered, which relates the fracture spreading rate to the molecular diameter and molecular weight of the internal gas involved.
Observation of the Relative Polarizations of Electronic Transitions
Authors: Williams Richard
Published: January 2005

The polarization of fluorescence of several aromatic systems in a rigid glass of propylene glycol at —78°C has been determined. Polarized exciting radiation absorbed in a single electronic band was used, enabling the determination of the polarization of higher electron transitions relative to that of the lowest singlet-singlet transition. Results are in agreement with current theoretical ideas for anthracene and several of its derivatives. Results for peri-condensed systems suggest the need for a more thorough examination of the free electron model for this type of system.
Dielectric Saturation of Associated Liquids
Authors: Schellman John A.
Published: January 2005

Equations are developed which take into account the effect of association in liquids on dielectric saturation. The treatment emphasizes the strong relation between dielectric properties and the mean fluctuation of electric moment of fluids in the absence of electric fields. For water the results indicate a saturation effect above five times the value predicted by the equations of Van Vleck, which is not applicable to associated liquids. The equations derived are rigorously applicable only to systems where the field strength is not subject to variations over distances of microscopic dimensions (like all other dielectric theories). However, when applied to a dielectric 5 A from a singly charged ion they indicate that saturation effects are negligible. If the present treatment is granted, the decrease in dielectric constant which arises from saturation is of the same order of magnitude as the increase in dielectric constant caused by electrostriction. A realistic theory of dielectrics in very strong fields must simultaneously include both effects.
Absolute Intensities of the 721 and 742 cm—1 Bands of CO2
Authors: Kostkowski Henry J. , Kaplan Lewis D.
Published: January 2005

The absolute intensities of the 0110→1000 and 0220→1110 bands of CO2 at 721 and 742 cm—1, respectively, have been determined with a curve-of-growth method utilizing the Elsasser periodic line pattern and a slit function calculation. The resulting intensities were S0110→1000329 °K=7.5 cm−2 atmos—1 and S0220→1110329 °K=0.22 cm−2 atmos—1. In addition the intensity of the 0310→1200 band at 740 cm—1 was estimated to be S0310→1200329 °K=0.032 cm−2 atmos—1.
Entropy of Mixing of Dilute Polymer Solutions
Authors: Emery Alden H.
Published: January 2005

The entropy of mixing of dilute solutions of high polymers has been calculated. The expression obtained employs a molecular dimension obtained from the intrinsic viscosity, contains no arbitrary constants, and appears to be valid from zero to about two percent polymer, the limit of the osmotic pressure data used.
Theoretical Investigations on the Light Scattering of Colloidal Spheres. III. Analytical Expressions for Turbidity Approximating the Performance of the Mie Equations Prior to the First Maximum
Authors: Heller Wilfried
Published: January 2005

Analytical expressions are developed for the specific turbidity in dispersed systems of light scattering spheres. They yield particle diameters approximating over an appreciable range of α and m values and within better than 5% those obtained from the Mie-equations. The m range encompassed satisfactorily by the equations exceeds appreciably the range of validity of the Rayleigh-Gans and Debye equations. The limiting lower and upper values of α and m to which the equations are applicable, are defined quantitatively.
Collision-Induced Dissociations in the Mass Spectrum of Acetylene
Authors: Melton C. E. , Bretscher M. M. , Baldock Russell
Published: January 2005

A number of collision-induced dissociations in the mass spectrum of acetylene are reported. The pressure dependence of these transitions was investigated in the range from 2×10—7 to 3×10—6 mm of Hg. Relative cross sections are given and compared with the corresponding ones for dissociation by electron impact. A metastable transition corresponding to the reaction C2H+→C2++H was observed.
Dispersion and Absorption of Sound in Liquids in General Chemical Equilibrium and its Application to Chemical Kinetics
Authors: Tabuchi Daisaku
Published: January 2005

It is shown that there occur dispersion and absorption of sound owing to chemical reaction in a liquid which is in general chemical equilibrium aA+bB+···[open phi]qQ+rR+···. From the acoustic characteristic equation, the velocity and the absorption coefficient of sound are derived, and the characteristics of the dispersion and absorption curves are examined. The velocity and the absorption coefficient of sound in liquid are derived in terms of the density, the static isothermal compressibility, the thermal expansion coefficient, the partial molar volume, the equilibrium constant, that is, the composition, the reaction heat at constant volume, the molar heat at constant volume, and the rate constant of chemical reaction. By measuring the velocity and the absorption of sound, it is possible to determine the rate constant of chemical reaction, the reaction heat, and the volume change. The application to solutions, especially to electrolyte solutions is shown, and in this case the activity coefficients may be used. As special cases, chemical reactions which are not accompanied by reaction heat or volume change are treated, and the results of Freedman and Manes are compared with the present one, and the differences are pointed out. Several examples of the general formulas are shown. Since it is easy to increase the frequency of sound, the method of measuring the velocity and the absorption coefficient of sound is adequate for determining the rate of a very fast reaction in the equilibrium state.
Infrared and Raman Spectra of Fluorinated Ethylenes. VII. 1,1-Difluoro-2,2-dibromoethylene
Authors: Theimer Rose , Nielsen J. Rud
Published: January 2005

The infrared absorption spectrum of gaseous CF2:CBr2 has been obtained with a Perkin-Elmer Model 112 double-pass spectrometer equipped with NaCl and CsBr prisms and with a 1—m cell. The Raman spectrum of the compound in the liquid state has been photographed with a 3-prism glass spectrograph of linear dispersion 15 A/mm at 4358 A. Polarization ratios were measured for the stronger Raman bands. The 12 fundamental vibrational wave numbers have been assigned as follows: 1718 (a1), 1307 (b1), 1005 (a1), 898 (b1), 598 (a1), 572 (b2), 399 (b1), 390 (b2), 324 (a1), 203 (a1), 168 (b1), and 151 (a2) cm—1. The 3 lowest are for the liquid, the others for the gaseous state. The observed spectra have been interpreted in detail. Thermodynamic properties of the compound in the ideal-gaseous state have been calculated for 4 temperatures above the boiling point.
Heats of Vaporization of 1,1,2-Trichloroethane, 1-Propanol, and 2-Propanol; Vapor Heat Capacity of 1,1,2-Trichloroethane
Authors: Williamson Kenneth D. , Harrison Roland H.
Published: January 2005

Heats of vaporization of 1,1,2-trichloroethane, 1-propanol, and 2-propanol have been determined at various temperatures. The vapor heat capacity of 1,1,2-trichloroethane has been measured at 96.76°C, 148.33°C, and 201.11°C.
Thermodynamic Functions of 1,1,2-Trichloroethane
Authors: Harrison Roland H. , Kobe Kenneth A.
Published: January 2005

The thermodynamic functions of 1,1,2-trichloroethane have been calculated by the methods of statistical mechanics. An assignment of the fundamental frequencies of vibration has been made and a barrier to internal rotation has been selected. The calculated heat capacities agree with experimental values.
On the Regression of Fluctuations
Authors: Fixman Marshall
Published: January 2005

Both the formal and molecular aspects of fluctuation theory are considered with the aim of computing transport coefficients. The formal theory of the regression of fluctuations is presented from the standpoint of least-square linear prediction theory. Thereby the transport coefficients are expressed in terms of correlations between fluctuations and time averaged fluxes. The necessary dynamics is developed with the assumption that the potential energy of interaction between a small group of molecules and the rest of the system decays only slightly during the minimum time interval required to establish the flow processes. The theory is briefly illustrated with an application to diffusion.
Effect of Surface Condition on the Fluorescence and Surface Photoconductivity of Anthracene
Authors: Lipsett F. R. , Compton D. M. J. , Waddington T. C.
Published: January 2005

When large crystals of anthracene are polished with abrasive powders and solvents, and are then exposed to air or oxygen for several days, the intensity of fluorescence and the hard vacuum value of the surface photoconductivity decrease markedly. With cleaved crystals or crystals grown from solution, however, the fluorescence remains unchanged, and the photocurrent alters in a different fashion. It is suggested that the abrasion of the polishing process facilitates the production of a film of anthracene peroxide or anthraquinone, which in turn causes the effect observed.
Proton and Nitrogen Magnetic Resonance Spectra and Structure of Nitramide and Nitrourethane
Authors: Ray James D. , Ogg Richard A.
Published: January 2005

Nuclear magnetic resonance spectra of both protons and N14 nuclei in nitrourethane and nitramide have been studied. Spectra are interpreted in terms of the structures R–NHNO2 and H2NNO2 for nitrourethane and nitramide, respectively. Protons have been established as all being of amino type.
Study of the Scintillation Process
Authors: Hardwick E. R. , McMillan W. G.
Published: January 2005

A phenomenological time-dependent relation between phosphor concentration and emission intensity, including effects of self-absorption, is derived for scintillation solutions. The dependence of the integrated intensity equation on concentration of phosphor and quencher is tested experimentally in several ways using α irradiation, and found to give agreement within the (occasionally large) experimental error. Application of this equation to measurements of the decline in scintillation efficiency of anthracene crystals on bombardment with α particles suggests a method of obtaining the effective exciton ``range,'' for which we estimate ∼3000 A as a lower limit. The question of the mechanism of energy transfer is discussed, and some photographic data are presented which indicate that the large (∼1 mm) transfer distances previously observed by Ageno et al. in similar experiments may have been due to phosphor photon absorption and reemission.
Curved Fluid Interfaces. III. The Dependence of the Free Energy on Parameters of External Force
Authors: Buff Frank P. , Saltsburg Howard
Published: January 2005

The parameter of external force dependence of the free energy Ω appearing in the grand partition function is first illustrated on the basis of ideal gas models. In order to obtain a corresponding asymptotic estimate of Ω for real fluids in the presence of external fields, our earlier hydrostatic results are transcribed into thermodynamic terms. The resulting expression for Ω is shown to yield work elements in agreement with the detailed theory and, furthermore, when Ω is subjected to an appropriate variational principle the earlier relations describing the surfaces are obtained. These asymptotic formulas demonstrate that for macroscopic applications the classical equations are completely valid. Since these equations determine the spatial distribution of fluids, their connection with Duhem's theorem is described.
Fibrous Growth of NaClO3
Authors: Sears Gerald W.
Published: January 2005

It has been observed by Kato [J. Phys. Soc. Japan, 1024 (1955)] that fine fibers of NaClO3 form on moist massive crystals of NaClO3 which are slowly desiccated. It is proposed that the growth occurs by a uniaxial screw dislocation mechanism in which the material transport occurs by hydrodynamic flow in an adherent film of solution on the fiber surface. The tractive force for film flow is furnished by a gradient in surface tension. The film solution becomes more concentrated during its flow to the fiber tip and the gradient in solute concentration causes a gradient in surface tension. The estimated film thickness is about 100 A. Periodic bends in the fiber can be accounted for by periodic precipitation of a minor impurity with limited solid solubility in NaClO3.
Raman Spectrum of Gaseous 1-Fluoro-1-chloroethylene
Authors: Nielsen J. Rud , Albright J. C.
Published: January 2005

The Raman spectrum of gaseous CFCl: CH2 has been obtained with the aid of a multiple-reflection Raman tube and a 3-prism glass spectrograph of linear dispersion 15 A/mm at 4358 A. All but one of the 12 vibrational fundamentals and several overtone or combination bands have been measured. The results are discussed.
Electrical Conductivity Measurements on Cuprous Halides
Authors: Wagner J. Bruce , Wagner Carl
Published: January 2005

The total electrical conductivity and the electron hole conductivity in solid CuCl, CuBr, and CuI between 250 and 450°C have been determined with help of ac measurements on samples between copper electrodes and dc polarization measurements on the cell

Cu|cuprous halide|graphite.
Thermal Conductivity of Gas Mixtures in Chemical Equilibrium
Authors: Butler James N. , Brokaw Richard S.
Published: January 2005

A general expression applying to the steady state has been derived which permits calculation of the increase in thermal conductivity due to chemical reaction in mixtures of gases in chemical equilibrium. In addition to the gas composition, heats of reaction and binary diffusion coefficients among the component gases are required.

In the case of a simple dissociation, the thermal conductivity may be related to the equilibrium heat capacity. This suggests a possible method for estimating heat transfer in various practical systems with dissociating gases.

Approximate calculations for dissociation of diatomic molecules at equilibrium show that the thermal conductivity may be an order of magnitude greater than in nonreacting mixtures. Calculations for the systems 2NO2⇆N2O4 and 6HF⇆(HF)6 are in satisfactory agreement with experiment.
Elastic and Force Constants of a Simple Tetragonal Crystal
Authors: Mitra G. B. , Gokhale B. V.
Published: January 2005

Lattice vibrations of a monatomic simple tetragonal crystal have been discussed and interactions of first, second, third, and fourth nearest neighbors have been taken account of. The equations of motion of an atom along the three crystallographic axes have been set up. Comparing with these the corresponding equations of elastic vibrations, the elastic constants of the simple tetragonal lattice have been expressed in terms of the various force constants and vice versa. Free electrons in the lattice have been supposed to give rise to an additional force constant which has also been evaluated in a similar way.
Decomposition of Carbon Dioxide by Ionizing Radiation. Part II
Authors: Harteck P. , Dondes S.
Published: January 2005

An extension of the research on carbon dioxide described in Part I was conducted at pressures from one atmosphere to fifty atmospheres, and on liquid carbon dioxide at 10°C, near the critical temperature. Also a novel method was developed in using the direct impact of the fission fragments on the gases (uranium-235 in contact with the gases on bombardment with thermal neutrons). The action of inhibitors other than nitrogen dioxide to stop the back reaction of the decomposed carbon dioxide was also investigated. Since the decomposition of nitrous oxide by ionizing radiation was determined as a dosimeter, parallel decomposition experiments were conducted with the nitrous oxide and carbon dioxide under identical conditions. The G values of the carbon dioxide decomposition were determined with and without inhibitors at high pressures and the liquid state by pile radiation and by the impact of fission fragments. The G values ranged from 0.005 to 8.5±0.5 depending upon conditions. The basic mechanism described in Part I was confirmed. No difference in behavior was noticed in the gas phase when irradiated with pile radiation or fission fragments.

In the liquid state, it could be shown that the ``hot spots'' or ``hot needles'' along the ionization track of the fission fragments are not ``hot'' enough to initiate the thermal decomposition, which in the case of nitrous oxide requires a heat of activation of 53 kcal and for carbon dioxide 128 kcal. However, two markedly different behaviors between the gaseous and liquid states were noted. First, the inhibitors became inefficient in the liquid carbon dioxide phase, and second, the G value for the decomposition of liquid carbon dioxide was found to be 4 to 5. These behaviors are not altered if the liquid carbon dioxide is irradiated with normal pile radiation or with fission fragments.
Reaction of Carbon Monoxide and Ozone
Authors: Harteck P. , Dondes S.
Published: January 2005

The reaction between ozone and carbon monoxide has been investigated at 35°, 100°, 180°, and 258°C. It could be shown that there is an initial period where the reaction proceeds an order of magnitude faster than after some carbon dioxide is formed. Further oxidation of carbon monoxide by ozone proceeds in the order of magnitude of the thermal decomposition of ozone.
Electronic Spectra of the Triarylmethyl Radicals
Authors: Murrell J. N.
Published: January 2005

The doublet electronic states of the triarylmethyl radicals are expanded in terms of functions describing states in which the ``nonbonding'' orbital is localized on the central carbon atom. This basic set of functions can be divided into three classes: those that correspond to singlet states of the aryl groups, those that correspond to triplet states of the aryl groups, and states in which an electron has been transferred to or removed from the central carbon atom. The spectrum of the triphenylmethyl radical is interpreted in this way. It is shown that the lowest band at 2.41 ev, although weak, arises from a symmetry allowed transition to a state of E symmetry (in the group D3). There are several states which can contribute to the first intense band, there being two main regions of absorption. Both the energies and relative intensities of the predicted near ultraviolet bands agree well with experiment.
Nuclear Quadrupole Interaction in Boron Compounds
Authors: Das T. P.
Published: January 2005

The quadrupole coupling constants of B11 in some boron compounds are investigated in detail. A Townes-and-Dailey type of interpretation for boron trimethyl gives better agreement with experiment than a detailed molecular orbital calculation, but it is pointed out that this agreement is to be regarded as fortuitous. It is concluded that if localized LCAOMO functions are formed from undistorted atomic orbitals to describe a bond, they lead to an underestimation of the field gradient at the nucleus due to the electrons. For borine carbonyl, an estimation of the ionic character of the BC bond is made from the observed quadrupole coupling constant of B11. With this estimate, the dipole moment associated with the BH3 group is obtained from the observed dipole moment of the whole molecule. The dipole moment of the BH3 group is also calculated using localized LCAOMO's for the BH bonds. This calculation gives the correct sign of the observed dipole moment, but overestimates its magnitude. Some comments are made on the quadrupole interaction tensor for B11 in kernite using a molecular orbital approach.
Nuclear Magnetic Relaxation in Polytetrafluoroethylene and Polyethylene
Authors: Wilson C. W. , Pake G. E.
Published: January 2005

Nuclear magnetic resonance studies of the linear chain polymer polytetrafluoroethylene (Teflon) indicate the coexistence of two phases, each characterized by its own pair of relaxation times T1 and T2. Decomposition of the complex resonance lines and complex saturation curves into normal curves permits determination of the fraction of nuclei in each phase. It is suggested that the phases are the crystalline and amorphous regions of these polymers, and some additional evidence to support this suggestion is presented.

The phase thought to be crystalline shows a marked line-narrowing at the first-order thermodynamic-transition point near 293°K.

The less complete data presented for polyethylene suggest the analogous presence of two phases, and the line-shape analysis yields reasonable values for the degree of crystallinity.
Vacuum Ultraviolet Photochemistry. Part V. Nitrous Oxide at 1236 A
Authors: Zelikoff Murray , Aschenbrand Leonard M.
Published: January 2005

The photolysis of nitrous oxide has been studied using krypton resonance radiation at 1236 A. The mechanism is found to differ from that at 1470 A and at 1849 A since the initial absorption act at 1236 A probably proceeds in a dual manner. One way leads to production of nitrogen atoms and nitric oxide molecules while the other produces nitrogen molecules and oxygen atoms. The mechanisms at the three wavelengths are unified into one consistent picture.
Kinetic Study of the Oxidation of Uranium Dioxide
Authors: Aronson S. , Roof R. B. , Belle J.
Published: January 2005

Oxidation of UO2 to U3O8 in dry air and oxygen at temperatures of 160 to 350°C proceeds by a two-step reaction. In the first step the tetragonal oxide of composition UO2.34±0.03 is formed. In the second step this tetragonal phase is converted to orthorhombic U3O8. The rate controlling process in the first stage is the diffusion of oxygen through the uranium dioxide lattice. The value found for the diffusion coefficient D is D=5.5×10−3exp[−(26 300±1500)/RT],where the activation energy is 26.3±1.5 kcal/mole. The second stage of the reaction proceeds by a process of nucleation and growth.
Asymptotic Relations in the Thomas-Fermi-Dirac Atom Model
Authors: Gilvarry J. J.
Published: January 2005

Asymptotic solutions of the Thomas-Fermi-Dirac equation for the case where the atom radius is vanishingly small (Fermi-Dirac limit) are considered. The limiting situation is examined in which the atomic number vanishes for a constant value of the Thomas-Fermi pressure (without exchange). It is shown that the pressure with exchange from the Thomas-Fermi-Dirac model approaches a finite limit in this case. The results yield limit curves approached for vanishing atomic number, by curves at constant atomic number of the pressure and other thermodynamic quantities with exchange, as a function of the pressure without exchange. The theoretical conclusions are confirmed by numerical data given by others and obtained directly by solution of the Thomas-Fermi-Dirac equation.
Exploding Wire as a Light Source in Flash Photolysis
Authors: Oster Gisela K. , Marcus R. A.
Published: January 2005

The exploding wire technique has been developed for use as a light source in flash photolysis. The method consists of discharging a bank of condensers, via a mechanical switch through a thin Nichrome wire. The wire explodes, emitting light rich in the ultraviolet region in less than a millisecond. The luminous efficiency in the 200 to 330 mμ region is of the order of 10% of the input. The minimum electrical energy input necessary to produce an explosion is equal to the energy required to vaporize the wire. The light output of the exploding wire as measured by uranyl oxalate actinometry and acetone photolysis is proportional to the electrical energy input. It was found to be highly reproducible. It was further observed that the exploding wire behaves as a line source. Because of the absence of a quartz or Pyrex tube in this source, it may find application in the far as well as in the near ultraviolet and in the visible spectral regions.
Electronic Spectral Shifts of Nonpolar Molecules in Nonpolar Solvents
Authors: Longuet-Higgins H. C. , Pople J. A.
Published: January 2005

A theory of the red shift of low-lying electronic bands of nonpolar molecules in nonpolar solvents is presented. The difference between the dispersion forces in the ground and excited states is investigated by perturbation theory and an approximate formula is derived according to which (in dilute solution) Red shift=16αBzR̄−6{14EαA+M2},where αA and αB are the molecular polarizabilities of the solute and solvent, respectively, M and E are the dipole moment and energy of the transition, and each solute molecule is supposed to be surrounded by z solvent molecules at a mean distance R̄.
B–Cl Distance in Boron Trichloride
Authors: Atoji Masao , Lipscomb William N.
Published: January 2005

An x-ray diffraction study of a single crystal of BCl3 has yielded a B–Cl distance of 1.75±0.02 A.
Crystal and Molecular Structure of Diboron Tetrachloride, B2Cl4
Authors: Atoji Masao , Wheatley Peter J. , Lipscomb William N.
Published: January 2005

B2Cl4 is a planar molecule, Cl2BBCl2, with a B–Cl distance of 1.73±0.02 A and a B–B distance of 1.75±0.05 A. The crystal structure is orthorhombic, with four molecules in a unit cell of dimensions a=11.90 A, b=6.28 A, and c=7.69 A. The space group, D2h15—P bca, requires that the molecules be centrosymmetric.
Theoretical Electronic Spectrum of the Allyl System
Authors: Hunt H. D. , Peterson D. L. , Simpson W. T.
Published: January 2005

Properties of π electrons in allyl anion, cation, and radical are calculated by including interaction between antisymmetrized products of molecular orbital functions. Detailed results in the form of energies and orbital composition of π-electron state functions for the anion as well as transition intensities and energies for all three molecules, including and excluding configurational interaction, are presented. The extent to which a valence bond type wave function resembles an obtained state function is investigated by the computation of overlaps between the two functions. The overlaps and energies of various valence bond type functions are presented and suggest a relatively greater applicability of the valence bond approach in the case of the neutral radical compared to that of the ions.
Small Angle X-Ray Scattering from Solutions of Alkali Metals in Liquid Ammonia
Authors: Schmidt Paul W.
Published: January 2005

The small angle x-ray scattering from solutions of lithium, sodium, and potassium in liquid ammonia has been measured using molybdenum K radiation. Scattering curves were obtained for a series of concentrations of lithium solutions at —75°C, for one concentration at —45°C and —75°C, for potassium, sodium, and lithium solutions of approximately the same molarity, and for lithium and sodium solutions near saturation. The scattering data indicate the presence of scattering centers of dimensions of the order of 15 A, with at most a few types of centers in a given solution, and with the type of center depending on the metal ion. There was no evidence for the simultaneous presence of cavities with diameters of the order of 8 A. Calculations indicate these cavities probably would have been observed if present. These results are in good qualitative agreement with the theory of Becker, Lindquist, and Alder. The ``hole theory'' developed by Lipscomb and by Kaplan and Kittel would require modification to account for the observed scattering.
Rates of Paramagnetic Pulse Reactions by Nuclear Magnetic Resonance
Authors: McConnell Harden M. , Berger Stuart B.
Published: January 2005

Certain fast chemical reactions involving both paramagnetic and diamagnetic molecular species are termed ``paramagnetic pulse'' reactions when each reaction event results in a change in a large hyperfine magnetic field acting at one or more of the molecular nuclei. The frequency distribution of the magnetic pulses is directly related to the reaction rate. The hyperfine intensity and frequency distribution of the paramagnetic pulses affects the nuclear resonance (NMR) line shapes. The Bloch equations are used to establish a quantitative relation between nuclear resonance line shape, nuclear, and electron relaxation times, and the reaction rate. The theory is discussed in terms of the Cu63 NMR work of McConnell and Weaver on electron exchange between Cu++ and Cu+ ions in hydrochloric acid solutions, and the H1 NMR work of Bruce, Norberg, and Weissman on the electron exchange between neutral and positive ion molecules of N,N′-tetramethyl-p-phenylenediamine.
Fractionation of Oxygen Isotopes in the Formation of Oxide Films on Copper
Authors: Brown John B. , Dole Malcolm , Lane G. A.
Published: January 2005

The fractionation of the oxygen isotopes in the formation of oxide films on copper has been measured at 0, 25, and 100°C on granular copper and copper foil by determining the O18/O16 isotope ratio in the residual unreacted oxygen gas after a fraction of the oxygen has reacted. An analysis is given of the mixing problem and of the kinetics of the reaction. Two fractionation factors, one of unity or less than unity for an initial rapid reaction and one greater than unity for the slower and (approximately) steady state reaction are required to explain the data. The fractionation factor for the steady state reaction is calculated to be 1.045, 1.042, and 1.037 at 0, 25, and 100°C, respectively. All of these values are greater than the lower limit of 1.029 given by the rate theory of Bigeleisen in contrast to an earlier conclusion of Bernstein.
Dielectric Properties of Some Liquid Alkyl Halides
Authors: Denney Donald J.
Published: January 2005

Dielectric dispersion and loss in the liquid alkyl halides at low temperatures can be represented by a skewed-arc locus in the complex plane similar to that found for polyhydroxy compounds. Small deviations at very high frequencies, f≫f0, account for 5% or less of the dipolar dispersion. As with the alcohols and glycols the Arrhenius rate plot exhibits strong curvature. These departures from Debye first-order rate theory and the concept of a temperature-independent ``molecular'' activation energy are discussed in relation to structural effects which may be the dominating factor in the dielectric behavior of liquids at low temperatures. The need for a detailed analysis of the dynamics of the relaxation process is stressed.
Study on the State of Nitrogen Adsorbed on Evaporated Barium Film
Authors: Sasaki Yozo
Published: January 2005

In order to clarify the nature of activated adsorption, the adsorption of nitrogen on the freshly evaporated barium film, the replacement of the adsorbed nitrogen by oxygen and the liberation of the nitrogen by means of electron impacts were studied. Immediately after the adsorption a portion of the activated adsorbed nitrogen is bound loosely to the surface of barium, and is gradually converted to a state of firmer binding which is similar to that involved in chemical reaction. The loosely bound nitrogen was ascertained to be in molecular state, and that its electronic configuration is not much perturbed from the ground state of nitrogen X1Σg+. The existence of ionized nitrogen molecule N2+(2Σg+) on the metal surface was suggested.
Variational Calculation of the Nuclear Magnetic Shielding of the Proton
Authors: McGarvey Bruce R.
Published: January 2005

A variational method employing the unperturbed ground-state wave function for the molecule is used to calculate the shielding of the proton in the hydrogen and hydrogen halide molecules. Surprisingly good results are obtained in view of the approximations employed in the calculation. The computations show that the shielding depends on the ionic character of the bond, the bond distance, and the number of electrons on the atom to which the hydrogen is bonded.
Higher Approximations for the Transport Properties of Binary Gas Mixtures. I. General Formulas
Authors: Mason Edward A.
Published: January 2005

Higher approximations for the transport properties of binary gas mixtures are derived: (1) by the method of Chapman and Cowling; (2) by an extension of a method due to Kihara. Particular attention is paid to diffusion and thermal diffusion because of their importance in obtaining information on the forces between unlike molecules. The results can be used to test the convergence and accuracy of the theoretical formulas for various molecular models, and to supply higher correction terms if needed.
Structure of the Methylamine Molecule. I. Microwave Spectrum of CD3ND2
Authors: Lide David R.
Published: January 2005

The spectrum of CD3ND2 has been investigated in the 24 000–36 000 Mc region and about thirty lines have been assigned. The rotational spectrum exhibits a fine structure as a result of internal rotation and inversion. An approximate treatment of these internal motions is formulated and shown to give an excellent fit of the observed spectrum. A treatment of Stark effects and nuclear quadrupole interactions is developed and applied to the CD3ND2 spectrum. The relation to the CH3NH2 spectrum is discussed.

Molecular constants of CD3ND2 determined from the spectral analysis are: torsional barrier height H=684.7±2 cm-1; dipole moment components μa=0.265 D, μc=1.299 D, total μ=1.326±0.015 D; N14 quadrupole coupling constants χaa=2.35 Mc, χbb=2.12 Mc, χcc=—4.47 Mc. Structural parameters calculated from data on CD3ND2 and CH3NH2 are: rCH=1.093 A (assumed), ∠HCH=109°28′ (assumed), rCN=1.474 A, rNH=1.011 A, ∠HNH=105°52′, ∠CNH=112°3′; the nitrogen atom is located 0.091 A from the CH3 symmetry axis.
Heat Capacity of Holmium from 15 to 300°K
Authors: Gerstein B. C. , Griffel Maurice , Jennings L. D. , Miller R. E. , Skochdopole R. E. , Spedding F. H.
Published: January 2005

The heat capacity of holmium has been measured over the range 15 to 300°K. Two maxima have been observed which occur at 19.4 and 131.6°K. The one at the lower temperature exhibits a dependence on the thermal history of the sample and this dependence was investigated. The thermodynamic functions have been tabulated and a correlation made of the contributions to the entropy at room temperature. The value of S0298.16 is 17.97 cal (°K)—1 (g atom)—1 to which the magnetic contribution is R ln (2J+1).
Hydrogen Bonding in Radical Reactions. Some Remarks on CF3 Radicals
Authors: Szwarc M. , Smid J.
Published: January 2005

Studies of the decomposition of acetyl or propionyl peroxide on the one hand and benzoyl peroxide on the other seem to demonstrate that Ph·COO radicals form hydrogen bonds with carboxylic acids, while the nonpolar alkyl radicals do not form such bonds.

The formation of hydrogen bonds facilitates the hydrogen transfer between the carboxylic acid and the polar radicals.
Electronic Structure of Ammonia
Authors: Duncan A. B. F.
Published: January 2005

A self-consistent field calculation of the normal state of the ammonia molecule is made in the molecular orbital approximation. The molecular orbitals are expressed as linear combinations of all valence and inner shell orbitals of the atoms, and all interactions of the ten electrons are included. The total molecular energy, —56.096 au, is 99.2% of the experimental value. The dissociation energy, 0.3308 au, is about 72% of the experimental value. The calculated dipole moment (1.486 Debye) is almost equal to the experimental value (1.46D). The two lowest ionization potentials are calculated as 9.94 and 16.20 ev, and are probably within one ev of the experimental values. An equivalent orbital representation is obtained from the molecular orbitals and directional features of distribution of electron density are discussed. The integrals over atomic orbitals were all evaluated by standard mathematical methods, which is discussed in an appendix.
Ultraviolet Spectra and Electronic Structure of Metallic Complexes. I. Chloroammine Cobalt (III) Complexes
Authors: Nakamoto Kazuo , Fujita Junnosuke , Kobayashi Masahisa , Tsuchida Ryutaro
Published: January 2005

In order to study the nature of the so-called ``first, second, third, and specific bands'' of the metallic complexes, the semiempirical M.O. method has been applied to a series of [Co(NH3)6—nCln](3—n) + (n=0, 1, 2 (cis, trans)) type complexes taking π electrons of the ligands into consideration. The agreement between the calculated and observed energies of transition is satisfactory partly due to the appropriate values of the parameters used. Moreover, the following conclusions have been obtained by the present calculation: (1) The magnitude of the splitting of the first band depends upon the overlap integral, S(3dπ, npπ) and also the ionization potential of the ligand (π). (2) The splitting of the first band in the cis-complex is small compared to that of the trans-complex, since, in the former, the three orbitals, from which electrons are excited to produce the low-energy absorptions, lie at nearly the same energy. (3) Two strong bands in the ultraviolet region are due to the transitions approximately from the ligand level to the metal level, and therefore, correspond to the so-called ``third bands.'' They will show ``blue-shift'' in polar media. (4) The general rule that the trans-complex shows the third bands at longer wavelength than that of the cis-complex can be accounted for more satisfactorily if the Cl–Cl interaction in the cis-complex is considered. (5) The spectra of other halogenoammine complexes are reasonably interpreted in a similar manner.
Fluorescent Lifetimes of Rare Earth Salts and Ruby
Authors: Dieke G. H. , Hall L. A.
Published: January 2005

The mean lives of the resonance levels of the trivalent ions of Sm, Eu, Gd, Tb, and Dy in pure crystalline compounds have been determined by a direct measurement of the decay of the fluorescence. They decrease from a maximum of nearly 0.01 sec for Gd+++ to either side to less than 10—5 sec for Sm+++ and Dy+++. The intensity of the observed fluorescence decreases with the mean life, which except for Gd+++ is controlled by interactions of the rare earth ion with the crystal lattice.
Adiabatic Correlations for the Formation of Ions in Degenerate Electronic States
Authors: Liehr Andrew D.
Published: January 2005

The adiabatic correlation theory of McDowell is modified to include degenerate electronic states. The modified theory is subsequently utilized to determine adiabatic correlations for the ions CH3+ and NH2+.
Magnetic Relaxation Spectroscopy with Ionic Solutions
Authors: Broersma S.
Published: January 2005

When the protons in a liquid are subjected to varying magnetic interactions, and a rapid averaging is prevented, it is possible to distinguish liquid elements, chemically similar, but differing in the amount of relaxation ∫0tdt′/T. The customary ac modulation of the magnetic field produces the required transient conditions. The phenomena of line broadening, line shift, and reversal of magnetization with time help to recognize the phases. The signal of the weak relaxation phase can easily be diminished by inducing eddy currents in the magnet iron.

Additional non-uniformities can be made in water by introducing dia- or para-magnetic ions. An analysis of the processes of relaxation and adsorption shows that these water molecules or protons prevail in the observation for which the time of adsorption is close to the local relaxation time. The transient rate of relaxation of the entire sample is approximately equal to this rate of adsorption, and to the sweep frequency at which the magnetizations of the phases balance.

The life time found for the protons in the inner layer of water surrounding trivalent ions, by studying concentrated diamagnetic solutions, is about 10 msec. For dilute paramagnetic solutions the values range from three hundred to one micro second, decreasing with the distance to the ion, increasing its magnetic moment. The activation energy involved times the power of its dependence upon the distance to the center ion, is 20 kcal/mole. The effective size of the atmosphere changes from one or two layers for dilute to two or three layers for concentrated solutions. Ice crystals with four layers radius and five milliseconds life time show up.
Infrared Studies of Hydrogen Bonding of Water by the Matrix Isolation Technique
Authors: Van Thiel Mathias , Becker Edwin D. , Pimentel George C.
Published: January 2005

The stretching and bending vibrational modes of the hydrogen bonded polymers of water have been studied by the matrix isolation technique using solid nitrogen at 20°K as a matrix. Absorptions are assigned to water monomers (3725, 3627, and 1600 cm—1), to dimers (3691, 3546, and 1620 cm—1) and to higher polymers (3510, 3355, 3318, 3222, and 1633 cm—1). The frequencies suggest that the dimers have cyclic rather than open (or bifurcated) structures. The absorption coefficients of the bending modes decrease slightly in the higher polymers while those of the stretching mode increase by a factor of about twelve. This intensity behavior cannot be explained solely on the basis of enhanced ionic character of the O–H group in the hydrogen bond.
Free Energy Functions for 54 Gaseous Elements
Authors: Kolsky Harwood G. , Gilmer Ruth M. , Gilles Paul W.
Published: January 2005

Tables of the free energy functions for 54 elements, each considered as an ideal monatomic gas, were calculated using a Los Alamos Scientific Laboratory IBM 704 computer for the temperature range 0 to 8000°K.
Nonstoichiometry and Lattice Defects in Uranium Hydride
Authors: Libowitz George G.
Published: January 2005

Expressions were derived for the hydrogen pressure over nonstoichiometric metallic hydrides from statistical mechanical considerations. Two separate relations were obtained depending on whether lattice vacancies or interstitial atoms were taken to be the cause of hydrogen deficiency in hydrides. For the case of one-to-one binary hydrides, the two equations become identical.

By comparing the pressure-temperature-composition data for uranium hydride with the derived equations, it was established that the nonstoichiometry of this compound was due to hydrogen vacancies in the lattice rather than interstitial uranium atoms. The energy necessary to form a hydrogen vacancy in uranium hydride was found to be 68.2 kcal/mole, while a value of 6.5 kcal/mole was determined for the interaction energy between vacancies.
Proton Magnetic Resonance Studies on Natural Rubber. II. Line Shape and T1 Measurements
Authors: Gutowsky H. S. , Saika A. , Takeda M. , Woessner D. E.
Published: January 2005

Proton magnetic resonance absorption measurements have been made on samples of uncured Hevea, balata, and Coral rubber as well as on vulcanized samples with up to 9% combined sulfur. The motions of the chain segments were studied by observing line shapes and spin-lattice relaxation times at temperatures between —190 and 150°C. Several types of data show different molecular mobilities for vulcanized samples with a given combined sulfur but prepared by curing mixes with different fractions of raw sulfur for different times. Line width studies of the uncured Hevea sample as a function of thermal history indicate that the molecular mobility decreases with increasing crystallinity. Chemical shifts were resolved in high resolution studies of solutions of uncured Hevea, balata, and Coral rubber. The T1 measurements, including observations at 20 and 28 Mc/sec on uncured Hevea and balata, exhibit systematic deviations from the BPP theory. The significance of the deviations is discussed.
Decomposition of Nitric Oxide and Nitrogen Dioxide by the Impact of Fission Fragments of Uranium-235
Authors: Harteck P. , Dondes S.
Published: January 2005

A study was made of the decomposition of nitric oxide and nitrogen dioxide using the fission recoil energy of 5 mg of uranium-235 oxide powder. The irradiations were conducted in a 23-cc quartz vessel, at a flux of 3×1012 neutrons | cm2 second, and at a temperature of 70°C in the Brookhaven National Laboratory Reactor. With a dose of 2×109 r, the over-all GNO is 9.5±1.0, using a radiation intensity of 1.0×107 r | min, a filling pressure of 500 mm at 21°C. With a dose of 108 r, the GNO is 13.8±1.4. Since three additional nitric oxide molecules are consumed for each nitric oxide molecule decomposed at 108 r, the GNO value calculated for the primary decomposition (including the dissociation due to ion-recombination) is 3.45±0.35.

The GNO2 value is 1.2 for a dose of 3×109 r and 0.5 for 5×107 r, conducted under a radiation intensity of 1.2×107 r | min and a filling pressure of 550 mm of the 2 NO2⇄N2O4 equilibrium at 21°C. For the principal reactions in the nitric oxide and nitrogen dioxide systems, when irradiated with ionizing radiation, a reaction mechanism is proposed which seems to explain the characteristic features of the system.
Proton Relaxation Times in Paramagnetic Solutions
Authors: Bloembergen N.
Published: January 2005

An exchange interaction is postulated between the electron spin and proton spin in adjacent water-molecules in paramagnetic solutions. In combination with the long electron spin relaxation times for Mn++ and Gd+++, an explanation is given why T1/T2 for protons is much larger than unity in solutions of these particular ions in high magnetic fields, whereas T1 is about equal to T2 in other solutions or in low fields.