bluuebunny/crossref_metadata_2025 huggingface dataset:
Improved Vibrational Potential for Diatomic Molecules
Authors: Beckel Charles LeRoy
Published: January 2005

Previous methods used to obtain approximate vibrational potentials for diatomic molecules have led to potentials which are unsatisfactory at large internuclear separations. This paper presents a method by means of which more satisfactory potentials can be constructed. Poeschl-Teller functions are fitted to data near equilibrium, and to these functions are added perturbations of the form T·tanh2avα(r—r0). The perturbations adjust the approximate potentials at large internuclear separations. This method is applied to several electronic states of H2, D2, and T2. The resulting functions are good approximations to the true potentials even for relatively large internuclear separations. Very near dissociation the approximate potentials deviate from the true potentials in a consistent manner.
Electron Affinities, Methyl Affinities, and Ionization Energies of Condensed Ring Aromatic Hydrocarbons
Authors: Matsen F. A.
Published: January 2005

The electron affinities of condensed ring aromatic molecules are calculated from half-wave-reduction potentials and the absolute potential of the normal calomel electrode. The results correlate with molecular orbital theory and frequency of absorption and extrapolate to the work function of graphite. A parallel correlation is made for the ionization energies. A correlation is also shown to exist between the electron affinity and the methyl affinity defined by Szwarc. Finally the results are discussed in terms of the approximate self-consistent field theory of Pople, from which it is possible to make an a priori estimate of the work function of graphite.
Correlation of Infrared Stretching Frequencies and Hydrogen Bond Distances in Crystals
Authors: Pimentel George C. , Sederholm Charles H.
Published: January 2005

Empirical correlations between X–H≡Y distance R and frequency shift of the X–H stretching motion Δv are presented for O–H≡O, N–H≡O, and N–H≡N hydrogen bonds. A linear correlation is possible provided a distinct straight line is assumed for each hydrogen bond type. The equations of the best straight lines and standard deviations are: O−H···O  Δν(cm−1)=4.43·103(2.84−R) σ(Δν)=199cm−1N−H···O  Δν(cm−1)=0.548·103(3.21−R)σ(Δν)=24cm−1N−H···N  Δν(cm−1)=1.05·103(3.38−R)      ?
Entropies of Hydration of Gaseous Oxy-Anions
Authors: Altshuller A. P.
Published: January 2005

The entropies of 17 oxy-anions have been calculated in the (hypothetical) gas state. The gas entropies for these ions have been combined with their molal entropies in aqueous solution, S̄0, where available, to calculate the entropies of hydration of 14 of these ions. The entropies of hydration of these ions having the formula, XOn—m, can be represented by the empirical equation ΔShyd=5+(29—4.5n)Z2.
Vibrational Spectra of Ethylene Oxide and Ethylene Oxide-d4
Authors: Lord R. C. , Nolin B.
Published: January 2005

The infrared spectra of gaseous ethylene oxide and ethylene oxide-d4 in the range 375—3800 cm—1 and the Raman spectra of the liquids have been determined. With the help of the infrared band contours and the product rule, a complete vibrational assignment has been made for both molecules. The assignments correlate well with those of cyclopropane and cyclopropane-d6.
Non-Newtonian Viscoelastic Properties of Rod-Like Macromolecules in Solution
Authors: Kirkwood John G. , Plock Richard J.
Published: January 2005

The theory of Kirkwood and Auer is extended to include the dependence of the viscoelastic moduli of solutions of rod-like macromolecules on rate of shear. Power series expansions in the rate of shear of the intrinsic viscosity and intrinsic rigidity are constructed. In the stationary case, the intrinsic viscosity is presented as a function of rate of shear with use of coefficients of the pertinent spherical harmonics kindly supplied by H. H. Scheraga.
Electronic and Vibrational States of Azulene
Authors: Sidman Jerome W. , McClure Donald S.
Published: January 2005

The absorption and emission spectra of azulene have been studied in a substitutional solid solution in napthalene at 20°K. The spectra are polarized and are very sharp, and from the polarization properties of the absorption transitions it has been determined that the first excited state at 14 652 cm—1 is Lb, 1B1 [we will designate an electronic state by giving first the Platt symbol (J. R. Platt, J. Chem. Phys. 17, 484 (1949) and then the C2v group symbol, Herzberg, Infrared and Raman Spectra of Polyatomic Molecules (D. Van Nostrand Company, Inc., New York, 1945)] (the transition with the ground state is transversally polarized), whereas the second excited state at 28 050 cm—1 is La, 1A1 (the transition with the ground state is long-axis polarized), in agreement with the theoretical predictions of Platt and Moffitt. Vibrational analyses have been performed for the two absorption transitions, and the second transition appears to be perturbed by vibrational-electronic interaction.

A sensitized emission spectrum has also been found, in which excitation of the napthalene leads to emission from the second excited state of azulene to the ground state. A vibrational analysis of the emission transition yields ground state vibrational frequencies which are in excellent agreement with the vibrations deduced from the infrared absorption spectrum.

Environmental effects are discussed, and an attempt is made to correlate the vibrations in the different electronic states.
Indirect Hyperfine Interactions in the Paramagnetic Resonance Spectra of Aromatic Free Radicals
Authors: McConnell Harden M.
Published: January 2005

It is shown that an electron spin polarization associated with an odd electron in a π-molecular orbital in an aromatic free radical can, through an atomic exchange coupling mechanism, produce an appreciable resultant electron spin polarization in s-atomic orbitals at the aromatic protons. This resultant spin polarization gives rise to hyperfine interactions with aromatic protons which are of the same order of magnitude as those observed in the paramagnetic resonance spectra of aromatic free radicals. An equation is developed which relates (proton-spin)-(electron-spin) hyperfine coupling constants to the π distribution of the odd electron in the aromatic free radicals.
Shock Front Thickness and Bulk Viscosity in Polyatomic Gases
Authors: Andersen W. H. , Hornig D. F.
Published: January 2005

The thickness of shock fronts in carbon dioxide and nitrous oxide gases has been measured by the light reflectivity method. The thickness of these fronts are in agreement with thicknesses predicted theoretically when only shear viscosity and heat conduction effects are considered. They demonstrate that the contribution of any real bulk viscosity is small. The molecular vibrations are not excited in the shock front and hence the large sound absorption in these gases in excess of that calculated using shear viscosity can only come from the vibrational excitation process. Real bulk viscosity in ideal gases is not a manifestation of vibrational excitation but only of the rotational excitation process.
Electronic Spectra of Cyclo-Octatetraene, Tetraphenylene, and s-Dibenzcyclo-Octatetraene
Authors: McEwen K. Lenore , Longuet-Higgins H. C.
Published: January 2005

The electronic transition energies of cyclo-octatetraene, tetraphenylene and s-dibenzcyclo-octatetraene have been calculated by treating each molecule as four separate π-electron subsystems, the excited configurations of which interact under the influence of the Hamiltonian for the complete system.

The calculated transition energies for cyclo-octatetraene and tetraphenylene are in good agreement with experimental data, while the calculations for s-dibenzcyclo-octatetraene suggest that the absorption data for this compound is in error.
Homogeneous Exchange Reaction Between Hydrogen and Deuterium
Authors: Boato G. , Careri G. , Cimino A. , Molinari E. , Volpi G. G.
Published: January 2005

The homogeneous exchange reaction between hydrogen and deuterium has been reinvestigated, to see whether a more satisfactory quantitative test of the transition state method could be obtained in this simple chemical reaction.

The reaction was studied in the temperature range from 916°K to 1010°K, where the heterogeneous contribution from the walls was found to be negligible. Preventing air from diffusing into the reaction vessel trough the walls, exchange rates lower by a factor of 2.0 than those obtained by previous authors were found in the whole temperature interval. The total activation energy was determined as 59.8±0.4 kcal/mole.

The validity of the transition state method was tested by extrapolation of the experimental data to a lower temperature region (283°—373°K) where independent experimental data were available. Comparison of the extrapolated values with the experimental ones leads to a very good agreement.
On the Degradation of Branched Chain Molecules
Authors: Simha Robert
Published: January 2005

A procedure for the derivation of the molecular weight distribution in a degrading branched polymer is developed. In the explicit calculations only sizes up to about twice the distance between branch points are considered. This is adequate to describe the rates of volatilization in the pyrolysis of polyethylenes. Expressions are given for an arbitrary distribution of branch lengths. If the rate of bond scission is uniform, the over-all rate is reduced in comparison with the linear case; the branches, if short, have a protective effect. The differences between C–H linkages on tertiary and secondary C's reverse the situation. However, the reaction pattern remains unchanged. The rates exhibit maxima which are only insignificantly displaced by the presence of (short) branches. Unless the reaction mechanism treated is profoundly altered or the differences between the two types of bonds are much larger than in small molecules, the existence of branches, per se, does not account for the observed differences in the kinetics of pyrolysis of polyethylene and the linear polymethylene.
Virial Coefficients of ``Parallel Square'' and ``Parallel Cube'' Gases
Authors: Zwanzig Robert W.
Published: January 2005

The second, third, fourth, and fifth virial coefficients are evaluated exactly for gases whose molecules interact in two dimensions as rigid elastic squares with their sides parallel or in three dimensions as rigid elastic cubes with their edges parallel. Upper and lower bounds on the virial coefficients of gases composed of rigid circles or rigid spheres are obtained in terms of the virial coefficients for the parallel squares and parallel cubes.
Isotopic Effects and Collisional Deactivation in the Mercury Photosensitized Decomposition of Ethylene
Authors: Callear A. B. , Cvetanović R. J.
Published: January 2005

Mercury photosensitized decomposition of C2H4, C2D4, cis-C2D2H2, and C2H4 with excess xenon added, has been investigated at room temperature. An isotopic effect in the intramolecular decomposition of ethylene has been established, as well as an extensive isotopic isomerization in the course of collisional deactivation of the energy rich molecules. The cis-dideuteroethylene isomerizes not only to the trans- but also to the anti-form. The experimental results are discussed in terms of the intramolecular decomposition and collisional deactivation of the excited molecules formed in the primary process.
Effect of Bromine on the Dark Conductivity of Silver Bromide
Authors: Luckey George W. , West William
Published: January 2005

The dark conductivity of silver bromide in a bromine atmosphere increases with increasing bromine pressure. The conductivity increases are proportional to the square root of the halogen pressure in the range between 10 and 200 mm of mercury, at temperatures between 25°C and 200°C. The increases agree with those calculated from the corrosion data of Wagner and Teltow, and they are probably caused by positive holes. The increases are affected by the purity of the crystals, and the rate of equilibrium attainment depends on the structure and purity of the samples. In particular, the presence of small amounts of silver in the crystals prevents attainment of equilibrium until all the silver is removed. The rate of silver removal depends on the positive-hole conductivity. The results are in good agreement with the corrosion mechanism suggested by Wagner.
Infrared Absorption Intensities and Bond Moments in BF3 and Related Molecules
Authors: McKean D. C.
Published: January 2005

The infrared absorption intensities of the fundamental vibration bands of BF3 have been measured and vibrational bond moments μ and their derivatives ∂μ/∂r determined. In the A2″ class, μBF=1.7 D; in the E′ class μBF=0.9 or 2.6 D, ∂μ/∂r = —6.1 or +4.0 D/A.

Inspection of the form of the bending modes suggests that deviations from the bond moment approximation occur such that μ(A2″) <μ(static) <μ(E′). The solution μ(E′) = 2.6 D is therefore preferred.

Re-examination of the data of Schatz and Hornig on CF4, SiF4, and SF6 in the light of the present results shows that the vibrational bond moments in these molecules are: μCF∼2.4, μSiF∼3.3, μSF∼2.7 D. These moments are roughly equal to Δr0, where r0 is the bond length and Δ the electronegativity difference between the atoms in the bond.

The available data on μ and ∂μ/∂r for the C–F bond in various molecules are compared and briefly discussed.
Infrared Spectrum and Molecular Constants of Carbon Dioxide. Part II. Levels 10°0 and 02°0, 10°1 and 02°1 Coupled by Fermi Resonance
Authors: Rossmann Kurt , France W. L. , Rao K. Narahari , Nielsen H. H.
Published: January 2005

Absorption bands of carbon dioxide involving the Fermi diads 10°0, 02°0 and 10°1, 02°1 have been investigated and molecular constants obtained. The variation in the centrifugal stretching constants which has been observed in the component levels is such that the average centrifugal stretching constant of the diad is very nearly the same as that of the vibrationless ground state of CO2.
Self-Diffusion in Liquid Gallium
Authors: Petit Jean , Nachtrieb Norman H.
Published: January 2005

Self-diffusion in liquid gallium metal at atmospheric pressure is described by the equation: D = 1.07 × 10—4 exp[—1122/RT] cm2 sec—1. At 30°C the effect of pressure on the rate of self-diffusion is given by: log10D = —4.7793—9.529×10—6P (kg cm—2). The activation volume at this temperature is 0.55 cm3 g atom—1. Although the Stokes-Einstein radius agrees quite well with the ionic radius of Ga+3, the temperature coefficients of viscosity and diffusivity differ somewhat.
Vacuum Ultraviolet Photochemistry. Part III. Acetylene at 1849 A
Authors: Zelikoff Murray , Aschenbrand Leonard M.
Published: January 2005

The products of acetylene photolysis at 1849 A were found to be a polymer resembling cuprene, hydrogen, ethylene, diacetylene, vinylacetylene, and benzene. The relationships of the quantum yields of these products to pressure of acetylene suggest that both free radicals and excited acetylene molecules are involved in the photolytic mechanism. This suggestion is strongly supported by the nature of the absorption spectrum, since in this wavelength region, the absorption is partly discrete and partly continuous.
Note on the Calculation of Energy Levels in Molecules with Internal Torsion
Authors: Swalen Jerome D.
Published: January 2005

Approximate formulas are given for calculating the matrix elements of the angular momentum operator of a symmetric top undergoing hindered rotation on an asymmetric molecule. These can then be used to calculate the effect of torsion on over-all rotation in microwave rotational spectra using the method of Wilson, Lin, and Lide.
Effects of a Concentration Dependence of the Sedimentation Coefficient in Velocity Ultracentrifugation
Authors: Fujita Hiroshi
Published: January 2005

The Lamm differential equation for the sedimentation process in the ultracentrifuge is solved in closed form for the case in which the sedimentation coefficient, s, decreases linearly with the concentration, C, by employing the assumption which was adopted originally by Faxén who considered a similar problem with s independent of C.

It is shown that, with increasing concentration dependence of s, the concentration gradient curve is markedly sharpened, and the whole curve is also noticeably shifted towards the solvent side, but symmetry of the curve is practically maintained except at the edges.

A simple and approximate equation which predicts the position of the maximum of a given boundary curve as a function of time for a given set of the parameters is derived. It is shown that this equation is useful for evaluating the sedimentation coefficient at a given concentration. An equation which also predicts the maximum height of the boundary curve as functions of time and related parameters with a satisfactory degree of approximation is obtained. Using this equation, reliable values of the diffusion coefficient may be obtained from sedimentation experiments when s depends linearly on C.
Photodecomposition of Formaldehyde; Stability of the HCO Radical
Authors: Klein Ralph , Schoen Louis J.
Published: January 2005

Observations on the photodecomposition of mixtures of normal and deuterated formaldehydes give reliable data for calculating the stability of the HCO radical. The relative occurrence of the intramolecular split and the H-atom dissociation reaction in the primary photochemical act is determined by the deviation of the apparent equilibrium constant for the hydrogen isotope product species from the actual constant. It is shown that a wavelength of 3650 A is effective for breaking the first CH bond in formaldehyde, and this leads to 27 kcal as a lower value for the heat of dissociation of HCO to H and CO. The intramolecular split reaction occurs not only at 3650 A, but also at 3130 A, and is an important if not the major primary photochemical process.
Calculation of the Detonation Properties of Solid Explosives with the Kistiakowsky-Wilson Equation of State
Authors: Cowan R. D. , Fickett W.
Published: January 2005

The Kistiakowsky-Wilson equation of state, pVg = RT(1+xeβx), where x = k/Vg(T+θ)α, for the gaseous detonation products of solid explosives has been re-examined in the light of new experimental data on detonation pressure and on the variation of detonation velocity D with loading density ρ0 for several RDX/TNT mixtures. The value β = 0.30 used in the past is too high to match the observed slopes of the D—ρ0 curves. The old value α = 0.25 is too small to match the experimental Chapman-Jouguet pressure of most of these explosives, but too large to match the pressure of pure TNT. A suitable compromise for the explosives considered is α = 0.5, β = 0.09, θ = 400°K.
Detection of Free Radical Absorption Spectra by Chemical Modulation
Authors: Bair Edward J. , Lund John T. , Cross Paul C.
Published: January 2005

A method is described for studying free radicals by absorption spectroscopy. The principal feature is the maintenance of an oscillating free radical concentration, which takes advantage of the high momentary concentrations that follow pulses of energy, and yet may be integrated to provide a continuous free radical absorption signal. The problems of detecting absorption in these transient systems are discussed using NH2 generated by an electrical discharge through ammonia as an example.
Normal Vibration Frequencies of CD3F. Structure of CH3F and CD3F from Infrared and Microwave Spectra
Authors: Andersen F. Allan , Bak Bo/rge , Brodersen Svend
Published: January 2005

The infrared absorption spectrum of CD3F has been studied. Simultaneously, the infrared spectrum of CH3F was reinvestigated. Fundamental vibration frequencies for CD3F were found together with Coriolis coupling factors for the three degenerate vibrations in CH3F and CD3F. The fine-structure analysis gave reliable values for the large rotational constants of CD3F and CH3F. The structure of the methyl fluoride molecule is discussed.
Matrices D—1 and G—1 in the Theory of Molecular Vibrations
Authors: Polo S. R.
Published: January 2005

A vector method to determine the elements of the matrices D—1 and G—1, used in the vibrational analysis of polyatomic molecules is presented. Examples are given to illustrate the method.
Rotation-Vibration Spectra of Deuterated Water Vapor
Authors: Benedict W. S. , Gailar N. , Plyler Earle K.
Published: January 2005

Spectra of heavy water have been obtained under high resolution between 1.25—4.1μ (2400—8000 cm—1). Approximately 4500 lines have been measured, and the majority of them analyzed into ten bands of D2O and nine bands of HDO. The analysis is described in some detail, spectra of all bands are shown and a partial table of lines and a complete table of energy levels are presented. The vibration-rotation constants are derived and compared with those of H2O.
Ionization and Dissociation of Nitrogen Trifluoride by Electron Impact
Authors: Reese Robert M. , Dibeler Vernon H.
Published: January 2005

A mass spectrometric study of nitrogen trifluoride provides data on the relative abundances and appearance potentials of the NF3+, NF2+, NF+, N+, F+, F—, and F2— ions. The heat of formation of the NF3 molecule is used to determine the probable processes of formation of the N+ and F+ ions and to calculate the ionization potentials of the NF and NF2 radicals.
Kinetics of Capillary Shear Degradation in Concentrated Polymer Solutions
Authors: Bestul A. B.
Published: January 2005

Intrinsic viscosities at successive stages of the process have been used to obtain the rates of mechanical shear degradation produced in concentrated solutions of polyisobutenes in cetane by capillary flow at several high rates of shear. Rates of degradation were obtained for several shearing temperatures, polymer concentrations, and initial molecular weights. Rate constants K are calculated on the basis that the process is a first-order reaction with respect to the polymer molecular bonds. K is treated as an inverse exponential function of the reciprocal of the rate of shear energy application J. Plots of logK versus 1/J for all shearing temperatures and polymer concentrations reported can be represented by a single straight line. The behavior of these plots with changing temperature supports the idea that the degradation process is a predominately mechanically, rather than thermally, activated reaction. Their insensitivity to polymer concentration supports the assumption that the degradation reaction is of first order. The rate of variation of K with J decreases with increasing initial molecular weight. This fact indicates that as the initial molecular weight increases the polymer molecular entanglements become increasingly effective in localizing mechanically applied shearing energy into the polymer molecular bonds as temporarily stored potential energy, as would be expected.
Evaluation of Collision Integrals Occurring in Higher Approximations to Diffusion Coefficients
Authors: Saxena S. C.
Published: January 2005

Several Chapman and Cowling Collision integrals for the Lennard-Jones 12:6 model have been evaluated over an extensive range of temperatures and utilized to calculate the second approximation to the thermal diffusion ratio for the case of argon-helium gas pair.
Spectra and Quantum States of the Europic Ion in Crystals. I. Absorption Spectrum of Anhydrous Europic Chloride
Authors: Sayre Edward V. , Freed Simon
Published: January 2005

Anhydrous europic chloride and single crystals of europic chloride dissolved in a preponderant proportion of isomorphous lanthanum chloride could be prepared so that they were sufficiently free of europous chloride to permit the study of their absorption spectra down to 3900 A. The crystal structure of these preparations was proved to be UCl3 type through the use of a trace of praseodymium chloride as an internal indicator. Because this structure is so well substantiated and is free of the ambiguity inherent in the structure of hydrated salts, the spectrum of these crystals provides a secure basis for resolving the conflicting interpretations of earlier spectrum analyses. The polarized spectra indicate that lines in the yellow, green, and blue visible regions arise from upper states with J values of 0, 1, and 2 as proposed by Joos and Hellwege rather than J's of 0, 2, and 3 as proposed by Gobrecht.
Vibrational Spectra of Fluorinated Aromatics. XII. m-Fluorochlorobenzene
Authors: Harris F. W. , Narasimham N. A. , Nielsen J. Rud
Published: January 2005

The infrared absorption spectra of gaseous and liquid m-fluorochlorobenzene have been obtained in the region 2—38μ with NaCl and CsBr prisms. The Raman spectrum of the liquid has been photographed with a 3-prism glass spectrograph of linear dispersion 15 A/mm at 4358 A. A complete assignment of the fundamental vibrational frequencies is given, and the spectra are interpreted in detail.
Magnetic Properties of a Gadolinium Orthoferrite, GdFeO3, Crystal
Authors: Gilleo M. A.
Published: January 2005

Gadolinium orthoferrite, GdFeO3, in single-crystal form exhibits magnetization between temperatures of 78 and 295°K which consists of a field independent part σ0 and a field dependent part χH for fields above 6000 oersteds. The parasitic ferromagnetization σ0 amounts to about 1% of the σ(Fe) available and may be attributed to imperfectly compensated antiferromagnetism of the Fe3+ ion sublattice. The susceptibility χ appears to be made up of a paramagnetic contribution from the Gd3+ ion sublattice and a contribution from the antiferromagnetic Fe3+ ion sublattice influenced by interaction between the two sublattices. The anisotropy of σ0 and χ changes with temperature. The maximum σ0 and minimum χ do not coincide as they would if both took the direction of the antiferromagnetic axis of the Fe3+ ion sublattice.
Determination of Accurate Water Vapor Calibration Points for Prism Spectrometers in the Region 1330—2100 cm—1
Authors: Jones Llewellyn H.
Published: January 2005

The spectrum of water vapor in the region 1330—2100 cm—1 has been observed with a CaF2 prism in a Perkin-Elmer double-pass spectrometer. A Friedel-McKinney equation [D. S. McKinney and R. A. Friedel, J. Opt. Soc. Am. 38, 222 (1948)] which was successful in determining frequencies for TBr and TCl was used to determine the water vapor frequencies. Many of these water vapor frequencies are presented as the best available calibration points in the 1300—2100 cm—1 region, accurate to ±0.3 cm—1.
Electronic Interaction in the Free-Electron Network Model for Conjugated Systems. I. Theory
Authors: Ham Norman S. , Ruedenberg Klaus
Published: January 2005

The free-electron network model for conjugated systems is extended to include electronic interaction. The free-electron wave functions are considered as molecular orbitals arising from an average one-electron potential, and a configuration interaction treatment with these MO's is developed. The integrals occurring in this procedure, in particular the electron interaction integrals, are analyzed and a convenient method for their computation in the FE model is suggested. The integral evaluation requires certain semiempirical parameters which are determined from the benzene spectrum.
Dielectric Properties of Nitrobenzene in the Region of Anomalous Dispersion
Authors: Clark George L.
Published: January 2005

The complex dielectric constant of highly purified nitrobenzene in the region of anomalous dispersion has been determined by measuring the input impedance of a variable length of a coaxial transmission line filled with the liquid. The measurements were carried out at frequencies from 0.65 kmcps to 3.00 kmcps in the temperature range between 15°C and 50°C. Good agreement was observed with an expression suggested by Cole and Cole, and the critical frequencies in this temperature region were found to be between 3 and 6 kmcps.
Electronic Interaction in the Free-Electron Network Model for Conjugated Systems. II. Spectra of Aromatic Hydrocarbons
Authors: Ham Norman S. , Ruedenberg Klaus
Published: January 2005

A theoretical calculation is presented for the main uv transitions of the polyacenes, azulene, phenanthrene, the isomers of naphthacene and the peri-condensed systems pyrene and coronene. A configuration interaction treatment, based on antisymmetrized products of free-electron molecular orbitals, is carried out, using the methods developed for this purpose in the previous paper. Transition energies, intensities and polarizations compare well with experiment. Particular emphasis is placed upon illuminating the various factors influencing the spectra in the series of molecules considered.
Correlation of Bond Length with Stretching Frequency for Carbon-Oxygen and Carbon-Nitrogen Systems
Authors: Layton E. Miller , Kross Robert D. , Fassel Velmer A.
Published: January 2005

Graphical correlations of stretching frequencies with bond lengths for C–O and C–N systems in various compounds are presented. The average deviations of the points from the respective curves are 0.023 and 0.020 A.
Spectra of Some Amino Acids, Peptides, Nucleic Acids, and Protein in the Vacuum Ultraviolet
Authors: Preiss John W. , Setlow Richard
Published: January 2005

The absorption spectra of several amino acids, peptides, nucleic acids, and a protein have been obtained down to 1450 A. The samples were in the form of thin films supported on calcium fluoride. All compounds studied had characteristic absorption spectra below 2000 A. In some cases, e.g., tryptophan, the absorption spectrum of the solid film showed pronounced difference from the spectrum of the molecules in solution. At 1900 A, the absorption coefficient of the protein chymotrypsin is the sum of the molecular extinction coefficients of its components. The instrument used was a vacuum grating-monochromator with hydrogen discharge light source.
Curved Fluid Interfaces. I. The Generalized Gibbs-Kelvin Equation
Authors: Buff Frank P.
Published: January 2005

The properties of curved fluid interfaces in the presence of external fields are examined from the molecular point of view and are shown to imply a generalized Gibbs-Kelvin equation. These results are then related to Gibbs' phenomenological treatment and thus provide expressions for the relevant thermodynamic parameters in terms of the detailed properties of the transition zone. The formulation leads to an asymptotic estimate of the free energy and to corrections for the Laplace equation determining the shapes of interfaces.
Determination of Diffusivities in Liquid Metals by Means of Temperature-Gradient Zone Melting
Authors: Wernick J. H.
Published: January 2005

Diffusivities of liquid alloys of Ge–Al, Ge–Au, and Si–Al have been measured by a new technique. Called temperature-gradient zone melting, the technique involves passing extremely thin molten zones through a solid crystal by means of a temperature gradient. Preliminary values of the diffusivities fall in the 10—5 cm2/sec range at temperatures of 530°C to 700°C.
Proton Relaxation in Solutions of Chromium (III) Complexes
Authors: Morgan L. O. , Nolle A. W. , Hull R. L. , Murphy J.
Published: January 2005

Spin-lattice relaxation times were observed for protons in a number of aqueous solutions of symmetrical chromium (III) complexes. The observed times were in the order to be expected if it is assumed that those ions displaying the greatest tendency to interact with solvent water also exhibit the greatest relaxation effect. Thus, relaxation times for protons in solutions of the ions Cr(H2O)6+3, CrF6—3, Cr(NH3)6+3, Cr(C2O4)—3, Cr(en)3—3, and Cr(CN)3—3 were observed to increase in the order given.
Ultrasonic Absorption Theory of Gierer and Wirtz
Authors: Beyer Robert T.
Published: January 2005

The absorption theory of Gierer and Wirtz is applied to a calculation of the temperature coefficient of the ultrasonic absorption coefficient for a number of liquids, and the results are compared with known experimental values. Where meaningful values are obtained in the theory, the temperature coefficient is always negative, in contrast to the sometimes positive coefficients that have been determined experimentally. It is concluded that the theory is not generally applicable.
Dielectric Absorption in Lithium Fluoride
Authors: Dryden J. S. , Rao D.A.A.S. Narayana
Published: January 2005

The dielectric loss in single crystals of lithium fluoride has been examined between temperatures of 0°C and 130°C. At the lower temperatures the dielectric loss, as a function of frequency, passes through a definite maximum and is quite distinct from the background loss due to dc conductivity. From the experimental results, the frequency factor (7×1012 sec—1) and energy barrier (0.65 ev) are derived. After darkening with x-rays the absorption disappears and reappears again after bleaching.
Normal Coordinate Treatment for the Out-of-Plane Vibrations of Ethylene-Type Molecules
Authors: Dowling Jerome M.
Published: January 2005

The s vectors for torsional and out-of-plane bending modes of vibration for ethylene-type molecules are given. Then F- and G-matrix elements are given for all ethylene-type molecules with the exception of C2XYZW isomers. Finally, numerical calculations are carried out for C2H4, asymmetric C2H2F2, asymmetric C2H2Br2, the cis- and trans-isomers of C2H2Cl2 and all of their deuterated analogs. The 57 out-of-plane fundamentals were calculated for the above 19 molecules. Of these 57 fundamentals 50 have been reported in the literature and are reproduced in this paper with an average deviation of 2.2 K or to 0.362% error.
Infrared Spectra of Hydrogen Cyanide and Deuterium Cyanide
Authors: Allen Harry C. , Tidwell Eugene D. , Plyler Earle K.
Published: January 2005

The infrared spectra of HCN and DCN have been investigated in the region 1900 to 8000 cm-1. Twenty-two bands of HCN and eighteen bands of DCN were measured. The newly measured bands together with previously known bands enable a complete determination of the vibrational anharmonic constants for the two molecules. A third-order resonance between levels of the type (v1,v2l,v3) and (v1+3, v2l, v3 — 2) is shown to be present in the HCN vibrational energy-level system.
Influence of Molecular Structure on Paramagnetic Resonance Line Widths
Authors: Walter Robert I. , Codrington R. S. , D'Adamo Amedeo F. , Torrey H. C.
Published: January 2005

Paramagnetic resonance absorption has been observed in a series of free radical triarylaminium salts and in a series of substituted 1-picryl-2,2-diarylhydrazyls. Within each series, the members differ from each other only in the substituents placed in certain aromatic ring positions in the molecules. Line-width measurements in fields of 3080 and 2 oersteds are reported for powder samples of these radicals, together with ``g'' values measured in the larger field. A correlation has been established between the line widths of the paramagnetic resonance absorption lines of the radicals and the Hammett sigma values of their substituent groups. In general, the line widths for both series of radicals decreased with increasingly negative values of the Hammett sigma constants of the substituents. Few compounds containing substituents with positive sigma constants have been observed. Relationships between sigma and line widths for this range of sigma values have been proposed on the basis of the expected electronic effects of such substituents, and are consistent with the available data except for halogen-substituted compounds. These results are interpreted in terms of the degree of delocalization of the unpaired electrons in the various free radicals studied. The effect of delocalization upon the exchange interaction of the unpaired electrons is also discussed in the light of the theories of exchange narrowing of paramagnetic resonance absorption lines.
Electronic States of Molecules. I. Electronic Structure of BH
Authors: Sahni Roop C.
Published: January 2005

The calculation of the wave function of the ground state (1 Σ+) of the BH molecule, by the self-consistent field (SCF) molecular orbital (MO) method, is reported together with its ionization potentials, dipole moment, total energy, and the binding energy. For these calculations, the interactions of all the electrons have been included explicitly, and all integrals have been computed exactly at the internuclear equilibrium distance, 1.2325 A, of BH. The electron distribution analysis is carried out to get intimate insight into the distribution of charges around and between the nuclei, and to determine the bonding and antibonding nature of MO's. This analysis supports the previous results of the SCF MO treatment of CO, where the most easily ionized electrons are in an MO which has a large gross atomic population, and the most bonding power resides in the lowest energy outer-shell MO. The comparison of the results of the present calculation with those of the previous calculations shows that the SCF MO treatment gives more accurate values of wave function and energy levels for a polar molecule than those for a homopolar molecule.
Proton Jumps and the Electrical Behavior of Ice and Ice-NH4F Solutions
Authors: Zaromb Sol
Published: January 2005

Previous suggestions that dielectric relaxation in ice may occur by means of proton shifts have been refuted by Bjerrum. Yet, the role of ions in this relaxation process cannot be ignored in view of the more recent studies on ice-NH4F solutions, which indicate that solute ions can accelerate the rotation of ice molecules at a distance of 30 A or more from any ion.

Simple electrostatic calculations show that proton jumps in ice would entail the formation of ``Bjerrum fault sites.'' In the case of pure ice, this might explain why: (a) the proton jump conductivity is much lower than in water at 0°C; and (b) the concentration of fault sites seems to be rather high, according to Bjerrum. Estimates of the frequencies of proton jumps and of activation energies show no disagreement of the proposed explanations with known facts.

In the case of ice-NH4F solutions, proton jumps occurring between second-neighbor ion pairs, F—–H2O–NH4+, may also induce fault sites at the neighboring molecules. This ion-pair mechanism would agree with the low activation energy for these rates and with the peculiar concentration dependence of the frequency factor.

Finally, the thickness of the ion atmosphere should, at equilibrium, be less in ice-NH4F solutions than in aqueous solutions of the same concentration. This, together with the above, might account for the changes with time in the dielectric relaxation rates of concentrated ice-NH4F solutions observed immediately after freezing.
Ionization on Platinum and Tungsten Surfaces. II. The Potassium Halides
Authors: Datz Sheldon , Taylor Ellison H.
Published: January 2005

The ionization of the potassium halides on tungsten follows the Saha-Langmuir equation and indicates the formation of stable partial films of halide. On platinum, however, reflection occurs amounting to more than 99% for KCl, KBr, and KI, and about 75% for KF.
Refined Theory of Ion Pairing. II. Irreversible Aspects
Authors: Reiss Howard
Published: January 2005

This paper applies the nonequilibrium distribution function for ion pairs, derived in paper I of the series, to the case of ionic mobility in an external electric field. The results are in good agreement with the simple theory of Fuoss and demonstrate the virtue of the latter.
Raman Spectrum of UF6
Authors: Claassen Howard H. , Weinstock Bernard , Malm John G.
Published: January 2005

Two of the 3 Raman-active fundamentals of UF6 have been observed at 666.6±0.3 (ν1) and 535±5 cm—1 (ν2) for a gaseous sample. The new value for ν2 is in good agreement with the value 532 cm—1 obtained earlier by Gaunt from infrared combinations. The sample of UF6 was contained in a Pyrex Raman tube and was irradiated for many hours with 4358 A light with no visible deterioration. Gaunt's thermodynamic functions remain valid.
Mass Spectrometric Study of Gaseous Species in the B–B2O3 System
Authors: Inghram Mark G. , Porter Richard F. , Chupka William A.
Published: January 2005

A combination of Knudsen effusion and mass spectrometric techniques have been employed in studying the species existing in the vapor in thermodynamic equilibrium with a condensed mixture of boron and boric oxide in the temperature range 1300°K to 1500°K. Positive ions were produced by electron bombardment of vapor effusing from the Knudsen cell and were analyzed mass spectrometrically. Ion currents of B+, BO+, B2O2+, and B2O3+ were observed. The mixture, B+B2O3, was shown to vaporize mainly as the gaseous molecule, B2O2. The heat of vaporization of B2O2(g) from the condensed phase is ΔH14000=94±8 kcal/mole. The ΔH00 for the reaction ⅔B(s)+⅔B2O3(g)→B2O2(g) is found to be 35.7±3.5 kcal. The BO+ and B+ ions observed were found to be formed mainly in processes of dissociative ionization. The concentration of BO(g) in the vapor is at least an order of magnitude lower than that of B2O2(g) showing the dimerization energy is greater than 99.6 kcal. Results obtained with pure B2O3 liquid in the Knudsen cell agree with earlier published work.
Gaseous Detonations. VIII. Two-Stage Detonations in Acetylene-Oxygen Mixtures
Authors: Kistiakowsky G. B. , Mangelsdorf Paul C.
Published: January 2005

Detonation waves in acetylene-oxygen mixtures containing slightly more than 70% acetylene were studied using a slit and a moving film camera combination. It was observed that an initially diffuse luminous region part way down the rarefaction wave gradually sharpens into a strongly luminous shock front which then overtakes the primary wave front. Thereafter, a single wave moves forward with a velocity intermediate between those of the two initial waves. The region behind the rear shock front shows strong luminous particle tracks, whereas the region between is free of them. These observations are interpreted as evidence that acetylene left over after the oxidation reaction decomposes into carbon and hydrogen only after an induction period which is a sensitive function of the temperature and concentration of acetylene. The hydrodynamic aspects of the observations are discussed and are found to be consistent with the above explanation.
Calorimetric Determination of Heats of Formation of Titanium Chlorides
Authors: Krieve Walter F. , Vango Stephen P. , Mason David M.
Published: January 2005

The heats of formation of TiCl4(l), TiCl3(s), and TiCl2(s) were determined by chlorinating Ti, TiCl3(s), and TiCl2(s), respectively, in a nickel-bomb calorimeter to give TiCl4(l). The directly measured heat of chlorination at 25° of Ti is —190.0±0.4, of TiCl3(s) is 20.9±0.1, and of TiCl2(s) is 69.9±0.8 kcal/mole—1. Relative to a value for the heat of formation of TiCl4(l) of —190.0±0.4, the corresponding values for the heats of formation of TiCl3(s) and TiCl2(s) are —169.1±0.4 and —120.1±0.8 kcal/mole—1, respectively.
Measurement of Equilibrium of the Reaction: TiCl3(s)+HCl(g) ⇋TiCl4(g)+1/2H2(g)
Authors: Krieve Walter F. , Mason David M.
Published: January 2005

Equilibrium in the TiCl3(s)–HCl(g) system was studied in the temperature range 350 to 475°C by measuring the total pressure in an isochoric vessel. The equilibrium data for the above reaction in this temperature range is given by log10K (atmos) = (—2.27×103/T)+1.82. From these data, the enthalpy and entropy of reaction at the average temperature of about 690°K are 10.4±0.4 kcal and 17.5±0.5 cal/deg, respectively. From an estimated value for the ΔCp of reaction, the enthalpy and entropy of reaction at 25°C are estimated to be 12.7±1.0 kcal and 22.5±2.0 cal/deg, respectively. The difference between the enthalpies of formation of TiCl3(s) and TiCl4(l) is 19.0±1.0 kcal/mole—1 at 25°C. The equilibrium is shifted toward TiCl4(g) and H2(g) with increase in temperature, and 25°C the reduction of TiCl4(g) by H2(g) to give TiCl3(s) is nearly complete, although the rate of the reaction is very low.
Disproportionation and Vapor Pressure of TiCl2
Authors: Farber Milton , Darnell A. J.
Published: January 2005

The disproportionation and sublimation of TiCl2(s) have been investigated by means of a molybdenum effusion cell in a temperature range of 800 to 900°K. Heats and entropies of reaction at the average temperature of 850°K were obtained for three reactions: (1) 2TiCl2(s)=TiCl4(g)+Ti;ΔH=49.5±1 kcal,ΔS=32.2±1 cal/°C.(2) 3TiCl2(s)=2TiCl3(g)+Ti;ΔH=87.2±1 kcal,ΔS=62.1±1 cal/°C.(3) TiCl2(s)=TiCl2(g);ΔH=46.8±1 kcal/mole,ΔS=30.7±cal/°C/mole.X-ray diffraction patterns of mixtures of TiCl2 and TiCl3 gave no evidence of any appreciable solid solution.
Infrared Spectra of High Polymers. I. Experimental Methods and General Theory
Authors: Liang C. Y. , Krimm S. , Sutherland G. B. B. M.
Published: January 2005

The problems involved in obtaining and interpreting the infrared spectra of high polymers are discussed. Experimental methods are described for recording the infrared spectrum, with particular emphasis on the techniques used in the region between 30 and 140 μ. The method for obtaining selection rules for high polymer spectra is described and the use of selection rules and other techniques for assigning fundamental frequencies is evaluated. The calculation of the skeletal frequencies of a polymer molecule is discussed in detail.
X-Ray Scattering by Liquid-Metal Alloys (a Kinetic Approach)
Authors: Ling Rufus C.
Published: January 2005

The Born-Green theory of liquids is extended to the case of liquid mixtures, and a formula for the x-ray scattering by such liquids is developed. The formula is used to calculate the x-ray scattering by a liquid sodium-potassium alloy, and fair agreement with the experimental scattering is found.
Energy of Interaction between a Hydrogen Atom and a Helium Atom
Authors: Mason E. A. , Ross J. , Schatz P. N.
Published: January 2005

The potential energy of interaction between a hydrogen atom and a helium atom has been calculated as a function of separation distance by standard quantum mechanical variation procedures. The approximate molecular wave functions used contained both homopolar and ionic contributions, and were constructed from 1s hydrogen-like atomic wave functions. All integrals involved have been evaluated accurately. The results are in agreement with a potential determined from measurements of the scattering of high velocity hydrogen atoms in helium gas. For separation distances greater than 1 A, the results have been combined with an estimate of the potential of the London dispersion forces, and the combination has been represented by an exp-six potential useful in the calculation of properties of gases.
Growth Mechanism of Near-Perfect Crystals
Authors: Sears G. W. , Coleman R. V.
Published: January 2005

Direct evidence is presented to show that whisker growth by vapor deposition occurs at the tip rather than the base. Platelets are shown to grow at constant thickness by the action of a set of crossed-screw dislocations, and whiskers are shown to bear no screw dislocations normal to their axis.
Growth of Mercury Platelets from the Vapor
Authors: Sears Gerald W.
Published: January 2005

A mechanism for the vapor deposition of mercury platelets is presented. The growth behavior is accounted for on the basis of a single screw dislocation in a [110] crystallographic direction. The growth of whiskers versus platelets is determined by preferential nucleation of (100) or (110) planes on the active sites.
Electron Attachment in Sulfur Hexafluoride Using Monoenergetic Electrons
Authors: Hickam W. M. , Fox R. E.
Published: January 2005

Electron attachment leading to the formation of SF6— and SF5— in sulfur hexafluoride has been investigated using nearly-monoenergetic electrons of established energies of less than 2 ev. The dissociative attachment process leading to the formation of SF5— maximizes at less than 0.1 ev and then decreases to zero at approximately 1.5 ev. In the case of resonance capture leading to the formation of SF6—, the capture process occurs at less than 0.1 ev and only over an energy range estimated to be not larger than 0.05 ev. This leads to an estimated cross section for this resonance capture process of 10—15 cm2. A discussion is given of the method used in the establishment of the electron energy scale at such low energies and the use of the resonance capture process for measuring electron energy distributions.