bluuebunny/crossref_metadata_2025 huggingface dataset:
Infrared Spectra and Molecular Structures of SiH3F, SiH3Cl, and SiH3Br
Authors: Newman Carolyn , O'Loane J. Kenneth , Polo S. R. , Wilson M. Kent
Published: January 2005

The structure of the e-type fundamentals of SiH3F, SiH3Cl, and SiH3Br has been resolved and analyzed. The values of the small amount of inertia thus obtained has been combined with microwave measurements to yield the dimensions of the SiH3 group in these molecules. It is shown that the differences in the structure of the SiH3 group are probably within experimental error. Several revisions have been made in the vibrational assignments for SiH3F and SiH3Cl.
Model for Metal Ammonia Solutions
Authors: Becker E. , Lindquist R. H. , Alder B. J.
Published: January 2005

A model is proposed for dilute metal ammonia solutions in which the neutral species is a metal ion solvated by ammonia molecules, with the valence electron from the metal ion localized on the protons of these ammonia molecules. This species can dissociate in a manner similar to an ion pair, and the equilibrium constant for this dissociation as estimated agrees with the one derived from electrical conductivity data. Also, two neutral species can associate to form a dimer species, and the calculated energy of formation of this dimer is in satisfactory agreement with the binding energy derived from magnetic susceptibility data. This model is consistent with the large volume increase on mixing and with some aspects of the absorption spectrum.
Microwave Spectrum of Chloroform
Authors: Wolfe Peter N.
Published: January 2005

A theoretical and experimental examination of the J=2→3 transition in CHCl335 permits the evaluation of the quadrupole coupling constant of the molecule as eQVzz=28.70±.08 Mc, and provides an improved value of the rotational constant, B=3302.41±.03 Mc. Two centrifugal distortion coefficients are also obtained: DJ=4.12±.43 kc and DJK=55±7 kc. The J=2→3 transitions in CHCl235Cl37 yield the following, revised structural parameters for chloroform: C–H=1.073 A, C–Cl=1.762 A, and Cl–C–Cl=110°55′. With the assumption of axial charge symmetry about the C–Cl bond direction, a, the revised bond angle gives eQVaa=-80.39±.22 Mc for the quadrupole coupling constant in CHCl335.
Coupled Anharmonic Vibrations as a Cause of Broadening of Spectral Bands: Hydrogen Bonded Systems
Authors: Frisch H. L. , Vidale G. L.
Published: January 2005

The broadening of molecular spectral bands in hydrogen bonded systems is calculated for a simple model of the hydrogen bonded molecule on the assumption that it is due to the precession of coupled anharmonic vibrations. The approximate classical mechanics of such a generalized system is developed in terms of known results in the theory of nonlinear mechanics. It is shown that when reasonable molecular parameters are substituted into the calculated broadening one obtains values consistent in all respects with the experimental data.
Long-Range Intermolecular Forces
Authors: Dahler John S. , Hirschfelder Joseph O.
Published: January 2005

The calculation of long-range intermolecular forces is systematized so as to apply to molecules in electronically excited states where resonance as well as electrostatic, induction and dispersion forces are encountered. Especial attention is given to deviations from the pairwise additivity of the energy of interaction of systems involving three or more molecules. Three types of nonadditivity are found. These are due to resonance degeneracy, molecular degeneracy, and multipole-induction effects. The following specific examples are considered: (a) the interaction energy of three hydrogen atoms, two in the ground state and the third in the first excited state; (b) the interaction of two polar, nondegenerate molecules with a hydrogen atom in its first excited state; and the multipole induction nonadditive interaction between (c) three polar molecules, and (d) three quadrupolar molecules.

Throughout these calculations the third and higher order terms in the perturbation are neglected.
Infrared Spectrum and Structure of Perchlorylfluoride
Authors: Lide David R. , Mann D. E.
Published: January 2005

The infrared spectrum of gaseous perchlorylfluoride, ClO3F, has been obtained over the range 3–43 μ. A satisfactory assignment has been achieved on the basis of a C3v model in which the four peripheral atoms are each bonded to the central chlorine. The a1 fundamentals occur at 1061, 715, and 549 cm—1; the e fundamentals are found at 1315, 589, and 405 cm—1. The stability of the C3v structure for ClO3F is discussed with reference to ClO4— and related molecules.
Importance of Doubly Excited Configurations in the Interpretation of Electronic Spectra
Authors: Murrell J. N. , McEwen K. Lenore
Published: January 2005

An investigation has been carried out to determine the importance of doubly excited configurations in calculating the energies of the electronic states of an aromatic hydrocarbon. It is found that the calculated low energy states of benzene are largely unaffected by consideration of doubly excited states, except for the appearance of an E2g state with energy comparable to that of the E1u states. In addition, inductive and mesomeric shifts in the lowest energy (α) transition have been calculated for all the distinct positions of substitution in benzene, in terms of two parameters which depend on the substituent. It is seen that the inclusion of doubly excited states in the calculation is necessary in order to predict these effects reliably.
Pure Rotational Spectra of CO, NO, and N2O between 100 and 600 Microns
Authors: Palik E. D. , Rao K. Narahari
Published: January 2005

The pure rotational absorption lines of carbon monoxide (CO) for J = 3 to J = 23, of nitrous oxide (N2O) for J = 19 to J = 40, and of nitric oxide (NO) for J = 5½ to J = 24½ have been observed for the first time. The possibility of using lines of CO and N2O for calibrating a far infrared spectrograph is considered. The pure rotational absorption spectrum of NO yields rotational constants of the molecule in the ground state.
Optical Rotatory Dispersion of Transition-Metal Complexes
Authors: Moffitt William
Published: January 2005

The electronic factors governing the rotational strengths of absorption band systems in certain transition-metal complexes are examined. Selection rules are derived which may facilitate the identification of these band systems.
Application of Free Volume Theory to Ion Pair Dissociation Constants
Authors: Gilkerson W. R.
Published: January 2005

Using Kirkwood's zeroth-order partition function for a particle in solution, an equation has been derived for the dissociation constant of an ion pair. The equation contains three adjustable parameters: the distance of closest approach, a, of the ions; Es, the difference in solvation energies of the ions and the ion pair; and (gvσ̄) which is a function of the free volumes available to the ions and ion pair. The latter two parameters account for specific solvent effects other than that due to the dielectric constant of the solvent. Comparison of the theory with the experimental data in several forms has been made.
Magnetic Susceptibilities of Uranium (V) and Uranium (III) Chlorides
Authors: Handler Paul , Hutchison Clyde A.
Published: January 2005

The magnetic susceptibilities of UCl5, UCl3, and solutions of UCl3 in LaCl3 have been measured in the temperature range from 14°K to 300°K. The results are presented graphically and their general form is discussed. The susceptibility of UCl3 apparently undergoes an antiferromagnetic transition just above the boiling point of H2. As UCl3 is diluted with LaCl3 the behavior of the magnetic susceptibility approaches closely that of Nd(C2H5SO4)3·9H2O. The magnetic behavior of UCl3 is consistent with that expected for an ion with three unpaired f electrons.
Viscosity and Density of the Liquid System TNT-Picric Acid and Four Related Pure Materials
Authors: Moore Donald W. , Burkardt Lohr A. , McEwan William S.
Published: January 2005

The viscosity and density of the system TNT-picric acid and four related substances have been investigated over a range of temperature which included both normal and supercooled liquids. The temperature-dependence of viscosity was found to be best represented by a continuous exponential function of the type η=A exp (B/T+C/T2), which yielded a good fit to the data even well into the supercooled region. Density in each case was found to vary linearly with temperature across the entire range. The results are interpreted as arising from an inverse temperature dependence of the flow activation energy, ΔEvis. It is suggested that ΔEvis may drop to zero at sufficiently high temperature and pressure.
Vibrational Intensities. VI. Ethylene and Its Deuteroisotopes
Authors: Golike R. C. , Mills I. M. , Person W. B. , Crawford Bryce
Published: January 2005

Absolute intensity measurements have been made on the fundamental vibrations of ethylene and four of its deuteroisotopes. The bands were pressure broadened with nitrogen at 50 atmos, and the intensities were determined by the method of Wilson and Wells except that the observed optical density was integrated against logv rather than v. Normal coordinates have been calculated, and the intensities have been interpreted in terms of quantities (∂p/∂Si) giving the change in dipole moment with respect to each internal symmetry coordinate. Data from the different isotopic species have been used to eliminate ambiguities in the interpretation. Effective bond moments are calculated for each symmetry coordinate.
Symmetries of Electric Fields About Ions in Solutions. Absorption and Fluorescence Spectra of Europic Chloride in Water, Methanol, and Ethanol
Authors: Sayre Edward V. , Miller Donald G. , Freed Simon
Published: January 2005

The theoretical and experimental correlations between the symmetries of the microfields about ions, the degree of splitting of energy levels, and the selection rules for radiation have been so successful for ions in crystals that the extension of this approach to discover the precise point symmetries about ions in solutions appears limited only by instances where the spectra of the solutions are sufficiently discrete. The spectra of crystals containing a rare earth ion in known local symmetry furnish the quantum characters of the energy levels and then the numbers of lines in the respective transitions of the ions in solutions lead to the symmetries of the fields about the dissolved ions.

Salts of europium which are regarded as strong electrolytes exhibit sufficiently sharp absorption spectra in solutions at room temperature while their fluorescence spectra become adequately discrete at the temperature of dry ice. The absorption spectrum of europic chloride in water proved to be the same as in a mixture of water and alcohol. The latter solutions furnished the fluorescence spectra at the temperature of dry ice. Fluorescence spectra of the alcoholic solutions in the form of glasses were obtained at 77°K and 4°K.

The symmetry of the microfields about the europium ions in the anhydrous alcohols was C2v while that about the ions in aqueous solutions was D2h.
Photochemical Separation of Mercury Isotopes. I. A Study of the Emission and Absorption Hyperfine Lines of Mercury at 2537 A
Authors: Osborn K. R. , McDonald C. C. , Gunning H. E.
Published: January 2005

An experimental and theoretical investigation has been made of the emission and absorption parameters in the excitation of Hg202 atoms in natural mercury to the 6(3P1) state by irradiation with the resonance line from an electrodeless discharge containing Hg202. The absorption has been studied as a function of (a) absorption path length, (b) the concentration of mercury in the absorption cell, (c) the pressure of certain foreign gases in the absorption cell, (d) the operating temperature of the lamp, and (e) the type of excitor used with the lamp.

The results of the study show that for the unique formation of Hg2026(3P1) atoms in natural mercury it is necessary to use a well-cooled source operating at the minimum power level consistent with steady radiation output. Furthermore, the pressure of foreign gas in the absorption cell must be kept low to eliminate Lorentz broadening effects on the absorption hyperfine line.

It has been found that the emission line from an electrodeless discharge operated at 26°C, and excited by a 2450 Mc oscillator, can be satisfactorily represented as a Doppler line modified by self-absorption. For the calculation of the frequency distribution of the emission line, the Doppler temperature of the emitting gas and the equilibrium temperature of the mercury in the lamp were taken as identical with the lamp wall temperature (26°C). The optical thickness of the path of self-absorption was evaluated from the dimensions of the lamp. It was found that the observed absorptions could be calculated directly from the ratio of the areas of the Doppler absorption line of the Hg202 atoms in the absorption cell to that of the self-absorbed emission line. The agreement between theory and experiment is taken as evidence that only Hg202 atoms are undergoing excitation under the defined conditions.

During the investigation the cross sections for Lorentz broadening of hydrogen, methyl chloride and isopropyl chloride were determined with respect to the Hg202 absorption line. The values found were respectively 53.1, 192, and 297×10—16 cm2.

This study was undertaken as a precursor to a systematic investigation of the reactions of various substrates with photo-excited mercury isotopes.
On the Relaxation of Vibrational Nonequilibrium Distributions. III. The Effect of Radiative Transitions on the Relaxation Behavior
Authors: Rubin Robert J. , Shuler Kurt E.
Published: January 2005

In previous papers of this series (Parts I and II) a theoretical study has been made of the collisional relaxation of a system of harmonic oscillators (with hv/kT≪1) from initial vibrational nonequilibrium distributions and of the influence of the collisional transition probabilities on the relaxation behavior. This paper is concerned with the extension of this study to include the effects of concurrent radiative transitions on the relaxation behavior. It was found that concurrent radiative transitions do not change the relaxation behavior of the system of harmonic oscillators from that found previously for purely collisional transitions. The only change is in the time-scale of the relaxation in that the expressions obtained in Part I must be multiplied by a factor of the form exp[—t/τ] where τ is the lifetime of the oscillators in their excited vibrational and electronic energy levels.
Radii of Transition Ions in Crystal Fields
Authors: Hush N. S. , Pryce M. H. L.
Published: January 2005

The radii of divalent and trivalent iron-group ions, unlike those of ions with spherically symmetrical ground states, do not vary regularly with atomic number. This is interpreted as an environmental effect, resulting from crystal field splitting of the lower energy levels. An approximate calculation of the crystal-field radius contraction has been made for the hexaquo complexes present in crystalline hydrates and in aqueous solutions of the divalent ions. When this is subtracted from the observed radii, the resulting ``corrected'' quantities exhibit the smooth variation with atomic number expected for free ions.
Comparative Calculations of LCAO-MOs of the Allyl Radical
Authors: Higuchi Jiro
Published: January 2005

Comparative calculations of LCAO-MOs are made for the π-electron system of the allyl radical, the LCAO-MOs obtained by various methods being discussed from the point of view of form, charge distribution and energy. For reference, the results using both the MO method with configuration interaction (CI) and the valence-bond method are given.
Dielectric Behavior of Water at Microwave Frequencies
Authors: Grant E. H. , Buchanan T. J. , Cook H. F.
Published: January 2005

An extensive examination of the dielectric properties of water at microwave frequencies has been made. The results have been fitted to various functions which have been derived from the Cole and Cole dispersion equation and it is concluded that the relaxation process in water is characterized by a narrow spectrum of relaxation times.
Relative Rates of Some Very Rapid Gaseous Bimolecular Reactions
Authors: Daen Jerome , Marcus R. A.
Published: January 2005

The present paper describes a steady-state flow apparatus which permits the measurement of relative rates of rapid gas phase bimolecular association reactions at very low pressures. Using this apparatus, the relative reactivities of the methylamines with boron trifluoride were determined over the pressure range 0.009 to 0.04 mm Hg. Within the experimental error the ratio of rate constants, kCH3NH2/k(CH3)3N, was found to be pressure independent and to have a value of 1/12. A small number of experiments was made competing monomethylamine and dimethylamine for BF3; for this system the ratio of rate constants, kCH3NH2/k(CH3)2NH had an average value of 1/5. In addition to the above, experiments were made on various phenomena such as the sorption of BF3 on various surfaces, the selectivity of a diffusion pump, and the extent of base exchange reactions, insofar as these factors pertained to the understanding of the relative rate measurements.
Stochastic Considerations on Chromatographic Dispersion
Authors: Giddings J. Calvin
Published: January 2005

The band-structure problem of chromatography is approached in this paper using concepts from discrete probability theory and passing to the limit for the continous case. Both the one-site and two-site problems are treated under the stipulation of linear adsorption properties. A two-site expression has been derived which is complicated only by the need to evaluate one integral numerically. The band structure is given for two hypothetical cases, one involving one-site and the other the more complicated two-site processes.
Electron Impact Studies on C2H5Cl, C2H5Br, and C2H5I
Authors: Irsa A. P.
Published: January 2005

The appearance potentials and process of formation of the C2H5X+, C2H5+, CH2X+, and HI+ ions have been studied. From the appearance potential data evidence is obtained for the following processes of production of these ions C2H5X+e=C2H5X++2eC2H5X+e=C2H5+X+2eC2H5X++e=CH2X++CH3+2e=CH2X++CH+H2+2eor C2H5I+e=HI++CH2=CH2+2e.These processes and their corresponding appearance potentials permit certain ionization potentials and bond energies to be derived. The ionization potentials obtained for the ethyl halides are I(C2H5Cl) ≤11.2±0.2 ev, I(C2H5Br) ≤10.7±0.1 ev, and I(C2H5I) ≤9.6±0.2 ev. The carbon-halogen bond energies of these ethyl halides as determined from process (b) are (C–Cl) ≤3.6±0.3 ev, (C–Br) ≤2.8±0.2 ev, and (C–I) ≤2.4±0.4 ev. Values of the carbon-carbon bond energy of C2H5Br and the ionization potential of CH2Br are estimated to be 3.6 ev and 9.1 ev respectively. The ionization efficiency curves of the negative halogen atoms from the ethyl halides are presented and some of their features discussed.
Diffusion of Radioactive Magnesium in Magnesium Oxide Crystals
Authors: Lindner Roland , Parfitt Geoffrey D.
Published: January 2005

The diffusion of Mg28 in crystal plates of MgO has been measured. Between 1400 and 1600°C the temperature function of the diffusion coefficient can be represented by the relation D=0.249 exp(—79.0 kcal/RT) cm2 sec—1.
Curved Fluid Interfaces. II. The Generalized Neumann Formula
Authors: Buff Frank P. , Saltsburg Howard
Published: January 2005

Following an analysis of the phenomenological concept of surface stress, the confluence properties of three fluid phases are examined from the molecular point of view. The detailed theory leads to a generalization of the Neumann surface tension triangle, which provides a boundary condition for the Laplace equations describing the surfaces of a fluid lens. It is found that the classical equation must be supplemented by a thermodynamic length parameter which, however, does not contribute to the Archimedean equilibrium of the lens. As in the preceding investigation, the first-order correction terms of the theory again provide criteria for the breakdown of thermodynamic concepts.
Comment on the Significance of Diffusion Potentials in Ion Exchange Kinetics
Authors: Schlögl R. , Helfferich F.
Published: January 2005

The effect of the electric potential produced by diffusion in ion exchange kinetics is examined for the film-controlled exchange of monovalent ions. It is shown that, rather than resulting in a minor correction, the electric field as a rule makes an essential contribution to the process.
Correlation Energies in Atoms and Electron Affinities
Authors: Arai Tadashi , Onishi Tsuyoshi
Published: January 2005

The well-known orbital approach is applied to the 2, 3, and 4 electron systems of atoms and ions, and the extent to which it can be applied and the apparent nature of the correlation energies are surveyed. It is then discussed how the apparent correlation energies can be extrapolated to estimate the correct energy values of negative ions for which observation has not yet succeeded. According to such estimations, the electron affinities of H and Li are obtained as 0.75±0.01 ev and 0.66±0.03 ev, respectively. Finally it is attempted to extend the discussion to more complicated systems.
Near Ultraviolet Spectrum of Crystalline Hexamethyl Benzene and the Structure of the Hexamethyl Benzene Molecule
Authors: Schnepp O. , McClure Donald S.
Published: January 2005

The absorption and fluorescence spectra of single oriented crystals of hexamethyl benzene were photographed at high resolution with polarized light at 20°K in the 2800 A region. The analysis shows that the 0–0 transition is observed with much greater intensity in light polarized perpendicular to the plane of the benzene ring than in light polarized in this plane. In the perpendicular component the vibrational structure of a weak allowed transition appears together with the 0–0 band. The in-plane spectrum is a forbidden transition, similar to the benzene 2600 A absorption. A detailed calculation shows that the perturbation by the crystal lattice cannot be the cause of the observed behavior of the 0–0 band in polarized light. It is concluded, therefore, that this behavior must be caused by the lowering of the molecular symmetry by the methyl groups. The probable symmetry of the molecule is S6. This symmetry approximately fixes the positions of the hydrogen atoms and determines the shape of the methyl rolling potential.
Rate of Dissociation of Bromine in Shock Waves
Authors: Palmer H. B. , Hornig D. F.
Published: January 2005

The rate of dissociation of bromine, pure and diluted with argon, was measured from 1200°K to 2225°K in shock waves, in order to study the mechanism of elementary reaction processes. The absorption coefficient of Br2 was measured over the same temperature range. In the case of dissociation produced by Br2–A collisions the reaction rate constant is reproduced over a range of 1027 by a collision theory equation. The activation energy is approximately equal to the dissociation energy of Br2, the frequency factor is about 6% of that deduced from the collision frequency, and it appears that both the vibration and rotation of the Br2 contribute energy to the dissociation. Br2 is roughly twice as efficient as A in producing dissociation at high temperatures. For dissociation produced by Br2–Br2 collisions the measurements are in agreement with a rate constant in which the activation energy equals the dissociation energy, the steric factor is from 1% to 10% and five to seven square terms (e.g., the two vibrations and one to three rotations) contribute to the energy of dissociation.
Calculation of the Heat Capacity of α Quartz and Vitreous Silica from Spectroscopic Data
Authors: Lord R. C. , Morrow J. C.
Published: January 2005

The heat capacity of α-quartz has been computed over the temperature range 10–700°K, and that of vitreous silica from 10° to 900°K. Debye θ's obtained from the T3 law below 10° were used for the ``translational'' degrees of freedom, and recent infrared and Raman data for the other frequencies. Cp—Cv was negligible for vitreous silica and was computed from compressibility and thermal-expansion data for α-quartz. Agreement with new Cp measurements is excellent for α-quartz (within 1% above 60°K) but is less satisfactory for vitreous silica because of inadequate knowledge of the distribution of frequencies below 500 cm—1.
Absorption Bands of Rubidium in the Presence of Hydrocarbons
Authors: Ch'en Shang-Yi , Jefimenko Oleg
Published: January 2005

Absorption spectra of rubidium in the presence of fourteen different hydrocarbons (methane, ethane, propane, n-butane, n-pentane, n-hexane, n-heptane, n-octane, n-nonane, n-decane, n-dodecane, cyclopropane, butene-2, and benzene) were studied. About one hundred new rubidium-hydrocarbon absorption bands associated with the first four members of the Rb principal series were observed. Some regularities in the occurrance of the bands were found. The positions of the bands are given and the properties of the bands are discussed.
Heat Conductivity in Polyatomic or Electronically Excited Gases. II
Authors: Hirschfelder Joseph O.
Published: January 2005

The usual Eucken equation for the heat conductivity of a molecule with internal degrees of freedom is derived and improved. In the improved form the correction to the coefficient of thermal conductivity for the internal degrees of freedom of the molecule is given by the factor 0.115+0.354 Cp/R. With the help of Part I, we prove that this approximation is valid only if the electronic states are not metastable and if the coefficients of diffusion of all the molecular quantum states are equal. The metastable electronic species should lead to anomalously large coefficients of thermal conductivity, whereas the usual excited electronic states, because of their gigantic size, should give a much smaller contribution to the coefficient of thermal conductivity than would be expected on the basis of the Eucken assumption.
Effects of High Pressure on the Near Ultraviolet Absorption Spectra of Benzene and Monosubstituted Benzenes
Authors: Robertson W. W. , Babb S. E. , Matsen F. A.
Published: January 2005

The near ultraviolet absorption spectra of benzene and several monosubstituted benzenes have been obtained in the vapor phase with partial pressures of nitrogen to 550 atmos and in hydrocarbon solution with pressures up to 5500 atmos. The spectra broaden asymmetrically and shift to longer wavelengths under pressure. The wavelength varies linearly with dielectric constant, both in the vapor phase and in solution, Δλ/ΔK lying between 20 and 29 A. A rough correlation is found between Δλ/ΔK and the oscillator strength of the transition.
Vibrational Spectra of Hexafluorobutadiene-1,3
Authors: Albright J. C. , Nielsen J. Rud
Published: January 2005

The infrared absorption spectrum of gaseous CF2:CF–CF:CF2 has been obtained with a Perkin-Elmer double-pass spectrometer equipped with prisms of LiF, NaCl, and CsBr. The Raman spectrum of the compound in the liquid state, at 20°C and —120°C, was photographed with a 3-prism spectrograph of linear dispersion 15 A/mm at 4358 A. Polarization ratios were measured for the stronger bands. Weakly exposed Raman spectra were obtained of the compound in the gaseous state at room temperature and in the crystalline state at —160°C. The spectral data are inconsistent with the assumption of the molecular symmetry C2h (trans-form), but can be interpreted satisfactorily on the basis of symmetry C2v (cis-form). However, the data do not exclude the possibilities that the molecular symmetry is C2 or that the compound consists of a mixture of molecules of different symmetries. All of the 24 fundamental vibration frequencies have been assigned, and the spectra have been interpreted in detail. Some peculiarities in the spectra and some uncertainties in their interpretation are pointed out.
Complete π-Electron Treatment of the Butadiene Molecule and Ion
Authors: Fain Janice , Matsen F. A.
Published: January 2005

The complete VB treatments of the π-electron energy levels of the butadiene molecule and ion are presented. The results for the molecule are in agreement with those of a SCF–CI calculation. It is found that the energy of the single structure, H2C=CH–CH=CH2, is very close to the result of the complete calculation. An expression for the ionization potential of the molecule is obtained.
Spectra of Some Symmetric-Top Molecules in the One- to Four-Millimeter Wave Region
Authors: Burrus Charles A. , Gordy Walter
Published: January 2005

Rotational transitions of several symmetric-top molecules have been measured in the 1 to 4 mm wave region. The molecular rotational constants for the most abundant isotopic species are: B0=8545.877 Mc/sec, DJ=2.960 kc/sec, DJK=162.9 kc/sec, for CH3CCH; B0=10 348.862 Mc/sec, DJ=11.3 kc/sec, DJK=—18.06 kc/sec, for CF3H; B0=4 594.262 Mc/sec, DJ=1.020 kc/sec, DJK=1.284 kc/sec, for OPF3; B0=7208.049 Mc/sec, DJ=7.556 kc/sec, DJK=—12.45 kc/sec, for Si28F3H; B0=2945.528 Mc/sec, DJ=0.3065 kc/sec, DJK=5.814 kc/sec, for CF3CN. These constants were found to predict all observed lines within the accuracy of measurement ∼±0.2 Mc/sec. Higher-order stretching terms are too small to measure in the present experiments.
Lattice Entropies—Entropies of Vaporization of Ions from Crystals
Authors: Altshuller A. P.
Published: January 2005

The entropies of vaporization of salts, the lattice entropies, have been calculated for salts containing both monatomic and polyatomic ions. The variations of the lattice entropies of these salts with valence type are discussed. The effects of ion size and ionic character on the lattice entropies also are considered.

The entropies of vaporization of single monatomic and polyatomic ions also have been computed. The effects of ion size, charge on the cation and anion, size of the central atom in oxy-anions, and the number of oxygen atoms attached to the central atom of the oxy-anions all are discussed.

The lattice entropies of monatomic salts should depend on the change from vibrational modes in the solid to translational modes in the gas. The lattice entropies of polyatomic salts depend in a complicated manner on the internal modes of motion in the gaseous polyatomic ions and in the solid.
Central-Field Approximation for the Electronic Wave Functions of Simple Molecules
Authors: Funabashi Koichi , Magee John L.
Published: January 2005

The use of a central-field type of molecular orbital for the electronic wave functions of simple molecules has been investigated and application has been made to H2, H2O and CH4.

Ionization potentials calculated with the use of these wave functions are generally in good agreement with experimental values. No empirical data have been used in these calculations except the known equilibrium dimensions of the molecules. Interactions of all electrons are included. Configuration interaction, however, is not used.

Excitation potentials for H2O and CH4 are not in very good agreement with experimental values, which possibly means that configuration interaction cannot be neglected in such calculations.
Electrical Properties of Phthalocyanines
Authors: Fielding P. E. , Gutman Felix
Published: January 2005

The electrical conductivity of single crystals of metal-free, copper, nickel, and cobalt phthalocyanines were measured over temperature ranges extending from 50° to 390°C. The weighted mean values of the activation energies obtained were: 1.71 ev for the metal-free, 1.60 ev for the cobalt, and for the nickel, and 1.64 ev for the copper substituted compounds. No significant difference in the activation energy of the metal-free compound was observed between directions parallel and perpendicular to the (001) face of the crystal. The results were well reproducible and showed no significant variation for different crystals. It is concluded that these compounds are, above room temperature, intrinsic semiconductors and that the introduction of a metal atom into the molecule produces comparatively little change in the activation energy of conduction. A thermoelectric power of +50 μv/°C was measured for metal-free and for copper phthalocyanine, indicating that the majority carriers are holes. Since the values of the constant σ0 were found to be in the order of 100 Ω—1 cm—1 it is concluded that their mobilities are rather low. Optical transmission spectra are reported for these compounds in solution as well as in the form of thin evaporated films. The energy of the first electronic transition evident in the film spectra agrees with the thermal activation energy for electrical conduction. There is little difference in the positions of the absorption maxima observed in evaporated films and in solution, although the intensities are altered. The photoconductive response resembles the spectral transmission characteristics of the compounds. The quantum efficiency is low.
Effects of Pressure on Ultrasonic Relaxation in Liquids
Authors: Litovitz T. A. , Carnevale E. H. , Kendall P. A.
Published: January 2005

Measurements of sound absorption as a function of pressure in carbon disulfide and glycerol indicate that the relaxation effects causing the compressional losses in these liquids react differently to pressure changes. In CS2 the relaxation frequency increased with increasing pressure. In glycerol the relaxation frequency dropped as the pressure was increased. These results are consistent with the view that different relaxation mechanisms exist in associated and nonassociated liquids. The direction of the pressure changes in each case is in accord with the view that thermal relaxation is the cause of compressional loss in nonassociated liquids and that structural relaxation is the predominant factor in associated liquids.

A detailed study of the thermal relaxation effects in CS2 showed that the variations in relaxation frequency with pressure could not be adequately explained by Kittel's theory of thermal relaxation in liquids.

Theoretical considerations of the relaxational part of the specific heat indicated that it should be only slightly pressure dependent.
On the Application of the Molecular Orbital Method to the Spectra of Substituted Aromatic Hydrocarbons
Authors: Goodman Lionel , Ross Ian G. , Shull Harrison
Published: January 2005

The MO theory of the spectra of substituted hydrocarbons is presented in rather general terms, with careful emphasis on the precautions to be observed in introducing the inevitable approximations. Previous treatments of the problem, notably by Sklar, Herzfeld, and Matsen, are then examined. Satisfactory calculaof energy-level shifts are considered to require closer attention to the definition and dissection of the perturbed Hamiltonian. The most interesting intensity effects concern the enhancement of weak transitions: here earlier treatments do not satisfy the requirements of orthonormality of the perturbed MOs, and unjustifiably neglect interactions with intense transitions. The consequences of neglecting overlap in these calculations are discussed in an appendix.
Sound Dispersion in Halo-Methane Mixtures
Authors: Amme Robert , Legvold Sam
Published: January 2005

Results of studies of the dispersion of ultrasound in mixtures of CHClF2 in CF4 and of CHCl2F in CClF3 at various concentrations are presented. In none of the eight mixtures studied is there evidence of multiple dispersion; each mixture exhibited a single relaxation time which falls between the relaxation times of the pure constituents. A simple method of averaging the various quantities entering into the prediction of collision lifetimes in the pure constituents is presented which yields lifetimes for the mixtures nearly matching those found by experiment.
Direct Correlation Functions for Argon
Authors: Reetz Arthur , Lund L. H.
Published: January 2005

Direct correlation functions as defined in the Ornstein-Zernike liquid model have been calculated from the argon x-ray scattering data corresponding to several points on the liquid-vapor transition curve. Graphs of these direct correlation functions are presented along with an integral check on their general validity. It is concluded these correlation functions derived from the x-ray scattering data are a reasonable representation of these functions.
Ionization Potentials of Some Molecules
Authors: Watanabe K.
Published: January 2005

The ionization potentials of eithty-nine molecules have been determined by photoionization measurements. The results are tabulated and compared with those obtained by spectroscopic and electron impact methods. Uncertainties in interpretation and several discrepancies are discussed.
Neutron Diffraction Study of Calcium Hydroxide
Authors: Busing William R. , Levy Henri A.
Published: January 2005

Single crystal neutron diffraction measurements on Ca(OH)2 at 20°C and —140°C confirm the x-ray structure and the hydrogen positions previously postulated. Refinement of the neutron data by Fourier and least squares procedures yields a detailed description of the thermal motions. The amplitudes of the motion of the hydrogen atoms are compared with those deduced from infrared and Raman studies. The O–H distance, after allowance for asymmetric thermal motion, is 0.984 A.
Collision-Induced Dissociations in the Mass Spectrum of Methane
Authors: Melton C. E. , Rosenstock H. M.
Published: January 2005

The mass spectrum of methane has been investigated in the pressure range 1×10—7 to 5×10—5 mm of Hg. A number of diffuse peaks were observed at nonintegral masses. These arise from dissociation of various ionized methane fragments on collision with residaul methane gas in the field-free region of the mass spectrometer. The linear pressure dependence of their relative abundance points to single-collision processes. No multiple-collision processes or truly unimolecular metastable transitions were observed. A parallel between electron impact and collision-induced dissociation is pointed out.
Coupling Strength for Resonance Force Transfer of Electronic Energy in Van der Waals Solids
Authors: Simpson William T. , Peterson Don L.
Published: January 2005

The interpretation of the absorption spectrum of a molecular crystal requires a knowledge of the strength of resonance force electrostatic interaction between molecules in the crystal as compared to an energy parameter characterizing the molecular vibrational level pattern. Depending on the relative magnitudes of these energy terms the spectrum reflects absorption by the crystal as a whole or by independent, though oriented molecules. These two familiar cases are examined from both stationary-state and time-dependent points of view with the object of defining the energy parameters. The resonance force interaction term is a theoretically derived quantity, the crystal electronic band width; the comparable vibrational energy term is shown to be the width of the total electronic band comprising all the vibronic transitions for an isolated molecule. Particular attention is given to the case in which these terms are nearly equal.
Energy States and Luminescent Processes in the ZnF2: Mn Phosphor
Authors: Johnson Peter D. , Hughes Floyd L.
Published: January 2005

Single crystals of ZnF2: Mn have a single symmetrical thermoluminescent peak when excited by monochromatic radiation of wavelength 1800 to 2300 A. The electron trap responsible for this peak is a metastable state of the activator. Excitation occurs first to a higher excited state from which both the emitting and trapping states are accessible. With 1850 A excitation, transfer to the emitting state from the initial excited state is approximately 4 times as probable as transfer to the trapping state. Untrapping occurs by a monomolecular process modified by thermally activated retrapping from the state governing the rate of emission. Energy level diagrams are proposed for the states of Mn++ responsible for absorption emission and trapping.
Microwave Spectrum, Structure, and Dipole Moment of s-trans Acrolein
Authors: Wagner Roselin , Fine J. , Simmons J. W. , Goldstein J. H.
Published: January 2005

The microwave spectrum of acrolein has been studied in the 19–37 kmc region. A series of R-type transitions was identified for the ground and three excited torsional states of the s-trans isomer and these spectra were successfully fitted in the rigid rotor approximation. Using the ground state moments and additional electron diffraction data a reasonable though not unique structure has been obtained. The torsional frequency was found to be 200±50 cm—1 from relative intensity measurements, and a lower limit of about 2300 cal was estimated for the barrier hindering trans-cis conversion. The dipole moment for the ground state was found to be 3.11±0.04 d, oriented about 14° from the carbonyl group. The results obtained and the absence of a strong s-cis spectrum establish the s-trans isomer as the predominant form.
Emission and Two-Body Recombination in Bromine
Authors: Palmer Howard B.
Published: January 2005

The visible emission from hot, partially dissociated bromine raised to temperatures as high as 2500°K by means of a shock wave has been studied as a function of wavelength and temperature. At total pressures around 1 to 2 atmos in a 1-in. shock tube, the emission is continuous. It is caused by two-body atom recombinations of two types, one involving two unexcited Br atoms and the other involving one excited atom and one unexcited atom. The first type yields excited Br2 molecules in the states 3π1u and 1πu, while the latter type produces excited molecules in the 3π0+u state. Proof of these mechanisms comes through analysis of emission spectra in terms of the potential diagram of bromine and through photomultiplier observations of the emission intensity at specific wavelengths as it varies with temperature and Br atom concentration. Some information is obtained on the shapes of the excited state potentials in the high energy region and an assignment of the transitions responsible for visible absorption in bromine is recommended.
Electronic Spectra of Cyclic Aromatic Hydrocarbon Radicals and Ions
Authors: Longuet-Higgins H. C. , McEwen K. Lenore
Published: January 2005

The electronic spectra of a series of cyclic unsaturated radicals and ions containing from three to eight carbon atoms have been calculated by a semiempirical molecular orbital method.
Potentiometric Titration, Association Phenomena, and Interaction of Neighboring Groups in Polyelectrolytes
Authors: Lifson Shneior
Published: January 2005

The partition functions and potentiometric titration equations are calculated for a number of types of polyelectrolytes, including polyampholytes and other electrolytic copolymers. The effects of the interaction between neighboring groups and of the electrostatic potential of the macromolecule as a whole are both accounted for independently, by treating the ionized macromolecule as a separate phase in equilibrium with the surrounding solution.

The possibility of association of monovalent cations with the acidic groups of polyacids is discussed, following the derivation of the titration equations for both the H+ ion and the associating metallic cation.
Infrared and Raman Spectra of Trans-Difluorodichloroethylene
Authors: Mann D. E. , Plyler Earle K.
Published: January 2005

The infrared and Raman spectra of trans-difluorodichloroethylene (t-C2F2Cl2) have been measured and an assignment of fundamentals made. They are, in cm—1: 1707, 1186, 632, 425, and 288 in ag; 333 and 140 in au; 529 in bg; and 1190, 892, 426, and 175 in bu. A table of thermodynamic functions is given for the molecule in the ideal gaseous state.
X-Ray Diffraction Study of the Cubic Phase of Ice
Authors: Shallcross F. V. , Carpenter G. B.
Published: January 2005

An x-ray diffraction study has been made of the cubic phase of ice previously reported by König from electron diffraction work. Cubic ice could be obtained only by direct crystallization from the vapor onto surfaces at low temperature. Condensation rate and surface conditions are critical variables in the formation of cubic ice. Powdered mixtures of cubic and hexagonal ice were studied at —190° and —130°C. The powder x-ray patterns confirm the diamond structure for the oxygen atoms; the cubic cell edge is a=6.37 ±0.02 A at —190°C.
Gallium: Thermal Conductivity; Supercooling; Negative Pressure
Authors: Briggs Lyman J.
Published: January 2005

The thermal conductivity of liquid gallium does not appear to have heretofore been measured. The method employed involved a comparison with the known thermal conductivity of mercury. The two liquids were sealed in two thin-walled glass tubes (30 cm long, 10 mm bore), the upper ends being inserted vertically through the bottom of a boiler containing boiling water. The tubes were coated to secure the same thermal emissivity. Two thermocouple loops which could be moved along the tubes served to establish points having the same temperature on the two tubes. The ratio of the squares of the lengths from the thermocouple junctions to the bottom of the boiler gave 3.51±0.03 as the relative thermal conductivity of gallium to that of mercury, or 0.336±0.005 watt/cm (°C) as the thermal conductivity of gallium between 30° and 100°C, based upon 0.0958 for mercury.

It was found possible to supercool liquid gallium to —28°C, or 58°C below its melting point, by exposing small drops on paper to a slowly decreasing temperature in a deep-freeze chamber with a circulating atmosphere.

An attempt to measure the negative pressure of gallium proved disappointing, for it was found that gallium does not ``wet'' the wall of an evacuated tube. With a partial evacuation, low negative pressures were measured which decreased (like water) as the melting point was approached.
Infrared Spectra of HDO in Water and Ionic Solutions
Authors: Waldron Robert D.
Published: January 2005

The infrared spectra of HDO in water and saturated metal halide solutions were investigated to study the interactions between ions and solvent molecules and the nature of hydrogen bonding in aqueous systems.

The fundamental and overtone bands of the OH and OD stretching vibrations are shifted to lower frequencies and the bending vibration shifts to higher frequencies as one passes from the gaseous to the liquid state. Similar shifts occur for the metal halide solutions, the magnitudes of which are sensitive to the anion species but relatively independent of the cations. The frequency shifts for ionic solutions increase in the order I-, Cl-, F-, with the shift in ion-free water about equal to that for Cl-. The data are analyzed in terms of four probable nearest-neighbor configurations in these solutions.

The vibrational anharmonicity of the OH stretching vibration in solution is nearly independent of the frequency shift and only slightly larger than the gas value. The dependence of frequency shift on the shortening of hydrogen bonds (volume contraction) and H-bond energy were studied and gave qualitative agreement with other systems previously investigated.
Equation of State of Water to 250 Kilobars
Authors: Rice Melvin H. , Walsh John M.
Published: January 2005

An equation of state for water, applicable in the pressure range 25 kilobars to 250 kilobars, is formulated in terms of experimental data obtained from shock wave measurements. This equation of state is used to calculate P-V relations for several adiabats and isotherms. Thermodynamic and hydrodynamic data along the Hugoniot curve are given as a function of shock pressure, and pressure-particle velocity relations for initial shocks followed by reflected shocks and rarefactions are given.
Absolute Intensities for the Ultraviolet γ Bands of NO
Authors: Weber D. , Penner S. S.
Published: January 2005

Absolute intensities have been measured for three of the ultraviolet γ bands of NO. The corresponding electronic absorption oscillator strength is estimated to be 0.0024±0.0004.
Absorption Spectrum of CO in the Vacuum Ultraviolet Region
Authors: Tanaka Y. , Jursa A. S. , LeBlanc F.
Published: January 2005

Using the continua of the rare gases and the hydrogen continuum as background, we investigated the absorption spectrum of CO in the region 1070–2500 A. Most of the intercombination bands expected in this region were observed, and the a—X, a′—X, and e—X bands were extended to v′=5, 21, and 17, respectively. The d—X bands, observed for the first time, were extended to v′=21, and the fourth positive bands were extended to v′=20. A brief discussion on the dissociation energy of the molecule is presented.