bluuebunny/crossref_metadata_2025 huggingface dataset:
Experimental Proof for the Existence of Nonthermal Rotational Distributions of OH (2Σ+) in Flames
Authors: Broida Herbert P. , Kostkowski Henry J.
Published: January 2005

Experiments have been carried out to determine whether nonthermal rotational distributions in the 2Σ+ electronic state of OH observed in certain flames are caused by self-absorption. A study of emission (single and double path) and absorption by OH between 3064 A and 3350 A in atmospheric and low-pressure flames has shown that self-absorption is negligible in at least two cases in which nonthermal distributions are found. This leads to the conclusion that anomalous ``temperatures'' of OH measured previously in hydrocarbon flames at low pressure and in highly diluted flames at atmospheric pressure are real.
Theory of the Ionization of Hydrogen and Lithium in Silicon and Germanium
Authors: Reiss Howard
Published: January 2005

This paper contains an effective mass-quantum mechanical investigation of the ionizability of interstitial hydrogen and lithium in germanium and silicon. It is concluded that hydrogen should not ionize while lithium should. This seems in accord with experimental findings.
On the Kinetic Energy of Molecular Electrons in Compressed Gases
Authors: Solem Anson , Jansen Laurens
Published: January 2005

A low density calculation of the change in kinetic energy of molecular electrons due to interactions is presented as a series in powers of the density. A detailed analysis is made of the contribution from the linear term. The interaction potential between two molecules is assumed to be of the Lennard-Jones (6—s) form with s equals 8, 10, 12, and 14. In addition contributions due to directional forces such as quadrupole induction and quadrupole orientation forces and anisotropy in the London forces are taken into account. These directional forces are cut off inside the molecular diameter. In general the directional effects are on the order of a few percent of the total change in the kinetic energy. Among the directional effects, that due to quadrupole induction is predominant at high temperatures for the gases nitrogen, carbon monoxide, carbon dioxide, ethylene, and ethane; at low temperatures the anisotropy in the London forces predominates. It is shown that the change in kinetic energy is more sensitive to the repulsive part of the potential field than the second virial coefficient.
Energy of Cohesion, Compressibility, and the Potential Energy Functions of the Graphite System
Authors: Girifalco L. A. , Lad R. A.
Published: January 2005

The lattice summations of the potential energy of importance in the graphite system have been computed by direct summation assuming a Lennard-Jones 6–12 potential between carbon atoms. From these summations, potential energy curves were constructed for interactions between a carbon atom and a graphite monolayer, between a carbon atom and a graphite surface, between a graphite monolayer and a semi-infinite graphite crystal and between two graphite semi-infinite crystals. Using these curves, the equilibrium distance between two isolated physically interacting carbon atoms was found to be 2.70 a, where a is the carbon-carbon distance in a graphite sheet. The distance between a surface plane and the rest of the crystal was found to be 1.7% greater than the interlayer spacing. Theoretical values of the energy of cohesion and the compressibility were calculated from the potential curve for the interaction between two semi-infinite crystals. They were ΔEc = —330 ergs/cm2 and β = 3.18×10—12 cm2/dyne, respectively. These compared favorably with the experimental values of ΔEc = —260 ergs/cm2 and β = 2.97×10—2 cm2/dyne.
Paramagnetic Resonance Absorption in Some Organic Biradicals
Authors: Jarrett H. S. , Sloan G. J. , Vaughan W. R.
Published: January 2005

Four compounds of the form 4,4′-polymethylenebistriphenylmethyl, one compound of the form (1,4-phenylene)bisdiarylmethyl, three compounds of the form (4,4′-biphenylene)bisdiarylmethyl, and one compound, 4,4′-oxybistriphenylmethyl have been shown to possess unpaired electrons by paramagnetic resonance absorption. The resonance spectra of 0.01 M solutions of these compounds in benzene exhibit a hyperfine structure arising from a spherically symmetrical contribution of the magnetic dipole interaction between the unpaired electron and the nuclear magnetic moments of the hydrogen atoms. The g-factors for the compounds investigated in the first three classes were found to be 2.0025±0.0004 and 2.0031±0.0004 for the last compound. Such a close approach of the g-factor to the free electron value plus the sharpness of the hyperfine structure lines indicates that the anisotropic contributions of the spin-orbit interaction, which would normally lift the degeneracy of the triplet state, are averaged out by the tumbling of the molecules.
Theoretical Pre-Exponential Factors for Twelve Bimolecular Reactions
Authors: Herschbach Dudley R. , Johnston Harold S. , Pitzer K. S. , Powell R. E.
Published: January 2005

The Arrhenius pre-exponential factor A has been calculated and compared with experiment for a group of twelve bimolecular gas phase reactions of simple inorganic molecules. The most detailed form of the activated complex theory, a cruder method of hydrocarbon analogy, and the simple collision theory were used. Necessary assumptions about the properties of the activated complex were made uniform for the whole set of reactions. Particular attention was paid to the treatment of internal rotations and vibrations. The agreement of the activated complex theory with experiment was found to be satisfactory.
On the Pressure Estimation in Impact Sensitivity Experiments on Explosives and the Problem of Initiation
Authors: Murgai M. P.
Published: January 2005

Pressures generated on the explosive layer under conditions of experiments on the impact sensitivity of explosives have been calculated making use of the basic assumptions embodied in the Hertz theory of impact, taking data from certain experiments on explosion. In the absence of any knowledge of the elastic constants of explosives under dynamic conditions of loading, calculations have been made for two sets of elastic constants, one for steel to steel impact and the other for steel to a solid having elastic constants one-tenth that of steel. The experimental pressures lie between these two values. A reinterpretation of the results leads to a relation between a mass m and its height of h for fifty percent explosion efficiency. The conduction at the solid air interface due to an entrapped gas bubble compressed by these pressures has been considered. The amount of the explosive heated to the optimum temperature required for explosion, within times comparable to impact explosion delays, has been shown to be of the order of the hot spot size found from other considerations. The variation of the height h and the pressure p of the gas surrounding the explosive layer for fifty percent efficiency is shown to be governed by the relation h/p2 = constant.
Study of the Wurtzite-Type Binary Compounds. I. Structures of Aluminum Nitride and Beryllium Oxide
Authors: Jeffrey G. A. , Parry G. S. , Mozzi R. L.
Published: January 2005

The c/a ratios of the hexagonal AlN and BeO structures show that they do not have a regularly tetrahedral distribution of bonds. The structural details have been studied by x-ray analysis and are discussed in relation to the concepts of the electronegativity and electroneutrality of atoms. This gives a basis for an understanding of the distribution of the wurtzite and zinc blende lattices in the binary compounds of the group III/V and II/VI elements.
Photoionization as a Source of Ions for Mass Spectrometry
Authors: Lossing F. P. , Tanaka Ikuzo
Published: January 2005

Some preliminary experiments are described in which ions are formed in the ionization chamber of a mass spectrometer by radiation from a source of far ultraviolet. Depending on the wavelength of the radiation and the ionization and appearance potentials of parent and fragment ions, it is possible to produce spectra which consist of the parent ion only. In one case a dissociative ionization process was observed. Free methyl radicals from the pyrolysis of mercury dimethyl were also detected by photoionization. Some possible applications of the technique to the measurement of ionization and appearance potentials and to special problems in mass spectrometry are discussed.
Correlation Splitting in Helium-Like Ions
Authors: Shull Harrison , Löwdin Per-Olov
Published: January 2005

The correlation effects in the ground state of the He-like ions are investigated by using the idea that the two electrons may occupy different orbitals in space. By using a scale factor η and a splitting parameter v, a radial function [open phi][r] is split into two different orbitals, [open phi][η(1+v)r] and [open phi][η(1—v)r], following Hylleraas [E. A. Hylleraas, Z. Physik 54, 347 (1929)], and Eckart [C. Eckart, Phys. Rev. 36, 878 (1930)]. It is shown that by using orbitals obtained by splitting a simple exponential function, a surprisingly large amount of the radial correlation energy may be taken into account, whereas an attempt to split the atomic self-consistent field function for He led to a negative result. The lowest triplet state is also treated by using the same approach.
Absorption Spectra of I2 and I4 in CCl4 Solution
Authors: Keefer R. M. , Allen Thomas L.
Published: January 2005

The absorption of light by solutions of iodine in carbon tetrachloride has been investigated from 250 mμ to 600 mμ. Deviations from Beer's law occur in the region below 420 mμ. In this region the apparent extinction coefficient of the iodine is a linear function of its concentration. This can be accounted for on the basis that a weak complex of formula I4 exists in the solution in equilibrium with the diatomic molecules: 2I2=I4. The true extinction coefficient of I2 and the product of the formation constant and the extinction coefficient of I4 have been determined as a function of wavelength in this region.
Shock Waves in Chemical Kinetics: Further Studies on the Rate of Dissociation of Molecular Iodine
Authors: Britton Doyle , Davidson Norman , Gehman William , Schott Garry
Published: January 2005

The rate of the dissociation reaction, M+I2[open phi] lim kRkDM+I+I,has been measured by the shock tube method for argon, helium, nitrogen, oxygen, and carbon dioxide as inert gases, M, in the temperature range 1000°—1600°K. The shock wave results by themselves and the comparison of the shock wave measurements with the room temperature measurements of kR by flash photolysis both show that kR has a negative temperature coefficient. The absolute value of this negative temperature coefficient derived from the shock wave measurements is greater than the value derived from comparison of the average high temperature result with the room temperature result for any particular gas. This may be due to experimental error in the determination of dkR/dT at the high temperatures, but it is believed that the values of kR determined in the middle of the temperature range studied are reliable.

The experimental evidence indicates that, for the measurements with CO2, the rate of vibrational equilibration is so fast that the observations made here pertain entirely to vibrationally equilibrated CO2. Evidence from other experiments indicates that the rate of vibrational relaxation in oxygen is such that most of the dissociation reaction occurs in relaxed O2, but that nitrogen remains vibrationally unexcited under the conditions of the dissociation reactions studied here.

The ratio, kR, 12/kR,A, of the efficiencies of iodine and argon as third bodies is not greater than 30 at 1300°K whereas it is 250–600 at room temperature. The hypothesis is proposed that in general the ratio kR, gas/kR,A for complex gases will decrease with increasing temperature.
Shock Waves in Chemical Kinetics. Rate of Dissociation of Molecular Bromine
Authors: Britton Doyle , Davidson Norman
Published: January 2005

The rate of dissociation of molecular bromine in argon-bromine mixtures has been measured in a shock tube and the rate constants for the reaction Br+Br+M→ lim kRBr2+M, in the temperature range 1400°—2700°K, computed. The data are not sufficiently accurate to reveal the temperature coefficient of kR. However, comparison of the average high temperature result, kR=3.4×108 liter2 mole—2 sec—1 at 1600°K, with the room temperature flash lamp result, kR=2.5×109, shows clearly that dkR/dT is negative. Experiments were performed with bromine: argon ratios of 0.01 to 0.10; the efficiency of Br2 as M, the third body for the recombination of bromine atoms, is not greater than 8 times that of argon. The agreement of the results of this investigation with those of an independent shock tube investigation by Palmer and Hornig is gratifyingly good.

The extinction coefficients of bromine at 436 mμ and 487 mμ were measured as a function of temperature.
Pure Quadrupole Resonances in Multichlorobenzenes
Authors: Bray P. J. , Barnes R. G. , Bersohn R.
Published: January 2005

The location and measurement of the nuclear quadrupole resonances of Cl35 in all multichlorobenzenes has been completed with the detection of resonance frequencies in five such compounds. A summary of the data on all the multichlorobenzenes is presented, including these reported for the first time: 1,2,3-trichlorobenzene; 1,3,5-trichlorobenzene; 1,2,3,4-tetrachlorobenzene; 1,2,3,5-tetrachlorobenzene; and pentachlorobenzene. These data indicate that the chlorine resonance frequency acquires frequency increments approximately proportional to the number of ortho chlorine neighbors. This effect may be interpreted primarily in terms of electron induction away from the resonant chlorine, although out of plane bending and double bond character also affect the resonance frequency. A correlation of the chlorine quadrupole frequencies with the Hammett sigma parameter is also given.
Concerning a Theory of Multilayer Adsorption, with Particular Reference to Adsorbed Helium
Authors: Steele William A.
Published: January 2005

A discussion is given of adsorption systems where the energy of an atom in the second layer is appreciably larger than the energy of an atom in the liquid. It is shown that low temperature films of helium will correspond to this model, rather than the model leading to the B.E.T. equation. It follows that the ``anomalous'' adsorption properties of helium have been inferred from unreal parameters which are a result of the application of the B.E.T. theory. An alternate method of analysis based on a more realistic model is proposed. When a typical case is treated in this manner, reasonable values for the parameters in question result.
Gaseous Detonations. IX. A Study of the Reaction Zone by Gas Density Measurements
Authors: Kistiakowsky G. B. , Kydd P. H.
Published: January 2005

An x-ray absorption photometer capable of measuring gas densities with extreme rapidity and reasonable accuracy has been developed to study the reaction zone in detonation waves. At low initial gas pressures this zone is readily observable as a density peak at the wave front lasting a few μsec.

In general the results agree with the hydrodynamic theory of the detonation wave. The observed densities at the end of the reaction zone (the Chapman-Jouguet state) compare well with the results of approximate equilibrium calculations and the observed shape of the density profile qualitatively confirms kinetic predictions. However, the observed peak densities are substantially lower than expected and the initial chemical reaction rates are faster. The most plausible explanation at present seems to be a lack of equilibration between translational and internal degrees of freedom in the shocked gas, lasting long enough for a substantial progress of the chemical reactions to take place.

The duration of the reaction zone in the mixtures studied is inversely proportional to the initial pressure of the detonating gas. This is true of the stoichiometric mixtures of hydrogen and oxygen which were studied most intensively. On varying the composition of these mixtures it is found that the duration is inversely proportional to the partial pressure of hydrogen and is independent of that of oxygen. An increase of the total pressure by the addition of a rare gas accelerates the reaction. Nitrogen and water vapor act as inert additives.

Replacement of some hydrogen by carbon monoxide does not alter the duration of the reaction zone. On the other hand, when small quantities of hydrogen are added to stoichiometric carbon monoxide-oxygen mixtures, the reaction times are found to vary as PH2—½. The addition of nitrogen has little effect on these mixtures but carbon dioxide proves to be a strong inhibitor.

Methane reacts with oxygen at a rate which is comparable with that observed for hydrogen, while acetylene oxidation is very much faster.
Boltzmann Equation from the Statistical Mechanical Point of View
Authors: Green Melville S.
Published: January 2005

The Boltzmann equation for a spacially uniform situation is derived by the method of expansion of the molecular distribution functions in powers of the concentration. These expansions are shown to imply that after a time which depends on the initial phase space distribution and for configurations in which the molecules are not too widely separated, all the distribution functions are functionals of the single-particle distribution. The single-particle distribution obeys an equation which is a generalization of the Boltzmann equation which includes the effects of triple and higher collisions. The triple collision term is given explicitly.
Molecular Composition of Alkali Halide Vapors
Authors: Miller R. C. , Kusch P.
Published: January 2005

An analysis of the velocity distribution of the molecules which escape through an ideal aperture from an isothermal enclosure has been made for ten alkali halides (CsCl, CsBr, RbCl, KCl, KI, NaF, NaCl, NaI, LiCl, and LiBr). It is found that there is a significant abundance of dimers in all cases except those of the cesium salts, and that an observable concentration of trimers occurs for NaF, LiCl and LiBr. Observation of the relative abundances of the polymers as the temperature of the effusing gas and the pressure within the source is varied permits the determination of the energy of dissociation of the dimer into two monomers and of the trimer into a monomer and dimer.
Tunneling Through High Periodic Barriers. I
Authors: Das T. P.
Published: January 2005

Analytic expressions for tunneling frequencies through high periodic barriers are derived. The expression for wells of threefold symmetry is applied to the analysis of microwave data on CH3SiF3, CH3SiH3, and CH3SiD3 and values of the barrier heights of 1 kcal, 1.5 kcal, and 1.5 kcal per mole, respectively, are obtained, which are in reasonable agreement with previously obtained values.
Reactions of Methane with Iodine Activated by Radiative Neutron Capture. II
Authors: Levey Gerrit , Willard John E.
Published: January 2005

Further experiments have been conducted to clarify the mechanism of the unique reaction whereby I128 freshly formed by the I127(n,γ)I128 process is able to replace hydrogen in methane (I128+CH4→CH3I+H). They show that the yield of CH3I128 is decreased by the presence of the inert gases He, A, and Xe but not to the extent which would be the case if the activation energy for the reaction were supplied solely by kinetic energy of the I128. I2, CH3I, C2H5I, C3H7I and NO, which have lower ionization potentials than that of the I atom are all more effective than the inert gases in reducing the yield. The organic yield of I128 is higher when alkyl iodides are used as the source of iodine than when I2 is used. The ability of the freshly formed I128 to react with C2H6 or C6H6 is much less than with CH4. Reactions of I2 with CH4 sensitized by argon and xenon occur when several hundred mm of the inert gas is present during exposures to 105r or more of gamma radiation.
Intermolecular Potentials of the Inert Gases from Solid State Data
Authors: Zucker I. J.
Published: January 2005

The constants α and β appearing in assumed interatomic energies of the type α/rm—β/r6, m>6, have been calculated for the rare gases for various m, using solid state data only. Using these results the equations of state of these gases in the solid phase have been calculated, and compared with recent experimental data. For neon, m = 14 gave excellent agreement, while for krypton and argon m = 12 gave reasonable agreement with experiment.
Infrared Spectrum of Water Vapor. Part I—The 6.26μ Region
Authors: Dalby F. W. , Nielsen H. H.
Published: January 2005

The absorption spectrum of water vapor has been measured from 5.26μ to 7.14μ. The spectra were observed with a Pfund-type vacuum spectrometer employing a 4500-line-per-inch echelette grating as the dispersing element. Lines separated by intervals of the order of 0.1 cm-1 were resolved. The rotational analysis leads to the following molecular constants for the H2O bending vibration: ν0=1594.78±0.10  cm−1A= 31.200±0.01  cm−1B= 14.679±0.005 cm−1C=  9.150±0.005 cm−1.
Ultrasonic Studies of Saturated Hydrocarbons at Low Temperatures
Authors: Young Jessie M. , Petrauskas A. A.
Published: January 2005

Ultrasonic propagation properties of 2-methylbutane, 3-methylpentane, n-pentane, 2,3-dimethylbutane, and 2,2-dimethylbutane were studied using a pulse method in the range from 1 mc to 35 mc and from 130°K to 280°K. These studies revealed the existence of an attenuation peak in 2-methylbutane, in 2,3-dimethylbutane, and in 3-methylpentane. These peaks were found to be consistent with a single relaxation process. Activation energies for the relaxation process in 2-methylbutane and 3-methylpentane were found to be about 4.7 kcal/M, and about 3.3 kcal/M in 2,3-dimethylbutane. No absorption was observed in n-pentane and 2,2-dimethylbutane. In a mixture of 3-methylpentane and n-pentane, measurements at 5 mc showed an absorption peak at the same temperature as in 3-methylpentane, reduced in amplitude in proportion to the reduction in the number of molecules of 3-methylpentane. These observations indicate that the mechanism of absorption is explainable in terms of a hindered rotation (about the middle C–C bond in butanes and about the 2nd and 3rd C–C bonds in 3-methylpentane), leading to potential minima of unequal values for the different rotational isomeric states. Such asymmetry in the different rotational isomers appears to be an essential requirement for ultrasonic absorption in these molecules.
Electrostatic Contributions to Thermodynamic Functions of Systems Containing Polymeric Ions
Authors: Harris Frank E. , Rice Stuart A.
Published: January 2005

The electrostatic free energy of systems containing polymeric ions has been evaluated using a model which preserves the inhomogeneous charge distribution of the polyion. The method used includes solution of the Poisson-Boltzmann equation with largely the Debye-Huckel approximations. Allowance has been made for the finite volume occupied by the polymer chain, for the ion atmospheres about both fixed and mobile ions, and for the removal of counter ions from the solution by ``site binding.'' A main conclusion of the work is the verification of the previously used postulate that the screened Coulomb potential is a valid first approximation to the potential of mean force between two charges in salt solution. However, it is found that the screening constant differs from that defined in the ordinary Debye-Huckel theory. It is also shown that a polyelectrolyte model using the screened Coulomb potential implicitly includes all ``osmotic'' forces arising from concentration gradients due to the charges. In salt solutions it is found that the small ions are ordinarily distributed in such a manner that the volume of a polyion is nearly electrically neutral, so that the main interactions between polyions are governed by their spatial dimensions rather than by their charge state. The small ions within the coil, referred to as ``volume bound,'' are distinct from the ``site bound'' counter ions introduced previously, and are trapped within the kinetic unit of a polymer only when it is solvent entrapping.
Photoionization and Total Absorption Cross Section of Gases. II. O2 and N2 in the Region 850–1500 A
Authors: Watanabe K. , Marmo F. F.
Published: January 2005

Absorption and photo-ionization cross sections of O2 were measured at a number of wavelengths primarily in the region 850–1100 A by a photoelectric method. The Rydberg bands H, H′, M and M′ were found to be strongly pre-ionized, and vibrational structures in the underlying continuum appeared to be present. The photoionization method gave 12.08±0.01 ev as the first ionization potential of O2. This value, combined with data from emission spectra, yielded a value 6.65 ev for the dissociation energy of O2+ and 16.83 ev for the third ionization potential of O2 (O2+A2Πu←O2X 3Σg-). In the case of N2, a number of ``windows'' were observed and it was not possible to establish the presence of an absorption continuum in the region 850–1100 A.
Theory of Rotational-Vibrational Interaction in Polyatomic Molecules
Authors: Bodi Lewis J. , Curtiss C. F.
Published: January 2005

Group theoretical considerations show that an eigenfunction of the Schroedinger equation for a polyatomic molecule may be written as a sum of products of representation coefficients of the group of three-dimensional rotations and functions which depend only upon the relative configuration of the atoms and hence only upon the normal coordinates. A perturbation solution of the Schroedinger equation is described which is based on zero-order wave functions which are consistent with this group theoretical result. All of the angular momentum operators appearing in the wave equation are shown to be recursion operators in the representation coefficients. Subsequent utilization of the orthogonality of the representation coefficients then leads to a set of coupled differential equations for the functions which depend only on the normal coordinates. This set of coupled differential equations is a generalization of the matrix equations for the rotational motion of a rigid body.

The functions of the normal coordinates are then expanded as sums of products of Hermite functions of the individual normal coordinates. Use of the orthogonality relations of the Hermite functions then yields a set of equations for the expansion coefficients. The eigenvalues of the associated matrix are then, of course, the exact rotational-vibrational energy levels of the polyatomic molecule. These energy levels are obtained approximately by a diagonalization in the rotational quantum numbers followed by a perturbation technique in which the coupling between vibrational levels is assumed to be small (except in the case of degeneracy). The lowest approximation to the energy levels contains terms which may be interpreted as due to coupling effects which in previous solutions appear only in higher order approximations.
Delta-Function Model. I. Electronic Energies of Hydrogen-Like Atoms and Diatomic Molecules
Authors: Frost Arthur A.
Published: January 2005

The electron in a one-electron atom or diatomic molecule is considered to move in one dimension on a line through the nuclei. The potential energy is taken as zero except at the nuclei where it goes to minus infinity as negative delta functions. The exact solution is easily obtained with the wave function accurately expressible as a linear combination of atomic orbitals. In contrast to the free electron model this method handles heteronuclear molecules, does not arbitrarily limit the coordinate, and can predict ionization energies.
Infrared Investigation of Acetic Acid and Acetic Acid-d Vapors and a Vibrational Assignment for the Monomeric Acids
Authors: Wilmshurst J. K.
Published: January 2005

The infrared spectra of acetic acid and acetic acid-d, as vapors at 150°C, have been obtained from 2–25μ and an assignment of the fundamental vibrational frequencies made for the monomeric acids, with the exception of the two low lying type A″ torsional frequencies. Infrared spectra of the two acids, in the vapor phase, have also been obtained over the 5–15μ region at 25°, 65°, 105°, and 150° and the effect of temperature on some of the frequencies discussed.
Energy Levels of the Coaxial Internal Rotator with Rectangular Potential Function
Authors: Halford J. O. , Vidale G. L.
Published: January 2005

For the coaxial internal rotator with rectangular potential function and freely variable valley breadth at constant periodicity, conditions are specified for an infinite number of points at which the borders of consecutive bands of energy levels must be exactly degenerate. As the valley breadth is changed through a degeneracy, the level of one symmetry relative to the potential function moves from the upper to the lower band of energy levels, or vice versa.

It follows that in the rotational region above the potential maximum the levels at the band limits can repeatedly cross and re-cross when the potential maximum is increased with all other factors constant.

Similar behavior will presumably occur with other potential functions.
Light Scattering by Glasses
Authors: Maurer R. D.
Published: January 2005

Previous light scattering investigations have shown that glasses contain inhomogeneities other than density fluctuations from room temperature agitation. These inhomogeneities were investigated by measuring the scattering by several types of commercial optical glass. For most glasses the angular variation of intensity was the same as scattering by a distribution of randomly oriented, anisotropic centers that are small compared to a wavelength of light. This is the same angular variation found for liquids. The scattered intensity was changed by annealing, showing that the inhomogeneities originate with the frozen liquid state. The data may be explained by assuming that the inhomogeneities are principally thermal fluctuations in the liquid which are frozen into the glass at high temperatures.
X- and γ Irradiation of Ferrous Sulfate in Dilute Aqueous Solution
Authors: Haybittle J. L. , Saunders R. D. , Swallow A. J.
Published: January 2005

The yield for the x- and γ-ray induced oxidation of ferrous ions in acid aqueous solution has been determined for x- and γ rays of effective mean energies from 21 kev to 7.6 Mev. For 60 kvp x-rays of effective mean energy, Ē, 21 kev, G=13.1±0.5 ferric ions produced per 100 ev absorbed; for 100 kvp x-rays (Ē=33 kev) G=14.7±0.5; for 220 kvp x-rays (Ē=56 kev), G=15.0±0.5; for Co60 γ rays (Ē=1.25 Mev), G=15.5±0.5; and for 30 Mev x-rays (Ē=7.6 Mev), G=16.3±0.6. In each case the energy absorbed in the solution was estimated by means of an ionization chamber.
Stability and Burning Velocities of Laminar Carbon Monoxide-Air Flames at Pressures up to 93 Atmospheres
Authors: Edse Rudolph , Strauss William A.
Published: January 2005

Bunsen-burner flames of carbon monoxide-air mixtures were investigated at ambient pressures up to 93 atmos. The experiments show that the critical velocity gradients at the burner tube wall for flash-back increase with pressure whereas the burning velocities decrease when the pressure is raised. However, in a previous investigation it was found that the burning velocities of hydrogen-oxygen flames increase with pressure. It is concluded that the burning velocities of carbon monoxide-air flames decrease with rising pressure because the rate of diffusion of active particles into the unburned gas is reduced with pressure while no increase in heat transfer occurs. In hydrogen-oxygen flames the rate of heat transfer increases because the flame temperatures are higher at elevated pressures because of the reduction in the degree of dissociation.
Out-of-Plane Force Constants of Benzene
Authors: Kakiuti Yuzo , Shimanouchi Takehiko
Published: January 2005

The out-of-plane force constants were calculated from the out-of-plane frequencies of C6H6, C6D6, and sym.-C6H3D3 molecules with the use of the least square method recently developed. The 45 frequencies of C6H6, C6D6, sym.-C6H3D3, p-C6H4D2, p-C6H2D4, and C6H5D molecules calculated from five force constants obtained are in good agreement with the observed, with the maximum and the mean deviations of 2.8 and 1.35%, respectively.
On the Theory of Electrolytic Crystal Growth
Authors: Vermilyea D. A.
Published: January 2005

Equations are developed for the current as a function of applied voltage during electrolytic solution or deposition at surfaces which are perfect, atomically rough, or smooth except for the steps of screw dislocations. It is shown that the surface structure does not influence the rate of deposition if the overvoltage is sufficiently high and the time long enough, the rate determining step being ionic discharge. At low overvoltages and short times, however, the surface structure plays a decisive role in determining the deposition rate. Changes in the surface configuration during growth, such as the change from a straight to a spiral dislocation step, lead to transient effects at the start of deposition or solution.
Contribution of Other than Next Neighbors in Energy Calculations for Non-Ionic Liquids and Solids
Authors: Crowell A. D.
Published: January 2005

The energy of interaction of an interior atom of a solid or liquid with the remainder of the atoms present is represented as consisting of two terms: (1) the interaction with Z next neighbors, and (2) the interaction with a uniform distribution of matter for the remainder of the atoms. If it is assumed that the energy of interaction between any pair of atoms in the solid or liquid can be written in the form kr—6, it is shown that the contribution from other than next neighbors is equivalent to the interaction with one more next neighbor. As an application of this result, the corrections to the results obtained for the solid-liquid interface tension at the melting point by the next-neighbor approach are calculated.
Theoretical Investigation of Vibrational Frequency Distributions for Molecular Crystals Having the Cyanogen Iodide Structure
Authors: Walnut Thomas H.
Published: January 2005

Frequency distributions are determined for a molecular stretching vibration band in a cyanogen iodide lattice. The eigenfrequencies of the vibrational problem are calculated with first order perturbation theory. Distributions for possible reasonable sets of coupling constants are determined. The behavior of the distributions near extremal values are computed by the method of van Hove. The behavior of the distributions between extremal values is obtained by interpolation based on a qualitative examination of the eigen-frequencies as a function of wave-number vector.
Matrix Isolation Studies: Infrared Spectra of Intermediate Species in the Photolysis of Hydrazoic Acid
Authors: Becker Edwin D. , Pimentel George C. , Van Thiel Mathias
Published: January 2005

The matrix isolation method has been used to investigate the photolysis of hydrazoic acid (HN3) suspended in xenon, argon, and nitrogen matrices at 20°K. Infrared spectra of the photolyzed material in argon and nitrogen matrices show absorption bands of NH3 and a number of other prominent spectral features that are probably due to unstable molecules, including intermediates in the formation of NH3. In a xenon matrix no new bands are observed on photolysis of HN3 at 20°K, but the presence of the imine radical (NH), or of nitrogen and hydrogen atoms, is inferred from the formation of NH4N3 when the material is warmed to 70°K. The mechanism of photolytic production of radicals in a matrix is examined, and the probable importance of the heat of fusion of the matrix is discussed. The utility of the matrix isolation technique in the infrared study of unstable reaction intermediates is demonstrated.
Vaporization Coefficient of Graphite and Composition of the Equilibrium Vapor
Authors: Thorn R. J. , Winslow G. H.
Published: January 2005

Direct comparisons of the rates of evaporation and of effusion from a Knudsen cell yield a value of about 0.15 for the vaporization coefficient of graphite. The absolute effusion rates, taken together with other data, not only confirm the existence of triatomic carbon in the equilibrium vapor but permit the evaluation of the thermodynamic properties of the triatomic vapor. In the region of 2400°K the vapor pressure of the triatomic form is logp3(atmos)=−40296.0T+9.811which yields 184.4 kcal/mole for the heat of sublimation and 77.41 eu for the entropy of C3. This value for the heat agrees with that obtained in mass spectrometric measurements by Chupka and Inghram. The partial pressures at 2400°K of C1, C2, and C3 are 4.29×10—8, 1.13×10—8, and 1.05×10—7 atmos respectively. A comparison with the mass spectrometric data yields 2.7 for the ratio of the ionization cross section of C3 to C1 and values of 0.37, 0.34, and 0.08 for the individual vaporization coefficients of C1, C2, and C3 respectively. The vapor pressure equations used to determine the amount of monatomic and diatomic carbon in the equilibrium vapor are discussed.
Theory of Internal Over-All Rotational Interactions. IV. Stark Effect in Nonrigid Internal Rotors
Authors: Kivelson Daniel
Published: January 2005

When a uniform electric field is applied to a nonrigid internal rotor, the ``Stark pattern'' of the energy levels is dependent upon the torsional motion. This dependence enters as a centrifugal distortion interaction and by means of the so-called ``repulsive effect'' of the potential barrier to internal rotation. These effects are small but observable and require that appropriate corrections be made in order to obtain an accurate and meaningful dipole moment from Stark effect measurements. The theory of the Stark effect in vibrating internal rotors has been formulated in this article with particular emphasis on its application to a molecule of C3v symmetry such as CH3SiH3. Krongelb and Strandberg have observed this effect in CH3SiH3.
Simple Molecular Orbital Treatment of Conjugation in Chlorobenzene
Authors: Howe John A. , Goldstein J. H.
Published: January 2005

Simple molecular orbital theory, with inclusion of overlap, has been used to calculate the electron distribution and energy levels in chlorobenzene. Spectroscopic parameters were used, supplemented by the value of βCCl previously obtained from quadrupole coupling data for vinyl chloride. Resonance dipole moments were also calculated for chlorobenzene and vinyl chloride. The results are in reasonable agreement with the observed dipole moment decreases and ionization potential shifts, assuming these to be chiefly brought about by conjugation.
Dislocations as ``Active Sites'' in Heterogeneous Catalysis
Authors: Cratty Leland E. , Granato Andrew V.
Published: January 2005

Experiments on the dependence of catalytic activity of nickel foils as a function of deformation and annealing are interpreted as evidence that dislocations are active sites in heterogeneous catalysis.
Vibrational Spectra, Potential Constants, and Calculated Thermodynamic Properties of cis- and trans-BrHC=CHBr, and cis- and trans-BrDC=CDBr
Authors: Dowling Jerome M. , Puranik P. G. , Meister Arnold G. , Miller Sidney I.
Published: January 2005

Raman displacements for the liquid and infrared absorption wave numbers for both liquid and gas, together with quantitative depolarization factors for the Raman lines and semiquantitative relative intensities for both Raman and infrared bands, have been obtained for cis- and trans-BrHC=CHBr and cis- and trans-BrDC=CDBr. Assignments, consistent with the selection rules, were made for the 4 molecules. As a further check on the assignments a normal coordinate treatment (Wilson FG matrix method) was carried out. The heat content, free energy, entropy, and heat capacity for each of the molecules were calculated for 12 temperatures from 100 to 1000°K for the ideal gaseous state at 1 atmos pressure. Finally the energy difference between the cis- and trans-isomers of C2H2Br2 has been calculated.
Microwave Determination of the Structure of Trifluorobutyne
Authors: Bak Bo/rge , Christensen Daniel , Hansen-Nygaard Lise , Tannenbaum Eileen
Published: January 2005

The microwave spectrum of the symmetric tops, CF3C≡C–CH3 and CF3C≡C–CD3, has been investigated. Excited vibrational state transitions were observed, but the l-type doublet fine structure was not resolvable. Since lines originating from species containing C13 in natural abundance were identified, only two assumptions were necessary in order to determine the 7 structural parameters. The parameters giving the best fit with the experimental data are: d(C,F) = 1.340, d(C(1), C(2)) = 1.455 = d(C(3), C(4)), d(C(2), C(3)) = 1.189, and d(C,H) = 1.097 A and the angles ∠F–C–F = 106°08′ and ∠H–C–H = 108°30′.
Infrared Absorption Spectra of Urea, Thiourea, and Some Thiourea-Alkali Halide Complexes
Authors: Stewart James E.
Published: January 2005

The infrared absorption spectra of urea, thiourea, and thiourea complexes with cesium bromide, potassium iodide, potassium bromide, sodium bromide, and sodium iodide have been observed from 2 to 40 μ, except for the sodium iodide complex which was studied between 2 and 15 μ. The vibrations of urea and thiourea are assigned on the basis of a planar C2v structure.
Spectra of Urea and Thiourea in the 3μ Region
Authors: Badger Richard M. , Waldron Robert D.
Published: January 2005

Observations are reported on the polarized infrared spectra of single crystals of urea and thiourea in the 3μ region. Complex structures accompanying the N – H fundamentals appear, at least in considerable part, to be attributable to combinations and overtones of fundamentals in the neighborhood of 1650 cm—1.
Calculation of Compressibilities of High Polymers from the Energy of Interaction between Chain Groups
Authors: Brandt Werner
Published: January 2005

A potential function for the interaction of long chain molecules in polymer lattices is formulated. The adopted model assumes polymeric substances to consist of imperfect assemblies of perfect chain crystals. The chains are infinitely long compared to the range of intermolecular forces so that end effects can be neglected. Each chain is composed of evenly spaced dipolar dispersion force centers, with dipole orientations perpendicular to and alternating along the chain axes. Pairs of force centers in neighboring chains interact according to a Lennard-Jones (12–6) potential and the electrostatic interaction terms. The interaction between neighboring force centers within a chain is assumed to be Hookian with a force constant calculated from combined valence bond distortions and valence angle deformations.

The lattice energies of five linear polymers are calculated. It is found that the contributions from induction terms are negligible. The contributions from dipole interaction terms depend on the mutual orientation of the chains and amount to only ca 0.1–1% of the lattice energies. To this accuracy, certain ``structure insensitive'' properties can be described by an equation of corresponding intermolecular states. This approach is shown to fail, if applied to ``structure sensitive'' properties, which depend strongly on the interplay of inter- and intramolecular degrees of freedom. Absolute calculations of specific polymer volumes over large pressure ranges are in agreement with experiment.
Atomic Scattering Factors Calculated from the TFD Atomic Model
Authors: Thomas L. H. , Umeda K.
Published: January 2005

Using the TFD electron density, recently published by one of us (T), the atomic scattering factor f0 has been calculated for neutral atoms as well as for singly through quadruply ionized positive ions with intermediate atomic numbers on the IBM 607 and 650. The f0 values thus obtained for Ar and Cu+ agree qualitatively with those calculated from the Hartree-Fock fields recently by MacGillavry et al. The experimental fact has been again confirmed, that the f0 value is not much influenced by the state of ionization. The effect of exchange has been displayed by the deviation of the TFD curve of the atomic scattering factor per electron f0 versus the Bethe variable ξ, from the TF universal curve. The TFD curve of f0 versus Z for a definite state of ionization has a slight minimum at a certain value of Z which increases with decreasing scattering angle and tends finally at vanishing scattering angle to a definite limiting value just corresponding to the maximum of 〈r2〉Av.
Ionization and Dissociation of Hexafluorobenzene by Electron Impact
Authors: Dibeler Vernon H. , Reese Robert M. , Mohler Fred L.
Published: January 2005

Mass spectra and appearance potentials are presented for the principal positive and negative ions of hexafluorobenzene along with comparative data for benzene. Although complete analysis of bond dissociation energies is prevented by lack of thermochemical data, the C–F bond is estimated to be 145 kcal. Qualitatively, the results indicate that C6F6 is thermally more stable than C6H6 and is a relatively stable configuration in the presence of ionizing radiation.
Lifetime Measurements of Metastable States in Molecular Nitrogen
Authors: Lichten William
Published: January 2005

The molecular beam method for the measurement of the lifetime of metastable states has been improved by the introduction of differential pumping, control of the energy of the bombarding electrons, and use of a movable detector.

A lower limit of 10—2 sec is obtained for the lifetime of the A 3Σu+ state of N2, in closer agreement with spectroscopic observations than the previous work of Muschlitz and Goodman.

The measured value of the lifetime of the a 1IIg state of N2 is (1.7±0.3)×10—4 sec.

Some new observations on metastable states of the rare gas atoms, A, Kr, and Xe; CO and H2 are mentioned briefly.
Third Virial Coefficient for Intermolecular Potentials with Hard Sphere Cores
Authors: Alder B. J. , Pople J. A.
Published: January 2005

A general method is described for evaluating the third virial coefficient for any intermolecular potential in which the interaction varies as a sum of inverse powers of the distance outside a hard-sphere core. The calculations involve only simple algebraic operations and can be extended to include angular dependent potentials, quantum effects, and mixtures of molecules. An illustrative calculation on a modified Lennard-Jones potential shows the dependence of the third virial coefficient on the repulsive forces.
Reaction Products of γ Picoline and Iodine
Authors: Glusker Donald L. , Miller Arthur
Published: January 2005

From the reaction products of γ picoline and iodine two distinct addition compounds have been isolated and studied by chemical, spectroscopic, and x-ray radial distribution methods. The second of these compounds to be isolated is an intermediate in the formation of the first, and is analogous to the addition compound of pyridine and iodine prepared by many workers. The x-ray radial distribution analysis of the first compound showed that the covalent bond in the iodine molecule had been broken, and the corresponding analysis of the second compound showed that the covalent bond was still present. A mechanism has been postulated for the reaction of the second compound with excess γ picoline to form the first compound.

The applicability of the Geiger counter x-ray diffractometer to the radial distribution method is discussed, and the theory for the radial distribution analysis of diffraction data consisting of discrete peaks is presented.