bluuebunny/crossref_metadata_2025 huggingface dataset:
An Asymptotic Expression for the Energy Levels of the Rigid Asymmetric Rotor
Authors: Golden S.
Published: January 2005

The energy matrix of the rigid asymmetric rotor, evaluated in terms of symmetric rotor wave functions, has been examined under conditions where J is increased indefinitely. Asymptotically, the energy matrix assumes a form that is very much like the matrix that may be obtained from the characteristic value problem of Mathieu's differential equation. The characteristic values of Mathieu's equation serve as the basis for a good approximation to the energy values of those asymmetric rotor levels which, for a given, large value of J, correspond to a small value of K in the limiting symmetric cases. The differences which exist between the two matrices are accounted for by a perturbation technique which permits an accurate determination of the energy values.

When the characteristic values of Mathieu's equation lead to a successful approximation to the energy values of the asymmetric rotor, an estimate may be made of the asymmetric rotor wave functions.
Force Constants and Frequency Assignments for Some Substituted Methylacetylenes
Authors: Meister Arnold G.
Published: January 2005

Force constants have been determined for methylacetylene using the Wilson FG matrix method. It was found that of the thirteen force constants required for the potential energy function for methylchloroacetylene, methylbromoacetylene, and methyliodoacetylene, eight could be transferred from the set obtained for methylacetylene. Since only four of the ten fundamental frequencies of the methylhaloacetylenes were used in establishing the force constants, all the frequencies were calculated to see if the sets of force constants for the methylhaloacetylenes were reasonable. With the exception of one frequency, the agreement between the calculated and observed values was within two percent. As the calculations served to identify the fundamental frequencies for the methylhaloacetylenes, it was found that previous assignments by Cleveland and Murray of the observed Raman frequencies for methylbromoacetylene and methyliodoacetylene had to be modified. New assignments are given for some of their observed values for these two molecules and assignments also are given for their observed Raman frequencies for a solution of methylchloroacetylene in ethylbromide for which they made no assignments. The fundamental frequencies for methyldeuteroacetylene also were calculated using the same force constants, interbond angles, and equilibrium values for the bond distances as for methylacetylene, in order to determine how a pure mass change affects the frequencies of methylacetylene. As a result of this investigation the C–C and C≡C stretching frequencies were found to be greater for the methylhaloacetylenes than for methylacetylene or methyldeuteroacetylene. The C — X (X = halogen atom) stretching frequencies for the methylhaloacetylenes were found to be less than for the corresponding methyl halides despite the fact that the C — X stretching force constant for the methylhaloacetylenes always was greater than for the corresponding methyl halides.
The Transport Properties for Non-Polar Gases
Authors: Hirschfelder Joseph O. , Bird R. Byron , Spotz Ellen L.
Published: January 2005

Chapman and Cowling have related the coefficients of viscosity, diffusion, thermal diffusion, and heat conductivity to a set of integrals, Ωn(l)(T) involving the law of force between pairs of molecules. We have evaluated these integrals for l=1, n=1, 2, 3; l=2, n=2, 3, 4, 5, 6; l=4, n=4, assuming that the energy of attraction is inversely proportional to the sixth power of the separation and the energy of repulsion is inversely proportional to the twelfth power. This assumption is excellent for spherical non-polar molecules and a big improvement on the Sutherland assumption. The mathematical analysis was very difficult but the results are simple. The transport integrals are evaluated for all temperatures in terms of the maximum energy of interaction and the collision diameters. This gives a ``corresponding states'' relationship which should apply to extremely hot and extremely cold temperatures where good experimental data are not available. The molecular constants can be obtained very accurately from experimental viscosity data, and they agree with values previously obtained from equation of state data.
The Energy of the C–H Bond in the Three Picolines (Methyl Pyridines)
Authors: Roberts J. S. , Szwarc M.
Published: January 2005

The pyrolysis of the three picolines was investigated and the rates of the decomposition were compared with the rate of the decomposition of toluene. It was found that the process of the decomposition of the picolines is analogous to that of toluene, i.e., the rate determining step is the splitting of the picoline molecule into H atom and a picolyl radical. Comparison of the decomposition rates of the picolines and of toluene made it possible to calculate the C–H bond energy for these compounds. These were estimated at 75.5 kcal./mole for α-picoline, 76.5 kcal./mole for β-picoline, and 77.5 kcal./mole for γ-picoline. It was concluded therefore that the resonance energy of the picolyl radical approximates within a few kcal. the resonance energy of the benzyl radical.
The Vapor Pressures of Some Alkali Halides
Authors: Cogin Geraldine E. , Kimball George E.
Published: January 2005

The vapor pressures of six alkali halides, NaBr, NaI, KI, CsCl, CsBr, and CsI, have been measured in the range from about 10−4-mm to 0.1-mm pressure. The measurements were made by the diffusion method, using an oxygen-coated tungsten filament as detector.
Fugacity Determinations of the Products of Detonation
Authors: Cook Melvin A.
Published: January 2005

By employing the equation of state derived from the hydrodynamic theory and observed detonation velocities, the thermodynamic equilibrium constant Kp(T) is derived in terms of the concentrations of the various gases comprising the products of detonation and the covolume α(v), which may be evaluated for any known or assumed density of the products of detonation. A reiteration method is developed for solving simultaneously as many equilibria as is necessary to define completely the composition of the products of detonation. The application of the theory is illustrated by calculations for TNT which are compared with experimental data as well as results obtained from the approximate partial pressure method. Calculations are presented for several additional explosives.
The Scattering of Light and the Radial Distribution Function of High Polymer Solutions
Authors: Zimm Bruno H.
Published: January 2005

A radial distribution function of polymer segments in a solution of a high polymer may be defined as a quantity proportional to the density of segments at a given distance from some given segment. An approximate expression is derived for this function for dilute solutions of chain molecules of moderate degrees of polymerization. By Fourier inversion a simple expression for the intensity of light scattering, as a function of angle and concentration, may be obtained.
Infra-Red Christiansen Filter Effect in Slurries of Organic Crystals
Authors: Price W. C. , Tetlow K. S.
Published: January 2005

The Christiansen filter effect in slurries of organic crystals is reported for the first time, in the infra-red. The main difference between the effect in molecular and in ionic crystals is that the Christiansen (transmission) peak and the ``Reststrahlen'' (reflection) peaks are much closer together for organic crystals since they are produced by a single frequency instead of a wide band of lattice frequencies. The Christiansen effect is much more selective in organic crystals since it occurs for some bands but not for others. This is thought to be due to the nature of the coupling between the particular vibration and the atoms or groups in the molecule which make major contributions to the polarizability.
Time-Dependence of Surface Tension of Solutions
Authors: Blair Charles M.
Published: January 2005

The slow rate of change of surface tension observed by Addison with aqueous solutions of fatty alcohols cannot be explained by diffusion alone. It is assumed that the adsorption of non-electrolyte solutes in the surface film is opposed by a constant potential energy barrier, and, on this basis, a relation between spreading pressure and surface age is developed. With the resulting equation, the experimental data of Addison are employed to evaluate the energy term. Nearly constant values for the assumed barrier are obtained, the actual calculated values, in calories per mole at 20°C, being about 1900 for isoamyl alcohol, 1300 for n-hexyl alcohol, and 700 for n-heptyl alcohol. A second relation between spreading pressure and surface age is derived on the assumption that the energy barrier is a linear function of spreading pressure. The use of Addison's data for isoamyl alcohol in this relation indicates that the spreading pressure-dependent portion of the barrier is small and of the same order of magnitude as the energy required to compress the surface film sufficiently to admit the entering solute molecule.
Indirect Measurement of Spectral Line Breadth in the Infra-Red
Authors: Thorndike A. M.
Published: January 2005

If infra-red absorption by a sample gas is measured at low resolution in the presence and absence of pressure broadening by a non-absorbing gas, information may be obtained concerning breadth and fine structure of individual rotational lines. Data on 590—cm−1 and 1285-cm−1 bands of N2O indicate self-broadening coefficients of about 0.21 and 0.13 cm−1 per atmosphere, respectively. These values may be compared with 0.20 cm−1 per atmosphere obtained by Adel and Barker by direct measurement on the 590-cm−1 band.
Ultraviolet Absorption Spectrum of Hydrogen Peroxide
Authors: Holt R. B. , McLane C. K. , Oldenberg O.
Published: January 2005

The absorption coefficient for hydrogen peroxide vapor in the wave-length range 1850–2200A was determined. A careful redetermination of the absorption coefficients for the vapor and for aqueous solutions at 2537A was also made.
Simple Expressions for the Heat Capacities of Gases
Authors: Crawford Bryce L. , Parr Robert G.
Published: January 2005

A table of constants is given whereby one may at once write down, knowing the vibrational frequencies, the best approximation of the form Cpo = A0+A1T+A2T2 to the heat capacity of a gas with translational, rotational, and vibrational (harmonic) degrees of freedom.
A New Method of Preparing Strongly Luminescent Thallium Activated Alkali Halides and Some Properties of These Phosphors
Authors: Hutten E. Hirshlaff , Pringsheim Peter
Published: January 2005

Phosphors with a bright visible fluorescence and a long lasting afterglow can be prepared by grinding potassium chloride with small amounts of a thallous salt in a mortar. The character of the luminescence spectra and the phosphorescence decay depends on the thallium concentration. The behavior of other alkali halides under the same treatment and some conclusions concerning the probable carriers of the luminescence are discussed.
An Asymptotic Expression for the Energy Levels of the Asymmetric Rotor. II. Centrifugal Distortion Correction
Authors: Golden S.
Published: January 2005

It has been found possible to develop perturbation operators for the centrifugal distortion terms that permit an approximate evaluation to be made of their contribution to the asymmetric rotor energy levels for large values of J. The procedure is based upon the asymptotic (J→∞) similarity between the matrices of the asymmetric rotor and that obtained from Mathieu's differential equation.
The Heat Capacity of Nitrogen Adsorbed on Titanium Dioxide Between 20°K and 80°K
Authors: Morrison J. A. , Szasz G. J.
Published: January 2005

A low temperature adiabatic calorimeter suitable for thermal measurements on adsorbed gases has been developed. Heat capacity values for two amounts of nitrogen adsorbed on titanium dioxide (rutile) are presented. While the measurements were complicated by the appearance of warm drifts in the calorimeter over part of the temperature range when nitrogen was present, it appears that at the concentrations used the adsorbate was present as a condensed phase.
Internal Molecular Motions of Large Amplitude Illustrated by the Symmetrical Vibration of Ammonia
Authors: Newton R. R. , Thomas L. H.
Published: January 2005

A general method is developed for separating slow internal motions of molecules from their rapid vibrations, with the rotational motion. The zero approximation for the slow motion can be obtained by Schrödinger's rule from the classical motion in which the rapid vibrations are replaced by constraints.

The theory is applied to the symmetrical double-minimum vibration of ammonia, the combined vibration-rotation energy levels being evaluated as characteristic numbers of a Sturm-Liouville equation in one variable. The microwave absorption frequencies of N14H3 and N15H3 are computed, also the pure rotation frequencies in the far infra-red.
Nuclear Resonance Absorption in Hydrated Crystals: Fine Structure of the Proton Line
Authors: Pake G. E.
Published: January 2005

Fine structure has been observed in the nuclear paramagnetic resonance absorption line for protons in crystalline hydrates. The magnetic field of 6820 gauss was provided by a permanent magnet, the inherent stability of which facilitated detailed study of line shape. Measurements on a single crystal of CaSO4·2H2O show a splitting into four component lines with maximum separation varying from zero to 22 gauss, depending upon the direction of the externally applied magnetic field in the crystal. Both the number of component lines and the dependence of their spacing on field direction are calculated by treating the magnetic dipole-dipole interaction as a perturbation of the proton two-spin system within the water molecule; the effect of the more distant protons, neglected in this calculation, gives a finite width to the component lines. Variation of the splitting with field direction determines the orientation of the line joining protons in the water molecule, which is found to be consistent with positions ascribed to hydrogen nuclei in the lattice through simple considerations of chemical bonding. The distance between protons in the water molecule is measured by the splitting to be 1.58A for CaSO4·2H2O; if one assumes an H–O–H bond angle of 108°, the O–H distance is 0.98A. Powdered hydrates show a characteristic fine structure arising from isotropic distribution in solid angle of single crystal granules. This type of fine structure determines the proton-proton distance somewhat less accurately than does the single crystal experiment.
The Conductance of Sodium and Potassium Chlorides in 50-Mole Percent Methanol-Water Mixtures
Authors: Schiff H. I. , Gordon A. R.
Published: January 2005

The conductance of NaCl and KCl in 50-mole percent methanol-water mixtures has been measured at concentrations from 0.0005 to 0.01 N. The data can be represented within experimental error by the Onsager-Shedlovsky equation, the limiting conductances being 66.62 and 75.10, respectively. The limiting conductances of chloride ion, obtained from these values, and the limiting transference numbers reported in the accompanying paper, satisfy the rule of independent ionic mobilities, but at finite concentrations the chloride ion conductance is less for the potassium salt than for the sodium. The decrease in limiting ion conductances as compared with those in water is greater than can be accounted for by viscosity alone. The results are also in disagreement with the Bjerrum theory of ion pair formation if the mean ionic diameter, determined thermodynamically, is significant in transport processes.
The Reaction of Hydrogen Atoms with Some Oxygen-Containing Organic Compounds
Authors: Trost W. R. , Darwent B. deB. , Steacie E. W. R.
Published: January 2005

The reactions of atomic hydrogen, produced by a discharge, with methyl ether, acetaldehyde, and ethylene oxide have been investigated.

The main products of the reactions are: from methyl ether—CH4,CO,H2O,C2H6, and HCHO;from acetaldehyde—CH4,CO, and C2H6;from ethylene oxide—CH4,CO, and CH3CHO.

The mechanisms of the reactions are discussed in detail and it is concluded that the primary reactions are: H+CH3OCH3→H2+CH3OCH2E=7.0 kcal.H+CH3CHO →H2+CH3COE≤6.0 kcal.H+(CH2)2O  →H2+C2H3OE=8.5 kcal.,and that the main secondary reactions in all cases are of the atomic cracking type: H+CH3OCH2→CH3+CH3O,H+CH3CO   →CH3+CHOor    →CH4+CO,H+C2H3O   →CH3CHOor    →CH4+CO.
A Simplified Method for Computing the Equilibrium Composition of Gaseous Systems
Authors: Krieger F. J. , White W. B.
Published: January 2005

A simplified procedure is described for computing, either manually or by means of punched cards, the equilibrium composition of a gaseous system of any degree of complexity. The method presents a system of n equations in n unknowns in such a form that each of the major components is given as a linear expression of the minor components only, while the logarithm of each of the minor components is given as a linear expression in terms of the free energy change for the dissociation reaction which defines the minor component and the logarithms of the major components and the total pressure. An iteration process then gives an exact solution with a rapidity which decreases as the fuel-oxidant mole ratio approaches the stoichiometric value.
The Mercury Photosensitized Reactions of Ethane
Authors: Darwent B. deB. , Steacie E. W. R.
Published: January 2005

The effect of pressure on the initial stages of the mercury photosensitized reactions of ethane has been investigated at room temperature. The production of methane increases with decreasing ethane pressure and is inhibited by the presence of molybdenum oxide. It has been shown that hydrogen atoms are produced in the initial stages of the reaction. It is concluded that the initial step is a C–H split and that an active ethane molecule is not formed. The dependence of quantum yields on pressure indicates that the initial step is about 100 percent effective and that inefficiency is caused by recombination of H and C2H5 resulting in the formation of ethane at high pressures by deactivation, and in the formation of methyl radicals at lower pressures.
The Temperature Coefficient of the Surface Tension of Liquid Metals
Authors: Skapski Adam S.
Published: January 2005

The author's approach is based on the conception of ``structure'' of liquids. From rather simple assumptions about the symmetry of configuration of the nearest neighbors the entropy change connected with bringing up N-Avogadro's atoms from the bulk of the liquid into its free surface is estimated and the temperature coefficient of the surface tension is calculated therefrom.

Two entropy terms are taken into consideration. The first term ΔSosc is due to the difference in the frequency of oscillation of the atom inside and on the surface, and is calculated from the respective number of neighbors. This term allows the calculation of the lower limit of the temperature coefficient of the surface tension (because the ``unsharpness'' of the free surface is not accounted for). The second term allows us to estimate—again from the number of the nearest neighbors in the bulk and on the surface—the maximal value ΔSconf, to account for the ``unsharpness'' of the surface.

The experimental data lie well within the calculated limits and almost coincide with the values calculated from (ΔSosc+½ΔSconf)/A where A is the surface occupied by N-Avogadro's atoms. The influence of the thermal expansion is expressed by the change of A with temperature.
The Fluorescence of Acetone Vapor1
Authors: Luckey George W. , Duncan A. B. F. , Noyes W. Albert
Published: January 2005

The ``blue'' fluorescence of acetone vapor has been photographed with a large Littrow-type spectrograph giving a dispersion of about 16A/mm in the range used. Numerous bands having a roughly uniform spacing of about 122±10–15 cm−1 have been observed and their frequencies determined. Certain suggestions are made concerning the vibration analysis, but neither a detailed analysis nor a discussion of the relationship of these bands to the absorption spectrum is justified at present. The existence of structure in this fluorescence shows that it is unnecessary to assume that dissociation of the molecule accompanies the emission of fluorescent radiation. On the other hand, the existence of structure cannot be taken to prove the absence of dissociation following the emission process.
Thermodynamic Properties of the Internal Rotator. Double Minimum with Repulsive Forces
Authors: Halford J. O.
Published: January 2005

The basis for calculating the thermodynamic properties of the unsymmetrical internal rotator from energy levels derived from the old quantum theory is described, and a method is outlined for calculations with a potential energy function consisting of linked sections of cosine curve with the width of each section proportional to the barrier height. A table of values of a general quantum number index for the cosine function is presented and its application to the unsymmetrical internal rotator is illustrated. Thermodynamic properties are calculated for a double minimum system of optical isomers for which the forces restricting rotation must be repulsive. It is found that the entropy of such a system may be greater by nearly 0.5 unit than that of the limiting system with equal potential maxima, that is, with the symmetrical cosine potential function.
Vibrational Spectrum and Thermodynamic Properties of Uranium Hexafluoride Gas
Authors: Bigeleisen Jacob , Mayer Maria Goeppert , Stevenson Peter C. , Turkevich John
Published: January 2005

The Raman spectra of liquid UF6 and of UF6 dissolved in C7F16 have been photographed. Three Raman lines are found for UF6 at 200, 511, and 656 cm−1. The infra-red spectrum of the gas has been obtained in the region between 2 and 17μ. A vibrational assignment of all the fundamental frequencies is made on the basis of the regular octahedral model. The calculated infra-red active overtones are in good agreement with experiment. Using 2.0A as the U–F distance from electron diffraction measurements, the entropy, heat capacity and — (F° — E0°/T) are calculated from 100°K to 1000°K for the gas. The calculated and experimental entropies are in good agreement.
Infra-Red Emission Spectra of Hot Liquids
Authors: Kapff S. F.
Published: January 2005

When a liquid is heated as a thin film, specific infra-red emission bands are observed, most of which are of the same wave-length as the absorption bands of the material. These emission bands are rapidly obscured by the background radiation as the thickness of the film is increased. The optimum sample thickness is of the order of 0.001 inch with most of the bands being obscured at thicknesses of 0.010 inch. The intensity of any band increases with temperature in accordance with the equation N1=N0e−E/RT. The value of E calculated from this equation has been found to agree in most cases with that calculated from the wave-length of the emission band. Certain bands have been observed which are not equivalent in emission and absorption. It has been tentatively suggested that these may be explained on the basis of overtone and combination bands.
The Ultraviolet Absorption Spectrum of Benzonitrile Vapor
Authors: Hirt Robert C. , Howe John P.
Published: January 2005

The ultraviolet absorption spectrum of benzonitrile vapor has been investigated, and many of the observed bands have been accounted for in terms of ground and excited state frequencies. The data obtained were compared with the data available from infra-red absorption spectra, the Raman effect, and early work on ultraviolet absorption spectra. The spectrum of benzonitrile vapor was shown to resemble closely the spectra of other monosubstituted benzenes, particularly in the spacing of the excited state bands from the zero-zero band.
Energy of H3+ and H3 by the Method of Molecular Orbitals
Authors: Pearson Ralph G.
Published: January 2005

A calculation of the energies of H3+ and H3 using MO's approximated as linear combinations of 1 S hydrogenic orbitals is made. The energy of H3+ is found to be −139 kcal. in good agreement with previous calculations and with the prediction of the crude MO method. The energy of H3, however, is higher than the energy of three separated H atoms in disagreement with experiment and the prediction of the crude MO method. The poor form of the second MO is blamed for the discrepancy, different effective nuclear charges being needed for the two MO's, or for different nuclei.
Sound Absorption and Velocity in Liquefied Argon, Oxygen, Nitrogen, and Hydrogen
Authors: Galt J. K.
Published: January 2005

The pulse method has been applied to measure the velocity and absorption of sound in liquefied argon, oxygen, nitrogen, hydrogen at 44.4 Mc/sec. The experimentally determined attenuation (α) is compared with the calculated attenuation due to viscosity (αvis) and the results indicate that relaxation processes are not an important mechanism for sound absorption in any of these gases, except perhaps for hydrogen. Measurements were also made at 14.8 Mc/sec., but the attenuations were too low for satisfactory precision. Indications, however, are that the attenuation varies as the frequency squared.
Nuclear Chemistry of Tellurium: Chemical Effects of Isomeric Transition
Authors: Williams Russell R.
Published: January 2005

The chemical consequences of isomeric transitions in the nuclei Te127, Te129, and Te131 have been investigated in aqueous solutions of varying composition. The nuclear reaction gives rise to chemical reduction or oxidation, and a mechanism has been proposed to account for the observed effects. Evidence has been advanced which indicates that the maximum efficiency of the chemical separation of the nuclear isomers can be taken as a measure of the degree of internal conversion.
A Search for Spectral Absorption in Active Nitrogen
Authors: Worley R. Edwin
Published: January 2005

The problem of absorption through active nitrogen has been re-attacked, using a 13-meter path, at pressures of a few millimeters. A supplementary observation of the O2 ``atmospheric'' bands indicated that an allowed transition would have been detected at a concentration of 1010 molecules/cm3 in the initial vibrational level. Absence of the O–O band of N2+ implies that the (unexcited) ion is not a primary carrier of the energy, as was proposed by Mitra. Failure to observe first positive bands (N2, B3Π←A3Σ) is discussed. A speculation is advanced concerning the activated molecules.
The Photo-Chemical Decomposition of Acetone at 3130A
Authors: Dorfman Leon M. , Noyes W. Albert
Published: January 2005

The photo-chemical decomposition of gaseous acetone in light of 3130A has been investigated at 26°C under conditions of high acetone pressure and low absorbed light intensities. The ratio C2H6/CO has been found to decrease substantially below unity at sufficiently low absorbed intensities, under which condition methane has been found as a major product, exceeding the amount of ethane at very low intensities. A kinetic analysis of these data has shown that only a free radical process for the formation of ethane and methane suffices to explain the experimental observations. The energy of activation for the reaction of a methyl radical with an acetone molecule to form methane has been determined as E = 6.5 kcal./mole.
Infra-Red Vibrations in NaCl
Authors: Markham Jordan J.
Published: January 2005

A detailed calculation has been made of the propagation properties of the lattice vibrations in NaCl. The phase velocity, the group velocity, displacement angle (angle between the particle displacement and the direction of propagation), and the displacement ratio were calculated as a function of wave-length for three directions of propagation. In these calculations, Born's theory was used. The crystal has a low pass (acoustical) and at times overlapping upper band (optical). At the lowest frequency the waves are simply elastic ones. As the frequency increases, the structure exhibits strong dispersion. In the limit of shortest wave-length, the group velocity approaches zero. The optical branch is highly dispersive at all frequencies. The group velocity is negative (on the single-zone scheme), and approaches zero at both the short and long wave-length limits. Generally, for both branches at the short wave-length limit the particle displacement lines up along the direction of nearest neighbors. Exceptions to this occur for propagation along some highly symmetrical direction.
The Energy of the C–H Bond in the Fluoro-Toluenes
Authors: Szwarc M. , Roberts J. S.
Published: January 2005

The pyrolysis of the three fluoro-toluenes was investigated, and it was shown that the mechanism of the decomposition is the same as suggested previously for the decomposition of toluene and the xylenes. The experimental results prove that the C–H bond energy in all fluoro-toluenes is nearly the same as the C–H bond energy in toluene, i.e., about 78 kcal./mole, thus showing that the field effect has very little influence on the bond energy. This conclusion definitely establishes the presence of hyperconjugation for para-xylene as the cause of the weakening of the C–H bond in the CH3 groups. The difference in the effects of dipoles on ionic and radical reactions is pointed out.
The Refractive Index of Several Hydrocarbons in the Near Ultraviolet Wave-Length Region
Authors: Lauer James L.
Published: January 2005

Index of refraction measurements were carried out with twenty-one liquid hydrocarbons, paraffinic, naphthenic, olefinic and aromatic, in their respective transparent regions between 220 and 420 millimicrons, both at 20° and at 25°C, to an average accuracy and precision of ±0.0002 in refractive index. The data for each compound were fitted to an empirical equation relating frequency and index, and from these the constants in the Sellmeier-Drude equation were calculated wherever possible. Interesting variations in these constants were observed for compounds of related structures. The instrument used for the measurements was the same as the one described in an earlier article (see reference 4).
Activation Energy for the Diffusion of Coupled Pairs of Vacancies in Alkali Halide Crystals
Authors: Dienes G. J.
Published: January 2005

The theoretical activation energy for the diffusion of neutral combined pairs of positive- and negative-ion vacancies in alkali halides has been determined. Changes in Coulombic, repulsive, and polarization energies were taken into account with appropriate corrections for second-order effects. Calculations for the rigid and distorted lattice showed that distortion effects during diffusion are of appreciable magnitude. This energy contribution has been estimated as accurately as possible near the saddle point. An activation energy of 0.375 ev was obtained for diffusion in the KCl lattice. This activation energy value shows that migration of neutral combined pairs of positive- and negative-ion vacancies, rather than diffusion via single vacancies, may well be the predominant process. The experimental evidence for this type of migration is discussed. It is concluded that diffusion by means of neutral combined pairs of vacancies is supported rather than prohibited by the theoretical results.
Cyclotron Targets: Preparation and Radiochemical Separation. III. Na22
Authors: Irvine John W. , Clarke E. T.
Published: January 2005

Two methods for separating Na22 from magnesium cyclotron targets are described. The first is a direct precipitation of NaMg(UO2)3(C2H3O2)9·6H2O or NaZn(UO2)3(C2H3O2)9·6H2O from an acetic acid solution of the target utilizing the normal sodium contamination of the magnesium for carrier. This is effective for as little as 1 mg Na in 5 g of Mg. If the sodium contamination is too small for precipitation, the bulk of the magnesium can be removed as Mg(NH4)2(CO3)2·4H2O which does not carry sodium. Deuteron excitation functions for Mg26(d,α)Na24 and Mg24(d,α)Na22 and thick target yields for the two sodium isotopes are given. The maximum values of the cross sections are σNa24=0.095×10−24 cm2 at 8.5 Mev and σNa22=0.16×10−24 at 9.5 Mev. With 14-Mev deuterons the thick target yields are Na24=8.7rd/μah and Na22=65mrd/μah.
Some Characteristic Frequencies in the Raman Spectra of Saturated Aliphatic Hydrocarbons
Authors: Sheppard N.
Published: January 2005

An analysis of the data presented in a recent compilation of Raman spectra of saturated hydrocarbons has been carried through with a view to the determination and assignment of vibration frequencies that are characteristic of particular molecular groups.

Suggested approximate assignments have been made for the rocking and wagging modes of CH2 groups (720–760 cm−1 and 1300–1340 cm−1, respectively) and for the deformation modes of CH groups (1330–1360 cm−1) in such hydrocarbon molecules.

Assignments previously made for the analysis of the Raman spectra of isobutane (trimethyl methane) and neopentane (tetramethyl methane) have been reviewed, and the results applied to the interpretation of observed characteristic frequencies of singly and double branched paraffins. Single branching of the hydrocarbons gives rise to characteristic frequencies in the regions 1180–1140 cm−1 and 830–790 cm−1, whereas double branching gives similar frequencies in the regions 1260–1190 cm−1 and 760–710 cm−1. These can probably be assigned to C–C stretching modes of vibration of the molecules. Other characteristic frequencies in the regions 970–950 cm−1 and 930–910 cm−1 occur in the spectra of single and doubly branched hydrocarbons, respectively, when these have at least two methyl groups attached to the branching carbon atom. They are probably caused by methyl wagging modes of these groups.
The Nature of Bond Orbitals in Quadricovalent Complexes of Transition Elements
Authors: Kuhn Hans
Published: January 2005

In quadricovalent complexes of transition elements (NiII, PdII, PtII, AuIII, AgII, CuII) the central atom uses four s or d orbitals of its outer shell for unshared electron pairs and two s or d and two p orbitals for bond formation. The problem here is to find the strongest possible four hybrid bond orbitals obtained by combining the two s—d and the two p orbitals available for bond formation. The strongest bond orbitals thus obtained are directed from the middle towards the four corners of a square, as it is expected from experimental evidence; they are composed of 4/9 s, 14/9 d, and two p orbitals, the strength being 2.943. These strongest possible orbitals are presumably used in complex of NiII, PtII, AuIII, and CuII, but probably not in complexes of PdII and AgII; in the latter two cases there must be assumed square bond orbitals of composition snd2−np2 with n somewhere between 1 and 4/9, i.e., orbitals of character between that of the strongest square bond orbitals of composition s4/9d14/9p2 mentioned above and that of sdp2 square orbitals discovered by Pauling.
Ionization Processes on Tungsten Filaments I. The Electron Affinity of the Oxygen Atom
Authors: Metlay Max , Kimball George E.
Published: January 2005

The electron affinity of the oxygen atom was determined to be 53.8±0.8 kcal./mole by measuring the ratio of ions to electrons leaving a hot tungsten filament in contact with nitrous oxide gas at a low pressure. Previous investigations of this quantity yielded discordant results. A possible reason for this disagreement is set forth.
Ionization Processes on Tungsten Filaments II. The Absorption of Fluorine on Tungsten
Authors: Metlay Max , Kimball George E.
Published: January 2005

Fluorine is found to form an adsorbed film on tungsten stable to temperatures above 2600°K. This causes a low accommodation for the thermal dissociation of fluorine. The adsorption is compared to that of oxygen on tungsten.
Dielectric Behavior of Solutions of Electrolytes in Solvents of Low Dielectric Constant. IV.A. Dielectric Absorption of Butyl Alcohol, B. The Second Wien Effect1
Authors: Strobel H. A. , Eckstrom H. C.
Published: January 2005

A. The absorption conductivity of n-butyl alcohol has been carefully determined by a calorimetric method, using two independent, specially purified samples. Its dielectric behavior proved in good agreement with Debye theory. The probable source of the error in earlier butyl alcohol measurements determined with the same apparatus was ascertained. A critical frequency of 305 Mc was calculated, which is about the average of most good literature values.

B. Several benzene solutions between 0.001–0.008 molar have shown increases in conductance with field strength at 60 cycles per second in accord with Onsager's theoretical treatment of the second Wien effect.
Further Alkylbenzene Spectra to 1750A
Authors: Platt J. R. , Klevens H. B.
Published: January 2005

The absolute absorption intensities of n-butyl-, secondary butyl-, and tertiary butylbenzene and of 1,3,5-trimethylbenzene (mesitylene) have been measured to about 1750A. Increased branching of the side chain shifts the 1900A and 2100A bands slightly to shorter wave-lengths but increases the total oscillator strength from 1.04 for n-butyl to 1.57 for tertiary butyl. The wave-length shifts are in the same direction, the intensity changes in the opposite direction from those observed in the 2600A bands of these same compounds. The mesitylene spectrum is about 1000 cm−1 to the red of the meta-xylene spectrum and its oscillator strength is reduced to 0.89, almost as low as that of benzene itself.
Contributions to the Theoretical Treatment of Ammonium. II
Authors: Horváth J. I.
Published: January 2005

In this second part of our paper we have determined the ionization energy of the ammonium molecule and the eigenfrequencies of the positive ammonium molecule ion. Because we know the electron distribution of the positive radical, we can determine the eigenfunction of the valence electron of ammonium in the same way as is done in cases of alkali metals with larger atomic number. In Section I of Part II we review this method. In Section II we determine the eigenfrequencies of the ammonium molecule ion by Neugebauer's method.
Diamagnetic Susceptibilities of Shared Electrons
Authors: Yang Tai-Yuan
Published: January 2005

By regarding the two shared electrons of a covalent bond as forming a doubly charged negative ion, and the molecule as consisting of positive and negative ions, one may, in some cases, assign diamagnetic susceptibilities to the constituent parts of the molecule. The values thus found are in good agreement with the experimental results.
Polarized Infra-Red Radiation as an Aid to the Structural Analysis of Long-Chain Polymers. I
Authors: Elliott A. , Ambrose E. J. , Temple R. B.
Published: January 2005

An experimental procedure is described for measuring dichroism in the infra-red spectrum of oriented materials. Oriented films of polythene, polyvinyl alcohol, polyvinyl chloride, polyvinyl acetate, and Nylon have been examined in the region 3600–700 cm−1, and the species (parallel or perpendicular) of many bands has been identified. The bearing of these results on current ideas concerning the structure of these polymers is discussed. A general result is that frequencies involving the motion of hydrogen atoms show rather low dichroism. On the other hand, very high dichroism has been found in some frequencies in which the motion is believed to be confined to other atoms.
The Absorption Spectrum of Diborane
Authors: Price W. C.
Published: January 2005

The absorption spectrum of diborane has been investigated in the infra-red from 1–25μ and in the vacuum ultraviolet down to 1000A. The rotational structure obtained for certain of the infra-red bands rules out the ethane-type structure but agrees very well with the interpretation of the electron diffraction results in terms of a bridge model. The ultraviolet spectrum indicates a simple electronic structure and a first ionization potential about 11–12 volts.
The Mercury Photosensitized Hydrogenation of Propylene
Authors: Moore Walter J.
Published: January 2005

The mercury photosensitized hydrogenation of propylene has been investigated at 30°, 110°, and 200°, using an 8/1 ratio of hydrogen to propylene. The hydrocarbon products were analyzed with a mass spectrometer. The occurrence of 2,3-dimethylbutane as the principal C6 product indicates that a hydrogen atom adds preferentially to the terminal carbon atom of propylene to form the isopropyl radical. Analyses of the C6 and C9 products suggests that the isopropyl radical adds preferentially to the middle carbon atom of propylene.
Asymptotic Behavior for the Particle Distribution Function of Simple Fluids near the Critical Point
Authors: Choy Teresa Ree , Mayer Joseph E.
Published: January 2005

Classical single-component fluids are considered in order to investigate the asymptotic behavior of the joint distribution function of l+m particles, ρl+m, for large separation between the set of l and m particles. Near the critical point the authors find ρl+m to be the product of ρl and ρm plus the long-range corrections. The critical singularities, such as the heat capacity at constant volume, are explained in terms of the authors' result on the asymptotic distribution function.
Triplet—Triplet Annihilation in Anthracene at Low-Excitation Intensities: Wavelength and Temperature Dependence
Authors: McMahon D. H. , Kestigian M.
Published: January 2005

The process of triplet—triplet annihilation in crystalline anthracene has been investigated at low-excitation intensities using a cw xenon-arc-lamp source. Bimolecular annihilation is observed by means of a subsequent fluorescence decay from the first excited singlet state to the ground state. The dependence of this fluorescence signal upon excitation power and excitation wavelength has been measured, as well as the temperature dependence, in the range from 80° to 500°K, of the cw fluorescence power and the fluorescence decay constant. The variations of fluorescence power and fluorescence decay constant with temperature can be explained by assuming the presence of two distinct trap levels for the triplet excitons.
Structure and Physical Properties of Solid and Liquid Vanadium Pentoxide
Authors: Allersma T. , Hakim R. , Kennedy T. N. , Mackenzie J. D.
Published: January 2005

The electrical resistivity of near-stoichiometric crystalline V2O5 has been measured as a function of crystal orientation and oxygen partial pressure from 25° to 300°C. Conductivity is insensitive to ambient atmosphere. The activation energy for conduction is 0.20 eV. Molten V2O5, however, is sensitive to oxygen partial pressure. Its conductivity is proportional to Po2−⅙. Anomalously high electrical resistivity was observed for glassy V2O5 films.
Mobility of Electrons and Positive Holes in Spectral Sensitization and in Desensitization of the Photographic Process by Dyes
Authors: Saunders V. I. , Tyler R. W. , West W.
Published: January 2005

The method of displacement, by pulsed electric fields synchronized with the exciting radiation, of the photographic images caused by electrons and positive holes, respectively, has been applied to the study of spectral sensitization of latent-image formation by dyes, and to the desensitizing effect of certain dyes, in thin, macroscopic, sheet crystals of silver bromide. In the spectrally sensitized process, free electrons are produced, with the same mobility as those excited by self-absorption by the silver bromide, but no mobile holes have been observed in the interior of the crystal in this process. The inability of the positive holes associated with the spectrally sensitized process to migrate into the interior is consistent with theoretical concepts regarding this process, but hole trapping by the dye may contribute to the observed nonmobility. Electron trapping by readily reducible dyes is demonstrated, consistent with a mechanism of photographic desensitization in which these desensitizing dyes act as alternative electron traps to the sensitivity centers in the silver halide crystal.
Study of the Structure of Vanadium in Soda—Boric Oxide Glasses
Authors: Hecht Harry G. , Johnston Theron S.
Published: January 2005

The EPR and optical spectra of vanadium in the Na2O–B2O3 glass system have been analyzed. It is found that the data can best be interpreted in terms of a vanadyl-type structure in a ligand field of fourfold symmetry. Good correlation of the optical and EPR data is achieved through molecular orbital calculations, which provide a qualitative description of the behavior of the coordination sphere as the Na2O content of the glass is varied. The model proposed is one in which there is a dilation of the ligand shell corresponding to the boric oxide anomaly superposed on an over-all tendency of the ligand—metal distance to decrease as [Na2O] increases. The hyperfine coupling terms as well as the g tensor and optical data support this model.
WKB Approximation of the Quantum Radial Distribution Function Applied to Fluid Neon
Authors: Jaen Jong K. , Khan Ashfaq A.
Published: January 2005

In order to determine the better of two neon intermolecular pair potentials, the expansion expression of the diagonal element D(r, r) of the normalized and symmetrized statistical density matrix given by exp(βF)〈r1,r2,···,rN|exp(−βH)S|r1,r2,···,rN〉is presented as a WKB expansion. Subsequently, the WKB approximation of the quantum radial distribution function g(r) for the pair potential is developed also by taking into account the particle exchange effect, and a new quantum effective pair potential is suggested. The theory is applied to fluid neon by using the Percus—Yevick and convoluted-hypernetted-chain integral equations. We used the Lennard-Jones 6–12 pair potential and the modified Buckingham—Corner 6-exp pair potential of neon at four temperatures. The comparison has been made between the theoretical relative-intensity curves of scattered x rays and their corresponding experimental curves, and also between the theoretical quantum radial distribution curves and their corresponding experimental curves with a theoretical estimate of the intensity at small-angle scattering. The theoretical result is in good agreement with the experimental result and is best for the modified Buckingham—Corner 6-exp pair potential.
Quantum-Mechanical Kinetic Theory of Loaded Spheres
Authors: Mueller John J. , Curtiss C. F.
Published: January 2005

The transport coefficients of a gas of loaded spheres, that is, spheres in which the centers of mass do not coincide with the geometrical centers, are considered. The amount by which the center of mass is displaced from the center of the sphere is denoted by δ and the diameter of the sphere is σ. The scattering amplitude and cross section are found as power series in δ/σ; the coefficients of the zero, first, and second power of δ/σ are obtained. Using these results, the quantum-mechanical expressions for the relaxation time, and coefficients of shear viscosity, thermal conductivity, and diffusion may be obtained explicitly to second order in δ/σ.
On the Evolution of the Classical One-Body Distribution Function
Authors: Mortimer Robert G.
Published: January 2005

The BBGYK hierarchy of equations is separated into an equilibrium and a nonequilibrium hierarchy by a method of Mayer, and the nonequilibrium hierarchy is truncated at its lowest member by the assumption that the two-body correlation function is given by its equilibrium value. This equation is solved formally by iteration in the case of small deviations from equilibrium, and the solution is partially summed to obtain a series in the strength of the potential. In the case of times not too distant from the initial time, the Fourier transform of this series is summed to give a solution in closed form.
Analysis of the NMR Spectrum of Pyridine
Authors: Castellano S. , Sun C. , Kostelnik R.
Published: January 2005

The proton spectrum of pyridine, recorded while irradiating the 14N nucleus in order to remove the proton—nitrogen coupling, has been completely analyzed in terms of chemical shifts and coupling constants. The parameters obtained from the analysis differ substantially from the values previously reported in the literature for this compound but are in good agreement with the data determined from the analysis of monosubstituted pyridines. The coupling constant between the α protons is negative.