bluuebunny/crossref_metadata_2025 huggingface dataset:
The Quenching of Mercury Resonance Radiation. I. The Effective Cross Sections of Paraffin Hydrocarbons
Authors: Darwent B. deB.
Published: January 2005

The effective cross sections of the paraffin hydrocarbons from ethane to n-heptane in quenching mercury resonance radiation (λ2537) have been measured by the technique of Zemansky. The effective cross section of ethane is much smaller than the value previously found by Bates. Neopentane is reasonably efficient in quenching λ2537 although it is not decomposed readily by Hg(3P1) atoms. Increase in molecular weight and, up to a point, in branching of the carbon skeleton are accompanied by increases in the effective cross section. The quenching efficiency of the paraffins depends on the number and type of C–H bonds in the molecule and is not primarily a function of the number of carbon atoms or C–C bonds. The effective quenching diameters of the C–H bonds are: primary 0.05 to 0.10A, secondary 0.50 to 0.65A, and tertiary 1.3A; the actual values depending to some extent on the nature of the rest of the molecule. The number of collisions necessary for quenching to occur on primary, secondary, and tertiary C–H bonds is, therefore, approximately 3000, 30, and 5, respectively.
Absolute Intensity of Light Scattering from Pure Liquids and Solutions
Authors: Carr C. I. , Zimm B. H.
Published: January 2005

The absolute scattering powers of several strongly scattering solutions of polystyrene were measured by three independent methods, using transmission, integrated scattering, and scattering at right angles respectively. When a number of factors involving the geometry of the measuring system and the refraction of the light at interfaces are taken into account all the methods give results in excellent agreement. The absolute scattering power of benzene and carbon tetrachloride were then determined by comparison with the polystyrene solutions and were found to be in good agreement with Einstein's theoretical equation, though at variance with most of the previously reported experiments. The scattering from solutions of dibenzyl and sucrose octaactetate were also measured and found to give results in good agreement with those calculated theoretically from the molecular weights of these substances. In the course of the measurements it was also necessary to study the reflection properties of MgCO3 and MgO surfaces in more detail than has been published heretofore.
The Structure of Para-di-chloro-benzene
Authors: Saksena B. D.
Published: January 2005

Two low frequency spectra of the crystal of para-di-chloro-benzene are reproduced, one showing the frequencies 27, 54, and 93 and the other 45, 57, and 84 cm−1. The former represent the spectra of a single crystal very slowly cooled from melt, and the latter of a crystal rapidly cooled. The three frequencies in the spectra of the single crystal have been shown to be rotational oscillations, the smallest frequency representing an oscillation about the axis of greatest moment of inertia which is the axis perpendicular to the plane of the molecule. From the x-ray data it is noticed that the molecules in the crystals of para-di-chloro-benzene and para-di-bromo-benzene are differently orientated, but they can be brought into juxtaposition by a rotation about this axis. The different orientations of the molecules in these crystals are however incompatible with the fact that these crystals are isomorphous and form mixed crystals. It has therefore been postulated that the crystal of para-di-chloro-benzene has a tendency to become disordered by the excitation of free rotation about the axis perpendicular to the plane of the molecule which results in the vanishing of the frequency 27 as noticed in the second spectrum. The apparently discordant results of Sircar and Venkateswaran on the temperature independence of Laue spots and Raman spectra and also those of Sircar and Vuks on the spectra of mixed crystals have been explained on this basis, and the frequencies of mixed single crystals of para-di-chloro- and para-di-bromo-benzenes have been calculated in good agreement with the observational data.
The Electric Conductivity of Weak Electrolytes and Ampholytes at High Electric Field Strengths
Authors: Blüh O. , Terentiuk F.
Published: January 2005

An oscillographic method has been devised for the investigation of the variation of the electrolytic conductivity with the electric field strength up to 100 kv/cm. The method has been used to measure the field effect in various weak electrolytes, particularly in ampholytes.
Collision Cross Sections of Hydrogen and of Deuterium
Authors: Amdur I. , Kells M. C. , Davenport D. E.
Published: January 2005

Total collision cross sections have been measured for hydrogen atoms, with energies between 300 and 800 ev, scattered in room temperature hydrogen, and for deuterium atoms, with energies between 500 and 1150 ev, scattered in room temperature deuterium. The H–H2 cross section has a pronounced maximum at 600 volts indicating the presence of inelastic scattering. In the case of D—D2 there is a similar effect, less pronounced, at about 800 volts.

Classical theory has been used to evaluate the repulsive potentials for the two systems on the assumption that smooth curves through the experimental results represent elastic cross sections, and that the atoms and molecules are mass points whose interaction forces are spherically symmetrical. For H–H2, the present potential has been combined with one previously obtained, and the results represented by V(r)=[0.708 exp(−29.9r2)+0.0607 exp(−0.942r2)]×10−10 ergfor r between 0.27 and 0.68A. The relation for D—D2 is V(r)=4.59×10−11exp(−5.17r2) ergsfor r between 0.29 and 0.56A. The D—D2 potential is considerably larger than that for H–H2 for r between 0.29 and 0.56A, but the difference decreases markedly as r increases. It is suggested that the apparent difference in the potentials may result from the assumption of spherical symmetry which, even on a relative basis, does not exist in the present case because of the difference in the nuclear statistics of H2 and D2.
The Absorption Spectra of Methane, Carbon Dioxide, Water Vapor, and Ethylene in the Vacuum Ultraviolet
Authors: Wilkinson Philip G. , Johnston Herrick L.
Published: January 2005

Quantitative absorption measurements were made of methane, carbon dioxide, water vapor, and ethylene at 30°C in a Cario and Schmidt-Ott vacuum fluorite spectrograph from 1400 to 2000A. Values of the atmospheric absorption coefficient, α, in the equation, I=I0 exp(—αx), ranging from two for carbon dioxide to 800 for ethylene were found. Resonance wave-lengths and oscillator strengths were calculated from absorption curves and found to be consistent with refractive index data.
Free Radical Formation in the Photolysis of Some Aliphatic Aldehydes, Acetone, Azomethane, and Diazoethane
Authors: Volman D. H. , Leighton P. A. , Blacet F. E. , Brinton R. K.
Published: January 2005

The formation of free radicals from some aldehydes, acetone, azomethane, and diazoethane was studied by use of the metallic mirror technique of Paneth. Various wave-length regions were used. Implications of the results for the mechanism of the primary process in the photolysis of the compounds are discussed.
A Calculation of the Energy Absorbed in a Spherical Volume Containing a Gas-Radon Mixture
Authors: Maxwell Charles R. , Henri Victor P.
Published: January 2005

A graphical method for the calculation of the energy absorbed from the alpha-particles emitted by radon and its decay products is described. Factors, calculated by this method, are presented for use in calculating the energy absorbed in any spherical volume. These factors are compared with similar factors calculated with analytical expressions presented by other investigators. The orders of magnitude of the energy absorbed from recoil atoms, beta-particles and gamma-rays are given.
The Infra-Red CO Bands as Wave-Number Standards in the Infra-Red Region
Authors: Rao K. Narahari
Published: January 2005

The predicted positions of the lines in the (1,0), (2,0) and (3,0) rotation-vibration bands of carbon monoxide are given and the possibility of using them as secondary standards in the infra-red region of the spectrum is discussed.
Statistical Mechanics of Adsorption. IX. Adsorption Thermodynamics and Solution Thermodynamics
Authors: Hill Terrell L.
Published: January 2005

This paper is a generalization of Part V of this series. We show here that the usual solution thermodynamics can be recast into an equivalent but alternative form which is more natural and useful in adsorption work. Relations between the two systems of thermodynamics are pointed out. The extension to the case of sorption from a mixture of gases is included.
The Vibrational Spectra of Molecules and Complex Ions in Crystals III. Ammonium Chloride and Deutero-Ammonium Chloride
Authors: Wagner E. L. , Hornig D. F.
Published: January 2005

The infra-red spectra of thin non-scattering films of NH4Cl and ND4Cl were obtained at 28°, −78° and −190°C. A convenient low temperature transmission type cell usable for such films is described. No indication of fine structure due to free rotation of the NH4+ ions was found. Instead, evidence is presented for the existence, both above and below the λ-point, of a torsional lattice mode involving the NH4+ ions. The limiting frequencies of the torsional oscillations were observed at about 390 and 280 cm−1 for NH4Cl and ND4Cl, respectively. These values agree quite well with the frequencies calculated on the basis of a purely electrostatic potential function. The spectra of the low temperature modifications indicate strongly that the structures belong to the space group Td1 in which the NH4+ ion symmetry is Td. Of the eight observed bands, two are assigned to the triply degenerate fundamentals ν3 and ν4, one to the overtone 2ν4, one to the combination ν2+ν4 which resonates strongly with ν3, one to the combination of the totally symmetric mode, ν1, with the limiting lattice frequency, ν5, and two to the combinations involving the lattice torsional mode, ν6, i.e., ν4+ν6 and ν2+ν6. The spectra of the room temperature modifications are consistent with a structure in which the NH4+ ion tetrahedra are randomly distributed between the two possible equilibrium orientations in each unit cell. The λ-point transformations are probably simple order-disorder transitions between the two modifications.
The Properties of n-Pentforane and Its Mixtures with n-Pentane
Authors: Simons J. H. , Dunlap R. D.
Published: January 2005

A sample of n-pentforane, C5F12, of high purity was made available by the operation of the electrochemical process for the production of fluorocarbons. The physical properties of this material were determined, and a study was made of the two-component, liquid-gas system of it with n-pentane, C5H12. Deviations from Raoult's law were found which were much greater than could be predicted by existing theories for solutions of nonpolar substances. In order to correlate the experimentally determined properties of these mixtures, it was necessary to extend the existing theories. This was done by assuming a new concept of possible significance in solubility relationships. This concept is pictured as the interpenetration of the molecules in the condensed state. For the particular system herein studied the interpenetration between hydrocarbon molecules is much greater than between fluorocarbon molecules, and the interpenetration between the fluorocarbon and hydrocarbon molecules is as small or smaller than that between fluorocarbon molecules. This additional concept has provided a means for correlating the measurements.
Substituted Methanes. I. Raman and Infra-Red Spectral Data, Assignments, and Force Constants for Some Tribromomethanes
Authors: Meister Arnold G. , Rosser Shirley E. , Cleveland Forrest F.
Published: January 2005

As a part of a systematic investigation of the vibrational spectra of substituted methanes and ethanes, Raman displacements, semiquantitative relative intensities, quantitative depolarization factors, and infra-red absorption frequencies in the region 700–5000 cm−1 have been obtained for CBr3H, CBr3Cl, and CBr4. Details about the design of the infra-red spectrograph are given. The Raman and infra-red spectral data in the literature for CBr3H, CBr3D, CBr3F, CBr3Cl, and CBr4 have been collected, tabulated, and critically examined in comparison with the present results and a decision was made as to the probable values of the Raman and infra-red data at the present time. Assignments of the observed Raman and infra-red bands, consistent with the selection rules, were made for all of the molecules. Finally, force constants were calculated for the five molecules, using a potential energy function containing all possible second degree terms.
The Electrical Charge of 18-Min. Br80 from Isomeric Transition
Authors: Wexler S. , Davies T. H.
Published: January 2005

The space between two concentric copper-amalgam electrodes was filled to several microns pressure with ethyl bromide containing 4.4-hr. Br80*. The distribution between electrode surfaces of 18-min. Br80 dissociated from ethyl bromide in consequence of the isomeric transition process was determined. The results establish the presence of positively charged 18-min. Br80 species among the decay products. At least 50 percent of the dissociations yield positive Br80 species. The remainder yield uncharged Br80 species.
Concerning the Work of Polarization in Ionic Crystals of the NaCl Type. III. Numerical Results for a Single Charge in the Rigid Lattice
Authors: Pré F. K. du , Hutner R. A. , Rittner E. S.
Published: January 2005

Numerical results determined from the theory presented in Part I are given for thirty-three substances.
A Photoelectric Investigation of the Cool Flame of Ether
Authors: Ouellet Ludovic , Leger Edouard , Ouellet Cyrias
Published: January 2005

A method is described, in which the light from a cool flame under the form of a static, uniform glow is measured as a function of time by means of a multiplier photo-tube and a single-sweep cathode-ray oscillograph. The circuit embodies an a.c.—d.c. amplifier and a slow sweep. Cool flames of diethylether-oxygen mixtures in a Pyrex cylinder 4.6 cm in diameter have been studied under the following range of conditions: 180–250°C, 0–150 mm and 5–95 percent ether. The pulsating glow, which lasts about 1 second, shows two and sometimes more maxima. The generally accepted lower pressure limits appear as regions of feeble but smoothly decreasing intensities. Under the conditions of our experiments, the temperature coefficient is negligible. Both intensity and integral emission increase regularly with the concentrations of the reactants and are maximum at 50 percent ether by volume, the variations being roughly symmetrical with respect to the partial pressures of either component. Variations of pressure and composition cause regular but considerable changes in the shapes of the oscillograms. Light and pressure pulses follow each other closely, suggesting that the latter are of mainly thermal origin and that the light intensities reflect the instantaneous reaction rates. The glow lasts longer in the wider vessels. In the presence of the reaction products, it either fails to appear or emits the normal amount of light. A preliminary analysis of the quantitative data is given and possible interpretations, in terms of oxidation mechanisms, are discussed.
Near Ultraviolet Absorption Spectra of Melamine and Some Related Compounds
Authors: Costa George W. , Hirt Robert C. , Salley D. J.
Published: January 2005

An absorption band of low intensity has been found in the 2800 to 3400A region for solutions of melamine, trimethylol melamine, trimethyl ether of trimethylol melamine, hexamethylol melamine, and cyanuric chloride. The band has also been observed in gaseous melamine at elevated temperatures. The band is believed to be due to a singlet-triplet transition, rather than analogous to the 2600A absorption system of benzene.
A Single Exposure Photographic Method for Depolarization Factor Measurements
Authors: Bender Paul , Lyons Philip A.
Published: January 2005

A single exposure photographic method for the measurement of depolarization factors in Raman spectroscopy is described. The accuracy of the results was tested by measurements with carbon tetrachloride and chloroform. The depolarization factors found for highly polarized lines were in good agreement with those given by the photoelectric method rather than with those of other photographic investigations.
Measurement of Normal Burning Velocities of Propane-Air Flames from Shadow Photographs
Authors: Andersen J. W. , Fein R. S.
Published: January 2005

The limitation placed upon the stroboscopically illuminated particle method of measuring the normal burning velocity by the heat capacity of the particles is discussed. A supplementary method of measuring the normal burning velocity using a modified Gouy procedure is presented. The line between the dark and light spaces on shadow photographs, taken at different distances from the flame to the film, is used in this method to define the flame area. This area is then extrapolated to the diametral plane of the flame. This procedure gives results that are consistent with the particle method of determining the normal burning velocity and its use is justified empirically. Burning velocities of propane-air flames are given.
Energy Levels and Thermodynamic Properties of the Internal Rotator
Authors: Halford J. O.
Published: January 2005

To facilitate the calculation of the thermodynamic properties of internal rotators lying outside the limits of available tabulations, methods of determining the energy levels are studied for the purpose of finding the most expeditious route to accurate results. It proves to be unnecessary in any case to calculate many levels from the wave mechanics. A partition function is set up in terms of the correct ground state and a series of approximate levels derived from the old quantum theory, and this is corrected to constancy by the successive substitution of correct levels, starting with the first excited state. A set of levels obtained in this way which gives the correct partition function always leads to correct values of all the thermodynamic properties.

To obtain accurate energy levels, the continued fractions of Koehler and Dennison are recommended as most convenient.
Infra-Red and Raman Spectra of Fluorinated Ethylenes II. 1,1-Difluoro−2,2-Dichloroethylene
Authors: Nielsen J. Rud , Claassen Howard H. , Smith D. C.
Published: January 2005

The infra-red absorption spectrum of gaseous 1,1-difluoro−2,2-dichloroethylene between 2 and 22.6μ has been investigated with a prism spectrometer of high resolution. The Raman spectrum of CF2:CCl2 in the liquid state has been photographed with a three-prism glass spectrograph of linear dispersion 15A/mm at 4358A. Quantitative polarization measurements have been made. The 12 fundamental vibration frequencies have been assigned, and the observed vibration spectra have been interpreted in detail.
The Mercury Photosensitized Reactions of Methyl Alcohol
Authors: Phibbs M. K. , Darwent B. deB.
Published: January 2005

The mercury photosensitized reactions of methyl alcohol have been investigated at pressures of 30 and 100 mm Hg and over a temperature range from 25° to 500°C. Below 400°C the products are almost entirely hydrogen and ethylene glycol and small amounts of carbon monoxide, formaldehyde and methane. It has been established that the primary step in the reaction mechanism is Hg(3P1)+CH3OH→CH2OH+H+Hg(1S0). There is considerable supporting evidence that the alternative split into H+CH3O does not occur.

Above 400°C the rates of production of CH2O and CO become significant and increase with rising temperature which has been explained by the fact that the decomposition of the CH2OH radical is taking place. An activation energy of 29 kcal. has been obtained for this decomposition reaction.
Argon Repulsive Potential from Collision Cross-Section Measurements
Authors: Amdur I. , Davenport D. E. , Kells M. C.
Published: January 2005

The total collision cross section has been measured for argon atoms, with energies between 300 and 1100 electron volts, scattered in room temperature argon. In the region between 700 and 1000 volts, the cross section shows a maximum indicative of inelastic scattering, probably due to ionization by the high energy atoms.

The repulsive potential between two argon atoms has been evaluated from elastic collision cross sections (deduced from observed values of the total collision cross section) using a method which takes account of the greater probability of small angle scattering by averaging the cross section over the length of the scattering path. The results may be expressed by V(r)=4.61×10−11/r4.33 ergsor V(r)=3.66×10−8 exp(−6.88r12) ergsfor values of r between 1.37 and 1.84A.
Isotope Effect in the Vibrational Frequency Spectra and Specific Heats of Sodium Hydride and Deuteride
Authors: Sayre Edward V. , Beaver Jacob J.
Published: January 2005

The prediction by the Born and von Karman lattice dynamics theory of the effect of isotopic substitution on crystal vibration frequencies has been determined by calculation of frequency spectra of sodium hydride and sodium deuteride. In each case 6690 of the lattice frequencies have been calculated with the aid of I.B.M. punched card computers. They have been chosen and weighted in such a way that the whole frequency spectra of the crystals are uniformly sampled. Both spectra exhibit acoustical branches which are nearly identical and optical branches, the frequencies of which are essentially in the ratio of the square root of two. In both cases, the optical branches extend somewhat uniformly over very broad ranges of frequencies, in marked contrast to the estimation of optical frequencies as a few monochromatic lines.

The molar heat capacities of these two compounds have been determined experimentally between 60 and 90°K with an adiabatic calorimeter and compared to corresponding curves calculated from the frequency spectra. The theoretical and experimental sets of curves possess the same general form. In both cases the deuteride values are higher than the hydride values, with the curves of the two substances diverging with increasing temperature. The theoretical curves, however, are nearly uniformly displaced from the experimental curves by about ten percent, an effect which could have arisen from an error in the repulsive force constants.
The Determination of Energy Levels from Thermodynamic Data. I. The Effect of Experimental Error
Authors: Blade Ellis , Kimball George E.
Published: January 2005

The problem of calculating energy levels from thermodynamic data can be reduced to that of inverting the Laplace transform, for which several procedures have been developed. Using the method of Widder, we show that the resultant calculated energy level density function consists of a series of broadened peaks, whereas in the true density the levels are represented by a series of Dirac delta-functions.

Alternatively, if the distribution of the energy levels is specifically assumed to be composed of discrete energies, the calculation reduces to the moment problem.

In either case the calculation is shown to have an inherent ``resolving power,'' in that levels within a certain closeness cannot be distinguished as separate. By a generalization of this idea, it is shown that the computation can lead to a knowledge of the over-all density of energy levels within a given region, but cannot reveal their exact locations.
Proton Nuclear Magnetic Resonance Studies in KH2PO4, KH2AsO4, NH4H2PO4, and NH4H2AsO4
Authors: Newman Roger
Published: January 2005

Studies have been made of the proton magnetic resonance absorption at 30 Mc/sec. in KH2PO4, KH2AsO4, NH4H2PO4, and NH4H2AsO4. Both line shapes and relaxation times have been measured from 87°K to 293°K.

The potassium salts show closely similar magnetic resonance properties. Their relaxation times show relatively small variation in the temperature interval studied. The characteristic times derived therefrom do not obey any simple exponential law in the reciprocal temperature. Single crystals of KH2PO4 do not seem to show anisotropy in the relaxation time. A formula is given which relates the anisotropy of the motion of magnetic dipoles to the anisotropy of transverse local field variation.

The ammonium salts show two minima in their relaxation time vs. temperature curves. One minimum corresponds to a temperature at which the acid hydrogens are the most effective relaxation agent and the other to a temperature where the ammonium ion hydrogens are most effective. The line shapes are also of a composite character. This is most clearly shown below 100°K where the absorption lines appear to be super-positions of the broad NH4 line for which that of NH4Cl is typical and the narrow line found in KH2PO4 or KH2AsO4.

Possible interpretations of the experimental results are discussed with reference to the motions of the protons in these crystals.
Note on Mayers' Theory of Cluster Integrals
Authors: Husimi Kodi
Published: January 2005

The cluster integrals, bl, in the condensation theory are expressible as a sum of products of irreducible integrals KR. The coefficient of each member of the sum is derived in a simple manner.
Magnetic Evidence for d3s Bond Hybridization in Chromium (II) Acetate. The Oxidation State of Chromium in a Reported Tris(8-Hydroxyquinoline) Chromium (II)
Authors: King William R. , Garner Clifford S.
Published: January 2005

Magnetic susceptibilities of solid Cr(OOCCH3)2 and its monohydrate were measured, and these compounds were shown to contain no unpaired electrons. This fact indicates that the four unpaired 3d electrons of the normal Cr++ ion are paired in these compounds, the three 3d orbitals thus made available being utilized in the formation of covalent bonds. The fourth covalent bond probably involves use of the 4s orbital of chromium. This evidence may constitute the first example of d3s bond hybridization postulated by Pauling. Susceptibility measurements were also carried out on tris(8-hydroxyquinoline) chromium (III) and a reported tris(8-hydroxyquinoline) chromium (II). The evidence indicates both to be the same compound, with the chromium having a tripositive oxidation state.
A Theoretical Basis for the Antoine Vapor Pressure Equation
Authors: Gutmann F. , Simmons L. M.
Published: January 2005

The Antoine vapor pressure equation logp = A − B / (t+C) is theoretically derived from van der Waals equation and the energy of an assembly of Einstein oscillators. The values of the Antoine parameter C are shown to be related to the characteristic frequency of the liquid. The values of this parameter obtained from vapor pressure data are shown to agree with those calculated from viscosity and from the velocity of propagation of sound.
The Infra-Red Absorption Spectrum of Diborane
Authors: Anderson W. E. , Barker E. F.
Published: January 2005

The infra-red absorption spectrum of diborane has been examined under high resolution from 3.7μ to 30μ with automatic recording grating spectrometers. The rotational fine structure in two bands of each of the three types characteristic of asymmetric top molecules has been measured. All results and observations are consistent with the conclusion that diborane has the bridge structure, and belongs to the same symmetry point group, Vh, as ethylene. The observation and structure of the band with center at 368.7 cm−1 provides spectroscopic evidence that the molecule is non-planar, and makes more definite the assignment of fundamental frequencies. Data on all bands fit quite well the symmetric top approximation, since accidentally two principal moments of inertia are approximately the same, and calculations yield accurate values for certain rotational constants.
The Vapor Pressure of Plutonium Halides
Authors: Phipps T. E. , Sears G. W. , Seifert R. L. , Simpson O. C.
Published: January 2005

Vapor pressure measurements have been made with three halides of plutonium by a modification of the Knudsen effusion method. Measurements with solid plutonium trifluoride from 1200°K to 1440°K give the vapor pressure-temperature relation log10pmm=12.468–21,120/T. Measurements with liquid plutonium trifluoride from 1440°K to 1770°K give log10pmm=11.273–19,400/T. Measurements with solid plutonium trichloride from 850°K to 1007°K give log10pmm=12.726–15,910/T; with liquid trichloride from 1007°K to 1250°K give log10pmm=9.509–12,590/T. Measurements with solid plutonium tribromide from 800°K to 929°K give log10pmm=13.386–15,280/T; with liquid tribromide from 929°K to 1100°K give log10pmm=10.321–12,360/T.
The Volatility of Plutonium Dioxide
Authors: Phipps T. E. , Sears G. W. , Simpson O. C.
Published: January 2005

The volatility of plutonium dioxide has been measured in the temperature range 1320°C to 1790°C by a modification of the Knudsen effusion method. The plutonium dioxide was heated in vacuum in a tantalum oven. Under these conditions the dioxide was reduced to a lower oxide, or oxides, which maintained a constant reproducible vapor pressure throughout further heating. Either an oxide was formed which was stable under the conditions of the experiment or thermal reduction continued with the formation of a second solid or liquid phase. The thermal reduction of the oxide was reversed by heating the reduced oxide in a low pressure atmosphere of oxygen.
Compressibilities, Force Constants, and Interatomic Distances of the Elements in the Solid State
Authors: Waser J. , Pauling Linus
Published: January 2005

Available data for the compressibilities of crystalline elements are used to calculate the force constants for the assumed Hooke's law interactions between adjacent atoms. On comparison of these constants and the equilibrium interatomic distances it is found that for many substances there holds the relation discovered by Badger for diatomic gas molecules: a linear relation between the reciprocal of the cube root of the force constant and the interatomic distance, for elements of a given row in the periodic table. Deviations from this relation are in the direction of increased compressibility. They are explained as resulting from changes in bond type (that is, in electronic structure) that permit the crystal to adjust itself to the increased pressure.
Statistical Mechanics of Adsorption. X. Thermodynamics of Adsorption on an Elastic Adsorbent
Authors: Hill Terrell L.
Published: January 2005

Thermodynamic equations are derived which should be useful in the analysis of experimental data and theoretical models referring to the adsorption of a one-component gas on an elastic adsorbent. This problem is closely related to the thermodynamics of adsorption of a solute from a liquid solution onto an elastic adsorbent immersed in the solution (e.g., a myosin thread).
The Kinetics of Phase Transitions in Binary Systems
Authors: Reiss Howard
Published: January 2005

A kinetic theory of phase transitions in two-component systems is presented which is applicable to the transitions, vapor to liquid and liquid to liquid. The rate of the transition is characterized by a two-dimensional vector which can be used in conjunction with the equation of continuity to develop a partial differential equation which determines the kinetics of the process.

A new type of energy surface is introduced, and an investigation of its salient features enables one to simplify the solution of the differential equation mentioned above. This purely kinetic treatment makes possible the evaluation of the unknown coefficient found in the older quasi thermodynamic treatment of transition rates in two component systems.
Absolute Intensities of Characteristic Infra-Red Absorption Bands of Aliphatic Hydrocarbons
Authors: Francis S. A.
Published: January 2005

Integrated intensities of the 2900, 1460, and 1370 cm−1 infra-red absorption bands have been measured for twelve aliphatic hydrocarbons. The results are interpreted on the basis that the hydrocarbon molecule behaves like a non-interacting mixture of [Complex chemical formula] structural groups. The unit structural group intensities are 4.41×10−7, 3.81×10−7, and 1.39×10−7 cm2/(molecule second) for the CH3, CH2 and CH groups respectively in the 2900 cm−1 band; 0.544×10−7 and 0.232×10−7 for the CH3 and CH2 groups in the 1460 cm−1 band; and 0.394×10−7 for the CH3 group in the 1370 cm−1 band. Values calculated for the CH bond dipole moment divided by the equilibrium CH bond length vary from approximately 0.2×10−18 to 0.4×10−18 c.g.s. units. Values of approximately −0.75×10−10 are obtained for the change in CH bond dipole moment with change in CH bond length.
Chemical Reactions of Energetic Chlorine Atoms Produced by Neutron Capture in Liquid Systems
Authors: Miller J. M. , Dodson R. W.
Published: January 2005

The fraction of the radioactive energetic chlorine atoms, formed by radiative neutron capture, that react with inactive carbon tetrachloride to give radioactive carbon tetrachloride, or with a solvent to give other radioactive organic halides, was studied as a function of composition in solutions of carbon tetrachloride in silicon tetrachloride, cyclohexane, and benzene. The reactions of similarly formed atoms were also studied for solutions of chlorine in cyclohexane and in benzene.

No significant effect of the temperature of the bombarded solution or of the energy of the neutrons was found.

The results are examined in terms of a theory which predicts the concentration dependence of some of the observed reactions, and alternative descriptions are suggested. It is concluded that the observed reactions occur before the recoil atoms are reduced to thermal equilibrium, and that particular reactions predominate in certain energy ranges.
Stability of Color Centers in Alkali Halides
Authors: Casler Ruth , Pringsheim Peter , Yuster Philip
Published: January 2005

Color centers have been formed in alkali halide crystals by exposing them to x-rays, electron bombardment, and pile irradiation, and their stability with respect to temperature and light bleaching has been investigated. In general such crystals contain centers of non-uniform stability. The lower the temperature at which the color centers have been produced, the more unstable they are on the average. In the absorption spectra taken at low temperature of crystals irradiated at low temperature new bands appear on the short wave-length side of the F-band which are never observed in crystals irradiated at room temperature and which, on warming the crystal to room temperature, vanish together with a part of the F-centers. It is suggested that the instability of some of the color centers formed at low temperature is connected with the presence of these new absorption bands.
Thermal Diffusion in the Critical Region. I
Authors: Pierce N. C. , Duffield R. B. , Drickamer H. G.
Published: January 2005

Thermal diffusion data in the critical region have been obtained for the system ethane-xenon using very low xenon concentrations and Xe133 as a tracer. The results indicate that even at pressures as low as four atmospheres and temperatures twenty degrees above the critical, the simple kinetic theory of gases is not adequate to explain thermal diffusion. In the critical region evidence is found for the existence of clusters of ethane.
Internal Motion and Molecular Structure Studies by Electron Diffraction. III. Structure of CH2CF2 and CF2CF2
Authors: Karle I. L. , Karle J.
Published: January 2005

The interatomic distances and vibrational amplitudes projected on the lines connecting pairs of atoms at equilibrium have been determined for CH2CF2 and CF2CF2 by an objective procedure for analyzing electron diffraction photographs. Distances involving hydrogen atoms have been evaluated and the procedure for resolving radial distribution peaks involving more than one distance is illustrated. The effects on the accuracy of the method of various characteristics such as sample spread and multiple scattering have been analyzed.
Hydrogen Peroxide in the Thermal Hydrogen Oxygen Reaction. II. Reaction of Hydrogen Peroxide with Hydrogen and Chain Initiation in the Hydrogen Oxygen Reaction
Authors: McLane C. K.
Published: January 2005

The reaction between hydrogen peroxide and hydrogen has been studied in the temperature range 470 to 500°C. The dependence of reaction rate on concentrations is rather complicated for hydrogen, and is between first and second order for hydrogen peroxide. The evidence presented favors the conclusion that the reaction proceeds by a chain mechanism involving no direct reaction between hydrogen and hydrogen peroxide molecules, at least at low hydrogen concentrations.

It was found that hydrogen oxygen mixtures undergo appreciable reaction at temperatures where the rate of reaction is normally very small if small amounts of hydrogen peroxide are first added.
Electrostatic Interaction in Hydrogen Bonding
Authors: Coggeshall Norman D.
Published: January 2005

An attempt has been made to calculate the frequency shift, the intensity of absorption, and the energy of association of a hydroxyl group which is a participant in a hydrogen-bonded complex. When a term expressing the polarization energy of a hydroxyl group due to electrostatic interaction is added to the Morse function, the Schrödinger equation may be solved. The calculated wave-length of maximum absorption agrees with the experimental value fairly well for benzyl alcohol and exactly for catechol. Agreement between calculated and observed absorption intensity is satisfactory. The association energy, calculated on the linear polymer model, agrees quite well with the experimental results reported by Mecke.
On the Structure of a Catalyst Surface. II
Authors: Sips Robert
Published: January 2005

Our previous results have been criticized by T. L. Hill on the ground that we considered energies of adsorption ranging from − ∞ to ∞. We have accordingly revised our former theory.

It appears that, if we assume localized adsorption without interaction, the possible mathematical forms for the adsorption isotherm are very limited. We have studied in detail, for the simplest of these, the distribution function for the adsorption energy. It turns out that this simplest isotherm is a generalization of both the Freundlich and the Langmuir isotherms.
The Electrostatic Contribution to the Lattice Energy of Some Ordered Spinels
Authors: de Boer F. , van Santen J. H. , Verwey E. J. W.
Published: January 2005

The electrostatic contribution to the lattice energy of some ordered spinels is calculated. It is made plausible that also in the case of certain spinels that do not show any long-range ordering, a considerable amount of short-range order is to be expected. As a consequence the lattice energy of ``inversed'' spinels containing different ions at octahedral positions, is increased with respect to the corresponding ``normal'' spinels containing one type of ions at octahedral interstices.
Isotope Effect on Bond Rupture by Electron Impact on Hydrogen, Deuterium, and Tritium
Authors: Schaeffer Oliver A. , Hastings Julius M.
Published: January 2005

The relative yields by electron impact of atomic and molecular ions, x+/x2+ ratios, from hydrogen, deuterium, and tritium have been measured with a 60° sector type mass spectrometer. It is shown that the major part of the previous disagreement between calculated and observed values can be understood on the basis of voltage discrimination by the ion source. By using magnetic scanning and a high ion accelerating voltage the experimental ratios are: H+/H2+=0.013, D+/D2+=0.0070, T+/T2+=0.0036 for 30 volt electrons. These are to be compared with the calculated ratios: H+/H2+=0.016, D+/D2+=0.0072, T+/T2+=0.0038.
Substituted Methanes. III. Raman Spectra, Assignments, and Force Constants for Some Trichloromethanes
Authors: Zietlow James P. , Cleveland Forrest F. , Meister Arnold G.
Published: January 2005

Raman displacements, semiquantitative relative intensities, and precise depolarization factors for trichloromethane, fluorotrichloromethane, and bromotrichloromethane were obtained in the liquid state. Several overtones and combination bands hitherto unreported are given and frequency assignments are made. The Raman data in the literature for CCl3H, CCl3D, CCl3F, CCl4, and CCl3Br in the liquid state have been collected and the probable values ascertained. Force constants in modified valence force potential functions containing all possible interaction constants were calculated for the five molecules.
Migration of Lithium and Several Multicharged Ions through Quartz Plates in an Electric Field. II
Authors: Gibson George , Vogel Richard C.
Published: January 2005

The kinetics of the migration of lithium ions through crystalline quartz plates has been studied. The migration is induced by an electric field and probably takes place through tunnels inherent in the crystal structure and parallel to the principal axis of the quartz. It was shown that the rate-determining step is not the migration with in the quartz plate, but is some step associated with the passage of the lithium ions into or out of the quartz plate. A previous investigation showed that the migration within the quartz plate is the rate-determining step for sodium ions.

It was demonstrated that neither magnesium, zinc, cadmium, nor bismuth ions will migrate through quartz plates under our experimental conditions. Copper ions migrated through the quartz plates but caused the plate to crack in each experiment.
The Reactions of Methyl Radicals. I. The Photolysis of Acetone
Authors: Trotman-Dickenson A. F. , Steacie E. W. R.
Published: January 2005

The photolysis of acetone has been investigated between 100°C and 300°C. The rates of production of carbon monoxide, methane and ethane have been measured over a range of acetone pressures from 3.9 to 100 mm and with a thirty-fold variation of light intensity. The methane and ethane formed can be quantitatively accounted for by the equations CH3+CH3=C2H6,  CH3+CH3COCH3=CH4+CH2COCH3.It is found that E3—½E2=9.7 kcal., where E2 and E3 are the activation energies of the above reactions. The photolysis of deuterated acetone has also been investigated, here E3′—½E2′=10.3 kcal. The collision theory ``steric'' or ``P'' factor for the second reaction is less than 10−3 in each case.
Molecular Orbital Predictions of Organic Spectra
Authors: Platt John R.
Published: January 2005

The energies of the first two to five electronic transitions of 16 conjugated molecules are predicted as simple one-electron LCAO molecular orbital transitions (with overlap included). Assignments of the observed levels to the predicted levels are made. Qualitative agreement is good when S=0.25 and β=23,000 cm−1 for ring systems.

It is shown that configuration interaction must be introduced to modify these energy predictions and to account for the intensities in some molecules (``round-field'') such as benzene, triphenylene, coronene, and porphine. This interaction is less important in other molecules (``long-field'') such as pyrene, biphenyl, and tetrahydroporphine.

Empirical groupings of intensities and luminescence lifetimes are shown for the different singlet-singlet and singlet-triplet band types of round-field hydrocarbons and for related molecules containing conjugated hetero-atoms. The alteration of these groupings in long-field molecules, and under jj-coupling, is described.
Diffusion of Lead Chloride Dissolved in Solid Silver Chloride
Authors: Wagner Carl
Published: January 2005

A particular solution of the differential equation of diffusion involving a diffusion coefficient proportional to concentration is presented.

From previous experiments by Wagner and Zimens the diffusion coefficient for the exchange of lead and silver ions, extrapolated to the concentration of a saturated solution of lead chloride in solid silver chloride, is calculated to be 2.4·10−9 cm2/sec. at 270°C. Therefrom it follows that the self-diffusion coefficient of lead ions equals 0.8·10−9 cm2/sec. In contrast, the self-diffusion coefficient of silver ions, derived from conductivity measurements of Koch and Wagner, amounts to 9.2·10−8 cm2/sec.
Self-Diffusion of Sodium in Sodium Chloride and Sodium Bromide
Authors: Mapother Dillon , Crooks H. Nelson , Maurer Robert
Published: January 2005

The self-diffusion coefficient of sodium in sodium chloride and sodium bromide has been measured as a function of temperature. A comparison of the self-diffusion coefficient with the electrolytic conductivity reveals that the Einstein relation is satisfied at high but not at low temperatures. The temperature dependence of the diffusion coefficient may be explained by the Schottky-Wagner vacancy theory if the presence of impurity ions is taken into account. A possible explanation for the failure of the Einstein relation in terms of association between multivalent foreign ions and vacancies is suggested.
Compressibility of Gases at High Temperatures. IV. Carbon Dioxide in the Temperature Range 0°—600°C, and Pressures up to 50 Atmospheres
Authors: MacCormack K. E. , Schneider W. G.
Published: January 2005

The compressibility of carbon dioxide has been measured in the temperature range 0°—600°C, at pressures up to 50 atmospheres, by a method employing gas expansion. Data are presented for the virial coefficients of the series equation, PV (Amagat Units) = AT+BTP+CTP12+DT P14+··· and values of PV (Amagat) at integral values of pressure and temperature.
Isoconjugate Spectra and Variconjugate Sequences
Authors: Platt John R.
Published: January 2005

Two molecules are isoconjugate or, more strictly, iso-π-electronic if they have the same number and geometrical arrangement of π-electrons bound about equally tightly in a planar conjugated system. Their π-electron spectra then show close resemblances. Example: aniline-styrene.

A variconjugate sequence is a series of such molecules in which the binding of some of the π-electrons and the appearance of the spectra slowly changes. Example: fluorobenzene (iso-π-electronic with benzene), phenol, aniline (iso-π-electronic with styrene). Here the heteroatoms are formally saturated and no transitions of nonbonding electrons (n-bands) are observed. Second example: phenyl cyanide (almost iso-π-electronic with benzene), benzaldehyde, phenyl azomethane (iso-π-electronic with styrene). Here the heteroatoms are formally conjugated and n-bands appear at long wavelengths in addition to the π-spectra. The location of the π-bands partly determines that of the n-bands.

The π-spectrum of every organic molecule with a closed-shell ground state lies on a variconjugate sequence between the π-spectra of two conjugated hydrocarbons. Several such sequences involving 90-odd compounds are displayed, showing the different binding of π- and n-electrons by different heteroatoms, and the interaction of n-bands of neighboring heteroatoms.

An examination is made of the general problem of assigning observed electronic transitions in organic-molecule spectra to particular theoretically predicted transitions. It is shown how variconjugate sequences could be useful in making such assignments.
The Phase Diagram of the BaO–TiO2 System
Authors: Statton W. O.
Published: January 2005

A method for accurately observing phase changes at high temperatures has been developed; it employs a microfurnace and uses samples of oxide mixtures weighing less than 1 mg. The samples were observed and their temperatures measured with an optical pyrometer specially adapted for this purpose and calibrated for the furnace radiation. An electrically heated resistance strip, in general of molybdenum, allows melting and crystallization of the oxide mixtures at any desired speed. The samples were placed directly on the strip and could be quenched by interruption of the current flow.

The binary system, BaO–TiO2, was investigated. The existence of four compounds, BaTi4O9, BaTi2O5, BaTiO3, and Ba2TiO4, was demonstrated by liquidus curves and x-ray diffraction. A phase change of BaTiO3 below the solidus temperature was observed; all oxide mixtures with less than 80 mole percent TiO2 showed this intermediate BaTiO3 phase at about 1450°C.

Single crystals of BaTi4O9, BaTi2O5, and BaTiO3 were grown from ternary melts of BaCO3, TiO2, and BaCl2. The compound, BaTi4O9, showed extensive polymorphism. Attack by molten BaO mixtures on molybdenum and platinum produced the compounds, BaMoO4, Ba3Pt2O7, and Ba3Ti2PtO9.