bluuebunny/crossref_metadata_2025 huggingface dataset:
Determination of Some Carbon-Chlorine Bond Dissociation Energies
Authors: Szwarc M. , Taylor J. Watson
Published: April 2005

An investigation of the pyrolyses of benzyl chloride and benzoyl chloride has been carried out by means of the ``toluene carrier'' technique. It is shown that the course of these reactions is analogous to that of the previously investigated pyrolyses of benzyl bromide and benzoyl bromide, i.e., the rate determining steps are C6H5·CH2Cl→C6H5·CH2·+Clor C6H5·CO·Cl→C6H5·CO+Cl.From kinetic data we obtained the activation energies of the rate determining steps, and we identify these activation energies with the respective C–Cl bond dissociation energies. Thus we derive D(C6H5·CH2−Cl)=68 kcal/moleand D(C6H5·CO·−Cl)=73.2 kcal/mole.The consistency of these data with the respective C–Br bond dissociation energies is very satisfactory. For example, the heat of formation of the benzoyl radical, derived from the D(C6H5·CO–Cl), is 15.7 kcal/mole, and that calculated from the experimentally determined D(C6H5·CO–Br) is 15.6 kcal/mole.
A Comparative Study of Accommodation Coefficients by the Temperature Jump and Low-Pressure Methods and Thermal Conductivities of He, Ne, and CO2
Authors: Thomas Lloyd B. , Golike Ralph C.
Published: April 2005

The temperature jump and low pressure methods are used to determine the accommodation coefficients of He, Ne, and CO2 on platinum under conditions as closely identical as compatible with the methods. Agreement is very close for He and for CO2, giving values centering about 0.176 for He and 0.78 for CO2. For Ne the results are ambiguous, giving good agreement with one sequence of preparation and giving temperature jump values 25 percent low with another. Variability is correlated with preparation history and variability with time is noted by both methods. Thermal conductivity values of He, Ne, and CO2 are given and compared briefly with values in the literature.
The Effect of Compression and of Hydrostatic Pressure on the Diffusion Anisotropy in Zinc
Authors: Liu T. , Drickamer H. G.
Published: April 2005

Measurements have been made on the rate of self-diffusion in single crystals of zinc along the directions both parallel and perpendicular to the C axis. The effects of compression by an applied force and hydrostatic pressure up to 10 000 atmospheres on the rate of diffusion were studied. The self-diffusion coefficients of polycrystalline zinc were also measured under both atmospheric pressure and compression.

The rate of self-diffusion in single crystals of zinc was found always to be larger in the direction parallel to the C axis, while the enthalpy of activation was found always to be smaller in this direction. Both compression and hydrostatic pressure tend to reduce the rate of self-diffusion, the greater effect being observed in the direction parallel to the C axis. Compression perpendicular to the direction of diffusion gave essentially the same effect as compression in the direction of diffusion. The enthalpy of activation was found to be increased 30 percent by the application of a pressure of 8000 atmospheres and to be decreased slightly by compression. The anisotropy in the rate of diffusion was found to decrease with increased hydrostatic pressure. The self-diffusion coefficients of polycrystalline zinc were found to be intermediate between the values observed in the two directions (parallel and perpendicular to the C axis) in single crystals and to be closer in magnitude to the values observed in the direction perpendicular to the C axis.
The Thermal Conductivity of Organic Vapors. The Relationship between Thermal Conductivity and Viscosity, and the Significance of the Eucken Factor
Authors: Vines R. G. , Bennett L. A.
Published: April 2005

The thermal conductivities of thirty-one polar and nonpolar organic vapors have been determined at pressures up to one atmosphere, over a temperature range from 40 to 160°C. The relation between thermal conductivity and viscosity is discussed in terms of the expression: K0MηCv0=f=ftransCvtrans+fintCvintCv0where, following a suggestion by Eucken, the ratio f is divided into separate components ftrans and fint, corresponding to the different rates of transfer of translational and ``internal'' (vibrational and rotational) energies.

Experimental values of f are not in accord with Eucken's original assumption that fint=1. For nonpolar vapors fint increases towards a high-temperature limit which is close to the theoretical value of 1.3. For polar vapors ftrans appears to be less than the theoretical value of 2.5, the decrease depending on the polar character of the molecule. These results are discussed with reference to energy exchanges occurring during collisions between complex molecules.
Electronic Structure of the Amylose-Iodine Complex
Authors: Murakami Hideo
Published: April 2005

The electronic structure of the amylose-iodine complex is studied on a different basis from that of the previous Stein-Rundle theory. First, the electron transfer from amylose oxygen to the iodine molecule is discussed from the viewpoint of Mulliken's intermolecular charge-transfer spectra. Then it is shown that the consideration of electronic interaction between neighboring iodine molecule ions and bond formation between oxygen and iodine gives a reasonable interpretation of bond number and absorption spectra. Last, the quantitative discussion of absorption spectra is performed by the application of the free-electron model to the system (I4—) which we consider to be the elemental unit in the polyiodine chain. The agreement between predicted and observed results is satisfactory if one considers the extreme simplification of the model.
Critical Phenomena in the Cyclohexane-Aniline System
Authors: Atack Douglas , Rice O. K.
Published: April 2005

Measurements have been made on the transition temperatures between one-phase and two-phase conditions in the cyclohexane-aniline system and on the densities of the coexisting phases, using an improved temperature control. The region of extreme cloudiness or wet fog, where the meniscus, if present, cannot be seen, and where density measurements are difficult because the density float cannot be seen, was investigated by means of a technique suggested by Zimm. In this procedure the temperature was raised, without stirring, to clear the wet fog without removing any density gradients which might have formed. The previous results of Rowden and Rice and Atack and Rice have been substantiated, and it is concluded with stronger evidence that there is an appreciable range of critical concentrations over which the transition temperature is constant.
Diffusion in CO2–CH4 Mixtures to 225 Atmospheres Pressure
Authors: Jeffries Q. R. , Drickamer H. G.
Published: April 2005

Diffusion coefficients have been measured in two mixtures of CO2 and CH4. (1) 50 mole percent CO2—50 percent CH4; (2) 75 mole percent CO2—25 mole percent CH4. C14 tagged CO2 was used, so that no gradient in chemical composition was necessary. For the first mixture the results agreed with Enskog's dense gas theory at all temperatures and pressures. For the 75 percent CO2 mixture at 25°C there was a positive deviation from theory, corresponding to the increased importance of glancing collisions for CO2 near saturation. The results are consistent with our previous data for self-diffusion in the two pure gases.
The Third Virial Coefficient of a Lennard-Jones Gas by Kihara's Method with Tables for the 6—9 Potential
Authors: Epstein Leo F. , Hibbert Celesta J. , Powers Marion D. , Roe Glenn M.
Published: April 2005

Kihara has shown that the third virial coefficient of a Lennard-Jones 6—9 gas can be expressed as a convergent power series of the form Σj βj(s)θ(s—6)j/s with θ=ε/kT. In this paper the coefficients βj(s), which are rather complicated double integrals, are developed and applied to the case s=9. For j<20 the coefficients are obtained by numerical quadrature, using high-speed computing equipment. Asymptotic formulas for arbitrary s are used to extrapolate the numerical results for s=9 into the range 20<j<100. Values of the normalized third virial coefficient, C9(0)(θ) and its derivatives, computed from Kihara's series, are tabulated for the range 0<θ<2. An asymptotic expression for C8(0)(θ) is used to extend the tables to higher values of θ.
The Development of a Quantum-Mechanical Model for the Lithium Fluoride Molecule
Authors: Benson G. C. , van der Hoff B. M. E.
Published: April 2005

A quantum-mechanical model of the LiF molecule is developed using four different forms of wave functions. The most refined form (Sec. III, part iii) considers the transfer of electrons to an excited state of the F— ion and possible covalency of the bond. This leads to values of the binding energy, internuclear distance, and dipole moment which are in reasonable agreement with available data. The inclusion of about 11 percent covalent character is essential for the success of the model proposed.
Vibrational Intensities in Diatomic Infrared Transitions. The Vibrational Matrix Elements for CO
Authors: Herman Robert C. , Shuler Kurt E.
Published: April 2005

Second-order perturbation theory has been employed to obtain general formulas for the (rotationless) vibrational matrix elements of diatomic molecules in infrared transitions. The mechanical and electrical anharmonicities have been taken into account by expanding the potential function in a power series through quartic terms and the electric dipole moment through cubic terms in the internuclear separation. The formulas obtained in this manner are shown to be quite accurate for the fundamental and the first two overtones.

These expressions were then employed to evaluate the vibrational matrix elements for CO (1Σ+) up to v′=4 using the experimental integrated absorption coefficients as auxiliary data for the determination of the electric dipole moment expansion coefficients. A comparison of the vibrational matrix elements for CO involving the use of perturbed harmonic oscillator wave functions with those obtained using Morse wave functions with both linear and quadratic expansion of the electric dipole moment indicates that the Morse treatment is applicable through higher vibrational quantum numbers and higher transitions than the perturbation treatment. The comparison furthermore shows that the simple Morse expression with a linear expansion of the electric dipole moment yields vibrational matrix elements which would appear to be sufficiently accurate for many purposes.

The anharmonic oscillator wave functions obtained would also prove useful in the evaluation of vibrational matrix elements in electronic transitions if the array for the harmonic oscillator overlap integrals were extended through higher vibrational quantum numbers.
Symmetry and Stability in Diborane and in Borine
Authors: Castellan G. W.
Published: April 2005

On the basis of the electronic state of diborane in the ethane structure proposed by Mulliken, a group theoretical theorem due to Jahn and Teller shows that the ethane structure is not a possible structure for diborane; a nontotally symmetric vibration will move the molecule to a more stable configuration of lower symmetry. Any of the common bridge structures on the other hand are possible structures for diborane. The ethane structure is a permissible structure for B2H6=. The argument is applied to the hypothetical molecule BH3, but the conclusion is that the instability of this molecule is not due to symmetry.
Generalization of the Radial Dilution Square Law in Ultracentrifugation
Authors: Trautman Rodes , Schumaker Verne
Published: April 2005

The classical square law of radial dilution, which relates the concentration of a single component to the boundary position in the ultracentrifuge cell, has been examined and found to be valid for a single component as well as for a multicomponent system even though the sedimentation rates are dependent on concentration.

The square law has been generalized to give corrected concentrations without the necessity of determining boundary positions explicitly. A system of warped coordinates has been introduced to simplify this application of the square law. A special template and its use is described which incorporates both the warped coordinates and the baseline and which enables very rapid reading of areas from routine ultracentrifugal runs.
The Determination of Concentrations in the Ultracentrifugation of Two-Component Systems
Authors: Trautman R. , Schumaker V. N. , Harrington W. F. , Schachman H. K.
Published: April 2005

An analysis of mass distribution in the ultracentrifugation of mixtures of two sedimentable components has been made. This treatment predicts the magnitude of the slow component concentration in the region between the slow and fast boundaries as well as the change in this concentration during the run. The theory has been applied to a series of mixtures and is in agreement with the experimental data. The existence of convection during the ultracentrifugation of mixtures is briefly discussed as well as the application of the theory to a determination of concentrations in unknown systems.
Scattering of High-Velocity Neutral Particles. III. Argon-Argon
Authors: Amdur I. , Mason E. A.
Published: April 2005

Total collision cross sections have been measured for argon atoms, with energies between 700 and 2100 ev, scattered in room temperature argon. Results obtained with two detectors of different geometric aperture are shown to be in accord when allowance is made for beam shape, intensity distribution, and scattering to a detector which is narrower than the beam, in accordance with procedures previously used for helium scattered in helium.

Potential energy information derived from the cross sections may be represented by V(r)=1.36×10−9/r8.33 ergsfor values of r between 2.18A and 2.69A, and appears to be consistent with that derived from measurements of gaseous compressibility, viscosity, and crystal properties.
Reaction of Cyclohexane with Mercury-6(3P1) Atoms
Authors: Beck P. W. , Kniebes D. V. , Gunning H. E.
Published: April 2005

An investigation has been made of the mercury-6(3P1)-photosensitized decomposition of cyclohexane at 29.30±0.01°C, under static conditions. The products of the reaction are hydrogen, bicyclohexyl, and cyclohexene, in order of decreasing importance. The mean quantum yields of cyclohexane disappearance, hydrogen formation, and cyclohexene formation were found to increase slightly with increasing substrate pressure; at 90-mm cyclohexane pressure, the values are 0.83, 0.43, and 0.03, respectively. Extrapolation to initial conditions of data on the variation of mean quantum yield with time at constant substrate pressure gave 0.55 for the initial quantum yield of hydrogen formation, and 0.17 for cyclohexene formation, independent of substrate pressure. From the foregoing initial quantum yield data, taken in conjunction with the stoichiometry of the reaction, a value of 0.93 was obtained for the initial quantum yield of cyclohexane consumption.

Absence of hexane, dodecanes, n-hexylcyclohexane, and low molecular weights products was taken as evidence of the stability of the cyclohexane ring during reaction.

The results of the investigation can be adequately accounted for by the following simple mechanism:(1) cyclo C6H12+Hg 6(3P1)→cyclo C6H11+H+Hg 6(1S0),(2) H+cyclo C6H12→H2+cyclo C6H11,(3) 2 cyclo C6H11→cyclo C6H10+cyclo C6H12,(4) 2 cyclo C6H11→bicyclo C12H22,(5) H+cyclo C6H10→cyclo C6H11.

Steps (1) to (4) describe the reaction under initial conditions.

From the initial quantum yield data the ratio k4/k3, the ratio of the rates of recombination to disproportionation for cyclohexyl radicals, was evaluated at 2.2. In short, recombination is approximately twice as fast as disproportionation for cyclohexyl radicals.
Hybridization and Ionic Character in the Hydrogen Chloride Molecule
Authors: Schatz Paul N.
Published: April 2005

Hybridization in the HCl molecule has been studied in terms of an spd hybrid valence bond function including an ionic term (H+–Cl-). The results indicate that the quadrupole coupling constant for gaseous HCl (not known experimentally) may be of the order of 100 percent larger than the value reported for the solid. It is found that the quadrupole coupling constant depends principally on the amount of ionic character and does not distinguish among various possible hybridizations.

The sign of the dipole moment is discussed briefly.
Raman Spectra and Potential Constants for CF3Cl, CF3Br, and CF3I
Authors: Taylor Robert Cooper
Published: April 2005

Raman frequencies have been obtained for gaseous CF3Cl and CF3Br and for liquid CF3I at —40°C. The assignments are in agreement with previous investigations. The spectra have been analyzed using a simplified, six-constant potential function of the Urey-Bradley type without the assumption of tetrahedral angles around the central carbon atom. In all three cases, it was found possible to reproduce the experimental frequencies to within less than their experimental error.
Infrared Studies of Solutions Involving Aromatics and Halogens
Authors: Haller Wolfgang , Jura George , Pimentel George C.
Published: April 2005

Infrared studies were made in the region 640—1400 cm—1 to investigate the effect of adding iodine to benzene, toluene, mesitylene, hexamethylbenzene, naphthalene, cyclohexane, and methylcyclohexane. Spectral changes were observed for each of the aromatics except for naphthalene. The enhancement of the mesitylene band at 1300 cm—1 was observed for mesitylene purified in five distinct ways. The enhancement of the hexamethylbenzene band at 1298 cm—1 was studied as a function of the concentrations in carbon disulfide solutions and correlates with the product of hexamethylbenzene and iodine concentrations. The effect of bromine on the spectrum of benzene was noted also. The results can be discussed in terms of weak complex formation or strong solvent perturbations.
Reduction of SrO by Methane
Authors: Moore George E. , Allison H. W. , Wolfstirn K. B.
Published: April 2005

The reduction of SrO supported on purified platinum or nickel filaments was investigated over the range 1050 to 1700°K. Reduction is rapid, and at least part occurs in two major steps: (1) the methane dissociates, depositing carbon in the oxide, which (2) then reacts with SrO to give Sr and CO.

When SrO is supported on platinum filaments a major part of the Sr enters the platinum. This is far less pronounced in nickel supports. Possible significance for the oxide cathode is discussed. Calculations indicate that SrC2 may also be formed.
Theory of Laminar Flame Stability. I. Analytic Stability Condition
Authors: Rosen J. B.
Published: April 2005

The stability of propagation of a laminar flame or combustion wave is studied for a general type of flame propagating medium. This is done by investigating the stability of the steady-state solution of the flame equations for such a system. The method is to solve the linearized system of partial differential equations resulting from an instantaneous heat release perturbation of the steady-state solution. An approximate solution in analytic form to this linearized partial system is obtained. This permits the statement of an analytic stability condition, and shows the existence of stability limits. The existence of stability limits is suggested as an explanation of inflammability limits.
Successive Orientational Transitions in Crystals
Authors: Krieger Theodore J. , James Hubert M.
Published: April 2005

An extended discussion is given of a crystal model showing successive ``rotational'' or orientational transitions. This model consists of an array of classical rotators with next-neighbor coupling, the potential energy of coupling being E(θij)=AP1(cosθij)+BP2(cosθij), where θij is the angle between the molecular axes of symmetry. It is treated by both the internal field approximation (Bragg-Williams approximation) and Chang's modification of Bethe's method. The internal field approximation is applied in two ways, the first involving use of consistency relations, the second involving calculations of the thermodynamic potentials. The consistency relations are shown to be equivalent to the condition that the free energy be stationary, but not necessarily a minimum, with respect to variation of the orientational distribution of the molecules. Depending on the relative values of A and B, the model shows a single second-order transition, a single first-order transition, two first-order transitions, or a second-order transition followed by a first-order transition as T rises. The treatment by Chang's method is not as complete as that by the internal field method, but gives confidence that the latter method is sufficiently accurate to indicate correctly the general behavior of the model. Transition temperatures are computed by both methods, latent heats and specific heats by the internal field method only. The relatively complex behavior of the model can be understood in general terms. In particular, when two transitions occur, the one at lower temperature marks a change from an ordered state in which molecular axes tend to be all parallel to a preferred direction (``ferromagnetic'' case) or alternately parallel and antiparallel (``antiferromagnetic'' case) to another ordered state in which parallel and antiparallel orientations are equally probable for each molecule; the second transition is to a state of complete long-range orientational disorder. There are suggestive similarities between the behavior of this model and the observed properties of the hydrogen and deuterium halides.
Quenching of Mercury Resonance Radiation. IV. Unsaturated Compounds
Authors: Darwent B. deB. , Phibbs M. K. , Hurtubise F. G.
Published: April 2005

The cross sections for quenching mercury resonance radiation by a number of mono- and di-olefins, acetylenes, substituted olefins, and other compounds containing multiply bonded atoms have been measured. The quenching cross sections of mono-olefins increase with increasing molecular weight but not with increased branching of the carbon skeleton. The position of the double bond has little or no effect on the cross section. The substitution of fluorine for hydrogen decreases the cross section of olefins. The presence of a second double bond does not alter the cross section. The double bond is more effective when between two carbon atoms than when it is between two nitrogens or carbon and oxygen. The cross sections of acetylenes are essentially the same as those of the corresponding olefins but here the substitution of N for CH does not appear to alter the effective cross section.
Microwave Spectrum and Dipole Moment of Pyridine
Authors: DeMore Billy B. , Wilcox W. S. , Goldstein J. H.
Published: April 2005

The microwave spectrum of pyridine has been studied in the region from 20 000 to 40 000 Mc. Twelve low-J R-branch lines have been identified. Analysis of the spectrum requires that the dipole moment lie in the a axis, and leads to the following values of rotational constants: a=6039.436 Mc, b=5804.997 Mc, c=2959.210 Mc, and κ=+0.847781. The dipole moment of pyridine vapor was found to be 2.15±0.05 D from quantitative Stark effect studies.
Organic Photoconductors. III. The Kinetics of Basic Fuchsin
Authors: Nelson R. C.
Published: April 2005

To account for the influence of temperature on rates and levels of conductance in basic fuchsin, two activation energies are required; for diffusivity and for quantum yield of charge carriers, and these are approximately equal having a value near 0.38 ev. Two regimes of behavior with respect to light intensity are found, one in which the response is proportional to the illumination, and another, which may be established by strong pre-illumination of the film, in which the response is as the square root of the light intensity. These observations are in accord with the hypothesis which was proposed to account for the inverse dependence of rate constant on initial conductance in crystal violet.
The Determination of the Potential Constants of SO2 from Centrifugal Distortion Effects
Authors: Kivelson Daniel
Published: April 2005

The microwave spectrum of SO2 was reanalyzed with particular emphasis upon the effect of centrifugal distortion. It was possible to fit the rotational spectrum to within a mean deviation of ±0.23 Mc using the energy expression given by Kivelson and Wilson. The rotational constants so determined are a=60778.79 Mc, b=10318.10 Mc, and c=8799.96 Mc. The four distortion constants could not be uniquely determined directly from the rotational spectrum.

The sets of potential constants determined by Wilson and Polo were used to calculate distortion constants and these in turn used to calculate frequency shifts due to centrifugal distortion. These shifts are critically dependent upon the set of potential constants used. By choosing a set of potential constants compatible with the infrared spectrum which also yield distortion frequency shifts in accord with those obtained from a direct analysis of the rotational spectrum, a very sensitive determination of the potential constants may be made. The resulting force constants are: fd=10.006×105 dyne cm—1; fα/d02=0.7933×105 dyne cm—1; fdd=0.0236×105 dyne cm—; fdα/d0=0.189 dyne cm—.
The Photolysis of Ammonia at 1849A in a Flow System
Authors: McDonald C. C. , Kahn A. , Gunning H. E.
Published: April 2005

An investigation has been made of the photolysis of ammonia at 1849A in a flow system at room temperature. The products of the reaction were found to be hydrazine, hydrogen, and nitrogen. The rate of decomposition of ammonia was independent of the linear flow rate but depended upon the ammonia pressure in the reaction zone. The fraction of ammonia decomposed which was recovered as hydrazine, while independent of ammonia pressure, increased markedly with increasing linear flow rate from zero in the static system to 0.84 at a linear flow rate of 1750 cm/sec.

It was found that the quantum yield of ammonia consumption under flow conditions was consistently higher by a factor of approximately two than for the static conditions at the same pressures.

A separate system was used to determine the extinction coefficient of ammonia at 1849A over the pressure range of the experiments. The value obtained was 1.21×103 liters-mole-1—cm—1.

A mechanism has been proposed which is in qualitative agreement with the observed facts.
Reactions of Free Radicals with Aldehydes. II. The Reactions of Methyl Radicals with Propionaldehyde
Authors: Volman David H. , Brinton Robert K.
Published: April 2005

The reaction of radicals derived from the thermal decomposition of di-t-butyl peroxide with propionaldehyde in the gas phase has been studied. The gaseous products were carbon monoxide, methane, ethane, propane, butane, and ethylene. A mechanism to account for the induced chain decomposition and product formation involving H atom abstraction by radicals and radical decomposition, combination and disproportionation is given. The energetics of H atom abstraction by methyl and ethyl were similar and lead to an activation energy of about 7.5 kcal/mole and a steric factor of about 10—3. These values are in good agreement with those found for H atom abstraction from acetaldehyde. Evidence is presented that H atom abstraction takes place with the carbonyl attached H for both acetaldehyde and propionaldehyde.
Rotational Energy Transfer in H2
Authors: Brout Robert
Published: April 2005

Rotational energy deactivation probabilities have been calculated for H2 using the quantum-mechanical method of distorted waves. Approximate procedures have been indicated for further extensions of these calculations to other symmetric diatomic molecules. Comparison with data from sound dispersion measurements shows good agreement between theory and experiment.
Semiempirical Potential Energy Functions. I. The H2 and H2+ Diatomic Molecules
Authors: Frost Arthur A. , Musulin Boris
Published: April 2005

After setting up certain theoretical criteria for a semiempirical potential energy function, two such functions for H2+ and H2 are constructed, the simplest of which has the form V=e-aR(e2R−b),where V is the potential energy with its zero corresponding to infinite separation. R is the internuclear distance, e the electronic charge, and a and b parameters. This function is used to correlate the experimental quantities: dissociation energy, equilibrium internuclear distance, force constant, third and fourth derivatives of V with respect to R, united atom energy, and critical distance.

A more complicated function is also presented which with one molecular parameter fixed by the dissociation energy is capable of then predicting internuclear distance and force constant.
The Photoconductivity of Anthracene. I.
Authors: Chynoweth A. G. , Schneider W. G.
Published: April 2005

Pure crystals of anthracene became photoconducting when illuminated with wavelengths lying within their fundamental absorption band. The majority carriers were positive holes, which, as they drifted through the crystal, took part in trapping processes. From the variation of the photocurrent with temperature it was concluded that the number of positive hole traps fell off exponentially as their height above the valence band increased. From the behavior of the photocurrent at various applied fields and light intensities, it was concluded that the conventional energy band diagram as used for inorganic substances could be applied to organic compounds also. Evidence was found, however, indicating that there were large potential irregularities in the energy levels throughout the crystal.
The Solution of the Boltzmann Equation for a Shock Wave using a Restricted Variational Principle
Authors: Rosen Philip
Published: April 2005

Using a variational method and the Mott-Smith velocity distribution function, the thickness of a plane shock wave is calculated for various Mach numbers. The results compare fairly well with those obtained by Mott-Smith. It is also shown that the Mott-Smith distribution function becomes a better choice as the Mach number increases.
The Infrared Spectrum of Ketene
Authors: Bak Bo/rge , Andersen F. Allan
Published: April 2005

The infrared spectrum of gaseous ketene has been reinvestigated in the 500—1200 cm—1 region with a recording prism spectrophotometer using KBr and NaCl optics. Because of an experimental procedure which enabled us to subtract the absorption of the impurities, a ketene absorption curve was obtained, probably more correct than that found by previous investigators. An interpretation of the numerous lines in the 500—1000 cm—1 interval is given, resulting in a reassignment of some of the fundamental vibrational frequencies. Thermodynamic functions are recalculated.
PVT Relations of Liquid Carbon Tetrachloride and n-Perfluoroheptane and a Test of the Clausius-Mosotti Equation
Authors: Alder B. J. , Haycock E. W. , Hildebrand J. H. , Watts H.
Published: April 2005

Values of (∂P/∂T)v for CCl4 and n-C7F16 have been measured over a range of approximately 20° and 160 atmospheres. The linear relation between P and T found in earlier studies to hold over 20 atmospheres for a number of liquids and solutions is here confirmed over the much larger range. One corollary is that (∂Cv/∂V)T=0; another is that the isothermal compressibility of C7F16, not hitherto known, is 2.38×10—4 atmosphere—1 at 25° and 1 atmosphere, and could easily be calculated for other temperatures. The terms in the equation (∂E/∂V)T=T(∂P/∂ T)v—P are given, also the function V2(∂E/∂V)T, shown in the earlier studies to be constant. Its value for CCl4 confirms the earlier studies; for n-C7F16 it is 101.5 atmospheres×liters.2

The dielectric constant of n-C7F16 has been measured at 16.0° and at 38.4°, and over a pressure range of 115 atmospheres. The values obtained conform closely to the Clausius-Mosotti equation, giving a molar polarization of 49.1 cc.
Deuterium Effect on Hydrogen Bond Distances in Hafnium Dihydride
Authors: Sidhu S. S.
Published: April 2005

X-ray diffraction data obtained for carefully prepared and annealed samples of HfH2 and HfD2 show that as deuterium substitutes for hydrogen atoms the hafnium-hydrogen bond distances decrease. The lattice as a whole contracts, and the density increases. Powder diffraction patterns and the structure data for the two compounds are presented.
Scattering of High-Velocity Neutral Particles. IV. He–A; A–He
Authors: Amdur I. , Mason E. A. , Harkness A. L.
Published: April 2005

Total collision cross sections have been measured for helium atoms with energies between 500 and 2100 ev, scattered in room temperature argon, and for argon atoms with energies between 600 and 2100 ev, scattered in room temperature helium. In each case, two detectors of different geometric aperature have been used, and potential energy functions have been obtained by procedures previously applied to helium scattered in helium.

The average function for the potential energy between a helium atom and an argon atom derived from the measured cross sections may be represented by V(r)=9.95×10−11/r7.25ergs,for values of r between 1.64A and 2.27A. Since this potential is in good agreement with the geometric mean of the potential between two helium atoms and that between two argon atoms in the range represented by the arithmetic average of the individual interaction distances, it is suggested that the parameters of a point repelling type potential function may, in general, be combined in this manner.
Solution Spectra and Oscillator Strengths of Electronic Transitions of Pyridine and Some Monosubstituted Derivatives
Authors: Stephenson Harold P.
Published: April 2005

The near ultraviolet absorption spectra of the following substances have been measured in iso-octane and ethyl alcohol solutions: pyridine, the isomeric picolines, 2- and 3-fluoropyridine, 2- and 3-chloropyridine, and 2- and 3-bromopyridine. Solvent effects were observed and oscillator strengths were measured for the singlet-singlet π—π* and n—π* electronic transitions which occur in the spectral region 34 000 cm-1 to 48 000 cm-1. It was found that in this spectral region the n—π* transition is missing in the case of 2-fluoro-, 2-chloro- and 2-bromopyridine.
Szilard-Chalmers Reaction in Crystalline Compounds of Chromium
Authors: Harbottle Garman
Published: April 2005

The Szilard-Chalmers reaction has been observed in a number of crystalline compounds of tri- and hexavalent chromium. The effect of neutron and external gamma irradiation has also been investigated. It was found that in a series of alkali chromates and dichromates the retention varied from 50 to 90 percent, while ammonium chromate and dichromate were much lower. The results are interpreted in terms of hotatom reactions of the recoil fragments in the crystal, and hydrolysis and reduction reactions taking place on dissolution of the crystals.
Infrared Absorption Studies of Aqueous Complex Ions: I. Cyanide Complexes of Ag(I) and Au(I) in Aqueous Solution and Adsorbed on Anion Resin
Authors: Jones Llewellyn H. , Penneman Robert A.
Published: April 2005

Techniques are described for obtaining infrared absorption spectra of complex cyanide anions in aqueous solution and adsorbed on anion resin. In the system AuCN–KCN–H2O, only the soluble complex ion Au(CN)2— is observed; the molar extinction coefficient (ε) is 477±25 mole—1 liter cm—1 at 2147±1 cm—1. When Au(CN)2— is adsorbed to the extent of 47 weight percent on Dowex-A-1 resin, its absorption maximum appears at 2138 cm—1. Three distinct silver cyanide complex ions were observed in aqueous solution: Ag(CN)2—, ε=264±12 at 2135±1 cm—1; Ag(CN)3—2, ε=397±23 at 2105±1 cm—1; Ag(CN)4—3, ε=556±83 at 2092±1 cm—1. Approximate values (calculated in terms of activities) of the dissociation constants for the tri- and tetra-cyanide complexes into the next lower complex are K3, 2=0.20±0.05 mole liter—1, and K4, 3=13,4±4 mole liter—1, respectively. Over ranges of silver concentrations from 0.1—1.0 formal and of free CN— ion concentrations from 0.05—1.5 molar, the concentrations of Ag(CN)2—, Ag(CN)3—2 and Ag(CN)4—3 can be calculated to within 5 percent (absolute) using values of the constants adjusted to best overall fit; in terms of concentrations, K3, 2c=0.108 and K4, 3c=2.85 mole liter—1.
Order-Disorder Phenomena
Authors: Linder Bruno
Published: April 2005

The thermodynamics of the order-disorder transition in β brass is explored by making the assumption that the energy difference between the disordered and ordered state has the form E0—BT2. Such a law suggests itself if the coupling of the thermal expansion to the order-disorder transformation is emphasized and the effect of short range order is neglected. The constant B is shown to be related to the lattice vibrations of both the ordered and disordered phases. A very rough estimate of B was obtained from electrical resistivity measurements, the assumption being made that the connection between the resistivity and the vibrational frequency, ρ∝T/MΘ2, holds. A heat capacity versus temperature curve, which was calculated on the basis of a nonconstant energy of disordering and which also includes the effect of lattice vibrations, is shown to agree well with the experimental one.

The usefulness of the form E0—BT2 is not confined to β brass and the same expression may be applied to systems other than solid-solid.
Cross Sections for Charge Transfer Collisions of Low-Energy Ions in N2 and O2
Authors: Potter Roy F.
Published: April 2005

Measurements have been made of the cross sections for charge transfer collisions between the low-energy (9—250 ev) ions, N2+, O2+, O+ and N+, and the molecules N2 and O2. Two reactions (N+, N2; O+, N2) have been reported by other workers and are compared with present work.

The experimental method utilizes a radio-frequency mass spectrometer as an ion source. The ions are collimated and enter a weak radial electric field of cylindrical symmetry. The secondary ions are separated from the primary beam and the ratio of the two currents is measured as a function of pressure.

Results are discussed in terms of the adiabatic collision condition and possible internal energy states of the ions and molecules.
The Valence Structure of the Boron Hydrides
Authors: Eberhardt W. H. , Crawford Bryce , Lipscomb William N.
Published: April 2005

A set of extended valence postulates is presented including the concept of the localized three-center bond. These postulates are applied systematically to the boron hydrides and account for their unusual geometry, their unexpected dipole moments, and the fact that they are not ``electron-deficient.''
The Electrical Properties of Some Complex Compounds. Part 2
Authors: Fielding P. E. , Mellor D. P.
Published: April 2005

The possibility of several complex compounds being intrinsic semiconductors is discussed in the light of experimental work presented in this paper and in Part 1. It is concluded that complexes containing metal atoms in different oxidation states in crystallographically equivalent positions are capable of acting as intrinsic semiconductors. Additional support is given to the alternative structure of Vortmann's salt proposed by Brimn.
Evaluation of Some Electron Repulsion Integrals Needed in Molecular Quantum Mechanics. A Method of Calculation of Two Electron Multi-Center Repulsion Integrals without the Use of the Neumann Expansion
Authors: Barker Roland S. , Eyring Henry
Published: April 2005

Consideration has been given to two of the electronic repulsion integrals arising in the quantum-mechanical energy calculation of the triatomic hydrogen molecular complex when no restrictions are placed on the effective nuclear charges of the composite atomic orbitals. The formulation of the integrals is first developed on a general basis and then restricted to the H3 molecule. The possibility of extension of the mathematical processes to similar electron interaction integrals in more complex molecules is pointed out. The integration formulas are given as rapidly converging series.
Infrared and Raman Spectra of 1,1-Dimethylhydrazine and Trimethylhydrazine
Authors: Shull E. R. , Wood J. L. , Aston J. G. , Rank D. H.
Published: April 2005

Infrared spectra of 1,1-dimethylhydrazine between 700 and 1600 cm—1 for the gas phase and between 700 and 3500 cm—1 for the liquid phase and of trimethylhydrazine between 700 and 3500 cm—1 for the gas and liquid phases are reported along with the Raman spectra of the two compounds. Frequency assignments are given for both compounds.
Vibrational Spectrum of Bromotrifluoroethylene
Authors: Mann D. E. , Acquista N. , Plyler Earle K.
Published: April 2005

The infrared spectrum of gaseous bromotrifluoroethylene F2C:CFBr has been investigated in the range 2—52μ. The assignment of fundamentals parallels that for chlorotrifluoroethylene very closely. The planar vibrational frequencies in cm—1 are 1783(ν CC), 1330(ν CF), 1203(ν CF), 1027(ν CF), 659(ν CBr), 510(δ CF2), 370(δ CFBr), 311(ρ CF2), 160(ρ CFBr), while the out-of-plane modes are assigned 538(β CF2), 355(β CFBr), and 150(τ). A table of thermodynamic functions for the ideal gas is given.
Ultrasonic Propagation and Its Relation to Molecular Structure in the Diols
Authors: Litovitz T. A. , Higgs R. , Meister R.
Published: April 2005

Measurements of viscosity, ultrasonic absorption, and velocity were made in a group of associated organic liquids, known as the diols. Included in the measurements were ethanediol, two isomers of propanediol, and three isomers of butanediol. In these liquids the values of absorption ranged from 1.66 to 2.20 times that value calculated from Stokes formula. The effect of the structural differences indicated the following, when the addition of CH2 groups was considered, (1) an increase in shear viscosity, (2) an increase in adiabatic compressibility, (βad), and (3) an increase in the ratio of αobs/αcalc. Effects caused by isomeric changes were (1) an increase in βad and (2) an increase in αobs/αcalc as the (OH) groups were brought closer together. It was concluded that a relationship existed between the ratio of αobs/αcalc and βad.

Measurement of absorption vs temperature in ethanediol over a viscosity range of 24:1 indicated that the difference in activation energy of shear and compressional viscosity could be no greater than 0.1 percent.
Thermal Diffusion in Mixtures of Tetrachloroethane with Normal Paraffin Hydrocarbons
Authors: Saxton R. L. , Drickamer H. G.
Published: April 2005

Thermal diffusion measurements have been made on a series of binary mixtures of normal paraffin hydrocarbons with tetrachloroethane over a range of temperatures from 5-55°C. The results are analyzed in terms of a previously published theory. The size of hole left by the hydrocarbon seems independent of chain length up to an eight or nine carbon chain. If the moving segment is assumed to be eight carbon atoms long, the size of hole left by the segment is independent of total chain length.
Static Space-Charge Effects in the Diffuse Double Layer
Authors: Macdonald J. Ross
Published: April 2005

Exact solutions of the static Debye-Hückel space-charge equations for one and for two blocking electrodes are compared analytically and graphically. It is found that the simpler one-electrode solution may be employed to characterize the diffuse double layer with high accuracy in most experimental situations in place of the less tractable two-electrode solution which involves Jacobian clliptic functions. Some consequences of the strong nonlinear voltage dependence of the exact solutions are considered and the application of the solutions to physical situations is discussed.
Polarization Effects in the Ionic Conductivity of Silver Bromide
Authors: Friauf Robert J.
Published: April 2005

Alternating current impedance measurements on samples of silver bromide with silver and with gold electrodes show the presence of polarization effects. These effects appear as a capacitive component of the impedance and a slight dependence of the resistance on the frequency of the measurement, and their dependence on temperature, frequency, pressure, voltage, and impurity content has been investigated. A macroscopic theory is developed to describe the motion of the mobile charge carriers (ionic defects) which exist in AgBr at elevated temperatures. The general equations contain the effects of conduction and diffusion currents, space charge, and formation and recombination. Since these equations are nonlinear, an approximation procedure is developed, which is valid for small values of the applied voltage. The results of the theory with appropriate boundary conditions give semiquantitative agreement with the temperature and frequency dependence of the observed results and afford a good qualitative description of all of the observed effects. It is concluded that Frenkel defects are responsible for the polarization effects and that the formation and recombination rate is smaller than might at first be expected.
The Ferrous Sulfate Radiation Dosimeter: A Calorimetric Calibration with Gamma Rays
Authors: Lazo R. M. , Dewhurst H. A. , Burton Milton
Published: April 2005

The ferrous sulfate radiation dosimeter (herein called the Fricke dosimeter) has been recalibrated by a calorimetric method in which assumptions regarding energy absorbed in the glass and the heat capacity of the calorimeter have been eliminated. The 100-ev yield, G(Fe++→Fe+++), is 15.8±0.3 for Co60 gamma radiation in agreement with the Hochanadel-Ghormley value. The result is compared with other G values reported in the literature and it is recommended that the low value be adopted for Co60 gamma radiation and for electrons in the 1—2 Mev range.
Rotational Spectrum of PH3
Authors: Nielsen Harald H.
Published: April 2005

Lines in the rotational spectrum of PH3, indentifiable with the rotation of the molecules in the first excited states of the frequencies ν2 and ν4, allow an independent test to be made of the Coriolis interaction between these states as calculated from the vibrational-rotational band spectrum. It is shown that the B values observed from the rotational spectrum for these states are consistent with those obtained from the information derivable from the vibrational-rotational spectrum.
Infrared Absorption Investigation on the Rotational Isomerism of 1,1,2-Trichloroethane
Authors: Kuratani Kenji , Mizushima San-ichiro
Published: April 2005

The energy difference between the rotational isomers of 1,1,2-trichloroethane has been determined in the gaseous and liquid states by the infrared absorption measurements. In the solid state, only one of the rotational isomers has been found to be stable. The different behavior in rotational isomerism between 1,1,2-trichloroethane and 2-methylbutane, both having the same skeletal configuration, has been explained in terms of the difference in the electrostatic part of the hindering potential.
The Surface Migration of Carbon on Tungsten
Authors: Klein Ralph
Published: April 2005

The surface migration of carbon on tungsten was observed with the field-emission microscope technique. The tungsten point was shadowed with carbon and heated to a given temperature; observations of the emission patterns were made at room temperature at various time intervals. The migration occurs at a measurable rate starting about 850°K. It is characterized by a sharp boundary of a form which clearly shows that the (011) and (121) planes are avoided. An activation energy of 55±7 kcal/mole was calculated for the process by application of the theory of diffusion with a sharp moving boundary.
Velocity of One Megacycle Ultrasonic Waves in Benzene and Toluene Solutions of Polystyrene
Authors: Fox William M. , Hazzard George W.
Published: April 2005

A standing wave, single crystal interferometer was used to measure the ultrasonic velocity in polystyrene having molecular weights from 4100 to 159 000. Most of the measurements were made with 2 g of polystyrene per 100 ml of solution, benzene being the solvent. Some measurements used similar concentrations with toluene as the solvent. In the range of temperatures from 8.95°C to 54.45°C the velocity attributable to the polystyrene had a negative temperature coefficient below 35°C and a positive one above 35°C. At a given temperature the velocity attributable to the polystyrene showed two minima when plotted as a function of molecular weight. These minima occurred at polystyrene molecular weights of 17 000 and 53 000. Suggestions, but no conclusions, are given for the cause of these minima or dispersive regions.