bluuebunny/crossref_metadata_2025 huggingface dataset:
The Lattice Vibration Specific Heat of Graphite
Authors: Krumhansl J. , Brooks H.
Published: January 2005

Recent experiments have shown that the specific heat of graphite varies as T2 instead of T3 between 15°K and 80°K. In this paper such a behavior is shown to be a consequence of the elastic anisotropy of graphite, and therefore an intrinsic property, rather than a particle size effect as suggested by Gurney, or a plate-like behavior as suggested by Komatsu and Nagamiya. The Gurney treatment is shown to be in error both as to the enumeration of modes, and as to the temperature range over which the particle size effect might be of significance. The Komatsu and Nagamiya treatment is shown to be inconsistent with elasticity theory. The present treatment employs a semirigorous analysis of the normal mode problem for the transverse vibrations, approximated for long wavelengths. It is found that experimental data from 15–1000°K can be well fitted by dividing the lattice vibrations into two types: (a) modes with atom displacements normal to the layer planes with a Debye temperature of 900°K, and (b) modes with atom displacements in the planes with a Debye temperature of 2500°K.
Energy Exchange in Molecular Collisions
Authors: Widom Benjamin , Bauer S. H.
Published: January 2005

A theory was developed for computing the probability of transition, upon molecular collision, between vibrational states, involving corresponding conversion of translational energy. A spherically symmetric Lennard-Jones 6–12 potential for interaction between the colliding molecules was introduced; their relative translational motion was described classically. Further, the theory was symmetrized to permit inclusion of collisions with nonzero impact parameters. As an example, the theory was applied to the CO2–H2O system. The effective collision diameter for an inelastic event was found to be of the observed order of magnitude, demonstrating not only the selective relaxation effect of water, but also its somewhat unusual temperature dependence.

Zener's solution of the problem for a head-on collision was generalized to three-dimensional collisions, assuming a spherically symmetric interaction potential; but the complete solution of this model, including a quantum-mechanical description of the relative translational motion, was not obtained. However, for such a potential it was possible to demonstrate that the semiclassical theory is an adequate approximation to the quantum theory result, whenever the relative translational energies are much greater than the energy of exchange.
Proton Magnetic Resonance of the CH3 Group. II. Solid Solutions of t-Butyl Chloride in Carbon Tetrachloride
Authors: Powles J. G. , Gutowsky H. S.
Published: January 2005

Measurements of the proton magnetic resonance absorption in solid solutions of t-butyl chloride in carbon tetrachloride are reported for temperatures above −195°C. The results confirm, in general, the phase diagram established previously by thermal and dielectric measurements. In addition, information is obtained on the CH3 group and molecular motions in the various phases. Rotation of the CH3 groups at −195°C depends on the composition. In solutions between 34.9 and 70.6 mole percent t-butyl chloride there is effective rotation of the CH3 groups about their C3 axes whereas in pure t-butyl chloride the CH3 groups are fixed at this temperature. For some compositions two separate phases are formed at low temperatures and the observed absorption agrees with that predicted from the properties and relative proportions of the protons in the two phases. Somewhat anomalous results were obtained for the more dilute solutions. For all compositions at temperatures above −150°C the resonance line narrows to about the same value, 3 gauss, and this is shown to be due to rotation of the molecule about the C–Cl bond in addition to rotation of the CH3 groups about their C3 axes. Other possible motions are discussed, and the second moment of the absorption line is calculated theoretically for complex motions of the CH3 group. The differences in the freedom of motion of the CH3 groups in the different phases are attributed to interactions both within a molecule and with neighboring molecules.
Vibrational Spectra of Fluorinated Aromatics. IX. p-Fluorotoluene
Authors: Ferguson E. E. , Hudson R. L. , Nielsen J. Rud , Smith D. C.
Published: January 2005

The infrared absorption spectrum of liquid p-fluorotoluene has been obtained in the region 2–38μ with the aid of LiF, NaCl, KBr, and KRS−5 prisms. The stronger bands of the gas phase have been scanned with NaCl and KBr prisms. The Raman spectrum of the liquid has been photographed with a three-prism glass spectrograph of linear dispersion 15A/mm at 4358A. A complete assignment of fundamental vibration frequencies is given, and the spectra are interpreted in detail.
The Microwave Spectrum of Phosgene
Authors: Robinson G. Wilse
Published: January 2005

The microwave spectra of C12O16Cl35Cl35 and C12O16Cl35Cl37 have been investigated in the region 23 000–28 000 Mc/sec. The analyses of the rotational spectra yield for the phosgene molecule: C–O distance=1.166±0.002A; C–Cl distance=1.746±0.004A; and Cl–C–Cl angle=111.3±0.1°. An analysis of the quadrupole hyperfine structure was made for both isotopic species and the quadrupole coupling constants were obtained for C12O16Cl35Cl35. An attempt is made to explain the large observed value of the field dyadic asymmetry parameter η.
Electronic Energy Levels of Molecular Oxygen
Authors: Meckler Alvin
Published: January 2005

A configuration interaction study of the lower-lying electronic energy levels of molecular oxygen is made. With the 1s and 2s shells kept filled, the remaining eight electrons are distributed among the twelve spin-orbitals arising from the 2p levels on each atom. The atomic functions are represented as Gaussians, which are poor atomic functions but facile integrands in many-center integrals. The molecular orbitals are formed as symmetrical linear combinations of the atomic orbitals, simply for convenience. Inclusion of all configurations implies complete equivalence of all possible constructions of linear combinations.

Out of the 495 configurations (many-electron determinants) a group of nine states of 3Σg− character is set up and twelve of 1Σg+ character. The interaction matrix of each block is computed and diagonalized (by electronic computer). The results for the ground state, which is a triplet, are very good. The binding energy is off by 2 percent, the internuclear distance is off by 1 percent, the fundamental nuclear vibration frequency is off by 4 percent. The lowest singlet state is not given as accurately.

The energies and wave functions for the lowest triplet and singlet are calculated and compared for various values of internuclear separation. Discussion is made of the validity of single configuration theory, from both the Heitler-London and Hund-Mulliken points of view.
The Photochemical Separation of Isotopes
Authors: Billings Bruce H. , Hitchcock W. J. , Zelikoff Murray
Published: January 2005

A method of successfully separating mercury isotopes by a photochemical process is described. The method involves the use of a monoisotopic resonance lamp as the source of light for the photochemical reaction. In this particular case a Hg198 lamp was used to excite only the Hg198 atoms. The excited Hg atoms react with water vapor to produce enriched mercuric oxide. In the first experiments an enrichment factor of 1.5 was obtained.

The analysis of the isotopes was undertaken by the use of multilayer dielectric Fabry-Perot interferometers.
Substituted Methanes. XVI. Vibrational Spectra, Potential Constants, and Calculated Thermodynamic Properties of Dibromodifluoromethane
Authors: Decker Charlotte E. , Meister Arnold G. , Cleveland Forrest F. , Bernstein Richard B.
Published: January 2005

Raman displacements, semiquantitative relative intensities, and quantitative depolarization factors of liquid CBr2F2, and infrared wave numbers and the percent transmission in the region 450–4000 cm−1 for gaseous CBr2F2 have been obtained. Satisfactory assignments were made for all the observed bands. Using the Wilson FG matrix method, with a potential function containing all possible second-degree terms, reasonable values of the potential constants were calculated. Finally, the heat content, free energy, entropy, and heat capacity for the ideal gaseous state at 1 atmos pressure were calculated for 12 temperatures, from 100 to 1000°K, using a rigid rotator, harmonic oscillator approximation.
On the Use of Ultrasonic Absorption for the Determination of Very Rapid Reaction Rates at Equilibrium: Application to the Liquid Phase Association of Carboxylic Acids
Authors: Freedman Eli
Published: January 2005

An equation is derived for the excess acoustic absorption in a liquid system due to the occurrence of a chemical reaction; the method used follows in part that used by Damköhler in the case of gases. It is shown that the gross reaction rate at equilibrium can in general be found once the frequency at which the maximum excess absorption per wavelength occurs has been found, provided thermodynamic data for the reaction are known.

The application of this method to the study of the kinetics of very rapid reactions is discussed and the effects of other causes of absorption are considered.

As another application of the results obtained the acoustic absorption of acetic and propionic acids is considered. A consistent interpretation of data in the literature is given on the assumption that the excess absorption is due to the perturbation of an equilibrium between monomeric and dimeric molecules. The mole fraction equilibrium constant KN, and the heat of reaction for the dimerization are calculated. The values found for acetic acid are KN(293°K)=61.97 and ΔH=−6.21 kcal/mole; for propionic acid, KN(281.2°K)=3.040×103 and ΔH=−9.33 kcal/mole. Rate constants and activation energies for the dissociation of the dimers are also calculated.
Note on Some Regularities of the Absorption Band Maxima of Colored Alkali Metal Halides
Authors: Glasner A. , Tompkins F. C.
Published: January 2005

The various relationships which exist between the absorption band maxima of colored alkali metal halides have been noted, and some simple empirical rules have been proposed for calculating certain crystal parameters from the position of these maxima.
The Correct Application of the Gibbs-Helmholtz Equation to Reversible Galvanic Cells in Which the Compositions of Some of the Phases Vary with Temperature
Authors: Barieau R. E.
Published: January 2005

The detailed proof is given that the Gibbs-Helmholtz equation dΔFcell/dT=—ΔScell is directly applicable to any reversible galvanic cell, regardless of how the compositions of any phases present may vary with the temperature.
Vibration Spectrum of a Simple Cubic Lattice
Authors: Newell Gordon F.
Published: January 2005

Analytic expressions are derived for the frequency distribution function g(f) of a simple cubic monoatomic lattice. Only nearest and next-nearest neighbor interactions are considered, and the latter are assumed to be weak compared with the former. The procedure is based upon considering the next-nearest neighbor interactions as a perturbation, and the results are correct to the first power of a parameter τ which is essentially a measure of strength of the next-nearest neighbor forces as compared with the nearest neighbor forces.

It has been known for some time that a simple cubic lattice with only nearest neighbor interactions degenerates into the equi alent of three independent one-dimensional lattices giving a nonzero g(f) for f=0 and an infinite value at the maximum frequency. If, however, one includes even a small interaction between next-nearest neighbors, the behavior of g(f) near both ends of the spectrum changes considerably; in fact it vanishes at both ends. For intermediate frequencies, g(f) is continuous but has four analytic singularities with vertical tangents of the type predicted by van Hove for a quite general type of crystal. Although the calculated g(f) is exact only in the limit τ→0, it does properly describe the exact location and type of singularities for 0≤τ≤1/10.
On Rates of Approach to Equilibrium
Authors: Bauer S. H.
Published: January 2005

The limiting conditions on the applicability of an exponential decay law for the rate of approach to equilibrium of a system which is near but not at equilibrium are discussed. Attention is called to a solution which is more general; it consists of a superposition of exponentials, with a spectrum of relaxation times.
Dielectric Properties of Hydrogen Halides. I. Hydrogen Bromide
Authors: Brown Norman L. , Cole Robert H.
Published: January 2005

Static dielectric constants of solid hydrogen bromide have been measured from 186 to 70°K, and dispersion and loss below 89°K in the frequency range 15 cy to 5 Mc. Special cell designs minimized formation of cracks and voids in the polycrystalline sample, as such flaws were shown by several lines of evidence to cause serious errors. Static dielectric constants above 117°K are in quite good agreement with Onsager's equation. In phase II, stable below 113°K, the dielectric constant rises to a peak of 200 at 89°K, then falls to a value of 32 at 70°K in phase III. The principal dispersion below 89°K follows a circular arc locus with α=0.3, and a rate expression with activation energy 2.7 kcal/mole. A second dispersion is observed at much higher frequencies with energy 1.59 kcal/mole, and it is suggested that the two dispersions are a consequence of crystal anisotropy.
The Thermal and Dielectric Properties of Crystalline Long-Chain Acetates
Authors: Meakins R. J. , Mulley Joan W.
Published: January 2005

This investigation deals with the normal long-chain acetates with 18, 20, 24, and 28 carbon atoms. When crystallized from the melt, these compounds first give the transparent α-phase which gradually changes to the white, opaque β-phase on standing or on cooling below a certain temperature. It is found that the acetates in the α-phase all give large dielectric absorption, whereas, in the β-phase the absorption is small, or, in some cases, negligible.

Of the long-chain compounds so far investigated, the acetates in the α-phase are unique in giving two absorption regions which appear to be the result of the rotational transitions of complete molecules. The maxima for the two regions are separated by about 7 decades in frequency. Measurements of the lower frequency absorption at various temperatures show that the associated energy barrier is very large compared with previous values for compounds of similar chain-length. To explain these results it is suggested that a molecule rotating in the crystal lattice of a long-chain compound possesses four positions of equilibrium instead of two, as previously proposed.

In addition to the two absorption regions mentioned above, the long-chain acetates in the α-phase give further absorption at still higher frequencies, which is probably caused by independent orientation of the polar groups near the ends of the molecular chains.
Heat Capacity of Chain Polymeric Crystals
Authors: Stockmayer W. H. , Hecht C. E.
Published: January 2005

A crude calculation of the frequency spectrum and heat capacity has been made for a simple model of a large crystal composed of long parallel polymer chains. The heat capacity is very unlike that of a cubic crystal but can be represented quite well with a simple two-parameter equation recently proposed by Tarasov.
The Infrared Spectra of the Methyl Chlorosilanes
Authors: Smith A. Lee
Published: January 2005

The infrared spectra of the series SiCl4 through SiMe4 have been obtained in the gas phase over the range 2–25 microns using CaF2, NaCl, and KBr prisms. The spectra are compared with Raman data for these compounds, and vibrational assignments are made. The methyl band at about 8 microns is shown to be associated with the symmetrical CH3 deformation, the bands around 12 microns with the methyl rocking and Si–C stretching vibrations, and the bands between 16 and 25 microns with the SiCl stretching modes. A comparison of frequencies for the members of the series has made it possible to assign fundamentals for all motions except those involving torsion of the Me group around its axis.
Ground and Excited Electronic States and Molecular Vibrations of Some Polyatomic Molecules
Authors: Duchesne Jules , Burnelle Louis
Published: January 2005

The vibration potential functions of electronic ground and excited states of molecules of C2v and D6h symmetry are computed and compared. From this, quantitative characteristics of the molecular orbitals belonging to the correlated angular molecules and to a negative ion are deduced and, in this connection, the structure of the CF2 and CH2 radicals is discussed. The behavior of the interaction terms is examined, and a rule concerned with their sign is obtained in the case of n→π* and π→π* transitions. Various other effects, such as the σ—π resonance and the part played by the lone-pair electrons, are studied.
Conjugation and the Intensity of the Infrared Carbonyl Band
Authors: Barrow Gordon M.
Published: January 2005

Data are given for the absolute intensities, in chloroform and carbon tetrachloride solutions and in the vapor state, of the carbonyl infrared absorption bands of a number of compounds in which the carbonyl group is conjugated by varying amounts. The absolute intensity differs in the different solvents and in the vapor, but the increase in intensity of a conjugated carbonyl over that of a simple ketone or aldehyde seems to be independent of the state. For most of these compounds a simple relation is shown to exist between this increase in carbonyl intensity with conjugation and the resonance energy of conjugation. This relation is expected from a consideration of the electronic configurations available to the normal and distorted molecule. That such compounds as the amides do not necessarily fit this trend is attributed to the geometric requirements on the molecule of these electronic configurations.
The Heat of Sublimation of Tin and the Dissociation Energy of SnO
Authors: Brewer Leo , Porter Richard F.
Published: January 2005

The heat of sublimation of tin has been redetermined and found to be 70±2 kcal/mole. This value combined with the heat of formation of gaseous SnO agrees with the linear Birge-Sponer extrapolation to the ground-state atoms.
The Crystal Momentum as a Quantum Mechanical Operator
Authors: Adams E. N.
Published: January 2005

The Schroedinger equation for a particle moving in a perturbed periodic potential is transformed into a representation called the ``Crystal momentum representation.'' It is shown that by use of this representation previous approximate ``effective mass'' equations can be readily derived and extended to arbitrarily high approximation. A theorem concerning weak space dependent perturbations is discussed.
Calculation of the Heats of Formation of Gaseous Free Radicals and Ions
Authors: Franklin J. L.
Published: January 2005

A simple method of calculating the heats of formation of gaseous free radicals and carbonium ions is presented, and a number of examples are given which show good agreement of calculated values with experiment. It is shown that the method permits ready calculation of bond strengths, including the strength of bonds in alicyclics, and the ionization potential of olefins, aromatics, and other unsaturates. The method is not directly applicable to the calculation of the ionization potentials of saturates.
The Effect of Pressure and Temperature on the Absorption Spectrum of Benzene in the Near Ultraviolet
Authors: Sambursky S. , Halperin A. , Henig H.
Published: January 2005

The absorption spectrum of benzene vapor in the near ultraviolet was photographed at temperatures varying from room temperature up to above the critical temperature (287°C), and at the corresponding pressures of the saturated vapor (from a few mm of mercury up to about 50 atmos).

Changes of the intensity distribution within each of the groups of bands were found, which gave a shift in the maxima of these groups, but even at the highest temperatures and pressures near the critical point, no measurable shift in the frequencies of the components of the groups was found. This shows that the effect of intermolecular forces on the frequencies of the bands is very small.

A short discussion of the results is also given.
Dynamics of the Graphite Lattice
Authors: Rosenstock Herbert B.
Published: January 2005

The distribution of frequencies of normal vibrations in the graphite lattice has been obtained in closed form for low temperatures in the two-dimensional approximation for the values (α, β, 0) and (α, β, α/2) of the force constants (α, β, γ) for nearest, second-nearest, and third-nearest neighbors. The frequencies run from 0 to a finite value ωmax, with two logarithmic peaks in their density. The specific heat has been calculated for two special sets of force constant ratios. Deviations from T2 dependence set in at temperatures much lower than predicted by Debye theory. Comparison with experiment leads to a numerical value for θ=ℏωmax/k, from which ωmax, and therefore also α and one of the macroscopic elastic constants, c44, may be calculated. θ and ωmax appear very sensitive to the assumed force constant ratios, c44 less so.
Temperature Jump and Velocity of Slip at the Boundary of a Gas
Authors: Payne Herbert
Published: January 2005

Approximate expressions are derived from the kinetic theory for the temperature jump and the velocity of slip occurring at an infinite plane solid surface of constant temperature bounding a gas whose state remains invariant throughout all planes parallel to the surface. These derivations differ from earlier ones in the elimination of an assumption, for which an argument is presented as to its untenability, regarding the distribution of the velocities of the molecules striking the surface. Instead, from the mathematical theory of non-uniform gases are derived conditions on this distribution sufficient to confine possible values of the temperature jump and slip velocity to within fairly close limits.
The Molar Activity Coefficients of Electrolytes Predicted from Conductivity Data
Authors: Marshall Henry P. , Grunwald Ernest
Published: January 2005

The molar activity coefficients of uni-univalent electrolytes may be predicted on the basis of conductivity data with an accuracy of at least 1 percent up to concentrations of the order of 0.01 M in solvents of dielectric constant as low as 10. The method is based on Bjerrum's theory of ion association,1 with the ion pair dissociation constant evaluated from conductivity data.4–6 The success of the method depends on the use of expressions for y′, the quasi-activity coefficient of the dissociated fraction, and for Λ, the equivalent conductivity, which go beyond the limiting law approximations of the interionic attraction theory. Equations (6), (8), (10), (12), and (13) have been developed for this purpose. In solvents of dielectric constant 10–40 the prediction involves no adjustable parameters characteristic of the electrolyte. The equations have been tested by comparing the conductivity-predicted y values for hydrochloric acid with those determined from emf measurements. To insure the significance of this comparison, new emf data for the cell Pt–H2(g)/HCl AgCl–Ag have been obtained for 82.00 wt percent dioxane (D=10.56) in the concentration range 0.0001–0.01 M.
Diffusional Processes in the Growth of Aerosol Particles. II
Authors: Frisch H. L. , Collins F. C.
Published: January 2005

The effect of the moving boundary of the growing aerosol particle upon the diffusional processes previously investigated for the special case of sinks with stationary boundaries is now discussed in detail. The zeroth-order approximation for the flux rate, valid for aerosol and most colloid systems, is found to be of the same analytic form as that for the stationary boundary case. A growth equation is derived for particles growing in the presence of a plurality of competing sinks which deplete the supersaturation. The growth equation here derived is found to be in satisfactory agreement with experiment in the case of barium sulfate crystals growing in aqueous solution. It is further shown that self-nucleated sols tend to monodispersity with growth. The effects of additional molecules becoming available for diffusion and of variability of the absorption probability are also discussed and evaluated for the special case of a single particle in the diffusion field.
Molal Volumes and Compressibilities of the System NaCl–H2O above the Critical Temperature of Water
Authors: Benson Sidney W. , Copeland Charles S. , Pearson David
Published: January 2005

From quantitative P, T, V, x data on the system NaCl–H2O in the supercritical region it has been possible to calculate apparent molal volumes, partial molal volumes, and compressibilities with accuracies of about 10 percent, 25 percent, and 15 percent, respectively.

The apparent molal and partial molal volumes of NaCl show similar, remarkable, and quite anomalous behavior. Above the critical temperature of the particular solution studied and at low NaCl compositions, the molal volumes are very large and negative, being of the order of magnitude of liters/mole. As the densities decrease, the values become more negative, pass through a minimum, and then rise again.

These minima decrease in absolute magnitude with increasing temperature, but seem to occur (for 0.2 percent solutions) at densities not very different from the critical density of water. When the partial molal volumes at constant temperature are plotted against partial densities of water, the results seem to fall on a smooth curve independent of the concentration of NaCl.

The compressibilities show a behavior which resembles that of the pure solvent and whose significance has heretofore escaped any detailed attention. They go through maxima at densities near the density at the critical temperature.

These observations can be accounted for qualitatively if it is assumed that above the critical temperature all fluids are capable of undergoing continuous, short-range condensation over a narrow range of densities near the critical density of the fluid.

The particular behavior of the NaCl–H2O systems emphasizes quantitatively the enormous effect of small amounts of solutes (capable of associating strongly with the solvent) on the behavior of the solvent near its critical temperature.
Primary Photochemical Process in Bromine
Authors: Kistiakowsky G. B. , Sternberg James C.
Published: January 2005

A kinetic investigation of the photobromination of ethylene has led to results which are in general consistent with the earlier work of Schumacher et al. The existence of an induced oxidation reaction was demonstrated in mixtures containing traces of oxygen, which is a very strong inhibitor of the ethylene-bromine chain reaction.

The relative quantum yields of the photobromination reaction were measured at six wavelengths using narrow pass Baird interference filters. The quantum yields were shown to be independent of wavelength between the limits of 4800 and 6800A. Radiation of 7150A wavelength is absorbed but is totally ineffective photochemically. These results were interpreted with the aid of spectroscopic information to mean that the photochemically effective transitions of bromine molecules in radiation of wavelengths longer than the convergence limit, 5107A, lead to the continum of the 3π1u state, which then dissociates in one elementary act to form two normal atoms. It is unnecessary to invoke the assumption of collisional dissociation of excited bromine molecules to explain their photochemical reactivity below the convergence limit.
Low Temperature Spectroscopy in the Farther Ultraviolet Region
Authors: Potts W. J.
Published: January 2005

Methods are presented which make possible quantitative spectroscopic measurements at liquid nitrogen temperatures from the visible region to as far as 1670A in the ultraviolet region.
The Configurations of Rotational Isomers and Their Normal Frequencies
Authors: Mizushima San-ichiro , Shimanouchi Takehiko , Nakagawa Ichiro , Miyake Akihisa
Published: January 2005

Normal frequencies of molecular configurations of different azimuthal angles of internal rotation have been calculated for various molecules showing rotational isomerism. It has been shown that one can tell fairly accurately the value of azimuthal angle by comparing the observed frequencies (especially the skeletal deformation frequencies) with those calculated for different configurations. The sum rule for the rotational isomers similar to that for isotopic molecules has been derived and has been shown to be very useful in assigning the observed frequencies. The product rule for rotational isomers derived in our previous paper has also been applied to this problem and has been shown to be useful in determining the azimuthal angles of rotational isomers.
The Infrared Spectra of Oriented Rhombic Sulfur Crystals with Polarized Radiation
Authors: Barrow Gordon M.
Published: January 2005

The infrared spectra, in the rock salt region, of oriented sections of single rhombic sulfur crystal have been obtained. The spectra of sections perpendicular to the c axis of the crystal, the 001 type planes, have been compared, under ordinary radiation with those of sections parallel to the c axis, 110 type planes. Most bands in the region investigated, 700 to 1500 cm−1, show differences in intensity in the two spectra. With a 110 section and radiation polarized at various angles, similar changes in intensity were observed. Both experiments lead to similar conclusions regarding the direction of the oscillating dipole in the vibrations giving rise to the observed bands. Assignments of the infrared active species (B2 or E1) in these bands are given but no attempt is made to explain them in terms of the fundamental vibrations.
An Investigation of the Thermoluminescence of Fluorite Colored by X-Ray Irradiation
Authors: Hill John J. , Aron Jack
Published: January 2005

The thermoluminescence resulting when calcium fluoride crystals colored by x-ray irradiation are heated, has been investigated in the region from 3200 to 6500A. First, the form of the emission spectrum was determined by the use of a spectrophotometer in conjunction with a photomultiplier tube as a detector, and fifteen emission bands were observed of which seven weak ones had not previously been reported. The peaks of these bands occurred at 3430, 3650, 3710, 3790, 3810, 4150, 4270, 4370, 4570, 4780, 4890, 5230, 5350, 5430, and 5740A. Second, continuous annealing curves or ``glow curves'' were obtained for the strongest emission bands by raising the temperature of the crystal at a constant rate and recording the intensity of the emitted light at the peak of each band. The maxima of the glow curves thus recorded fall into two groups. In group 1, three maxima located at approximately 197, 285, and 310°C were observed. In group 2, five intensity maxima could be distinguished, the lowest occurring at approximately 70°C and the highest at 245°C. The corresponding activation energies were calculated, and in two cases were checked by carrying out the annealing at fixed temperatures. These results are consistent with the assumption that two distinct types of imperfections are responsible for the thermoluminescence of calcium fluoride. The optical absorption appears to be the result of the imperfections associated with group 2.
The Effect of 1470A Irradiation of Nitrogen-Hydrogen Mixtures and of Ammonia
Authors: Wijnen M. H. J. , Taylor H. Austin
Published: January 2005

The characteristics of a xenon resonance lamp were studied, using carbon dioxide as an actinometer, to determine the influence of the xenon pressure in the lamp on the intensity of the 1470A radiation. The xenon sensitized photosynthesis of ammonia was studied both in static and in flow systems. No ammonia could be detected. Some experiments on the photolysis of ammonia at 1470A are reported and discussed. The present work furnishes the first direct chemical evidence rejecting the value of 171.3 kcal per mole as the dissociation energy of nitrogen.
The Effect of Pressure on Self-Diffusion in Carbon Disulfide
Authors: Koeller R. C. , Drickamer H. G.
Published: January 2005

A method has been developed for measuring diffusion coefficients in liquids to 10 000 atmospheres pressure. Measurements have been made over this pressure range at 0°, 20°, and 40°C for the system CS2–CSS35. The results are interpreted in terms of the enthalpy, entropy, and volume of activation as a function of temperature and pressure.
Streaming Potentials across Glass Capillaries for Sinusoidal Pressure
Authors: Packard Robert Gay
Published: January 2005

A mathematical expression for the streaming potentials developed across capillaries for sinusoidal pressure variations is derived. Glass capillaries are used to check the theory experimentally, and good agreement is obtained for all samples tested.
Electric Dipole Moments of Several Molecules from the Stark Effect
Authors: Ghosh S. N. , Trambarulo Ralph , Gordy Walter
Published: January 2005

The following molecular electric dipole moments, in Debye units, have been obtained from the Stark effect of pure rotational spectra observed in the microwave region: 0.234±0.004 for NF3; 1.03±0.01 for PF3; 1.77±0.02 for POF3; 3.00±0.02 for HCN; 3.92±0.06 for CH3CN; 3.83±0.06 for CH3NC; 1.79±0.02 for CH3F; 0.75±0.01 for CH3CCH; 1.26±0.01 for SiF3H. All values apply to the ground vibrational state.
On the Ultraviolet Absorption Spectra of Uninegative Ions
Authors: Friedman Harold L.
Published: January 2005

New spectral data are reported for NO2−, ClO2−, and ClO− in aqueous solution.

The theory of the electron transfer spectra of aqueous halide ions is extended to uninegative polyatomic ions by allowing for the greater excitation energy of the polyatomic radicals produced in the act of absorption, as compared with the excitation energy of the atoms produced from halide ions. This additional excitation energy arises from the operation of the Franck-Condon principle in determining the internuclear distances in the radical. Tri-iodide ion is the only one of the uninegative ions for which the required data are available and for which these data are not consistent with the assignment of the intense ultraviolet bands to transitions involving transfer of an electron to the solvent.

It is found that the low intensity absorption bands of NO2− and ClO2− coincide with the bands predicted by R. S. Mulliken for triatomic oxide molecules (AO2), with the same numbers of valence electrons.
Rotational ``Temperatures'' of OH in Diluted Flames
Authors: Kane W. R. , Broida H. P.
Published: January 2005

The effects of gaseous diluents upon the distribution of rotational energies of the electronically excited OH(2Σ+) radical in flames at atmospheric pressure have been studied. Helium, argon, nitrogen, and oxygen have been added to stoichiometric mixtures of fuel and oxygen in amounts up to 90 percent of the total volume. In the reaction zones of the acetylene and methane flame diluted with helium, argon, or nitrogen, a departure from rotational equilibrium is found which increases with increasing dilution. This effect is absent in the hydrogen flame and in flames with excess oxygen. Vibrational and electronic nonequilibria are also indicated. These results are consistent with the hypothesis proposed in connection with low pressure studies (see references 2 and 4) that excited OH is formed in an exothermic reaction imparting high rotational energy to the products. Persistence of this rotational energy throughout the radiative lifetime, 10−6 sec, or 104 collisions, is indicated.
Infrared and Raman Spectra of Fluorinated Ethanes. V. The Series CF3CF3, CF3CF2Cl, CF3CFCl2, and CF3CCl3
Authors: Nielsen J. Rud , Liang C. Y. , Smith R. M. , Smith D. C.
Published: January 2005

The infrared spectra of CF3CF2Cl, CF3CFCl2, and CF3CCl3 vapors have been obtained in the region from 2 to 38μ, and the spectra of liquid CF3CF2Cl and CF3CFCl2 in the region from 2 to 22μ, with the aid of LiF, NaCl, KBr, and KRS−5 prisms. The Raman spectra of all three compounds in the liquid state, and of gaseous CF3CF2Cl, were studied with a three-prism glass spectrograph of linear dispersion 15A/mm at 4358A. Depolarization ratios were determined for most of the Raman bands.

All fundamental vibration frequencies except the lowest (torsional) have been assigned for each molecule, and the observed spectra have been interpreted in detail.
On the Interaction of Closed Shells
Authors: Margenau H. , Rosen Philip
Published: January 2005

In calculating repulsive forces between closed shells, two essentially different methods have been used. It is shown in this paper that they should not be expected to give equal numerical results, and attention is called to some finer methodological points in the theory of exchange forces. Tables I—III give numerical results for the interaction of neutral He atoms.
A Detailed Formulation of Kinetic Processes. II. The Role of Collision Processes
Authors: Benson Sidney W. , Axworthy Arthur E.
Published: January 2005

A detailed treatment is given of the activational processes occuring in both unimolecular and bimolecular processes. Such a treatment leads very naturally to the postulate of two critically energized species, one related to the products and one to reactants. In the case of unimolecular isomerizations it is shown that the properties of either one or both of these species may dominate the rate of the nonequilibrium reaction rate expression, and the form of the rate expression is given in terms of the Slater theory of unimolecular reactions.

In the case of unimolecular decompositions, only the complex corresponding to reactants is important, whereas in the inverse case of association reactions only that for the products is of importance. Both of these types of reactions have the same form of pressure dependence in the steady-state concentration region. The above considerations apply even when the reactions are not reversible. That is, the critically energized complex related to products is still of importance in determining the reaction rate. In the case of bimolecular and higher order processes, a detailed investigation shows that the activational processes are always maintained at their equilibrium values, and there is no region in which the rate constants will show a significant dependence on concentration of inert gas.
A Theory of Cooperative Phenomena. III. Detailed Discussions of the Cluster Variation Method
Authors: Kurata Michio , Kikuchi Ryoichi , Watari Tatsuro
Published: January 2005

A series of approximations for the statistical mechanics of order-disorder, proposed by Bethe, Takagi, Yang-Li-Hill, Kikuchi, and others, are investigated in detail in two ways. (1) A new interpretation of the method for constructing the combinatory factor is presented in order to give a better understanding of the nature of approximations. (2) The partition functions with approximate combinatory factors are expanded to compare with the rigorous expansion and the discrepancies between them are investigated in detail. One of the conclusions is that in order to obtain a higher approximation, it is necessary to use the basic figure ``closed'' with respect to the cluster of the preceding approximation. In appendices, an improved treatment of the body-centered cubic lattice (Ising model) is given, and Bethe's fundamental assumptions are derived from our scheme.
Rotation-Vibration Spectra of Diatomic and Simple Polyatomic Molecules with Long Absorbing Paths. IX. The Spectra of the HCN and DCN Molecules from 2.5μ to 0.5μ
Authors: Douglas A. E. , Sharma D.
Published: January 2005

The photographic infrared spectrum of HCN has been investigated using a 6-meter concave grating spectrograph and absorption paths up to 600 meters. The near infrared spectra of HCN and DCN have been investigated using a grating infrared spectrometer with a lead sulfide cell as a detector. The interference fringes from a Fabry-Perot etalon have been used as wavelength standards for the recording spectrometer. Twenty-four bands of HCN and six bands of DCN have been measured. From these measurements earlier work has been corrected, and the zero-order frequencies and anharmonic constants have been determined for both HCN and DCN. Perturbations have been found in the vibrational levels of HCN. Corresponding perturbations occur in the Bv values, and it has been shown that even apparently unperturbed Bv values are not linear functions of the vibrational quantum numbers. The Be values for HCN and DCN were found to be 1.4849 cm−1 and 1.2118 cm−1. From these Be values the C–H and C–N internuclear distances in the equilibrium position have been found to be 1.0657A and 1.1530A, respectively. From the zero-order frequencies the force constants have been determined.
Note on the Absorption Spectrum of Iodine in Oxygenated Solvents and the Dissociation of Iodine Water
Authors: Katzin Leonard I.
Published: January 2005

Data are presented on factors in the appearance of the tri-iodide absorption spectrum in solutions of iodine in water and in the alcohols. Some implications of the dissociation of iodine in water for the theory of the iodine-solvent interaction are pointed out.
The Microwave Spectrum and Structure of Chlorine Trifluoride
Authors: Smith D. F.
Published: January 2005

A microwave spectrometer designed for the study of the microwave spectra of corrosive fluorine compounds has been used to observe and measure a portion of the microwave spectrum of chlorine trifluoride. A number of transitions have been identified, and from these the moments of inertia and quadrupole coupling coefficients of both Cl35F3 and Cl37F3 obtained. An intensity alternation was observed showing that the ClF3 molecule has a C2v axis and is planar. The moments of inertia confirm this and further show that ClF3 has a distorted ``T'' structure with one short (1.598A) and two long (1.698A) ClF bonds. The angle between the two different kinds of ClF bonds is 87°29′. The quadrupole coupling coefficients χaa(Cl35F3)=−81·2 mc, χbb(Cl35F3)=−64·7 mc, χcc(Cl35F3)=146 mc agree with the observed frequency, f(Cl35F3)=75.1295 mc, of the pure quadrupole spectrum of ClF3, which corresponds to an eqQ of 150 mc.
The Shape and Thickness of Shock Fronts in Argon, Hydrogen, Nitrogen, and Oxygen
Authors: Greene E. F. , Hornig D. F.
Published: January 2005

Measurements of shock front thicknesses in argon by the reflectivity method have been extended to Mach 2.09, and the shape of the front has been investigated by comparing the experimental results with the reflectivity expected on the basis of five simple models for the density change through the front. The thicknesses agree with Zoller's calculations but for the strongest shocks are considerably greater than those of other theoretical estimates. The magnitude and form of the reflectivity (as a function of λ/L cosθ) of shock fronts in three diatomic gases have been used to study the rate of equilibration of rotational with translational energy. Hydrogen requires more than one hundred and fifty collisions for this equilibration, while nitrogen and oxygen equilibrate much more rapidly. For the latter two gases there is evidence that at least two relaxation times are involved in the equilibration.
Dielectric Relaxation and the Internal Field
Authors: Powles J. G.
Published: January 2005

The paper discusses the relation of the relaxation time τ of a dielectric to the measured decay time of polarization T and proposes a new expression for the internal field in a dielectric subjected to an alternating field. It is found for this expression that 1<T/τ<32 and that in most instances no serious error is incurred in using T instead of τ. Application to the case of several distinct relaxation times shows that the new expression gives relations between the complex dielectric constant and frequency which are observed experimentally.
Infrared Intensity Measurements on Nitric Oxide, Hydrogen Chloride, and Hydrogen Bromide
Authors: Penner S. S. , Weber D.
Published: January 2005

The results of absolute infrared intensity measurements are described for the fundamentals and first overtones of NO, HCl, and HBr. The new data are used to estimate the dependence of electric moment on internuclear distance.
Photoelectric Observation of the Rate of Recombination of Iodine Atoms
Authors: Marshall Royal , Davidson Norman
Published: January 2005

The rate of the homogeneous three-body recombination of iodine atoms, I+I+M→I2+M, d[I2]/dt=k[I]2[M], is measured. A short intense pulse of light from a flash lamp dissociates 1–9 percent of the ca 1018 iodine molecules in a 200-cc cell, and the subsequent recombination of iodine atoms is followed by fast photoelectric techniques.

The measured values of k at room temperature are 4.2(±0.4)×109 liter2 moles−2 sec−1 (argon), 58(±4)×109 (neopentane), 65(±6)×109 (pentane). The value for neopentane is the same at 200°C.

The large values of the recombination rate constants indicate that an important recombining process consists of a ``sticky'' collision between an I atom and an M molecule or atom, leading to the formation of a complex IM, which reacts with a second I atom. The lifetimes of the collision complexes are estimated.

The rates of the reverse process, the dissociation of I2 by collision with M, are calculated; the pre-exponential factors are extraordinarily large.

The extinction coefficients of gaseous iodine have been remeasured.
The Decomposition of Nitrate Crystals by Ionizing Radiations
Authors: Hennig Gerhart , Lees Robert , Matheson Max S.
Published: January 2005

Sodium nitrate, potassium nitrate, and potassium chlorate have been exposed two to four weeks in the experimental thimble of the Argonne Heavy Water Pile. After exposure these salts evolve a gas when dissolved in water or when melted or heated to a crystal transition point. The gas yields are in sodium nitrate ca 0.3, in potassium nitrate ca 0.8, and in potassium chlorate 2.0–3.0 molecules gas/100 ev. For the nitrates this gas has been shown to be largely oxygen which is trapped during irradiation in the gaseous form in small pockets in the crystal. This conclusion is based on the paramagnetism of the irradiated crystals, on chemical analysis of the evolved gases, and on measurements of the amounts of gas liberated in crushing experiments. When irradiated crystals are heated below the melting point, the gas pockets grow and coalesce, this being accompanied by a decrease in crystal density. In irradiated nitrates, oxygen and nitrite ion are formed in equivalent amounts. Experiments with low energy x-rays indicate that most of the decomposition results from electronic ionization and excitation and not from elastic collision of the bombarding particles.
Elastic Scattering and Neutralization of Low Velocity Hydrogen Ions in Methforane and Ethforane
Authors: Simons J. H. , Garber C. S.
Published: January 2005

The low velocity scattering of H+, H2+, and H3+ in both methforane and ethforane has been measured at ion velocities of less than 150 volts. Ion neutralization was detected and measured for all three ions in both fluorocarbons and elastic scattering potential functions evaluated for all six interactions. These measurements are compared with similar ones made on the hydrocarbons methane and ethane.