bluuebunny/crossref_metadata_2025 huggingface dataset:
Recognition and Classification of Semiconducting Compounds with Tetrahedral sp3 Bonds
Authors: Mooser E. , Pearson W. B.
Published: January 2005

In previous publications we have shown how certain conditions are always fulfilled in the chemical bonding of an intrinsic elemental or compound semiconductor. These conditions are said to specify a ``semiconducting bond'' and this concept has proved useful in explaining and predicting the occurrence of semiconductivity in substances. We now extend the use of this concept in giving a systematic classification of a large group of compounds in which the well-known sp3 tetrahedral bonds occur and whose structures are closely related to the zinc blende and wurtzite lattices. This treatment has led to the discovery that many compounds, whose electrical properties have not previously been examined, are indeed semiconductors.
Infrared Spectrum of Dinitrogen Tetroxide
Authors: Wiener Robert N. , Nixon Eugene R.
Published: January 2005

The infrared absorption spectra of polycrystalline films of N2O4 at —180° have been examined in the region from 3500 to 400 cm—1 and found to be entirely consistent with the reported x-ray crystal structure. Four of the five infrared active fundamentals have been observed and values for three of the infrared inactive fundamentals, in good agreement with reported Raman data, have been inferred from combination bands. Other combinations indicate at least two torsional lattice modes in the range of 18 to 30 cm—1. Several isotopic frequencies were also identified in the spectrum of solid N2O4 containing about 34.5 atom % of N15.
Generalized Equations for the Ionization of Solid Particles
Authors: Einbinder Harvey
Published: January 2005

A generalized formula is derived for the ionization of spherical solid particles of submicroscopic size by allowing for multiple ionization. A system of simultaneous equilibrium equations is set up connecting successive states of ionization. Its solution yields a generalized formula that reduces to the Saha equation when only single ionization can occur. When the particles are multiply ionized, the equation can be simplified by the method of steepest descents, Ne/N(rkT/e2) ln(K/Ne)+12,  (Ne/N≳3),where Ne is the electron concentration, N is the number density of solid particles, r their radius and K=2(2πmkT/h2)32 exp(—[open phi]/kT).

This equation is applied to the observations of Shuler and Weber on the ionization of free carbon particles produced in rich acetylene-oxygen flames. Their data are consistent with a work function [open phi] = 4.35 ev, identical with that of graphite, and particle radii between 55 and 85 A.
Carbon Isotope Effect during Oxidation of Carbon Monoxide with Nitrogen Dioxide
Authors: Johnston Harold S. , Bonner William A. , Wilson David J.
Published: January 2005

By use of naturally occurring C12 and C13 isotopes in carbon monoxide, the effect of carbon mass on the rate of the reactionCO+NO2=CO2+NOhas been studied in a 15–1 Vycor flask, in the temperature range 540–727°K, and at pressures between 1 and 20 mm. The rate constant for the reaction was k=12×1012 exp (—31,600/RT) cc mole—1 sec—1. The ratio of rate constants k12/k13 was 1.022 at 540°K, 1.019 at 638°K, and 1.016 at 727°K. An activated complex was set up with normal bond distances and normal force constants, and with the reaction coordinate explicitly given in terms of internal coordinates with an interaction term such that the restoring force on an antisymmetric stretching symmetry coordinate is reduced to zero. By means of E. B. Wilson's FG matrix methods, a vibrational analysis was made of the activated complex, all vibration frequencies were determined for one species, and shifts in frequency due to isotopic substitution were computed by a perturbation method. Similarly, the ratio of effective mass of the reaction coordinate was evaluated, and calculations were checked by the Teller-Redlich product rule. The isotope rate effect was computed by Bigeleisen's formulation of the activated complex theory. For a set of force constants well within the range of normal values and for normal bond radii, calculated isotope rate ratios at all temperatures are in excellent agreement with observed ones.
Rate Constants of Second-Order Reactions from Kinetic Current Measurements
Authors: Reynolds W. L. , Prager Stephen
Published: January 2005

Kinetic currents have been calculated for the case where the solution contains two electroactive species, one of which may undergo a second order reaction with the reduced form of the other. The results have been applied to the reaction between ferrous versenate and cumene hydroperoxide, assuming the diffusion co-efficients of all species to be equal. The calculated and observed rate constants are found to differ by 33%, which constitutes reasonable agreement in view of the assumptions made.
Rate of Recombination of Radicals. III. Rate of Recombination of Ethyl Radicals
Authors: Shepp A. , Kutschke K. O.
Published: January 2005

The rate constants for the recombination (k2) and the disproportionation (k3) of ethyl radicals have been determined by applying the theory of the rotating sector to the photolysis of diethyl ketone. The values of k2 are 1.5±1×1013, 2.0±0.5×1013, and 4.2±0.8×1013 cc mole—1 sec—1, at 50°C, 100°C, and 150°C, respectively. The ratio k3/k2 is taken to be 0.12 from other work. An Arrhenius plot of these results indicate an energy of activation for k2 of 2.0±1 kcal/mole. These results are shown to be in agreement with existing theories. A simplified transition state theory calculation of k2 is offered, based on the change in the number of degrees of freedom from radicals to activated complex.
Magnetic Susceptibility of Neutron-Damaged Graphite
Authors: Hove John E. , McClelland J. D.
Published: January 2005

Previous work on the magnetic susceptibility of graphite as it is affected by temperature and bromination is extended to include effects of neutron irradiation at about room temperature. Data taken at both room temperature and liquid nitrogen temperature are analyzed and yield consistent values for the number of electrons trapped out by damage defects, thus further establishing the validity of the theory. The trapping rate of electrons, with neutron exposure, is found to be slightly nonlinear and a fair fit of the empirical curve is number of trapped electrons per carbon atom=1.4×10—4t2/3,where t is the flux in mwd/ct. This two-thirds power dependence cannot be taken too literally, since neither the quantity nor quality of the data is sufficiently good. Data are also given for the buildup of paramagnetic centers as damage increases.
Relationship of the Second Virial Coefficient to Polymer Chain Dimensions and Interaction Parameters
Authors: Orofino T. A. , Flory P. J.
Published: January 2005

A useful approximation has been found for the excluded volume integral for the interaction of a pair of polymer molecules, represented by Gaussian distributions of chain segments about their respective centers of gravity. By means of this approximation, the theoretical expression for the second virial coefficient in the expansion of the osmotic pressure is represented over the entire range of polymer-solvent interaction by A2=const ([η]/M) ln[1+(π12/4)X1+(π12332/32)X2].X1 and X2 are related to the thermodynamic interaction parameters χ1 and χ2, respectively, in the semiempirical expression for the solvent chemical potential μ1—μ10=RT[ln(1—v2)+(1–1/x)v2+χ1v22+ χ2v23+···] where v2 is the volume fraction of polymer and x the ratio of molar volumes of polymer and solvent. Inclusion of the higher term χ2v23 (and X2) constitutes a refinement over the treatment previously published. It is shown that the influence of X2 may be appreciable for low molecular weights and in poor solvents; its effect vanishes as the molecular weight becomes large. However, if X2≠0, the temperature at which A2 for a given polymer-solvent pair becomes zero will, in general, depend upon the molecular weight. The similar influence of this term on the expression for the intramolecular expansion factor is smaller, although not necessarily negligible.

Interaction parameters (χ1) are calculated from second virial coefficients for a number of polymer-solvent systems, and these are compared with the χ1 values obtained from intrinsic viscosities (intramolecular theory). The good agreement obtained offers strong evidence for the general validity of the intermolecular (A2) and intramolecular theories.

A 2 increases slightly more rapidly with decrease in M than theory predicts. On the whole, however, the consistency of results is gratifyingly good.

The intrinsic viscosity increases linearly with A2M in poor solvents. This relation must be replaced by one of approximate direct proportionality in good solvents.
Calculation of the Surface Energies of Alkali Halide Crystals
Authors: van Zeggeren F. , Benson G. C.
Published: January 2005

Rapidly converging lattice sums for the electrostatic and van der Waals contributions to the surface energy of a generalized sodium chloride crystal have been derived. As special cases numerical values of these sums for the {100} and {110} faces of a NaCl-type crystal and for the {110} face of a CsCl-type crystal were computed. Surface energies for {100} faces of NaCl-type alkali halides and for {110} faces of both NaCl-and CsCl-type alkali halides have been calculated.
Vibrational Spectrum of Borine Carbonyl
Authors: Bethke George W. , Wilson M. Kent
Published: January 2005

The infrared spectra of both solid and gaseous BH3CO, 10BH3CO, BD3CO, and 10BD3CO have been obtained. In addition some observations have been made on the Raman spectra of the gaseous compounds. Fundamental frequencies have been assigned to all normal modes and the vibrational potential constants for borine carbonyl have been approximated by means of a simplified force field.
Relaxation-Time Model for Free-Radical Concentration
Authors: Giddings J. Calvin
Published: January 2005

The accuracy of the quasi-equilibrium approximation in chemical kinetic studies is examined using a relaxation-time model. Two distinct cases arise: the time-lag case and the diffusion case. In each case, the proposed model leads to exactly the same result as an approximate mathematical treatment.

The kinetic processes in a flame front are examined, and are shown to involve both the time-lag and diffusion cases. Again, the model is justified by an independent approximate method. The model is next examined in that region of the flame where the kinetic processes are most important, that is, near the point of maximum reaction rate. A very simple expression is found for the radical concentration at this point. This expression is justified through numerical examples.
Evaporation of Metal Crystals
Authors: Hirth J. P. , Pound G. M.
Published: January 2005

A mechanism for vaporization of solid metals involving monatomic ledges on metal crystal surfaces is deduced, and an equation is derived for evaporation rate in terms of the dynamics of these ledges. It is shown that crystal edges are a ready source for monatomic ledges. The limiting expression for the vaporization coefficient of large, perfect crystals is given as a function of pressure and temperature by α=⅔(p/pe)+⅓, where pe is the equilibrium vapor pressure. Various predictions of this theory are compared with available experimental results.
Intensities of Infrared Bands in Solution. I. Benzene Solutions
Authors: Ferguson Eldon E.
Published: January 2005

It is shown that the molar extinction coefficients of band maxima of infrared ``inactive'' fundamentals of benzene in solution are markedly sensitive to the nature of the solvent. CS2, C6H5Br, C6H5Cl, and C5H6N enhance the inactive benzene fundamentals while CCl4, cyclohexane, and several normal paraffins diminish the extinction coefficients. The extinction coefficients are shown to change linearly with solvent concentration for C6H6–CCl4 and C6H6–CS2 solutions. The intensity changes in solution are shown to correlate with an approximate calculation of intermolecular dispersion forces between benzene and solvent molecules.

The inactive fundamentals of several methylene halides also exhibit this ``solution sensitivity.'' The technique of enhancing inactive fundamentals in solutions is shown to be useful for the purpose of identification of these fundamentals in infrared spectra.
Studies of I Atom and Br Atom Recombination Following Flash Photolysis of Gaseous I2 and Br2
Authors: Strong R. L. , Chien J. C. W. , Graf P. E. , Willard J. E.
Published: January 2005

The method of flash photolysis has been used to determine the rate constant, k, in the expression d(X2)/dt = k(X)2M for the combination of iodine atoms in argon, and of bromine atoms in argon, oxygen, and nitrogen. At room temperature nitrogen is approximately 1.3 and oxygen 2.2 times as effective as is argon in serving as a ``third body'' for the combination of bromine atoms. Measurements of the rate constants at a series of temperatures up to 160° give apparent activation energies of —1.4 kcal/mole for I in A, —2.0 kcal/mole for Br in A and —1.2 kcal/mole for Br in O2. The (I2)/(A) ratios used in the iodine atom studies were in the range of the ``tail'' of the (I2)/(A) vs k plot of the Cambridge group and the k values are in agreement with their results. Estimates of the maximum ``thermal effect'' possible in the bromine atom studies, compared with the experimental results, indicate that such effects were probably negligible. Experimental tests and calculations of the effect of nonuniform illumination of the reaction cell by the flash lamp indicate that the observed rate constants are quite insensitive to this factor.
Kinetics of the Nitrogen Dioxide Catalyzed Oxidation of Nitric Oxide
Authors: Ray James D. , Ogg Richard A.
Published: January 2005

The rate constant for the reverse reaction of the rate controlling step (NO+O2+NO2=NO2+NO3) of high pressure nitrogen pentoxide decomposition has been determined to be 6.58×107 cc2 mole—2 sec—1. This reaction was found to be the rate-controlling step in the nitrogen dixoide catalyzed oxidation of nitrosyl chloride to nitryl chloride. The equilibrium constant at 25° for the reaction ClNO+NO2=ClNO2+NO as evaluated from the kinetic data was found to be 1×10—4.
Ionic Conductivity of Calcium Fluoride Crystals
Authors: Ure Roland W.
Published: January 2005

Transference number measurements on pure and doped crystals show that the predominant defect in CaF2 crystals in the anti-Frenkel disorder type involving equal concentrations of negative ion vacancies and negative ion interstitials. The mobilities of the F— vacancy and F— interstitial have been determined by measuring the electrical conductivity of crystals doped with NaF and YF3. The activation energy for mobility of the vacancies varies from 20±1.5 kcal/mole at 200°C to 12±1 kcal/mole at 600°C. For the interstitials, the mobility in the range from 690 to 920°C is given by u=(1.34×107)T−1 exp[−(19±4)×103/T] cm2/sec volt.The number of anti-Frenkel defects in the pure crystal in the range from 640 to 920°C is given by n0=2.96×1025exp[−(16.3×103)/T] cm−3.
Streaming Birefringence of Polymer Solutions : Anisotropy of Internal Fields
Authors: Čopič Milan
Published: January 2005

In the case of nonvanishing difference between indexes of refraction of the polymer and the solvent, the anisotropy of the internal electric field contributes a new term, called the form anisotropy, to the difference of polarizabilities of the long chain molecule. The form anisotropy is proportional to the square of the difference between indexes of refraction of the solvent and the polymer; hence it is responsible for the parabolic dependence of the streaming birefringence on the index of refraction of the solvent. Moreover, the form anisotropy is dependent upon the molecular weight of the polymer and on the nature of the solvent in contrast to the intrinsic anisotropy, which is a function of the internal constitution of the long chain molecule only. Different effects, caused by the presence of the form anisotropy, are discussed using the dumbbell model for the soft and the rigid macromolecules for illustration. Some experimental data obtained on polystyrene in different solvents are compared with the theory.
Integral Equation Method for Determining Approximate Fluid Distribution Functions
Authors: Poirier Jacques C.
Published: January 2005

A general method for determining distribution functions in fluids is presented. The method consists of expanding the distribution function for a partially coupled subset of particles in the system in a multiple Taylor's expansion in the coupling parameters. The resulting set of linear integral equations may be solved by using an approximation less drastic than the superposition approximation. In the next to lowest approximation, the radial distribution function is obtained analytically for point ions and for an exp-exp potential.
Coupling of Optic and Acoustic Modes of Vibration in Crystals
Authors: Bauer Ernest
Published: January 2005

The transition probability for transfer of energy from one optic to two or three acoustic modes of vibration has been calculated for sodium chloride, and found to be of the order 1012 per sec at low temperatures.
Use of Interpolation Theory in the Study of Phosphorescence
Authors: Honig J. M.
Published: January 2005

It is shown that data pertaining to the intensity of the afterglow radiation of phosphors must lie within definite bounds if these data are to be represented by the simple first-order or second-order decay schemes, modified by the introduction of distribution functions for the electron traps. These extremal functions are evaluated, without requiring a knowledge of the actual trap distribution, by application of interpolation theory. It is pointed out that if in any time interval the experimental data fall outside the prescribed bounds this is a clear indication that the corresponding simple decay scheme is inapplicable to the data. Under favorable conditions the interpolation theory will therefore give a clearcut indication whether the data follow a first- or second-order scheme or whether more complex mechanisms are required in their interpretation.
Vibrational Spectrum and Structure of the Tropylium Ion
Authors: Fateley William G. , Lippincott Ellis R.
Published: January 2005

The infrared and Raman spectra of tropylium ion, C7H7+, are presented and discussed in terms of possible structures. An assignment of the fundamental frequencies has been made for a D7h structure and used to carry out a normal coordinate analysis. The Wilson FG technique was used to calculate valence force symmetry constants and valence force constants. A comparison of the vibrational spectrum and force constants with those for benzene indicates a striking similarity between the two structures. The structure of tropylium ion was concluded to be a planar aromatic D7h molecule ion.
Theoretical Study of the Hyperfine Structure in the Inversion Spectra of the Deutero-Ammonias
Authors: Hadley George F.
Published: January 2005

The energy splittings in the inversion spectra of N14D3, N14HD2, and N14DH2 caused by nitrogen and deuteron quadrupole interactions with the molecular electric field, the interactions of the nuclear spins with the molecular magnetic field, and the spin-spin interactions are found. The molecular coupling scheme of Van Vleck is used to treat the Hamiltonian to second order in the electronic energies. Group theory is used to select wave functions which simplify the solution of the secular equations. For N14D3 thirteen constants appear in the energy expressions. Order of magnitude estimates for eleven of these constants can be made using data from the experimental work on N14H3. No estimate is made of the deuteron quadrupole coupling constants. With N14HD2 and N14DH2 twenty-four constants appear in each case. Order of magnitude estimates can be made for only nine of these.
Analysis of High-Resolution NMR Spectra
Authors: Anderson Weston , McConnell Harden M.
Published: January 2005

Van Vleck has shown the usefulness of moment calculations in the interpretation of magnetic interactions found in crystals. This approach has been extended to include liquids where separate resonances may be well resolved. In a simple chemical system containing only two groups of nuclei, this procedure allows the direct calculation of the spin coupling constant and the chemical shift in terms of directly measured quantities; in more complex systems, it allows some information to be obtained without finding the complete solution to a particular problem.
Ultraviolet Absorption of Pyrazine Vapor Due to n — π Transition
Authors: Ito M. , Shimada R. , Kuraishi T. , Mizushima W.
Published: January 2005

The near ultraviolet absorption spectrum of pyrazine vapor was photographed and measured. A tentative vibrational analysis was made for some of the bands in the longest wavelength discrete band system (3200 A system), due to the n — π transition. The spectral band feature shows that the 3200 A system is a superposition of two absorption systems which belong to different electronic transitions. It appears that this conclusion is also supported by simple theoretical considerations.
Lattice Vacancy Theory of the Liquid State
Authors: Mueller Charles R. , Stupegia Donald C.
Published: January 2005

Using the simple lattice vacancy or ``hole'' theory of the liquid state as a starting point, various modifications were investigated. The best partition function found involves changes only of the term (Na+Nb)!/Na!Nb! in the simple ``hole'' theory. Na and Nb are the number of molecules and holes, respectively. This model involves a change in analogy with the Flory approximation for solutions and corresponds roughly to utilizing holes one-third the size of molecules. For the usual average of the rare gases the critical temperatures are about 5% too high, critical volumes 27% too high, a PcVc/RTc about 8% too high.

The slope of the plot of lnP/Pc vs Tc/T is about 5% in error. The slope of the rectilinear diameter plot is about 10% in error. Co-existing phase densities are reasonably good in the liquid region and, in addition, rather remarkable results are obtained for the vapor phase.

The model has been extended to binary solutions and predicts the thermodynamic quantities of mixing quite well for the few cases where calculations have been made.
Quantum-Mechanical Effects in Gas Dynamics
Authors: Laitone E. V.
Published: January 2005

Recent analytical studies by Morgenstern led him to conjecture that the Boltzmann equation, describing the kinetic theory of a rarefied gas, cannot predict general spatially nonhomogeneous solutions. Morgenstern proposed a modified collision integral that can provide more general solutions, but still reduces to that of Boltzmann for the spatially homogeneous case.

The present paper points out that this proposed collision integral can be made physically plausible by introducing recent contributions from the quantum-mechanical studies of transport processes by Ross and Kirkwood. However, it is indicated that when the higher order corrections beyond the Navier-Stokes order of approximation are to be considered then the density-dependent symmetry effects due to Bose-Einstein statistics, and other quantum-mechanical effects, in addition to the introduction of the scattering cross section, may have to be included.
Vibrational Spectrum and Structure of Metal-Cyanide Complexes in the Solid State. I. KAg(CN)2
Authors: Jones Llewellyn H.
Published: January 2005

The infrared spectra of solid KAg(CN)2 and the mono- and di-substituted C13 and N15 species have been observed. The seven fundamental vibrations of the linear, symmetrical Ag(CN)2— ion have been assigned at 2146, 360, 2140, 390, 250, 310, and 107 cm—1 for the species containing C12 and N14.

From the observed frequencies of the normal and isotopic species, force constants were calculated for two possible structures: N–C–Ag–C–N and C–N–Ag–N–C. It is shown that the latter structure gives unreasonable force constants, and that therefore the cyanides are probably bound to the silver through the carbon atom. Relative amplitudes of the atoms during the vibrations are shown.
Multiple Relaxation Times in Nonrigid Solute Molecules
Authors: Davies Mansel , Meakins R. J.
Published: January 2005

This paper describes the first detailed investigation of the dielectric behavior of liquid solutions of large solute molecules possessing small polar groups capable of rotation about a chemical bond. Three hindered hydroxy-compounds are chosen as examples and their dielectric properties in Decalin solution are measured at frequencies up to 2.4×1010 cps which includes the region of maximum absorption. In each case two distinct absorption regions are obtained, in contrast to the results for the rigid molecule o-dichlorobenzene, which gives a Debye curve with a single relaxation time.

A comparison of the calculated and observed dipole moments supports the theory that in each case the lower frequency absorption is due to the rotation of the main part of the molecule and the higher frequency absorption is due mainly to the independent orientation of the hydroxyl group by rotation about the C–O bond.

The activation energies and frequency factors for the dielectric mechanisms are determined, where possible, from the displacement of the absorption with temperature. The activation energies for complete molecule rotation and for independent hydroxyl orientation are similar. The frequency factor for the hydroxyl mechanism is larger, however, and this accounts for the higher frequency of the absorption due to this mechanism.
Investigations on Cuprous Sulfide
Authors: Wagner J. Bruce , Wagner Carl
Published: January 2005

The activity of copper in cuprous sulfide as a function of the copper-to-sulfur ratio has been determined with the help of coulometric titrations. The homogeneity range of cuprous sulfide at 400°C extends from a copper-to-sulfur ratio of 1.9996±0.0002 for samples coexisting with metallic copper to a ratio of less then 1.93 for samples coexisting with digenite (Cu1.8S). The ratio of the effective mass of electron holes to that of the free electron has been found to be 7±2 at 435°C. Preliminary conductivity measurements suggest a considerable increase of the mobility of electron holes with an increasing copper deficit of the samples presumably due to fewer collisions of electron holes with excess electrons.
Investigations on the Reduction of Silver Sulfide and Cuprous Sulfide by Hydrogen
Authors: Kobayashi Haruo , Wagner Carl
Published: January 2005

The rate of removal of sulfur from silver sulfide and cuprous sulfide at 300 and 385°C, respectively, has been determined as a function of the metal activity in the sulfide with the help of electrochemical measurements. From the results, it is concluded that hydrogen molecules react mainly with sulfur atoms adsorbed on Ag2S but with sulfur ions adsorbed on Cu2S. The significance of the results for the interpretation of catalytic reactions is discussed.
Pi-Electron Structure of Butadiene
Authors: Berry R. Stephen
Published: January 2005

The spectrum and structure of butadiene have been considered by application of several nonempirical methods to the problem of the energy levels of the π-electron system. Six spatial configurations of the nuclei have been treated, of which three correspond to the trans- form of the molecule and three, cis. The methods used include the use of antisymmetrized molecular orbitals with and without configuration interaction, electron-pair bonds, a model based on two neighboring vinyl radicals, and the method of atoms in molecules as applied to the preceding techniques. A comparison of the results given by the different theories permits an evaluation of the theories, at least in the case of unsaturation electrons.
Mechanism of the Gas Phase, Thermal Decomposition of Ozone
Authors: Benson Sidney W. , Axworthy Arthur E.
Published: January 2005

The pyrolysis of ozone has been reinvestigated experimentally, and it is now shown that most of the known data are quantitatively explained on the basis of the simple mechanism, M+O3[open phi] lim 21M+O2+OO+O3→ lim 32 O2,where M may be O2, O3, CO2, N2, He, etc. There is no evidence for a direct bimolecular reaction of ozone to produce O2 nor is there any evidence for important surface effects or energy chains. On the other hand, the results at very fast rates of decomposition indicate an acceleration which can be accounted for in terms of temperature gradients in the system. This region is usually very close to the thermal explosion limit.

The values found for the rate constants are (for M equal to O3), k1=4.61±0.25×1012 exp(−24 000/RT) liter/mole−sec,k2=6.00±0.33×107exp(+600/RT) liter2/mole2−sec,k3=2.96±0.21×1010exp(−6000/RT) liter/mole−sec.

The relative efficiencies of O2, N2, CO2, and He in activating O3 (compared to O3 itself) are, respectively, 0.44, 0.41, 1.06, and 0.34.

As expected for energy transfer processes, k1 has an abnormally high pre-exponential factor, and k2 has correspondingly a negative energy of activation. It is further inferred that Reaction 3 which produces two O2 molecules with 99 kcal of excess energy between them does not produce more than one excited electronic state of O2 and that these hot O2 molecules are not very efficient in exciting O3 to decomposition. Calculations of the entropy of activation of Reaction 1 can be made and are shown to be in good agreement with this conclusion. From these findings it appears that the high quantum yields found in the photolysis of O3 at short wavelengths, if real, probably are attributable to metastable O atoms [1D] produced in the primary process which can generate chains in O3.

It can be shown that the homogeneous production of O atoms from O2 at high temperatures proceeds through two different paths having different activation energies, the lower energy path involving O3 as an intermediate.

Finally, possible mechanisms are considered for the chemical sensitization of the thermal explosion of O3 and its catalytic decomposition by H donors.
Discrimination between ``Radiative'' and ``Nonradiative'' Transfer of Molecular Excitation Energy in Liquid Systems
Authors: Weinreb A.
Published: January 2005

A method for discriminating between radiative and nonradiative transfer of molecular excitation energy in liquid systems is described. A quenching agent is added, which quenches the transfer process and the competition between quenching and nonradiative transfer is utilized. The method is applied to the system diphenyl oxazole+diphenylhexatriene in toluene. A tentative method for the quantitative evaluation of the part each transfer mechanism plays when both are acting is given, and, qualitative agreement, at least, with the theory of Förster on transfer of energy is obtained.
Infrared Band Contours. I. Spherical Top Molecules
Authors: Edgell Walter F. , Moynihan Robert E.
Published: January 2005

The relationships between the absorption coefficient, the true average absorption coefficient, and the pressure independent ``average'' absorption coefficient are considered. It is found that the absorption coefficient will equal the pressure independent average absorption coefficient provided that certain conditions are fulfilled. These conditions may be satisfied for heavy spherical tops but not for light molecules. The average absorption coefficient is obtained for fundamental bands of spherical tops including the interaction between the rotational angular momentum and the vibrational angular momentum of degenerate modes. The form of the band envelope is described and found to be in general agreement with experimental bands. The separation between the P and R maxima is found to be proportional to 1—ζ and this relation may be used for computing Coriolis constants. The band envelopes for CF4 are measured and zeta values obtained from the P–R separation. They are found to be in good agreement with the sum rule. Finally, the zeta value for the CO stretching vibration of Ni(CO)4 is obtained from the 5μ band envelope and conclusions are drawn regarding the form of the vibration.
Infrared Spectrum of Hydrogen Sulfide in the 2.6-Micron Region
Authors: Savage Carleton M. , Edwards T. Harvey
Published: January 2005

The infrared absorption spectrum of hydrogen sulfide (H2S), in the region from 3730 cm—1 to 4030 cm—1, has been measured under high resolution. Calibration was made from emission lines of argon, observed in the second order, using Edser-Butler bands. The absorption has been assigned to two overlapping combination bands, a type A band (n1,n2,n3) = (0,1,1) at 3789.07 cm—1, and a type B band (1,1,0) at 3779.23 cm—1, plus overlapping water vapor absorption. The excited state inertial parameters in cm—1 giving the best fit to the data were found to be A*B*C*(0,1,1)10.5179.1244.619(1,1,0)10.5958.9854.603
Dielectric Losses of Doped Colored Crystals
Authors: Jacobs G.
Published: January 2005

The dielectric losses of KBr single crystals doped with BaBr2 at different concentrations, both uncolored and additively colored, have been measured. A maximum in the dielectric loss versus frequency curve in the additively colored crystal was observed. This relaxation maximum was found to be due to the presence of Z2 centers. Some remarks are made concerning the activation energies involved.
Microwave Spectrum and Molecular Structure of Bromine Trifluoride
Authors: Magnuson D. W.
Published: January 2005

The moments of inertia and quadrupole coupling coefficients of both Br79F3 and Br81F3 were determined from a number of microwave transitions. From the moments of inertia the bromine trifluoride molecule was found to have a planar distorted — T structure with one short, 1.721 A, and two long, 1.810 A Br–F bonds. The FBrF′ angle was found to be 86° 12.6′.
Theory of Nuclear Magnetic Shielding in Molecules. I. Long-Range Dipolar Shielding of Protons
Authors: McConnell Harden M.
Published: January 2005

The general nuclear magnetic shielding theory of Ramsey is developed for the case of ``long-range'' nuclear shieldings. Such shieldings arise from the magnetization induced in molecular electrons localized to groups one or more bond lengths removed from the shielded nucleus. Order-of-magnitude calculations indicate that these long-range shielding fields can make significant contributions to proton chemical shifts in, for example, aromatic hydrocarbons and alkyl halides.
Structure in Ionic Solutions. I
Authors: Brady G. W. , Krause J. T.
Published: January 2005

X-ray diffraction studies have been made of concentrated KOH and KCl solutions. The radial distribution function for KOH indicates that the hydration number of K+ is 4, in agreement with the theoretically calculated value of Bernal and Fowler. It appears that K+ which is close in size to the H2O molecule enters substitutionally into the pseudostructure of H2O without disturbing the structure to any marked extent. The quantitative evaluation of the data on KCl solutions is more difficult because the first peak in the distribution function is not symmetrical. However, the results indicate that the Cl— ion disrupts the H2O structure and leads to an increase in the number of H2O nearest neighbors.
Normal Coordinate Analysis of Halogenated Ethylenes. II. Perhalogenated Ethylenes
Authors: Mann D. E. , Fano L. , Meal J. H. , Shimanouchi T.
Published: January 2005

The methods described in the preceding paper have been applied to the normal coordinate analysis of the fundamental vibrations of 27 perhalogenated ethylenes which contain F, Cl, or Br. Force constants for the planar modes of the key molecules, C2F4, C2Cl4, and C2Br4, have been obtained by an adjustment procedure based on the method of least squares. The agreement between the calculated and observed fundamentals is quite good. The constants established for the key molecules were then used, either directly or with a simple interpolation scheme, to calculate the fundamentals of the remaining 24 ethylenes. Comparisons with experimental results have been made where possible and indicate good agreement for the out-of-plane as well as inplane vibrations. The planar normal modes of C2F4, C2Cl4, and the 5 fluorochloroethylenes are depicted.
Thermodynamics of the V–O System : Dissociation Energies of VO and VO2
Authors: Berkowitz Joseph , Chupka W. A. , Inghram Mark G.
Published: January 2005

The molecules vaporizing from V2O5(s) and VO(s) have been determined employing a mass spectrometer to analyze the vapors effusing from Knudsen cells containing these materials. The vapor over the V2O5 loaded cells was found to contain V4O10(g), V6O14(g), V6O12(g) with some evidence for V4O8(g) and V2O4(g). Since both the composition and the partial pressures varied with time no quantitative data could be obtained for these molecules. By contrast, both the composition and partial pressures of the vapor over VO(s) were essentially constant with time. The molecules observed were V(g), VO(g), and VO2(g). A thermodynamic treatment of the data yields 6.4±0.2 ev and 12.8±0.2 ev, respectively, for the atomization energies of VO and VO2.
Structure of the Methylamine Molecule. II. Theory of Internal Motions and Application to CD3ND2
Authors: Kivelson Daniel , Lide David R.
Published: January 2005

A general theory is developed for the two low-frequency internal motions which influence the microwave spectrum of methylamine. The interactions of the over-all and internal rotations with the inversion motion are treated quantum-mechanically for the case where the potential barriers to inversion and internal rotation are high. The theory justifies the method of analysis of the CD3ND2 spectrum which was given in paper I of this series. An expression is obtained for the empirical inversion parameters FKτ defined in I, and is shown to give an excellent fit of the experimental results for CD3ND2. The inversion splitting constant obtained from this calculation is 2246.0±5 Mc. The significance of this constant and of the other molecular parameters which enter the theory is discussed.
SCF LCAO MO Study of Li2
Authors: Faulkner James E.
Published: January 2005

An LCAO molecular orbital calculation using the full six-electron Hamiltonian has been performed on Li2 at a nuclear separation equal to the experimental internuclear distance. The molecular wave function consisted of one antisymmetrized product made up of molecular orbitals formed as the best linear combinations of Slater 1s, 2s, and 2pσ atomic orbitals. The orbital exponents for these atomic orbitals were respectively 2.69, 0.64, and 0.53 as determined by a variational calculation on the lithium atom. In computing the molecular dissociation energy, the energy of two separated lithium atoms was taken to be that obtained by this variational calculation. The computed dissociation energy was found to be 0.33 ev compared with the experimental value of 1.05 (where a slight correction for zero-point energy has been made). The ratio of the computed molecular ground-state energy to the experimental is 0.9902 while the difference of these quantities is 4.00 ev. Certain other molecular constants are calculated and compared with available experimental data.
Absolute Temperatures below 1°K : Chromic Methylammonium Alum as a Thermometric Substance
Authors: Ambler E. , Hudson R. P.
Published: January 2005

The method of gamma-ray calorimetry has been employed to determine the entropy-temperature relation for a single-crystal of chromic methylammonium alum in the range 0.015°—1°K. A critical discussion of possible sources of error is given; the accuracy in T is estimated to be approximately 5% throughout the region investigated. There is close agreement between the Hebb-Purcell theoretical S—T relation and the present data down to 0.07°K. The fact that the susceptibility-entropy relation varies considerably for different specimens at temperatures below 0.06°K suggests that S—T measurements are of limited value in that region, especially from a thermometric point of view.
Electronic Spectra and Structure of the Carbonyl Group
Authors: Sidman Jerome W.
Published: January 2005

A theoretical treatment of the electronic structures of compounds containing the carbonyl group has been developed. The method employs the self-consistent field (SCF) procedure to determine the best molecular orbitals, for the lowest configuration, which can be formed as linear combinations of the atomic orbitals (LCAO—MO). Semiempirical methods are used throughout to determine the numerical values of all core parameters and electronic repulsion integrals. By a judicious choice of parameters and integrals it is possible to describe semiquantitatively the π-electron ionization potentials, n→π and π→π electronic transition energies, and π-electronic contribution to the dipole moment of formaldehyde, glyoxal, and p-benzoquinone. The effect of configurational interaction (CI) upon the calculated transition energies is considered for the n→π and for the π→π transitions.
Lattice of Partly Permanent Dipoles
Authors: Toupin R. A. , Lax M.
Published: January 2005

The electric susceptibility of a lattice of partly permanent dipoles is determined as a function of the temperature and molecular parameters. The calculation is based on the spherical model approximation. The susceptibility has a discontinuous slope at a critical temperature Tc. Numerical techniques are developed for the evaluation of Tc which may have application elsewhere in the statistical theory of lattices. The theory predicts a critical temperature of 98°K for solid hydrogen bromide which corresponds to a measured value of 89°K.
Photochemical Studies in Flash Photolysis. I. Photolysis of Acetone
Authors: Oster Gisela K. , Marcus R. A.
Published: January 2005

The high-intensity flash photolysis of acetone was investigated using an exploding wire as a light source. Experiments were conducted with the unfiltered light of the flash, containing light in the near as well as in the far ultraviolet region of the spectrum. The results show that the C2H6/CO ratio in the reaction products is about 1.25 and is fairly insensitive to variation in acetone pressure. Addition of small amounts of biacetyl lowers the ratio still further. This is attributed to the deactivation of a long-lived excited acetone molecule formed in the ultraviolet region below 210 mμ. Addition of butane lowers the ratio far below unity.

The CH4/CO ratio has the constant value of 0.1 for various light intensities, acetone pressures, pressures of added butane or of carbon dioxide.

A convenient way of separating small amounts of ethane from very large amounts of carbon dioxide is described.
Infrared Spectrum of Trifluoroacetic Acid Vapor
Authors: Kagarise R. E.
Published: January 2005

The infrared absorption of trifluoroacetic acid vapor in the region between 2 and 24 μ has been studied as a function of temperature. At room temperature both monomer and dimer molecules are present, while at 100°C the vapor is predominantly monomeric. On the basis of the resulting intensity changes it has been possible to conclusively identify the bands due to the two species. A partial assignment of the fundamental modes of vibration has been made using these data and the previously published spectrum of the deuterated acid.

The heat of dissociation (ΔH) for the dimer-monomer reaction has been determined from the temperature dependence of the OH stretching bands and found to be 13.7±0.4 kcal/mole.
Application of the Series Method of Imperfect Gas Theory to Other Problems in Statistical Mechanics
Authors: Hill Terrell L.
Published: January 2005

Certain well-known series expansions have proved very useful in imperfect gas theory. Series formally identical with those of imperfect gas theory can also be developed in other, quite unrelated, problems in statistical mechanics. Criteria for the existence of this formal analogy and examples are discussed.
Thermodynamics of the Ta–O System : The Dissociation Energies of TaO and TaO2
Authors: Inghram Mark G. , Chupka William A. , Berkowitz Joseph
Published: January 2005

Mass spectrometric analysis of the vapor in thermodynamic equilibrium with mixtures of Ta(s) and Ta2O5(s) has shown TaO and TaO2 to be the predominant gaseous molecules present. The experimental data yield 8.4±0.5 ev and 15.0±0.5 ev for the energies of atomization of these molecules at 0°K.
Microwave Spectrum, Structure, Dipole Moment, and Quadrupole Coupling Constants of Formamide
Authors: Kurland Robert J. , Wilson E. Bright
Published: January 2005

The microwave spectra of formamide, and the isotopic species 1, 2 N di-deutero formamide, 1 N mono-deutero formamide (cis) and (trans), have been investigated. The rotational constants obtained from the frequencies of assigned rotational transitions lead to the following effective structural parameters: for the bond distances, there results C–O = 1.243±0.007 A, C–N = 1.343±0.007 A, N–H = 0.995±0.007 A, and for the bond angles ∠HNH = 118.98±0.50°, ∠ NCO = 123.58±0.35°, ∠NCH = 103.9±1.2°. The molecule is planar. Stark effect measurements yield values for the dipole moment components which, when combined with assumed approximate bond moments and the structural parameters, give the magnitude and the direction of the dipole moment. The dipole moment is thus equal to 3.714±0.06 Debyes and makes an angle of 39.6° with the C–N bond. The quadrupole coupling constants, Xa = 1.9 mc, Xb = 1.7 mc, Xc = -3.6 mc, were calculated from the frequency shifts of the hyperfine splittings observed for several rotational transitions.

The structural parameters and quadrupole coupling constants are discussed in terms of the bonding characteristic of the N–C–O linkage in formamide and related compounds.
Chemical Etches and Etch Pit Patterns on PbS Crystals
Authors: Brebrick R. F. , Scanlon W. W.
Published: January 2005

Chemical etches have been found which polish or remove thick surface layers from PbS crystals. One of these etches results in the formation of etch pits. The dissolving action of this etch on PbS, PbSe, and PbTe and the etch pit patterns formed by it on natural and synthetic PbS crystals are discussed.
On the Pressure Broadening in the Gamma Bands of Nitric Oxide
Authors: Thorson Walter R. , Badger Richard M.
Published: January 2005

A quantitative reinvestigation of the pressure broadening in the γ(0,0) and γ(1,0) bands of nitric oxide has established that the pressure effect is not abnormal as has sometimes been supposed and that the collision diameter of the excited NO molecule is approximately 3.8 A.
Successive Ionization Potentials of Unsaturated Hydrocarbons
Authors: Hush N. S.
Published: January 2005

The second π-ionization potentials, corresponding to the process R+→R+++e, are calculated for a number of unsaturated hydrocarbon molecules R. The SCF LCAO molecular orbital method, together with semiempirical values proposed by Pariser and Parr and Hush and Pople for interaction and core integrals, has been employed. The value obtained for benzene (16.9 ev) is in good agreement with that reported by Hustrulid, Kusch, and Tate (17.2±1.0 ev).
Thermodynamic Properties of the Gaseous Alkali Halides
Authors: Rice Stuart A. , Klemperer William
Published: January 2005

The thermodynamic properties of the alkali halides in the gas phase have been computed for the temperature range 298.16°K to 2000°K. These data are applied to the determination of the dimer concentration in the gas. It is concluded that there is very little dimer and/or higher polymer in the gas, in agreement with previous infrared spectroscopic studies.
Improved Approximation for the Potential of Spherical Polyelectrolyte Molecules in Solution
Authors: Lifson Shneior
Published: January 2005

An improved approximate solution of the Poisson-Boltzmann equation for spherical polyelectrolytes is suggested. It is compared with the results of a numerical solution of the same equation by Wall and Berkowitz, as well as with an approximation proposed by Osawa, Imai, and Kagawa.