bluuebunny/crossref_metadata_2025 huggingface dataset:
The Infrared Spectrum of Chlorine Dioxide
Authors: Nielsen Alvin H. , Woltz P. J. H.
Published: January 2005

The infrared spectrum of ClO2has been reinvestigated from 2–40μ. Several new bands have been discovered, among them the bending frequency ν2 at 445 cm−1. This band has the doublet character required if the molecular model is to be an obtuse triangle in accord with electron diffraction experiments. Three bands, ν1, ν2, and 2ν1, were resolved with prism and grating methods, and the spacing of the Q lines was found to be about 3.0 cm−1. An A″—B″ value of 1.413 cm−1 was obtained from the analysis of ν2, and this value also is in excellent agreement with the electron diffraction measurements. Moments of inertia computed from the r(Cl–O) = 1.49A and 2α (apex angle) = 118.5° obtained from a combination of electron diffraction and infrared data are IA=16.09×10−40 g cm2, IB=86.35×10−40 g cm2, and IC=102.43×10−40 g cm2. A band which cannot be ascribed to an impurity was found at 290 cm−1. The possibility that this band results from polymerization of ClO2 is suggested.
Application of Eller's Optical Machine to the Determination of the Molecular Structure of Gases by Electron Diffraction. II. Nonrigid Molecules
Authors: Bru L. , Rodriguez M. Perez , Cubero M.
Published: January 2005

In this work we shall demonstrate the possibility of applying Eller's optical machine, as an auxiliary method of making calculations, to the study of the determination of the structure of gaseous molecules (nonrigid molecules) by means of the diffraction of electrons. The particular case of the CF3–C≡CH will be used as an illustration.
Absorption Spectra of SH and SD Produced by Flash Photolysis of H2S and D2S
Authors: Ramsay D. A.
Published: January 2005

H2S and D2S were irradiated in a flash photolysis apparatus, and the absorption spectra of the products were photographed within 1 millisecond of the photolysis flash using the second order of a 21 ft grating spectrograph. The (0,0) and (1,0) bands of SH and SD were observed and analyzed. The following molecular constants for SH were obtained: 2Σ+ state: Be′=8.5381 cm−1, αe′=0.5091 cm−1, re′=1.4215A, ν00=30,662.42 cm−1, ΔG½′=1784.63 cm−1, γ0=0.313 cm−1. 2Π state: B0″=9.4611 cm−1, r0″=1.3503A, A=−376.96 cm−1. The rotational lines of the (1,0) SH band were observed to be diffuse, indicating a predissociation in the first vibrational level of the 2Σ+ state. This establishes an upper limit of 92.7 kcal and a lower limit of 66.3 kcal for the ground state dissociation energy of SH.
Dielectric Constants of Solutions of Charged Particles
Authors: Fraenkel George K.
Published: January 2005

Calculations are carried out to determine the relation between the dielectric constant of solutions of large charged particles and the charge distribution on the particles. It is shown that if the hydrodynamic forces cause the particles to rotate about a point fixed in each particle, the dielectric constant is determined by the dipole moment about this point.
Infrared Spectroscopy and the Character of Chemical Binding
Authors: Mecke R.
Published: January 2005

The importance of the study of the intensities of vibrational bands yielding information concerning the charge distribution in chemical bonds is stressed.

A method is developed for obtaining bond moments in the ground state by the extrapolation of the values calculated for the transition moments of the bond, these being obtained from intensity measurements on the fundamental and overtone bands.

An empirical attempt is made to explain the total moment as the sum of an ionic, a polar, and an inductive component. Agreement between experimental results and the empirical relations is good for OH and CH bonds in a large number of compounds.
The Molecular Structure of Arsine
Authors: Nielsen Harald H.
Published: January 2005

The method discussed by Nielsen for determining the rotational term values for the vibration states ν3 and ν4 has been applied to the spectrum of AsH3 and by this means the Coriolis factor ζ4(z) has been determined. The value of ζ2(z) was known from an earlier work as was the value B(xx). This permits the evaluation of B(zz) when use is made of the zeta sum rule for pyramidal XY3 molecules, i.e., ζ2(z)+ζ4(z)=(−1+(B(xx)/2B(zz)). These constants lead to values for the AsH distance r0=1.523A and for the H–As–H angle α=91°34′.
The Complete Symmetry Group for Internal Rotation in CH3CF3 and Like Molecules
Authors: Minden Henry T.
Published: January 2005

The symmetry for the wave functions of molecules like CH3CF3 is analyzed, and a new group, C9 is proposed. The irreducible representations in C9 are derived in the general case for the nuclear spin and internal rotation factors of the wave function. The procedure is described for determining the symmetry and statistical weight of any given internal rotation, vibration energy level.
Enhancement of X-Ray Induced Absorption Bands in Alkaline Earth Compounds
Authors: Schulman James H. , Ginther Robert J. , Kirk Russell D.
Published: January 2005

It is deduced that the incorporation of monovalent positive ion impurities in alkaline earth salts should increase the discoloration of these compounds by ionizing radiations. This deduction is confirmed experimentally with alkaline earth fluorides and strontium sulfate ``sensitized'' with alkali-ion impurities. As predicted, M+3-ion and X−-ion impurities poison the sensitizing effect of the M+1-ion impurities.
The Reaction of Ethyl Radicals with Deuterium
Authors: Wijnen M. H. J. , Steacie E. W. R.
Published: January 2005

The reaction of ethyl radicals with deuterium has been studied. The ethyl radicals were produced by photodecomposition of diethyl ketone. As activation energy was found E=13.3±0.5 kcal. From this value it may be concluded that the activation energy is about 11.5±1 kcal for the reaction of ethyl radicals with hydrogen.
Dielectric Constant Measurements of Chlorine Trifluoride at 9400 mc/sec
Authors: Magnuson Dale W.
Published: January 2005

The dielectric constant of chlorine trifluoride was determined at 9400 mc/sec by measuring the change in the resonant frequency of a cavity when it is filled with the vapor. Corrections were made for the amount of dimer formed. The monomer molar polarization was best represented by P=15.944+1882.0/T°K cc and the dipole moment was 0.554 Debye unit. The average dimer molar polarization was found to be 49.8 cc assuming no dipole moment.
The Configurational Distribution Function in Quantum-Statistical Mechanics
Authors: Goldberger M. L. , Adams E. N.
Published: January 2005

The function F{N} which gives the relative probability of a configuration {N} is studied for the case of a quantum-mechanical system to which classical statistics can be applied. By means of a device originally used in quantum electrodynamics F{N} is obtained in a new form which is very closely related to the form of the analogous classical distribution FCL{N}. The new form of F{N} shows clearly how the difference between F{N} and FCL{N} is related to the uncertainty principle. As an illustration of the utility of the methods presented here several applications are presented. The first application is a high temperature development of F{N} as a power series in ℏ/kT which is carried through to the fourth order. The second application is the development of F{N} as a series of configuration space integrals. A previously published low temperature development of F{N} is obtained in a simple manner, and it is shown that all higher terms in the development can be written down explicitly by starting from the new form of F{N}. Finally, several integral equations for F{N} are presented which give physical insight into its structure, by establishing mathematical analogies with such physical processes as neutron diffusion.
Correlation of Hammett's σ-Values with Electron Densities Calculated by Molecular Orbital Theory
Authors: Jaffé H. H.
Published: January 2005

It is shown that Hammett's σ-values can be correlated with electron densities calculated by the MO LCAO method. Since Coulomb and exchange integrals for atoms other than carbon are not accurately known, an absolute calculation of σ's is not possible. Nevertheless, σ-values permit derivation of a self-consistent and reasonable set of parameters which can be used to calculate reasonable values for absorption frequencies, mesomeric moments, and orienting power of the substituents.
The Origin of the Ultrasonic Absorption in Liquids. II
Authors: Herzfeld Karl F.
Published: January 2005

Excess absorption in nonassociated liquids has been explained by the same mechanism as is responsible for molecular absorption in gases, namely, slow exchange of energy between internal and external degrees of freedom.

In this paper the rate of energy exchange is calculated for benzene and found to be three times too rapid. The Lennard-Jones interaction potential and model of the liquid are used; the fourth-order terms in the interaction provide the coupling between internal vibrations and Debye waves.
The Raman Effect of Vinylidene Chloride
Authors: Joyner Powell , Glockler George
Published: January 2005

The Raman spectrum of vinylidene chloride is reported. An assignment of fundamental vibrational frequencies is made and the overtone and combination frequencies interpreted. A method of accurately marking faint Raman lines for measurement is described.
The Kinetics of the Fast Gas-Phase Reaction between Nitryl Chloride and Nitric Oxide
Authors: Freiling Edward C. , Johnston Harold S. , Ogg Richard A.
Published: January 2005

The kinetics of the fast reaction between nitryl chloride and nitric oxide has been studied by absorptiometric methods in two systems of greatly different surface-to-volume ratio and over a temperature range from 1° to 71°. The pressure of each reactant has been varied from 0.1 mm to 18 mm and the total pressure from 0.2 mm to 384 mm. The reaction proceeds quantitatively according to the equation ClNO2+NO=NO2+ClNO.It is homogeneous and first order with respect to each reactant. The second-order rate constant is expressed by the equation k=0.83×1012 exp(−6900/RT)cc mole−1 sec−1.An elementary bimolecular mechanism is proposed.
Lifetimes of Active Molecules. II
Authors: Marcus R. A.
Published: January 2005

Experimental data on the atomic cracking of propyl radicals and on the deuterization of methyl radicals are compared with some theoretical calculations. With the aid of some assumptions concerning intramolecular energy transfer in the dissociating molecules involved in these and other reactions and concerning the corresponding activated complexes, data on a number of free radical reactions are correlated.
The Combination Band ν1+ν2+ν3 of Heavy Water Vapor
Authors: Dickey F. P. , Guderjahn C. A. , Palik E. D.
Published: January 2005

The vibration-rotation band ν1+ν2+ν3 in the heavy water vapor (D2O) spectrum has been remeasured. An analysis of the rotational structure has been carried out. From the interpretation of the data the value of the band center has been determined as well as the values of the reciprocals of inertia effective in this vibration state. The frequency ν1+ν2+ν3 is found to be 6533.4 cm−1. The effective reciprocals of inertia are A(V)=15.70 cm−1, B(V)=7.19 cm−1, and C(V)=4.69 cm−1.
On the Frequency Dependence of the Viscosity of High Polymer Solutions
Authors: Cerf Roger
Published: January 2005

The ultrasonic shear waves technique introduced by Mason offers the possibility of measuring the viscosity of a liquid in laminar flow at ultrasonic frequencies. A dilute high polymer solution exhibits, besides the usual shear viscosity, a shear elasticity as well for rather low frequencies (of the order of 105). A theory is given for infinitely dilute solutions using as a model for the chain molecule an elastic sphere. This model, which the author has used previously for the theory of flow birefringence, represents the limiting case of complete impermeability. The theory is compared with experimental results of Baker, Mason, and Heiss and of Rouse on polystyrene. The theory gives a good picture of the phenomena as a whole and is particularly successful in describing the apparently anomalous temperature dependence of the elasticity coefficient of polystyrene solutions at high frequencies. The interest of combining results on flow birefringence and on high frequency viscosity measurements is emphasized, as well as the possibilities of the latter technique for determining the molecular elasticity and internal viscosity as a function of frequency. On the basis of preliminary results for a sample of polystyrene of molecular weight 130,000, the tentative conclusion is given that the elastic sphere model will not have a quantitative significance for chains of such a low molecular weight and that it might be necessary to take into account the effect of permeation.
The Pyrolysis of n-Butyl-Benzene and the Heat of Formation of n-Propyl Radical
Authors: Leigh C. H. , Szwarc M.
Published: January 2005

It has been shown that the pyrolysis of n-butyl-benzene results in its dissociating into benzyl and n-propyl radicals, C6H5·CH2·CH2·CH2·CH3→C6H5·CH2·+·CH2·CH2·CH3,and the propyl radicals subsequently decompose to give ethylene and methyl radicals, CH3·CH2·CH2·→CH3·+C2H4. By the use of the toluene-carrier technique, it has been possible to measure the rate of reaction (1) by measuring the rate of formation of ethylene. The activation energy of reaction (1) has been thus determined at 65 kcal/mole. The latter value has been identified with the C6H5·CH2–C3H7 bond dissociation energy, i.e., D(C6H5·CH2–CH2·CH2·CH3)=65  kcal/mole. Since D(C6H5·CH2–C3H7)=ΔHf(C6H5·CH2)+ΔHf(n−C3H7)−ΔHf(n·C6H5·C4H9) and ΔHf(C6H5·CH2)=37.5 kcal/mole, one may compute the unknown value for ΔHf(n—C3H7), namely, ΔHf(CH3·CH2·CH2·)≈24 kcal/mole. Having ΔHf(n—C3H7), we calculated the dissociation energy of the primary C–H bond in propane at D(C3H7–H)=ΔHf(n−C3H7)+ΔHf(H)−ΔHf(C3H8)≈100  kcal/mole. This value for D(CH3·CH2·CH2–H) is compared with the findings of other workers. It agrees well with the recent findings of Stevenson, although the existing indirect chemical evidence seems to require a lower value.
Kinetics of Solidification of Supercooled Liquid Mercury Droplets
Authors: Turnbull David
Published: January 2005

The solidification rate of supercooled liquid mercury droplets is strongly dependent upon the nature of foreign substances on their surface or suspended in them. Droplets (2–8 microns diameter) coated with mercury laurate solidify at rates that are proportional to droplet volume and satisfactorily described by the theory of homogeneous nucleation of crystals. Droplets coated with mercury acetate solidify with frequencies that are proportional to droplet area and in good agreement with the theory of heterogeneous nucleation.

The results on Hg2I2-coated droplets are interpreted on the hypothesis that nucleation is effected by suspended crystallites of one kind. For some droplet dispersions the kinetic results are apparently best described by a multiplicity of solidification frequencies/area or volume. Various hypotheses for this multiplicity are considered.
The Hot Atom Chemistry of the Propyl Bromides; Effect of Phase and Recoil Energy on Retentions
Authors: Fox Maurice S. , Libby W. F.
Published: January 2005

The yields of the various organic radiobromides formed by neutron irradiation of liquid and solid iso and normal propyl bromides at various temperatures have been determined. Very careful purification of the propyl bromides has given good reproducibility and evidence that the main features of the hot atom chemistry of the propyl bromides have been discovered.

The solidification at the melting point results in a threefold or larger increase in yield of certain products, presumably those formed by epithermal bromine atoms, and a smaller increase for the remainder of the products, such as the mother molecule, presumably formed by hot reactions. Isomerization of isopropyl to n-propyl appears to occur with high probability in epithermal reactions. The epithermal production of bromides of considerably higher boiling point than the mother molecule has been confirmed and the phenomenon discussed theoretically.

Apparently the retentions in the solid phase depend on energy of the recoil bromine, 36-hr Br82 showing 93 percent retention in solid n-propyl vs 80 percent for the 18-min and 4.4-hr Br80's. This is in contrast to the liquid retentions in which no difference has been observed. On this basis it is concluded that the average recoil energy of the 36-hr Br82 is less than those of the two Br80 isomers and that the latter two differ relatively little.

The theoretical implications of the observed product distributions and the phase effect on these distributions and the sensitivity to recoil energy are discussed.
The Microwave Spectrum of CF3SF5
Authors: Kisliuk P. , Silvey Gene A.
Published: January 2005

The pure rotational spectrum of CF3SF5 has been observed in the microwave region. It is confirmed that the structure is almost certainly trifluoromethyl sulfurpentafluoride, and some evidence relating to the molecular parameters is obtained. Several vibrational states have been observed, including the torsional vibration from which the height of the potential barrier can be estimated as 220 cm−1.
Hindered Intermolecular Rotation in the Solid State: Thermal and Dielectric Phenomena in Long-Chain Compounds
Authors: Hoffman John D.
Published: January 2005

It has been assumed that the potential energy barrier hindering rotation of chain molecules about their long axes in the solid state has one deep minimum and Ω other minima with a potential energy V above that of the deeper well. Molecular models suggest Ω should be between 8 and 18. Application of the Bragg-Williams cooperative approximation to this system leads to first-order thermal and dielectric transitions. Dielectric and thermal data on n-C22H45Br, n-C30H61Br, and n-C28H58 show that the transitions are first-order. The static dielectric constant of the polar compounds calculated from Onsager's equation on the basis Ω=12 agree closely with experiment. The model suggests the existence of two Debye-type loss regions below the transition temperature. Loss data confirm this and further indicate Ω is close to 12. There is no evidence of resonance absorption. Ω may also be found from the entropy of transition at constant volume, R lnΩ. Thermal data on all three compounds are consistent with a value of Ω of 12. The theory indicates that the transition temperatures of a homologous series should arise almost linearly with increasing chain length if the chains do not twist appreciably. Data from the literature confirm this.
The Absolute Configuration of Optically Active Molecules
Authors: Wood William W. , Fickett Wildon , Kirkwood John G.
Published: January 2005

The problem of the absolute configuration of optically active molecules is investigated with the aid of the Kirkwood theory of optical rotatory power. Absolute configurations are assigned to the enantiomorphs of 2,3-epoxybutane and 1,2-dichloropropane. The assignments are consistent with the established experimental configurational relationships between these compounds. The Fischer convention is confirmed as a structurally correct representation of absolute configuration. The magnitudes of the calculated rotations of the compounds are in reasonably good agreement with experiment. The theory accounts satisfactorily for the effect of temperature and solvent on the optical rotation of 1,2-dichloropropane.
On the Distribution Function in Phase Space, with Application to the Stationary State of an Ideal Gas
Authors: Ikenberry Ernest
Published: January 2005

An infinite set of partial differential equations which are to be satisfied by the coefficients in a Bruns' series expansion of the distribution function, as a consequence of the principle of ``conservation of density-in-phase,'' are obtained. By means of these equations there are derived meteorologically useful expressions for the density and temperature gradients in an ideal gas.
Thermodynamic Properties of the Fluorine Atom and Molecule and of Hydrogen Fluoride to 5000°K
Authors: Cole Leland G. , Farber M. , Elverum G. W.
Published: January 2005

The evaluation of the thermodynamic functions Cp0, S0, —(F0—E00)/T, and (H0—E00)/T of the fluorine atom and molecule and of hydrogen fluoride from 100°K to 5000°K have been made by statistical calculations from available spectral constants for the atom and for hydrogen fluoride; for fluorine the constants have been derived or estimated from the Raman shift in gaseous fluorine, the equilibrium internuclear distance from electron diffraction measurements, and the heat of dissociation obtained recently by R. N. Doescher at this Laboratory. These results have been combined with the thermodynamic functions of hydrogen to evaluate the heats and free energies of dissociation and dissociation constants for the equilibria F2⇌2F, HF⇌½H2+½F2, and HF⇌H+F.
The Lennard-Jones 12:6 Potential and the Viscosity of Gases
Authors: Whalley E. , Schneider W. G.
Published: January 2005

The viscosity of several simple gases is discussed with reference to the Lennard-Jones 12:6 potential. The predicted and experimental viscosities agree well at moderate temperatures, but the agreement is not so good at higher temperatures, and for some gases, no possible choice of the force parameters will predict the correct temperature variation of the viscosity at high temperatures.
The Spectra of HCl, NH3, H2O, and H2S from 100 to 700 Microns
Authors: McCubbin T. King
Published: January 2005

This paper reports the pure rotation spectra of HCl, NH3, H2O, and H2S in the region of the far infrared from 100 to 700 microns. Observations were made using an instrument which had a resolving power of from 1 to 2 cm−1 in that region of the spectrum.
The Electrical Conductivity of Liquid Selenium and Selenium-Tellurium Mixtures
Authors: Lizell B.
Published: January 2005

The electrical conductivity of liquid selenium and selenium-tellurium mixtures was studied in detail. Measurements in the temperature range 230° to 500°C from dc to 1 mc/sec indicated the conductivities to be frequency-independent at low field strength (<5 v/cm). For larger fields (5 to 250 v/cm) the conductivity increases and higher dc than ac values result. Adding increasing amounts of tellurium to selenium produced a continuous rise in conductivity from 1.26×10−4 ohm−1 cm−1 (pure Se) to 2.08×10−1 ohm−1 cm−1 (50.3 percent Se, 49.7 percent Te) at 480°C and a decrease in activation energy from 1.14 ev to 0.84 ev. Comparatively good reproducibility was obtained in the measurements. An attempt to study ionic migration in liquid selenium by tracer methods has thus far not given satisfactory results. The conductivity values obtained for pure selenium are in good agreement with those presented by Henkels but disagree with those of Borelius. The electrical characteristics of liquid selenium and selenium-tellurium mixtures indicate that hole conduction as pictured for selenium in the solid state cannot be considered as an adequate explanation of the conduction process in these liquids. A complex mixture of conduction by electrons, holes, and ions is believed to exist.
Spin-Orbit Interaction in Aromatic Molecules
Authors: McClure Donald S.
Published: January 2005

The matrix elements of spin-orbit interaction are obtained for polyatomic molecules using M.O. wave functions, taking account of configurational interaction. These results are then applied to the calculation of singlet-triplet transition probabilities in aromatic compounds. It is shown without evaluation of integrals that intercombination transitions in these compounds should be much weaker than in most other classes of organic compounds. This is in agreement with experimental results on the phosphorescence lifetimes of these compounds.
Effect of Polar Solvents on the Absorption Frequency of n→π Electronic Transitions
Authors: McConnell Harden
Published: January 2005

A variety of spectroscopic data shows that the absorption frequencies of n→π electronic transitions progressively increase in the series of solvents, paraffin, alcohol, and water. This general effect of polar solvents on the frequency of n→π transitions is related to the characteristic change in the molecular charge distribution accompanying this type of transition. In certain cases solvation effects can be of considerable value in distinguishing between n→π and π→π electronic transitions.

Evidence is presented which indicates that the absorption bands of the ions, NO3− (32,000 cm−1), CO3= (46,000 cm−1) and CS3= (20,000 cm−1) are n→π transitions.
The Mean Amplitudes of Thermal Vibrations in Polyatomic Molecules. I. CF2=CF2 and CH2=CF2
Authors: Morino Yonezo , Kuchitsu Kôzo , Shimanouchi Takehiko
Published: January 2005

A normal coordinate treatment based on the potential function of Urey-Bradley type has been applied to CF2=CF2 and CF2=CH2 molecules by taking into account the repulsions between nonbonded atoms in addition to the valence force field. The mean-square amplitudes of thermal vibration of the atomic distances in these molecules have been calculated by the use of the normal coordinates and compared with those obtained by I. Karle and J. Karle from the electron diffraction investigation.
The ``α''-Band of Formaldehyde and the Relation Between the Ultraviolet Absorption and Fluorescence Systems
Authors: Dyne P. J.
Published: January 2005

A fine-structure analysis is presented of part of the ``α''-band of formaldehyde which lies at λ3700. It is shown that the ``α''-band and the ``A'' band of formaldehyde which lies at λ3530 have neither the upper nor the lower state in common. It is also shown that the lower state of the ``α''-band is one in which one quantum of the antisymmetric vibration ν6″ is excited. The vibrational structure of the fluorescence system is discussed in the light of these results.
Polarizability Model of Effective Charges
Authors: Matossi Frank
Published: January 2005

The effective charge dμ/dr (μ=dipole moment, r=interatomic distance) is computed for linear diatomic and triatomic molecules from an expression for μ which includes the effect of induced atomic dipoles. Agreement with observation is possible only if the atomic polarizabilities α are considered to be variable with r. α′=dα/dr is obtained in good numerical agreement with values previously derived from Raman effect data. Thus, a reasonably consistent classical picture can be established that covers dipole moments, infrared intensities, and Raman line depolarization factors.
Normal Frequencies of a Simple Cubic Lattice. III
Authors: Halford J. O.
Published: January 2005

For a simple cubic crystal, with forces resisting displacement along and perpendicular to the connecting line between closest neighbors, the secular equation for the internal motions is rigorously broken down to ultimate factors of the form ν2=νx2+α(νy2+νz2),in which νx, etc., are the normal frequencies of the one-dimensional crystal.

The corresponding frequency distribution shows no indication of the ``infinities'' found by Montroll for a model with central forces between first and second neighbors.
The Spectra and Electronic Structure of the Tetrahedral Ions MnO4−, CrO4−−, and ClO4−
Authors: Wolfsberg Max , Helmholz Lindsay
Published: January 2005

We have made use of a semiempirical treatment to calculate the energies of the molecular orbitals for the ground state and the first few excited states of permanganate, chromate, and perchlorate ions. The calculation of the excitation energies is in agreement with the qualitative features of the observed spectra, i.e., absorption in the far ultraviolet for ClO4−, two strong maxima in the visible or near ultraviolet for MnO4− and CrO4= with the chromate spectrum displaced toward higher energies. An approximate calculation of the relative f-values for the first transitions in CrO4= and MnO4− is also in agreement with experiment.

The data on the absorption spectra of permanganate ion in different crystalline fields is interpreted in terms of the symmetries of the excited states predicted by our calculations.
An Investigation of the Pyrolyses of Cumene, t-Butyl-benzene and p-Cymene, and the Relevant Bond Dissociation Energies
Authors: Leigh C. H. , Szwarc M.
Published: January 2005

The pyrolysis of cumene, p-cymene, and t-butyl-benzene has been investigated. From the experimental data the relevant bond dissociation energies and the heats of formation of the respective radicals have been computed.
Mechanism of Bond Rupture in HBr80 Following Isomeric Transition
Authors: Magee John L. , Gurnee E. F.
Published: January 2005

The work of Hamill and Young (previous paper, this journal) has demonstrated that only a fraction of HBr80(g) and DBr80(g) bonds are ruptured following isomeric transition in Br80. It is known that this transition is completely converted and from the theoretical work of Cooper it is to be expected that all Br80 atoms should be separated from chemical combination. This paper presents a brief theoretical consideration of the rupture mechanism in HBr80 in an attempt to understand why the rupture does not always occur.

Approximate potential energy curves for some of the various molecular ions HBr+z which form during the Auger shower following conversion have been constructed. It is found that there is a very great possibility that these ions all have lowest electronic states which are stable with respect to the dissociation process HBr+Z→H++Br+(Z−1),and the possibility for nonrupturing is thus qualitatively explained for the charging process, since the entire charging time is short compared with molecular collision time in the gas phase. A further necessary condition for nonrupturing (as measured by Hamill and Young) is that the ions can be discharged in collisions without rupture. This process is also considered briefly.

The complete rupture of the C–Br80 bond (in CH3Br80(g)) is also considered and explained qualitatively. In this case no stable molecular states exist for the ions and rupture occurs during the charging process.
Infrared Spectra of Some Alkyl Silanes and Siloxanes in Gaseous, Liquid, and Solid Phases
Authors: Šimon I. , McMahon H. O.
Published: January 2005

Infrared spectra of tetramethylsilane, hexamethylsiloxane, and several siloxanes with a different number of substituted ethyl groups have been studied in a wave number interval from 690 to 1400 cm−1. The spectra of methylated compounds have been obtained in gaseous, liquid, and solid phases, and splitting of some of the bands on transition from liquid to solid state has been observed. The strong infrared band observed at approximately 1075 cm−1 in the spectra of dimeric siloxanes is classified as a bond-stretching vibration of the oxygen bound to two silicons.
Note on Diffusion-Controlled Reactions
Authors: Reid A. T.
Published: January 2005

Two diffusion problems arising in an application of the Smoluchowski collision theory of reaction rates in solutions are considered. The diffusion equations are nonhomogeneous due to the introduction of an expression for the rate of production of the reacting particles. Two cases are considered: (1) The rate is constant, and (2) the rate is a linear function of the concentration. Solutions are obtained by the method of the Laplace transformation.
Equation of State Computations
Authors: Mayer Joseph E. , Careri Giorgio
Published: January 2005

A logical computation method is suggested for approximating the thermodynamic properties of a simple molecular system. In this method the thermodynamic functions of a nonequilibrium system are computed exactly. The state of the system is then varied at fixed volume and temperature so as to give a minimum Helmholtz free energy, consistent with such conditions as are imposed to permit the exact computation. The condition under which this method leads to self-consistent equations is discussed. The method is then applied in a way that is very close to the Lennard-Jones and Devonshire cell method, but with cells of variable size. The distribution within a cell is assumed to be Gaussian. The method is numerically far easier than the cell method, and apparently somewhat better.
The Infrared Absorption Spectra of Cis- and Trans−1,2-Dichlorohexafluorocyclobutane
Authors: Lacher John R. , Büchler Alfred , Park J. D.
Published: January 2005

The thermal dimerization of chlorotrifluoroethylene leads to 1,2-dichlorohexafluorocyclobutane consisting mainly of the high boiling isomer. On the other hand, the photochemical or catalytic chlorination of hexafluorocyclobutene yields a dichloride consisting mainly of the low boiling isomer. These isomers may be readily separated by fractional distillation. Dielectric constant measurements permit one to indicate that the high boiling one is cis and the low boiling is the trans. The infrared spectra in the sodium chloride region were measured and compared with the existing data on the Raman spectra.
Steric Factor and Activation Energy of the Reaction Na+C2H5Cl = NaCl+C2H5
Authors: Cvetanović R. J. , Le Roy D. J.
Published: January 2005

The reaction between atomic sodium and ethyl chloride has been studied over the range 260° to 380°C by the diffusion flame method. From the temperature coefficient of the rate constant the activation energy was found to be 10.2 kcal per mole. The maximum uncertainty in this quantity from all causes, is estimated to be ±0.5 kcal per mole. The steric factor was 1.0±0.3, based on the customary value assigned to the collision diameter.
Studies of Ionization Efficiency. Part II. The Ionization Potentials of Some Organic Molecules
Authors: Morrison J. D. , Nicholson A. J. C.
Published: January 2005

The ionization potentials of some 83 organic molecules have been measured with the mass spectrometer, using the critical slope method to interpret the ionization efficiency curves for the molecular ions. A self-consistent group of values has been obtained in which the main relationships between ionization potential and molecular structure can be clearly distinguished. The results are compared with those obtained by spectroscopic and other methods, and some regularities in the discrepancies are pointed out.
Calculation of Some Electronic Energy Levels of Sulfur Hexafluoride
Authors: Duncan A. B. F.
Published: January 2005

An attempt has been made to calculate the coefficients in LCAO molecular orbital functions of SF6, and ionization and excitation energies of this molecule, using a self-consistent field method. The lowest ionization potential computed is 20.1 ev. Excitation energies to some forbidden and allowed levels are obtained, but are too large to be considered trustworthy. The present treatment was restricted in detail to twelve electrons, six from the sp3d2 valence configuration of sulfur, and six 2pσ of fluorine. The other electrons were treated in smoothed-out core potentials of the sulfur and fluorine atoms. It is believed that unexpectedly large errors may have been introduced by the neglect of detailed interactions of these electrons, and that the molecular orbitals in which they might be put are of importance.

The present calculation is purely theoretical and only the empirical value of the S–F bond distance has been used. All necessary integrals have been evaluated, most of them for the first time, and are collected in tables.
Vibrational Intensities. II. The Use of Isotopes
Authors: Crawford Bryce
Published: January 2005

Two rules are presented which relate the intensities of vibrational fundamentals of different isotopic species. They are thus analogous to the Teller-Redlich product rule which relates frequencies. They apply to either infrared or Raman intensities. One rule permits the calculation of dipole-moment derivatives without the determination of normal coordinates. The application of the rules is illustrated.
Gaseous Detonations. V. Nonsteady Waves in CO–O2 Mixtures
Authors: Kistiakowsky G. B. , Knight Herbert T. , Malin Murray E.
Published: January 2005

The velocity of steady detonation waves in 2.5 CO–O2 mixtures containing hydrogen agrees with the calculations of the Chapman-Jouguet theory. When all sources of hydrogen atoms are eliminated from such mixtures, much hotter shock waves must be used to initiate detonation. The detonation waves in hydrogen-free mixtures are stable but nonsteady. The velocities observed by piezoelectric pressure gauges undergo violent and not very regular fluctuations similar to, but not identical with, spinning detonations. Moving film slit photographs show that these fluctuations are caused by detonation fronts developing behind the forward shock, overtaking it at irregular intervals, and decaying in their stead. Similar detonation fronts are observed in delayed initiations of explosive mixtures capable of stationary detonation, but the waves upon initiation and after a few fluctuations settle into the stationary Chapman-Jouguet regime. Photographic observations show that the detonations developing behind the shock front are initially localized near the opposite walls of the cylindrical tube, while the guage records demonstrate that the fronts of nonsteady waves are not normal to the tube axis but undergo irregular girations. The significance of these observations in terms of the rates of chemical reactions in shock fronts is discussed.
Interactions of Closed Shell Ions
Authors: Montet George L. , Keller Seymour P. , Mayer Joseph E.
Published: January 2005

Equations are written for the binding energy of a finite number of ions at fixed coordinate positions. Each ion is assumed to have a lowest nondegenerate (closed shell) configuration. In the Heitler-London approximation the state of the assembly is assumed to be: (a) a properly antisymmetrized sum of products of one-electron functions, and, (b) the constituent one-electron functions are assumed to be linear combinations of only the one-electron functions composing the ground states of the isolated ions. We use, for each ion a, its density matrix ηa(qi,qj)=Σψνa(qi)ψνa*(qj)with qi, qj the coordinates, including spin, of a single electron, and the sum including all filled one-electron functions, ψνa, of the ground state of ion a. The binding energy, consistent with the two assumptions (a) and (b) is then derived and found to be expressible in a reasonably compact exact form, using this density matrix. By making use of an approximate expression for the density matrix the integrations occurring in the energy expression are tractable.
A Detailed Formulation of Kinetic Processes from the Point of View of the Activated Complex
Authors: Benson Sidney W.
Published: January 2005

By combining Slater's classical treatment for the adiabatic decomposition of an unstable molecule with the Lindemann mechanism for collisional activation it is possible to make a uniform and consistent treatment of kinetic processes of all orders. The high pressure rate constants may then be represented by kobs=α·〈ν̄〉·K#·exp(−E*/kT),where 〈ν̄〉 is a root mean square average of the ``n'' normal modes of vibration of the activated complex, E* is the minimum energy required for reaction, α is a ``transmission coefficient'' which is unity for unimolecular processes and between ½ and 1 for higher order reactions, and K# can be interpreted in terms of an entropy of activation. A more complicated expression is obtained for lower pressures in the case of unimolecular reactions.

The theory is sufficiently detailed to allow predictions on the relation of molecular structure to the pressure region in which collisional activation becomes a limiting rate factor for unimolecular reactions. Similarly predictions may be made concerning the nature of recombination processes and their pressure and temperature dependence. It is shown that recombination processes will have a negative temperature coefficient and in addition the mean life of the activated complex will vary inversely with some power of the strength of the bond being formed. As a result of this, recombination will be more efficient in photochemical or, more generally, low temperature chain reactions than in pyrolytic reactions and consequently chain lengths will be longer in the latter.
Polarization in Electrolytic Solutions. Part II. Measurements
Authors: Jaffé George , Rider John A.
Published: January 2005

The object of the present investigation was to supply material for testing the theory given in the preceding paper. Therefore, the ``polarization capacitance'' and the ``excess resistance'' of electrolytic solutions were measured over wide ranges of frequency and concentration, and for different plate distances. Also the material of the electrodes was modified, and some temperature coefficients were measured.

After the general introduction (Sec. I) the method used is described in Sec. II; it is essentially a Jones bridge method, with suitable modifications. In Sec. III the cell is described. Section IV deals with the general scope of the measurements and with the procedure in performing them. The range of frequencies was, as a rule, from 18 to 18,000 cps; the molar concentrations varied from 10−4 to 10−2 g-eq/liter. In addition to solutions of KCl and MgSo4, conductance water was investigated. Electrodes of Al, Ni, Au, and Pt were used. In Sec. V a survey of the results, independent of any theory is given. Finally, in Sec. VI the results are compared with those of the theory, by analyzing completely several series of measurements referring to water and KCl solutions. A quantitative agreement can be realized, if (a) the effect of the solvent is taken into account, and if (b) it is admitted that there are, in ``conductance water,'' ions of considerably (about 100 times) lower mobility than the ordinary electrolytic ions. With these assumptions the concentrations and the mobilities of the ions can be determined. Finally, the rate constants which are characteristic of the presented theory can be evaluated.
Temperature Dependence of the Viscosity of Associated Liquids
Authors: Litovitz Theodore A.
Published: January 2005

By assuming that the activation energy for flow in associated liquids is proportional to the inverse square of the absolute temperature, an empirical expression for the viscosity is obtained, which fits the data well. An empirical expression for the activation energy of mixtures of associated liquids is also proposed.
Transition Probabilities III. Dipole Velocity Computations for C2 and N2+. The Question of Degree of Hybridization
Authors: Shull Harrison
Published: January 2005

Previous computations of transition probabilities for hydrogen using the dipole velocity operator are here extended to the diatomic molecules C2 and N2+ with particular reference to the former. Whereas previous calculations have shown the dipole length method to be relatively insensitive to the effective nuclear charge, the present computations show great sensitivity of the dipole velocity method to the ratio of the effective Z of the bonding orbital to that of the antibonding orbital. The results are less sensitive to the absolute magnitude of the Z's. The results are discussed with respect to reasonable assignments for the degree of s and pσ-hybridization of the respective orbitals and with respect to reasonable choices for the effective Z values. It is concluded that the degree of hybridization is most probably considerably higher than previously estimated. The dipole velocity method is a promising one for further development.
Dielectric Dispersion in Materials Having a Distribution of Relaxation Times
Authors: Macdonald J. Ross
Published: January 2005

On the basis of considerable experimental evidence, a particular form for the dielectric loss factor, ε″, is assumed to hold for many materials exhibiting a distribution of relaxation times. The dielectric constant, ε′, corresponding to the assumed form of ε″ is then computed by means of the Kronig-Kramers relations and tabulated as a function of log frequency and of the distribution function half-width parameter, α. Using these results, experimental ε′ and ε″ curves can be easily tested for mutual consistency and can be fitted individually. In conclusion, a brief discussion of other methods of dealing with the many-relaxation-time dispersion problem is given.
The Time Dependence of the Potential in Electrode Reactions
Authors: Busing William R. , Kauzmann Walter
Published: January 2005

Changes in the potential of an electrode with time during electrolysis at constant current are controlled by two factors: (1) the charging and discharging of the double layer capacitor (causing ``capacitive'' changes) and (2) alteration of the composition and other properties of the electrode and the adjacent solution (causing ``non-capacitive'' changes). Equations are derived for the capacitive changes in potential, assuming that the current-voltage relation across the electrode surface is given by Tafel's law.

An experimental study has been made of the potential accompanying the evolution of oxygen from 1N KOH at a platinum anode. When the current was held constant the potential increased slowly with time. When the current was interrupted the potential rapidly decreased, the decay being faster the higher the initial potential. The decay generally followed the above-mentioned equations for a capacitive change in potential, thus making it possible to evaluate effective Tafel constants of the electrode at various stages during electrolysis. These constants were found to depend very much on the time and on the current density, indicating that the electrode surface undergoes important changes. The behavior of the potential on increasing or decreasing the current has also been studied. This too reflects changes in the electrode surface.

Most of these variations can be understood if it is assumed that the electrode surface is non-uniform, the current being carried by relatively few active centers. The non-uniformity is similar to that encountered in ordinary catalysis, but is more complex since the same centers may not be active at all potentials. A simple graphical method of dealing with such a non-uniformity has been developed. It is based on the assumption that Tafel's law is valid for each microscopic element of the surface, and allows the Tafel constants to vary from one element to another. The electrode as a whole may then no longer obey Tafel's law. The concepts of poisoning and promotion, so important in catalysis, are readily incorporated and explain most of the observed results in a direct manner.
Statistical Theory of Networks of Non-Gaussian Flexible Chains
Authors: Wang Ming Chen , Guth Eugene
Published: January 2005

The aim of this paper is to develop a selfconsistent theory of rubber-like materials consisting of networks of non-Gaussian chain molecules. Three kinds of series developments are derived for the distribution function of perfectly flexible single chains from the Fourier integral solution of Rayleigh; namely, (1) long chains with actual extension much less than the maximum extension, (2) long chains with actual extension comparable to the maximum extension, and (3) short chains. In the non-Gaussian network theory, the leading term of the series (2) is used as the starting point for the individual chains of the network. Calculations are made for the case where the free junctions are moving with no restriction, and for the case where the free junctions are assumed to be at their most probable positions. The final expressions of the elastic energy for the two cases are compared, and it is shown that the percentage difference of the two expressions is of the order 1/n (n being the average number of links per chain), which is negligible for sufficiently large n. Finally an expression of the elastic energy is obtained with the assumption that all junctions are fixed and is shown to be, in general, a function of three strain invariants. The interdependence of the coefficients of the invariants is shown. Comparison of theory and experiment is given. Because of the interdependence of the coefficients only part of the observed deviations from Gaussian theory can be explained by our molecular theory. The remaining discrepancies must be ascribed to van der Waals forces. This should show up in the (not yet investigated) temperature dependence of these discrepancies.