bluuebunny/crossref_metadata_2025 huggingface dataset:
Note on a Nitrogen Molecule Calculation
Authors: Wolfsberg Max
Published: January 2005

Recent calculations of the binding energy of the nitrogen molecule carried out by Kopineck are examined by means of molecular orbital calculations. The Hellmann-Kopineck procedure of omitting certain permutations in a valence bond procedure is investigated. It is concluded that the Kopineck calculation should not be used as an argument favoring the 9.8 ev value for the binding energy (D00) of the nitrogen molecule.
Applications of the Free Volume Theory of Binary Mixtures
Authors: Salsburg Zevi W. , Kirkwood John G.
Published: January 2005

Detailed calculations for the free volume theory of binary mixtures are presented and compared with experimental results. It is found that this theory predicts heats of mixing and volumes of mixing larger in magnitude than the observed values and excess entropies of mixing which are smaller than the experimental results. The theory, however, does predict a volume contraction, a negative excess entropy of mixing and a positive heat of mixing for solutions of carbon tetrachloride and neopentane in qualitative agreement with recent observations.
Diffusion and Thermal Diffusion of Isotopic Gases
Authors: Holleran Eugene M.
Published: January 2005

The thermal diffusion ratio, RT, for argon and neon isotopes is known to be a linear function of lnT over a considerable temperature range. It is shown that d lnD/d lnT must also be approximately linear in lnT, and that the diffusion coefficient, D, should therefore obey an empirical equation of the form D=αT(β+γlnT),where α, β, γ are constants. Considerable latitude is possible in the values of these constants which can reproduce the diffusion data available at the present time. Satisfactory values of β and γ can be found from thermal diffusion data. Except for the factor α, D(T) can thus be calculated from RT(T). It is also possible to calculate the thermal diffusion ratio as a function of temperature from measurements of the diffusion coefficient, but completely reliable results require more extensive diffusion data than is now available.
Kinetics of the Fast Reaction between Nitrogen Dioxide and Fluorine
Authors: Perrine Richard L. , Johnston Harold S.
Published: January 2005

The rate of the reaction between nitrogen dioxide and fluorine to form nitryl fluoride has been measured at 27.7, 50.4, and 70.2°. Light absorption by nitrogen dioxide was used to follow the reaction. By using a 22-liter Pyrex flask and by going to low concentrations of reactants, between 0.5 and 20×10−8 moles cc−1, the rate of this fast reaction was reduced to a convenient value. The rate was found to be first order in each reactant, and it showed no dependence on nitryl fluoride. The proposed mechanism is NO2+F2→ lim k1NO2F+F (slow),NO2+F+M→ lim k2NO2F+M (fast).The empirical second order rate constant is k1, that of an elementary bimolecular reaction. If the rate constant is written as Ae−E/RT then A is 1.6×1012 cc moles−1 sec−1 and E is 10.5 kcal.
The Entropy of Aqueous Oxy-Anions
Authors: Connick Robert E. , Powell Richard E.
Published: January 2005

The entropies of oxy-anions of the formula XOn−Z are well represented by the equation S̄20=43.5–46.5 (Z−0.28n). Species containing hydroxyl groups are included by disregarding the hydroxyl groups in counting the number of oxygens n. The form of the equation is partially justified on the basis of a model. Binuclear ions are treated by calculating for the two halves separately and making a correction for the entropy of dimerization.
Lifetime of the 3Σu+ State of Nitrogen
Authors: Muschlitz E. E. , Goodman L.
Published: January 2005

A new method is proposed for the measurement of the ``free space'' lifetimes of particles in metastable states. An average lifetime of 2.3×10−4 second is obtained for nitrogen molecules in the A 3Σu+ state. The method also gives the collision diameter for collisions between metastable and normal N2 molecules as 3.8A. Measurements of the appearance potential for molecules in the A state are presented.
Nuclear Magnetic Resonance Multiplets in Liquids
Authors: Gutowsky H. S. , McCall D. W. , Slichter C. P.
Published: January 2005

Multiple magnetic resonance lines have been observed for H1, F19, and P31 nuclei in compounds such as PH3, PF3, F2PO(OH), and BrF5, in the liquid state. The multiplets consisted of two to seven equally spaced narrow components, symmetrically placed about a central frequency, and with splittings from 0.02 to 0.8 gauss. These multiplets arise from a new variety of interaction among the nuclear moments in a molecule. Resonance lines were found to be multiple either when a nucleus interacted with a different species of nucleus or when there was interaction between nuclei of the same species with resonance frequencies separated by a chemical shift. No compounds exhibited multiplets attributable to interactions among structurally equivalent nuclei. Nor were multiplets caused by nuclei whose electric quadrupole moments were coupled to a direction fixed in the molecule.

The number and relative intensities of the components of a multiplet were determined by the number and statistical weights of the various nuclear spin orientations of the nuclei causing the splitting. In a given molecule, the ratio of the multiplet splittings of the two different resonance lines was inversely proportional to the ratio of the gyromagnetic ratios of the interacting nuclei. The splittings were independent of applied magnetic field at 4180 and 6365 gauss; they were independent of temperature over ranges from 55°C to −130°C. In PF5, the one gas examined, the splitting of the doublet fluorine resonance was the same in the gas and liquid phases; also, the doublet was demonstrated to arise from coupling with the phosphorus nucleus, rather than from a chemical shift between the resonances from the apex and meridian fluorines in the bipyramidal structure, as proposed earlier.

All of the above characteristics are accounted for theoretically by assuming the magnetic nuclei interact via magnetic fields inside the molecule. The qualitative aspects are predicted by coupling of the form A12μ1·μ2 between the nuclear moments μ1 and μ2. The coupling constant A12 depends upon the detailed mechanism, which must involve the molecular electrons. Second-order perturbation theory was used to calculate the relative magnitudes of coupling via the electron orbital and the electron spin magnetic moments. The electron spin mechanism was found to give splittings ten to twenty times the orbital. Approximate calculation of the electron spin mechanism in several simpler cases gave good agreement with experiment. The influence upon the splittings of electric quadrupole coupling and spin-lattice relaxation was considered and is discussed briefly.
Field Emission from Nickel Surfaces
Authors: Gomer Robert
Published: January 2005

An account of field emission experiments on clean and contaminated nickel surfaces is presented. It is concluded that the equilibrium shapes of Ni single crystals are close to spheroidal with flat regions at low index directions. Evidence for the formation of surface phases of carbon, silicon, and oxygen on Ni is presented. A method for studying the diffusion of Si in Ni is described. Chemisorption of O2 on Ni is briefly described. A method for studying grain boundary migration is given.
The Emission Spectrum of OH from 1.4 to 1.7 μ
Authors: Benedict W. S. , Plyler Earle K. , Humphreys C. J.
Published: January 2005

The first overtone region of OH has been measured in emission from an oxyacetylene flame in the region of 1.6μ. The rotational structure in the P branch of the 2→0 band, from K=4 through K=19, of the 3→1 band, from K=4 through K=15, and of the 4→2 band, from K=4 through K=10, has been identified. For each K value there are four lines. These are resolved for values of K>7. From the intensities of the lines, a vibration-rotation temperature has been determined. For the mixture of gases burned in this work with small flames, it was found that the ``temperature'' was 2600±100°K.
On the Existence of a Hidden Transition in Biphenyl
Authors: Wenzel Anneliese
Published: January 2005

The 2500A transition of biphenyl is interpreted as a superposition of a strong and a weak transition corresponding to the 2100A and 2600A transitions of benzene. Evidence for the location of the weak transition near 2700A is given. The spectra of the m- and p-polyphenyls are interpreted similarly to the biphenyl spectrum. Bending has about the same effect on the intensity and the position of the first strong transition of polyphenyls with m- and p-structure as it has on the corresponding transition of cata-condensed hydrocarbons.
A (K+2)nd Order Formula for Asymmetry Doublets in Rotational Spectra
Authors: Kivelson Daniel
Published: January 2005

Higher order perturbation theory is used to derive a formula for K type doubling of the energy levels of a rigid asymmetric rotor. The result is ΔW=ΔW0[1+{A+BJ(J+1)+CJ2(J+1)2}β2],where ΔW0 is the Wang2 Kth-order result for the splitting of the energy levels, β is an asymmetry parameter, and A, B, C are independent of the structural parameters and of the quantum number J. A, B, C, have been tabulated for all values of K up to K=14.
Theory of the Stark Effect of Asymmetric Rotator with Hyperfine Structure
Authors: Mizushima Masataka
Published: January 2005

The Stark effect of asymmetric rotator is calculated, including the effect of hyperfine structure, for weak and stronger field cases. The result includes the Stark effect of symmetric rotator and linear rotator as special cases.
On the Presence of Free Sodium in Sodium Chloride Crystals Containing Color Centers and Color Center Precursors
Authors: Hacskaylo Michael , Otterson Dumas
Published: January 2005

The presence of ``free sodium'' in NaCl crystals containing color centers and color center precursors, as indicated by the results of Hacskaylo and Groetzinger, has been confirmed by the use of a more precise method of chemical analysis. The present measurements were carried out by dissolving the crystals in question in a solution containing an indicator, p-nitrophenol, and determining the resulting change in the optical density of the solution at a wavelength of 415 mμ. The ratio of the number of ``free sodium'' atoms to vacancy pairs was about one for crystals which had been subjected to electrolysis and about one-tenth for crystals irradiated with x-rays, independent of whether these crystals had been first subjected to electrolysis.
The Effect of Pressure on Diffusion in Water and in Sulfate Solutions
Authors: Cuddeback R. B. , Koeller R. C. , Drickamer H. G.
Published: January 2005

Diffusion coefficients are presented as a function of pressure to 10 000 atmospheres for the following systems: THO−H2O  0∘−25∘−50∘;0.1 N H2S35O4  −0.1 N H2SO4    0∘−5∘−25∘−50∘;0.1 N Na2S35O4 −0.1 N Na2SO4   0∘−25∘−50∘;1.0 N Na2S35O4 −1.0 N Na2SO4   0∘−25∘−50∘;0.1 N K2S35O4  −0.1 N K2SO4    0∘−25∘−50∘.The results are interpreted in terms of the activation volume and the tetrahedrally coordinated structure of water. It is found that pressure tends to break down the structure, and in certain regions an increase in diffusion coefficient with pressure is noted.

In the salt solutions the water structure is controlling with some added effects due to solvation and ionic interaction.
Adiabatic Correlation Rules for Reactions Involving Polyatomic Intermediate Complexes and their Application to the Formation of OH(2Σ+) in the H2–O2 Flame
Authors: Shuler Kurt E.
Published: January 2005

Adiabatic orbital and spin correlation rules applicable to a detailed study of elementary chemical reactions involving nonlinear polyatomic intermediate complexes have been formulated and are presented together with some pertinent correlation tables. These correlation rules and tables permit the determination of the adiabatically allowed term manifold of reaction products from the states of the separated reactants without reference to their detailed electronic configurations. The formulation presented here utilizes group theoretical arguments relating to the symmetry properties of the reactants, the intermediate reaction complex, and the products and is based principally upon the results obtained previously by Mulliken for the resolution of species into those of point groups of lower symmetry. The effects of the change of the (geometrical) configuration of the intermediate reaction complex during reaction and of the electronic-vibrational coupling on these correlations have been considered in detail. It is concluded that strict orbital electronic correlation rules are operative only for reactions where neither the reactants nor the products are polyatomic. For reactions involving polyatomic reactants and/or products, the vibrational-electronic coupling weakens the simple orbital electronic correlations so that detailed vibronic correlations will be necessary. The spin correlation rules, however, are not affected by these interactions and are identical with those given by Wigner and Witmer for atomic and diatomic systems.

These correlation rules are then applied to a study of the reactions H+O2→[HO2]→OH*+OO+H2→[OH2]→OH*+H which may be of importance in the production of electronically excited OH[OH(2Σ+)] in the hydrogen-oxygen flame. The mechanism of these reactions is investigated with special reference to the predissociating OH(2Σ−) state discussed recently by Gaydon and Wolfhard. It is suggested that the interaction of and the consequent radiationless transition between HO2 intermediate reaction complexes is primarily responsible for the formation of OH(2Σ+) in its observed vibrational nonequilibrium distribution with the specific enhancement of the levels v′=2 and 3.

The adiabatic correlations for the special case of association (and dissociation) reactions involving linear polyatomic intermediate complexes and products are considered briefly in the Appendix. It is concluded that vibronic correlations are required for the determination of the product term manifold for these reactions.
The Infrared Spectra of Three Solid Phases of Methyl Ammonium Chloride
Authors: Waldron R. D.
Published: January 2005

Infrared spectra are presented for three crystalline phases of methyl ammonium chloride which occur at different temperatures. The spectrum of the high temperature structure reveals apparently degenerate vibrational frequencies for the perpendicular bands indicating little or no distortion from a threefold symmetry axis for the methyl ammonium ion. The intermediate and low temperature structures show increasing distortion of the cation as evidenced by increasing splitting of the degenerate absorption bands amounting to about 10–40 cm−1 in the low temperature form, where the torsional vibration about the C–N axis becomes infrared active.

An assignment of frequencies is made in satisfactory agreement with a valence-force normal coordinate treatment and the isotope product rule. A simplified calculation of the height of the potential barrier to internal rotation was made yielding the approximate value, V0=1670 cm−1.
A Semi-Empirical Theory of the Electronic Spectra and Electronic Structure of Complex Unsaturated Molecules. II
Authors: Pariser Rudolph , Parr Robert G.
Published: January 2005

The theory of electronic spectra and electronic structure, the elucidation of which was begun in the first paper of this series, is further developed and applied to ethylene, butadiene, benzene, pyridine, pyrimidine, pyrazine, and s-triazine.

A realistic and consistent LCAO-MO π-electron theory should allow the σ-electrons to adjust themselves to the instantaneous positions of the mobile π-electrons. This is accomplished in the theory by assignment of empirical values to the Coulomb electronic repulsion integrals and Coulomb penetration integrals which enter the formulas, these values being obtained in a prescribed way from valence state ionization potentials and electron affinities of atoms. Use of the empirical values in the molecular orbital theory reduces the magnitude of computed singlet-triplet splittings and the effects of configuration interaction without complicating the mathematics. From the valence-bond point of view, ionic structures may be said to be enhanced.

The applications to hydrocarbons and heteromolecules which are considered show that the theory can correlate known π-electron spectral wavelengths and intensities very successfully, which, together with the simple structure of the theory, signals that manifold applications of the theory are in order elsewhere.
Application of the Cell Method to the Statistical Thermodynamics of Solutions. II. Experimental
Authors: Mathot V. , Desmyter A.
Published: January 2005

In connection with the theory of solutions proposed by Prigogine and Mathot [J. Chem. Phys. 20, 49 (1952)], total vapor pressures and volume changes on mixing have been measured for the systems: CCl4–C(Me)4  IC6H12–C(Me)4  IIC6H6–C(Me)4  III.Volume changes only for the systems: CCl(Me)3–CCl4  IVCCl2(Me)2–CCl4  VCCl3(Me)–CCl4  VIC(Me)3OH–CCl4  VII.

For the first three systems I, II, and III, one observes a positive excess free energy (positive deviations to the Raoult law) together with a negative excess volume (contraction on mixing), whereas for the last four IV, V, VI, and VII there is a gradual passage from negative (IV) to positive (VII) excess volume. These results are discussed in terms of the molecular interactions AA, BB, and AB. Reasonable agreement is observed between Prigogine and Mathot's theory and experiment.
The Vibration Frequencies of the Halogenated Methanes and the Substitution Product Rule
Authors: Pitzer Kenneth S. , Gelles Edward
Published: January 2005

The extension of the Teller-Redlich product rule to the substitution of different atoms or groups, which was previously applied to the methyl benzenes, is here applied to the halogenated methanes. The rule is found to hold accurately enough to be useful in assigning fundamental frequencies or in computing unobserved fundamentals.
The Bipyramidal XY5 Molecular Model. Part I. Classical Vibration Problem
Authors: Ziomek Joseph S. , Mast Cecil B.
Published: January 2005

Symmetry coordinates are set up from the standpoint of group theory for describing the normal modes of oscillation of the XY5 molecular model in such a manner that maximum factorization of the secular determinant is accomplished. The cubic and quartic portions of the anharmonic potential function are derived, and the components of vibrational angular momentum are set down. The complete valence-type potential function is discussed. Explicit relations are derived between the force constants occurring in the secular determinant and the physical valence force constants.
Some Optical Properties of Potassium Iodide-Thallium Phosphors
Authors: Yuster Philip H. , Delbecq Charles J.
Published: January 2005

The absorption spectra of potassium iodide-thallium phosphors have been studied at both liquid nitrogen and liquid helium temperatures. Eight absorption bands have been observed which are due to the presence of thallium. The maximum absorption coefficients of four of these bands appear to vary linearly, while the other four appear to vary with the square of the thallium concentration. The origin of these bands is discussed in terms of an extension of the model proposed by Seitz.
A Study of Three-Center Integrals Useful in Molecular Quantum Mechanics
Authors: Barker Roland S. , Eyring Henry
Published: January 2005

An integrated equation for the three-center nuclear attraction integral has been formulated in a general way for Slater-type atomic s orbitals arising from any integral principle quantum number. No restrictions are placed on the effective nuclear charges or the interatomic distances. The formulation is expressed linearly in terms of certain auxiliary functions which are discussed in detail. Numerical values of some of the auxiliary functions for the triatomic hydrogen molecule are cited as examples of this exact formulation. An alternative approximate formulation is also given.
Substituted Methanes. XIV. Vibrational Spectra, Potential Constants, and Calculated Thermodynamic Properties of Bromochloromethane
Authors: Weber Alfons , Meister Arnold G. , Cleveland Forrest F.
Published: January 2005

Raman displacements, semiquantitative relative intensities, quantitative depolarization factors, and wave numbers for the infrared bands in the region 400–3000 cm−1 have been obtained for CH2BrCl. A reasonable set of potential constants has been determined using Wilson's FG matrix method. The thermodynamic properties—heat content, free energy, entropy, and heat capacity—have been calculated from the spectroscopic and molecular structure data for 11 temperatures from 100 to 1000°K.
Statistical Thermodynamics of Rubber Elasticity
Authors: James Hubert M. , Guth Eugene
Published: January 2005

The basic concepts and procedures underlying the theory of rubber elasticity are analyzed. The arguments advanced by Wall and Flory against the network theory of the authors are shown to be without foundation. The alternative theory which they advocate, and which is rather widely used, is criticized on two grounds: (a) it assumes a distribution of chain extensions that does not vary with network extension in the way the actual distribution functions can be shown to vary, and (b) the methods used to compute the numbers of network configurations from the distributions of chain extensions are invalid, except in the most trivial cases. The concept of ``interval dilation entropy'' is discussed and is shown to lack any physical basis. It is concluded that all the methods of calculation that lead to logarithmic terms in the network configuration entropy are incorrect, and that these terms, which affect the theory of swelling, should be discarded.
Thermodynamic Functions from Mayer's Theory of Ionic Solutions. II. The Stoichiometric Mean Ionic Molar Activity Coefficient
Authors: Poirier Jacques C.
Published: January 2005

The formula for the stoichiometric mean ionic molar activity coefficient of strong electrolytes in aqueous solution at 25°C arising from Mayer's theory is compared with published experimental data. The agreement is good for sodium chloride to a concentration of about 0.4 molar; calcium chloride to a concentration of about 0.07 molar; zinc sulfate to a concentration of about 0.01 molar; and lanthanum chloride to a concentration of about 0.017 molar. Tables facilitating the computations and practical methods for the determination of the parameter of closest interionic approach and of the activity coefficient are given.
An Application of Perturbation Theory to the F and G Matrix Method of Calculating Molecular Vibration Frequencies
Authors: Higgs P. W.
Published: January 2005

The F and G matrix form of the secular equation for molecular vibrations may be split into two approximate equations, of which one has as its roots the high frequencies (corresponding to relatively rigid bonds, etc.), the other the low frequencies (corresponding to relatively weak bonds, etc.). With the aid of the eigenvectors of these two equations, the exact equation is transformed into a form which yields the corrections to the approximate frequencies by a straightforward application of perturbation theory. The use of the correction terms so derived and the convergence of the perturbation series are illustrated by a discussion of the totally symmetric modes of ethylene.
Ultraviolet Absorption Spectra of Derivatives of Symmetric Triazine. I. Amino Triazines
Authors: Hirt Robert C. , Salley D. J.
Published: January 2005

The near ultraviolet solution spectra of twenty one mono-, di-, and triamino derivatives of symmetric triazine are reported. The addition of amino groups to the s-triazine ring introduces electrons which can interact with those of the ring, with resultant changes in the intensity and position of the absorption bands. The spectra of mono-, di-, triamino-s-triazine may be arranged in a Platt sequence along with that of trichloro-s-triazine and that expected for s-triazine.
The Separation of the Rotational Coordinates from the N-Particle Schroedinger Equation. II
Authors: Curtiss C. F.
Published: January 2005

Group theoretical methods are used to separate the rotational coordinates from the N-particle Schroedinger equation and obtain a set of equations which are particularly applicable to the study of collisions involving two sets of particles or two molecules. The coordinates used to describe the configuration of the N particles in a center of gravity coordinate system are those describing the orientation of the system as a whole, the relative orientation and separation of the two molecules, and the internal configuration of each of the molecules. Coupled differential equations involving only the coordinates describing the internal configuration and separation of the molecules are obtained. As a special case the equations are applied to a system consisting of two diatomic molecules.
A Molecular Theory of Stress Relaxation in Polymeric Media
Authors: Scott K. W. , Stein R. S.
Published: January 2005

The application of the kinetic theory of rubber elasticity to the description of the relaxation of cross-linked networks is only permissible in cases where the rate determining process is slow compared to the rate of diffusion of the polymer chains. Relaxation resulting from chemical reactions causing breaking of network crosslinks and formation of new crosslinks is a process of this type.

In this paper, a differential equation is proposed which describes the rate of relaxation in terms of the rates of the molecular processes. A simplified solution of this equation is given, and the consequences of the solution are discussed.
The Determination of the Fluorescence Lifetimes of Dissolved Substances by a Phase Shift Method
Authors: Bailey E. A. , Rollefson G. K.
Published: January 2005

The lifetimes of fluorescent substances are determined by exciting the fluorescence with light modulated at a high frequency and measuring the difference in phase between the exciting light and the resulting fluorescence. The exciting light is modulated by an ultrasonic standing wave in a liquid which causes the latter to act as an intermittent diffraction grating. Photomultiplier tubes are used to pick up the exciting and fluorescent light. Tuned circuits are used to isolate a single harmonic of the signal from the phototubes and the phase shift determined by comparison with a calibrated phase shifting circuit. The phase angle φ is related to the lifetime by tanφ=ωτ. In which ω is 2π times the frequency of modulation and τ is the lifetime of the excited state. The data show that lifetimes can be determined with a precision of 1 to 2×10−10 second.

The lifetimes of acridone in neutral solution (saturated to 10 percent saturated) and quinine sulfate (4×10−6 to 4×10−5M) in 0.01 M nitric acid are independent of the concentration. The values found are acridone 1.59±0.01×10−8 second, and quinine sulfate 2.28×0.02×10−8 second. The lifetime of fluorescein in 0.005M potassium hydroxide increases with concentration over the range 10−6 to 5×10−4M. This fact can be explained by assuming that some of the fluorescent light is absorbed and re-emitted. The lifetime of fluorescein extrapolated to zero concentration is 4.5±0.1×10−9 second.
The Infrared Spectra of HCl, DCl, HBr, and NH3 in the Region from 40 to 140 Microns
Authors: Hansler R. L. , Oetjen R. A.
Published: January 2005

The pure rotation spectra of HCl, DCl, HBr, and NH3 in the region from 40 to 140 microns as measured with an automatic-recording grating spectrometer are presented in tabular and graphical form. A photograph of a recorded spectrogram provides an indication of the quality of the data. A comparison of the experimental results with figures based on accepted values of the molecular constants shows substantial agreement.
Diffusion in the System CH4—TCH3 to 300 Atmospheres Pressure
Authors: Jeffries Q. R. , Drickamer H. G.
Published: January 2005

Diffusion coefficients have been measured in the system CH4—TCH3 to 300 atmospheres pressure. In general the results are consistent with the predictions of Enskog's dense gas theory. At the highest densities, the diffusion coefficients are lower than the theory predicts. This is expected as, at these densities, unevaluated terms in the dense gas correction become significant.
The Effect of Pressure on Diffusion in the System CCl4–SnI4
Authors: Doane E. P. , Drickamer H. G.
Published: January 2005

Diffusion coefficients have been measured for the system CCl4–SnI4 using I131 tagged SnI4. Isotherms were obtained at 50°C and 75°C to 2000 atmospheres pressure. The results are interpreted in terms of the activation enthalpy, entropy, and volume. Below 1000 atmospheres the diffusion mechanism differs only slightly from that in effect at atmospheric pressure. At higher pressures orientational effects are observed.
Negative Cluster Concentrations
Authors: Kilpatrick John E.
Published: January 2005

The number of clusters of a given size in a real gas frequently turns out to be negative. Nevertheless a model based upon the cluster idea leads to the correct virial expansion. This model is tested further by a direct calculation of the gas imperfection entropy from the possibly complex entropy of formation and of mixing of these clusters.
A Model of Metal-Ammonia Solutions, with Reference to Electron Spin Resonance Experiments
Authors: Kaplan J. , Kittel C.
Published: January 2005

An explanation is given of the extreme sharpness of the electron spin resonance line in solutions of potassium in liquid ammonia, as reported by Hutchison and Pastor. Motional narrowing of the width associated with dipolar and hyperfine interactions results from the rotation and diffusion of ammonia molecules. The model of metal-ammonia solutions used in the calculation is shown to be supported by thermal, magnetic, volumetric, and conductivity data. The model pictures the electrons removed from the potassium atoms as located in cavities in the liquid, the cavities having approximately the volume of two to four ammonia molecules. The electrons in the cavities are in equilibrium with respect to the reaction 2e⇆e2+0.2 ev, where e2 represents two electrons in a singlet state in one cavity. The electrons in cavities may perhaps be thought of as in molecular orbital states on the protons of the adjacent NH3 molecules.
The Interaction with Molecular Rotation of the Nuclear Electric Quadrupole Moments of Two Nuclei Having Spins 3/2
Authors: Robinson G. Wilse , Cornwell C. D.
Published: January 2005

The theory of nuclear electric quadrupole effects in molecules is applied to the particular case of a molecule containing two nuclei each having spin 3/2. The matrix elements of the first-order Hamiltonian of interaction between the nuclear electric quadrupole moments and the molecular rotational angular momentum are determined in the I1I2IJFMF representation. In one particular case the secular equations may be solved explicitly for the energy levels in terms of J, and the general solutions as well as their numerical values for J≤12 are given. For the other cases, higher-order secular equations must be solved, and to facilitate this, coefficients in the expanded secular determinants have been computed. The method for obtaining relative line strengths for transitions is described, and numerical values of these are given for some transitions. Applications to the analysis of rotational spectra are also discussed.
Empirical Considerations of Entropy. III. A Structural Approach to the Entropies of Aqueous Organic Solutes and Complex Ions
Authors: Cobble James W.
Published: January 2005

A method for estimating the entropy of complex aqueous organic solutes and related species has been developed by a structural extension of a method of Powell and Latimer for simple solutes. The agreement between calculated and observed values is, in general, good, although systematic deviations begin to occur for very complicated and large solutes. The method is extended to the calculation of the entropies of charged organo-metallic complex ions with good success, and possible applications to systems of biological interest are indicated.

Subsequent to the development of the general method for estimating the entropies of aqueous solutes, an empirical equation is also given for calculating gaseous entropies of both inorganic (ionic) and organic molecules from their structures.
Vibrational Spectra of Fluorinated Aromatics. VI. Fluorobenzene
Authors: Smith D. C. , Ferguson E. E. , Hudson R. L. , Nielsen J. Rud
Published: January 2005

The infrared absorption spectra of gaseous and liquid fluorobenzene have been obtained in the regions 2–22μ and 2–38μ, respectively, with the aid of LiF, NaCl, KBr, and KRS−5 prisms. The Raman spectrum of the liquid phase has been photographed with a three-prism glass spectrograph of linear dispersion 15 A/mm at 4358A. A complete assignment of fundamental vibration frequencies is given, and the spectra are interpreted in detail.
Hindered Rotation Involving Two Asymmetric Groups
Authors: Burkhard Donald G.
Published: January 2005

The wave equation is derived for two partially asymmetric tops rotating about a common axis and subject to an arbitrary hindering potential. Matrix elements of the Hamiltonian are evaluated using the hindered-rotation wave functions derived by Koehler and Dennison on the basis of a simplified model.

Evaluation of matrix elements involving the Eulerian polar angle is carried out by obtaining and making use of the factorizations of the symmetric-top wave equation.
Free-Electron Network Model for Conjugated Systems. III. A Demonstration Model Showing Bond Order and ``Free Valence'' in Conjugated Hydrocarbons
Authors: Platt John R.
Published: January 2005

A mechanical model of a conjugated hydrocarbon has been constructed, based on the free-electron density theorems of Ruedenberg and Scherr. Stiff steel music wires strung on dowels above a baseboard follow the carbon skeleton. When the height of the wire above the board at each atomic position is fixed to constant theoretical values, and when simple boundary conditions are met at branch points and terminal atoms, then the height in the centers of bonds is a direct measure of electron density and bond order and ``free valence.'' The measured heights may be used to predict bond lengths and positions of substitution, even for large or unsymmetrical molecules which are hard to handle theoretically. The model should be especially useful for demonstrations and for giving students a feeling for electronic behavior in conjugated systems.
The Diffusion of Iodine in Carbon Tetrachloride under Pressure
Authors: Haycock E. W. , Alder B. J. , Hildebrand J. H.
Published: January 2005

The diffusion of iodine in carbon tetrachloride was studied over a temperature range from 10 to 55°C and a pressure range from 1 to 200 atmospheres by the capillary cell technique and by an optical comparison method. The results of the two methods agree well, and the data can be represented by an activation energy at constant pressure of 3300 cal/mole compared to an activation energy at constant volume of 1070 cal/mole.
Nuclear Quadrupole Effects and Electronic Structure of Molecules in the Solid State
Authors: Townes C. H. , Dailey B. P.
Published: January 2005

Measured nuclear quadrupole effects in solids are discussed, compared with nuclear quadrupole coupling in gases, and correlated to some extent with molecular structure in the solid state. The iodine crystal affords a good example of intermolecular interactions in the solid state. In this crystal, nuclear quadrupole effects combined with crystallographic information show two intermolecular covalent bonds per atom, each of about 9 percent importance.
Spectroscopic Studies in the Near Ultraviolet of the Three Isomeric Dimethylbenzene Vapors. III. Fluorescence of Meta-Dimethylbenzene
Authors: Rao V. Ramakrishna , Sastri Mantrala L. N.
Published: January 2005

The fluorescence spectrum of meta-xylene has been obtained in low dispersion using Fe spark lines and a mercury arc lamp for excitation. About 26 bands were measured. They are discussed in their relation to the corresponding absorption spectrum.
Photochemical Oxidation-Reduction and Photocatalysis. The Photochemical Activity of FeCl4− in Alcohol as Oxidizing Agent and as Catalyst
Authors: Brealey G. J. , Uri Norbert
Published: January 2005

A true photocatalytic reaction in which the concentration of the sensitizer remains constant is described in this paper. It is shown that FeCl4− acts as a photocatalyst for the oxidation of alcohol by thionine. In the absence of thionine FeCl4− is the oxidizing agent. A mechanism is put forward which includes (1) photoexcitation, primary dark back reaction and separation of the primary product, (2) oxidation of the CH3CHOH radical by FeCl4−, (3) reaction between two CH3CHOH radicals, (4) oxidation of FeCl4= by thionine. The latter occurs because of a considerable shift in the oxidation-reduction potential by the complexing of both ferric and ferrous iron. Various constants and constant ratios are evaluated from the experimental results.
The Microwave Spectra and Molecular Structures of Trifluoromethyl Bromide, Iodide, and Cyanide
Authors: Sheridan John , Gordy Walter
Published: January 2005

The pure rotational spectra of trifluoromethyl bromide, iodide, and cyanide have been studied in the microwave region. The B0 values in Mc/sec were determined as follows: 2098.06 for CF3Br79; 2078.50 for CF3Br81; 1523.23 for CF3I; 2945.535 for CF3CN14; 2855.859 for CF3CN15. The nuclear quadrupole couplings, eQq, are in Mc/sec: 619 for Br79; 517 for Br81; −2150 for I127; −4.70 for N14. With any reasonable assumption of bond angles, dCF is found to be 1.33±0.015A in each molecule. The other distances depend more strongly on the assumption of the bond angles. With ∠FCF assumed to be 108°±1°, as suggested from other similar molecules, the values, dCBr = 1.91±0.02A, dCI = 2.14±0.02A, dCC = 1.46±0.02A, are obtained, where the additional assumptions dCF = 1.332A for CF3I and dCN = 1.158A for CF3CN are made.
Specific Heat of Synthetic High Polymers. I. A Study of Polyethylene Including a Statistical Theory of Crystallite Length
Authors: Dole Malcolm , Hettinger W. P. , Larson N. R. , Wethington J. A.
Published: January 2005

Data are given for the specific heat of granular, sheet, annealed, and drawn samples of polyethylene from −20° to 200°C. From the data, changes in enthalpy and entropy between these temperatures have been calculated and an estimate made of the free energy of the cold drawing process. The percentage of crystallinity calculated from the enthalpy value is given as a function of temperature and compared with similar estimates from x-ray and density measurements. The applicability of Flory's important theory of crystallization in high polymers to the polyethylene data is studied. A new statistical treatment of crystallite length distribution similar to, but more mathematically exact than Flory's, is also presented. Curves based partly on theory and partly on experiment are given for the weight distribution of crystallites as a function of chain length for annealed and drawn polythene.
Spectroscopic Studies in the Near Ultraviolet of the Three Isomeric Dimethylbenzene Vapors. II. Absorption Spectra of Meta and Ortho Dimethylbenzene
Authors: Cooper C. D. , Sponer H.
Published: January 2005

The vapor absorption spectra of meta- and ortho-xylene were obtained with a 3-meter grating spectrograph. The m-xylene spectrum has the least number of bands and the most diffuse appearance. Its 0, 0 band is located at 36955 cm−1. The o-xylene spectrum consists of many very sharp bands, several of which must be assigned to v—v transitions. Its 0, 0 band is found at 37308 cm−1. Vibrational frequencies of 965, 675 and 470 cm−1 are found in the upper level of the meta-spectrum and are correlated with the ground-state frequencies of 995, 725, and 510 cm−1. In the ortho spectrum ground-state vibrational frequencies of 1233, 1054, and 736 cm−1 are correlated with the excited state values 1195, 939, and 692 cm−1, respectively. Assignments of the different frequencies are discussed. The Tesla luminescence spectrum of meta-xylene is interpreted along with the absorption spectrum.
Dipole-Dipole Interaction in Simple Lattices
Authors: Berlin T. H. , Thomsen J. S.
Published: January 2005

A mathematical model, the spherical model, of electric dipole-dipole interaction in simple lattices is discussed. The partition function for the system, assuming just nearest neighbor interaction, is evaluated for one- and three-dimensional simple lattices. Only the three-dimensional lattice exhibits a phase transition. The transition is discussed. The transition behavior in the presence of an external field is also analyzed, and the electric susceptibility is computed.
Some Molecular Constants of HC13N
Authors: Kagarise R. E. , Rix H. D. , Rank D. H.
Published: January 2005

The 003, 103, and 004 rotation-vibration bands of HC13N have been observed in the photographic infrared region of the spectrum. In addition, the Raman spectrum of the liquid was obtained with sufficient dispersion to measure the isotopic shift of ν1. Values are given for B′, B″, D′, and D″ of the three infrared bands as well as for α1 and α3.

The average values of B″=1.44006 is in excellent agreement with B″=1.44008 calculated from microwave data and the velocity of light as c=299,776 km/sec.
Infrared Spectrum and Molecular Constants of Carbon Dioxide. Part I. ν2 of C12O216 at 15μ
Authors: Rossmann Kurt , Rao K. Narahari , Nielsen Harald H.
Published: January 2005

The vibration-rotation band associated with the fundamental bending vibration of CO2 has been reinvestigated with a 2000 lines/inch grating mounted in a vacuum chamber. The P and R structure has been resolved up to J=60. The molecular constants have been evaluated and they are summarized in Table II. Within the accuracy of the present data it has not been possible to detect any change in the centrifugal stretching constants between the two states involved in this transition.
Quadrupole Coupling and Bond Character in the Vinyl Halides
Authors: Goldstein J. H.
Published: January 2005

Quadrupole coupling data obtained from microwave spectroscopy are utilized in assessing double-bond character in planar molecules such as the vinyl halides. The approximations involved and the effect of structural uncertainties have been considered in detail. An uncertainty of 20% or less is estimated for the calculated values of δ, the number of halogen py electrons lost as a result of double bonding. Application of the method to vinyl chloride and vinyl iodide yields δ values of 0.06 and 0.03, respectively. A revised value of −72 Mc for (eQq)bond in vinyl chloride is reported. The present results are compared with conclusions based on other molecular properties.
Substituted Ethanes. IV. The Rotational Isomers of 1,1,2,2-Tetrachloroethane: Assignments to the Normal Vibrations
Authors: Zietlow James P. , Cleveland Forrest F. , Meister Arnold G.
Published: January 2005

The wave numbers of the normal vibrations of trans 1,1,2,2-tetrachloroethane and some of the fundamentals of the deuterated molecule were calculated by the Wilson FG matrix method. The infrared spectrum of 1,1,2,2-tetrachloroethane has been obtained from 530 to 4000 K (K=kayser=cm−1). Complete assignments of all the observed Raman and infrared bands have been made and some unobserved fundamentals have been computed.
Excited States of the Naphthalene Molecule. II. Further Studies on the First Singlet—Singlet Transition
Authors: McClure Donald S.
Published: January 2005

The polarized fluorescence and absorption spectra of naphthalene and naphthalene d-8 have been studied under the conditions described in Part I for the absorption of ordinary naphthalene. When all the data are examined and compared with the Raman assignments, a complete set of totally symmetric fundamentals for the first excited state can be found. The b1g-modes which bring about the short-axis absorption of naphthalene may be combinations rather than fundamentals. The short-axis fluorescence shows that b1g-combinations rather than fundamentals bring about vibrational-electronic interaction, yet most of the short-axis fluorescence has ag-origins. This latter fact is not completely understood, although partial explanations are offered. It is deduced from the vibrational pattern of the absorption and emission spectra that a change in length of the central link and a slight expansion of the rings are the most important geometry changes occurring in the transition to the first excited state. The symmetry in this state remains D2h.
Excitation and Dissociation of Molecules Due to β Decay of a Constituent Atom
Authors: Wolfsberg Max
Published: January 2005

The theory of electronic, vibrational, and rotational excitation of a molecule, specifically a diatomic molecule, due to β decay of a substituent atom is presented. The nature of the vibrational and rotational excitation for certain specific cases is mathematically investigated. The problem of dissociation arising from the excitation of rotations is discussed. It is shown that it is very difficult to obtain exact figures on the probability of dissociation due to the excitation of vibrations and rotations. Molecular orbital wave functions are employed to gain some insight into the electronic excitation of the daughter molecule. A very rough calculation is made of the probability of nondissociation in the decay of C14 labeled ethane.
Halogen Catalyzed Decomposition of Nitrous Oxide
Authors: Kaufman Frederick , Gerri Norman J. , Pascale Donald A.
Published: January 2005

The thermal decomposition of N2O in the presence of added Cl2, Br2, I2, and C2H5I was studied over the temperature range 876 to 1031°K. The catalytic reaction was found to be first order in N2O and in atomic halogen concentration. The rate constants are in the order Cl>Br>I. Activation energies of 33.5, 37, and 38 kcal and pre-exponential factors of 1.3, 2.0, and 2.8×1014 cc mole−1 sec−1 were found for the Cl, Br, and I reaction. A probable mechanism is discussed and qualitative evidence provided for a high rate constant for the dissociation of Cl2, analogous to reported values for Br2 and I2.
Some Semiempirical Quantum-Mechanical Calculations for Ammonia and for Diimide
Authors: Wheland G. W. , Chen P. S. K.
Published: January 2005

Quantum-mechanical calculations by the naive, semiempirical LCAO MO method have been made for the ammonia and the diimide molecules. With the use of parameters obtained by fitting the empirical data for ammonia, it has been calculated that the activation energy for the syn-anti interconversion of diimide should be about 33 kcal per mole.
Near Infrared Spectrum of Nitrous Oxide
Authors: Plyler Earle K. , Tidwell Eugene D. , Allen Harry C.
Published: January 2005

Twelve previously unreported bands of nitrous oxide have been observed under high resolution. The results of the analyses of these bands are given. A precise value of ν2 is derived from a difference band and four constants in the quadratic vibrational energy expression are given. The role of Fermi resonance is discussed briefly.
Dipole Moment of HD
Authors: Blinder S. M.
Published: January 2005

The HD molecule has a small permanent electric dipole moment as a consequence of the asymmetry of nuclear vibration. The complete molecular Hamiltonian contains a term which is not invariant to inversion of electronic coordinates through the molecular center. This gives rise to an axial asymmetry of electronic charge. Treating the term as a perturbation, it is found that the 1Σg+ electronic ground state is perturbed only by states of 1Σu+ symmetry. Assuming that only the lowest such state (the B state) contributes, an upper bound on the permanent moment is established. For the ground vibrational state this is computed to be 8.89×10−4 Debye unit, directed in the sense H+D−.