bluuebunny/crossref_metadata_2025 huggingface dataset:
Infrared Absorption of Zinc Oxide and of Adsorbed CO2. II
Authors: Matsushita Sanjuro , Nakata Toshiko
Published: January 2005

Reversible changes due to gas adsorption in spectra of powdered zinc oxide were observed. In the range 2000∼1200 cm—1, CO2 gave increases in absorption at 1640 and 1430 cm—1 on adsorption at 20°C and at 1570 and 1380 cm—1 at 200°C. These results could be interpreted by assuming that CO2 adsorbed at 20°C is combined with surface oxygen, but that at 200°C bonded to surface zinc. Another change, a decrease in the conduction-electron absorption of the solid, was found in the case of adsorption at 200°C. Similar decreases by adsorption of O2, C2H4, and H2 (of opposite sign) are reported. Correlation between the adsorbed state of CO2 and influences of the adsorption on electrons in the solid is discussed. Some data on adsorption velocities and adsorbed quantities of CO2 are given.
Mass Spectrometry of Ions in Glow Discharges. I. Apparatus and Its Application to the Positive Column in Rare Gases
Authors: Knewstubb P. F. , Tickner A. W.
Published: January 2005

An apparatus is described which samples and analyzes ions from a glow discharge. Results are given for the positive column of discharges in argon, krypton, and mixtures of the two, at pressures between 0.4 and 1.0 mm and current densities in the range 0.035 to 0.105 ma/cm2. In general, the results are in reasonable agreement with those of other workers, but some differences are noted.

The results appear to favor the formation of A2+ by the reaction Ar*+Ar→A2++e, but it is not possible to rule out conclusively the three-body process Ar++2Ar→Ar2++Ar. Traces of hydrogenous impurities (especially water) appear to interfere with molecule ion formation.

The formation of ArH+ from impurities is also studied and the results suggest that it may be formed from any or all of Ar+, Ar2+ or Ar*. Experiments in which 1.25% hydrogen is added to the argon suggest that ArH+ is not formed mainly by the reaction of Ar+ with H2 but that the reaction of metastable argon atoms with hydrogen atoms should be seriously considered.

The visible structure of a striated positive column is found to be reflected in the ion concentrations which vary differently for different ions. The effect seems to be related to fluctuations in the potential gradient which may be enhanced by the formation of negative ions.
Oxygen-17 NMR Shifts in Aqueous Solutions of Rare-Earth Ions
Authors: Lewis W. Burton , Jackson Jasper A. , Lemons Joe Fred , Taube Henry
Published: January 2005

Paramagnetic and diamagnetic shifts of the O17 NMR signal in aqueous solutions of the rare-earth ions at room temperature have been observed. The shift arises from the isotropic part of the hyperfine interaction between the O17 nucleus and the thermal average value of the spin of the rare-earth ion. The direction of the shift is in all cases opposed to the spin magnetization of the rare-earth ion. This result is explained through the formation of covalent bonds in the hydrated ion involving the rare-earth 6s orbital.
Role of f-Orbital Electron Wave Function Mixing in the Concentration Quenching of Eu3+
Authors: Van Uitert L. G. , Linares R. C. , Soden R. R. , Ballman A. A.
Published: January 2005

The dependencies of intensity of emission of Eu3+ upon its concentration have been examined for several oxide systems which differ in structural arrangements and cation charge type. The data show that concentration quenching increases with the rise of perturbing influences which probably result from the mixing of the f-orbital wave functions of different Eu3+ ions through a lattice band process.
Many-Electron Theory of Atoms and Molecules. I. Shells, Electron Pairs vs Many-Electron Correlations
Authors: Si̇nanoğlu Oktay
Published: January 2005

A theory is developed (a) to see what the physically important features of correlation in atoms and molecules are; (b) based on this to obtain a quantitative scheme for N-electron systems as in He and H2; (c) to see what happens to the ``chemical'' picture, to semiempirical theories, and to shell structure, when correlation is brought in. It is shown why, unlike in an electron gas, in many atoms and in molecules mainly pair correlations are significant. In configuration-interaction, multiple excitations arise not as three or more electron ``collisions,'' but as several binary ``collisions'' taking place separately but at the same time. The validity of theory is shown on Be, LiH, and boron. The theory does not depend on any perturbation or series expansion and the r12-coordinate method can now be used for an N-electron system as in He and H2.
Effect of Reactor Length on the Formation of Detonation in Saturated Knallgas-Steam Mixtures
Authors: Luker James A. , Adler Leonard B.
Published: January 2005

Reactor length is an external variable governing the formation of detonation in certain gaseous mixtures which has received only limited attention.

Data presented herein show a qualitative relationship between reactor length and the effect of end-reflected precompressional shock waves on the deflagration process. Within a specific length range for certain gaseous mixtures, shortening the reactor may enhance the formation of detonation while lengthening the reactor will retard the reflection effects which accelerate the predetonation flame. For proper experimental definition of the formation of detonation in mixtures exhibiting long induction distances, reactor length must be considered along with the other major external variables.
Complex Cluster Integrals for an Augmented Gaussian Gas
Authors: Tanaka Tomoyasu , Meijer Paul H. E. , Fox John N.
Published: January 2005

It has been shown by Montroll, Berlin, and Hart that complex cluster integrals can be evaluated very easily if the actual Ursell-Mayer f function is replaced by a Gaussian. The possibility of using a more realistic function was suggested by the same authors. We have carried out the actual calculation of the cluster integrals for four particles and determined the dependence of the parameters on the temperature. It is shown that the integration problem is reduced to the evaluation of higher derivatives of the so called graph determinant. The method can also be used to calculate the effective interaction between two articulation points of a complicated cluster. The importance of the nonring diagrams is stressed by some numerical estimates of discrepancy between actual condensation and the divergence of the ring series.
SCF-LCAO-MO Wave Functions for the Bifluoride Ion
Authors: Clementi E. , McLean A. D.
Published: January 2005

Several SCF-LCAO-MO wave functions for the ground state of HF2— are reported. The best one has a total energy∼4 ev higher than the estimated Hartree-Fock energy for HF2—, and it is about 30 ev lower than the energy corresponding to an SCF-LCAO-MO wave function with minimal basis set. These wave functions give indications as to what, in the SCF-LCAO-MO framework, is the smallest basis set which would give a wave function with total energy very near the Hartree-Fock energy. The importance of inclusion of a 2pπ STO on the hydrogen atom is discussed.
Ground State SCF-LCAO-MO Wave Function for the Carbonyl Sulfide Molecule
Authors: Clementi Enrico
Published: January 2005

The ground state SCF-LCAO-MO wave function for the carbonyl sulfide molecule is presented and analyzed. All the 30 electrons are included in the computation and all the integrals are accurately computed with McLean's automatic program. A brief discussion of some of the excited states is given at the end of the paper.
Absorption and Photoionization Coefficients of Propylene and Butene-1 in the Vacuum Ultraviolet
Authors: Samson J. A. R. , Marmo F. F. , Watanabe K.
Published: January 2005

Absorption and photoionization coefficients of propylene and butene-1 vapors have been measured by the photoelectric technique in the spectral region 1050–2000 A. Two Rydberg series were observed in propylene yielding series limits of 9.74 and 9.80 ev. From the photoionization coefficient curves ionization potentials of 9.73 and 9.80 ev were observed for propylene, and 9.58 ev for butene-1.
Some Properties of Bismuth Perovskites
Authors: Buhrer Carl F.
Published: January 2005

The crystallographic and dielectric properties of complex perovskites are described in terms of average A- and B-site ionic radii, charges, and electronic structures. The relative importance of these to the ferroelectric state is evaluated by a study of a number of solid solutions containing trivalent bismuth. Two new ferroelectrics, Bi0.5K0.5TiO3 and Bi0.5Na0.5TiO3, and the phase diagrams of the systems BixKxBa1–2xTiO3, Bi0.5KxNa0.5—xTiO3, BixKxPb1–2xZrO3, and BixNaxPb1–2xZrO3 are reported.
Electrical Conductivity of Proteins. II. Semiconduction in Crystalline Bovine Hemoglobin
Authors: Rosenberg Barnett
Published: January 2005

Evidence has been presented to show that crystalline bovine hemoglobin is a semiconductor in the dry state. The semiconduction activation energy is 2.3 ev. This is similar to the values obtained for a number of other proteins, chromoproteins, and biological structures which have proteins as the main constituent. The effect of adsorbed water is to increase the conductivity enormously. The dependence on the amount of adsorbed water is exponential, in agreement with the results of Baxter and Spivey. In the ``wet'' state, the protein is still a semiconductor, but the semiconduction activation energy is lower. The dependence of the activation energy on the amount of adsorbed water is given by EW=ED−δm.It has been proved that this is the only effect of water in causing the increase in conductivity. The value of σ0 in the semiconduction formula is 7×103[Ω—cm]—1 and is independent of the adsorbed water content. The effect of water adsorption on the conductivity is reversible when the water is desorbed. Experimental evidence, which strongly indicates that the conductivity process in the wet protein is electronic rather than ionic, has been given previously by the writer.

A theory is developed which shows that the effect of adsorbed water in increasing the dielectric constant of the protein lowers the work necessary to separate the charges due to the increase in the polarizability of the medium. This leads to a prediction that the dependence of the dielectric constant on the adsorbed water content should be of the form κ′=κ/(1−κχm).Some previous measurements of Medley and King are in semiquantitative agreement with this. The theory also predicts that for higher adsorbate concentrations, the conductivity should become constant (saturation effect). Again, the measurements of Medley and King confirm this. This saturation effect allows an estimate to be made of the radius of the polarization (R) and the ionization energy minus the electron affinity (I — A) for the protein. R≈2.8×10—8 cm and I — A≅10 ev. Both values are in reasonable agreement with expectations.
Absorption Spectra of Ferric Iron-Containing Oxides
Authors: Wickersheim K. A. , Lefever R. A.
Published: January 2005

The interpretation of the absorption spectra of the ferric iron-containing oxides is extended and clarified. Largely on the basis of existing data it is shown that the majority of the discrete absorptions can be related to energy differences obtained from (cubic) crystal field calculations applied to Fe3+ provided a reduction of the 6S—4G separation (relative to the free ion value) is first introduced. The strong, continuous absorption which characteristically obscures the region above 20 000 cm—1 in the undiluted ferric oxides is assigned to charge transfer transitions. One low-energy absorption band (not characteristic of the iron oxides) found in the spectrum of lithium ferrite is tentatively assigned as the photoionization of a charged anion vacancy.
Ionic Complexes of Xe and C2H2 Produced by the Radiolysis of These Gases
Authors: Rudolph P. S. , Lind S. C. , Melton C. E.
Published: January 2005

Binary mixtures of acetylene and the noble gases were irradiated by 90 ev electrons at pressures up to 1.3 mm in the ionization chamber of a research mass spectrometer. Various proportions of the mixtures and a range of pressures were employed in this study. Ionic complexes, [XeC2H]+ and [XeC2H2]+, were observed in the C2H2–Xe system. The intensity ratio [XeC2H2]+/[XeC2H]+ increased linearly with increasing pressure. No ionic complexes were observed in the other mixtures. A series of reactions involving Xe+ is presented.
Raman Spectral Studies of the Effects of Electrolytes on Water
Authors: Walrafen George E.
Published: January 2005

Photoelectric Raman spectra of water at temperatures from 2° to 94°C have been obtained for the spectral region of about 0–4000 cm—1. Comparisons of these spectra, with Raman spectra of bromide and chloride solutions, indicate that certain intensities, which are increased by lowering the temperature of water, are also increased by electrolyte addition. Such intensity increases of Raman bands of the bromide and chloride solutions appear to be related to the ordering of water and ions. Other Raman bands of water, for which intensity increases occur with lowering of temperature, decrease in intensity with electrolyte addition. Those effects apparently are related to O–H···O bonds.

The intensities of various bands studied, e.g., the librational bands, were observed to increase linearly with electrolyte concentration. In addition, marked intensity increases with increasing anionic size, i.e., Br—>Cl—, were observed, but the effects of the cations, while similar with respect to increasing size, appear to be relatively small.

The linear intensity increases have been explained in terms of the concentration of ordered water-electrolyte units. The size effects have been considered in terms of the polarities of the bonds of those units.
Approximate Radial Functions for First-Row Transition-Metal Atoms and Ions. I. Inner-Shell, 3d and 4s Atomic Orbitals
Authors: Richardson James W. , Nieuwpoort W. C. , Powell R. R. , Edgell W. F.
Published: January 2005

Orthogonal radial wave functions of first-row transition-metal atoms and ions for 1s, 2s, 3s, 4s, 2p, 3p, and 3d electrons have been constructed using a minimum set of normalized Slater-type functions. Special attention is given to the 3d orbitals, for which it is necessary to use the ``double-zeta'' form; i.e. two Slater-type functions of different effective nuclear charges. Free parameters are determined by maximizing overlap with recently available self-consistent field functions. The simplified functions obtained are judged to be adequate for use in calculations of chemical bonding. Implications are drawn regarding the overlap criterion and systematization of the parameters found.
Chain Model for Polyelectrolytes. VII. Potentiometric Titration and Ion Binding in Solutions of Linear Polyelectrolytes
Authors: Kotin Leonard , Nagasawa Mitsuru
Published: January 2005

The electrostatic potential about a rodlike polyion in an aqueous solution containing added simple electrolyte is calculated by numerical integration of the Poisson-Boltzmann equation. The results are applied to the calculation of the ionic distributions about the polyion and the potentiometric titration curves of polyweak acids. The nature of ion binding is discussed in terms of a molecular model and it is found that the degree of ion binding f* may be expressed as f*=1−(2Ne2/DkTL)−1,where the parameters are defined in the text.
Fluorescence Energy Transfer and Oxygen Quenching in Solutions of Diphenyloxazole in Cyclohexane
Authors: Weinreb Arye
Published: January 2005

The fluorescent intensity of solutions of diphenyloxazole (PPO) in cyclohexane is measured as a function of concentration for excitation by γ rays. The fluorescence spectrum of the solutions when excited by uv is also recorded. These uv measurements, together with the results of β excitation, were used to examine the quenching influence of oxygen on the solute fluorescence and on the energy transfer from cyclohexane. The decay times of the solutions are measured. The results are interpreted to show: (1) a tendency of PPO to form molecular complexes in cyclohexane and (2) a ``static'' character for the oxygen quenching of cyclohexane. The dependence of transfer probability on solute concentration is discussed.
Heat Capacity and Entropy of CuCl2 and CrCl2 from 11° to 300°K. Magnetic Ordering in Linear Chain Crystals
Authors: Stout J. W. , Chisholm R. C.
Published: January 2005

The heat capacities of CuCl2 and CrCl2 have been measured between 11° and 300°K. The contributions to the entropy and heat capacity arising from the ordering of the magnetic moments are evaluated. Maxima in the heat capacity are found at 23.91±0.1°K for CuCl2 and 16.06±0.05°K for CrCl2. Both compounds show gradual maxima in the magnetic contribution to the heat capacity at higher temperatures. These are interpreted as short-range one-dimensional ordering arising from relatively strong antiferromagnetic coupling within the chains of atoms which make up these crystals. At lower temperatures relatively weak interactions between atoms in different chains cause the development of long-range order. By use of the Ising model to describe interactions within a chain and a molecular field to describe the secondary interactions, an approximate theoretical treatment is given. Smooth values of the heat capacity, entropy, enthalpy, and free energy are tabulated at selected temperatures. The values of the entropy and enthalpy at 298.15°K are: CuCl2, S° = 25.83±0.05 cal deg—1 mole—1, H°–H0° = 3581±7 cal mole—1; CrCl2, S° = 27.56±0.05 cal deg—1 mole—1, H°–H0° = 3593±7 cal mole—1. By use of equilibrium data of Doerner and of Sano the standard heat of formation of CrCl2 is calculated to be —94.52±0.4 kcal.
Kinetic Study of the Formation and Reaction of CN Molecules in Shock Waves
Authors: Patterson W. L. , Greene E. F.
Published: January 2005

The decomposition of gaseous BrCN in shock waves has been measured over the temperature range 2500–7000°K by following the light emitted by CN and C2. The rate of the reaction in 1 and 5% mixtures with Ar is —d[BrCN]/dt=2.0×1012T½ exp (—90.5 kcal mole—1/RT) [Ar] [BrCN] mole cc—1 sec—1. The subsequent disappearance of CN as determined by both the loss of CN and the formation of C2 is consistent with the reaction 2CN→C2+N2 for which the bimolecular rate constant is 1.6×1015 exp (—43 kcal mole—1/RT) cc mole—1 sec—1.
On the Optical Spectra of Some Transition Metal Pentacyanonitrosyl Complexes
Authors: Gray Harry B. , Ballhausen C. J.
Published: January 2005

The visible absorption spectra of the ions [Fe(CN)5NO]2—, [Mn(CN)5NO]3—, and [Cr(CN)5NO]3— are interpreted using a crystal field level scheme of C4v symmetry. Assuming a strong axial compression to be present a self-consistent assignment is obtained for both the 3d5 and 3d6 electronic configurations.
Structure and Surface Binding: N and CO on Tungsten
Authors: Ehrlich Gert
Published: January 2005

The energetics of the interactions of N2 and CO with initially clean tungsten surfaces are analyzed to establish the dependence of chemisorption upon surface structure. For N2, calorimetric measurements yield a heat of adsorption of ∼90 kcal mole—1, constant over the range of coverages accessible at T=300°K. This suggests that the equilibrium binding sites for nitrogen are energetically equivalent. Desorption obeys bimolecular kinetics, with an activation energy of ∼81 kcal mole—1, unchanging to the highest surface concentrations (n∼250×1012 molecules cm—2).

This constancy confirms the energetic equivalence of the surface sites filled by nitrogen, and demonstrates the presence of adatoms without lateral interactions. Alternative proposals for the occupation of binding sites of different strengths are examined and rejected as caused by experimental error.

In contrast, evolution of CO takes place in distinct steps, with activation energies of 53, 75, and ∼100 kcal mole—1 for β material. Stepwise desorption stems from the arrangement of CO binding sites. These differ in strength, are widely separated from one another, and presumably consist of planes with different crystallographic orientation.

Despite the constant heat of adsorption, the presence of an activation barrier to surface diffusion, amounting to ∼35 kcal mole—1 on the approaches to the (100), demonstrates that binding of nitrogen atoms does depend on surface structure. In the regions between equilibrium sites, a nitrogen adatom is less firmly bound. On the (110) planes, in which each tungsten atom has six nearest neighbors, the binding energy of a nitrogen adatom is lowered to such an extent that at room temperature these areas should be bare. This is confirmed by direct observation in the field ion microscope. Such ``structural exclusion'' arises from the high dissociation energy of N2, which precludes occupation of sites accessible to other, less strongly bonded molecules. For nitrogen atoms only a narrow band in the total spectrum of binding energies is available. Structural exclusion is also shown to be in accord with the following unique properties of nitrogen layers: (1) The limited concentration (∼40% of the total number of surface sites) achievable at room temperature; (2) The presence of an additional and heavily populated binding state (γ) at T<200°K; (3) The absence of interactions between adatoms.
Dynamic Aspects of Bond Alternation in Cyclic Polyenes
Authors: Gouterman Martin , Wagnière Georges
Published: January 2005

The theoretical shapes of the potential curves for bond alternation in ground and excited states in cyclic polyenes are given. It is shown that the current MO model tends to give a rather small barrier to tunneling between the two alternating nuclear configurations, and that the barrier disappears in the excited states. If the potential curves do differ between ground and excited states, peculiar progressions should appear in the spectrum. An analysis is presented of the low-temperature spectrum of C18H18 that shows no such effect. It is suggested that the success that bond alternation has had in interpreting various phenomena is due to the fact that it makes the electrons less free than current models would have, but that this effect may stem from other subtler causes.
Electronic Energy of HF as a Power Series in the Internuclear Distance
Authors: Reid Charles E.
Published: January 2005

The electronic energy of HF has been expressed as a power series in the internuclear distance. Bingel's formulas for the coefficients of R2 and R3 have been verified by an independent method of derivation, and an expression for the coefficient of R4 has been derived. Numerical calculations of these coefficients have been carried out; the results, though not highly accurate, suffice to show that because of the very short range of practical convergence, this series is useless for calculating properties of the HF molecule.
Hellmann-Feynman Theorem and Correlation Energies
Authors: Stanton R. E.
Published: January 2005

A proof is offered for the applicability of the Hellmann-Feynman theorem to Hartree-Fock wave functions. In conjunction with Sinanoğlu's theory of correlation energies, this leads to the idea that Hartree-Fock potential energy surfaces and exact potential energy surfaces are parallel over short distances. Finally, a new method of calculating dissociation energies is presented.
O–H–O and O–D–O Potential Energy Curves for Chromous Acid
Authors: Snyder Robert G. , Ibers James A.
Published: January 2005

On the basis of infrared data it is concluded that the O–H–O bond in HCrO2 (chromous acid) is symmetric, whereas the O–D–O bond in DCrO2 is asymmetric.
Diffusion Kinetics in Radiation Chemistry. I. Generalized Formulation and Criticism of Diffusion Model
Authors: Kuppermann Aron , Belford Geneva G.
Published: January 2005

A generalized formulation of the diffusion-kinetic model of track effects in radiation chemistry is presented and criticized. It permits consideration of complex mechanisms, arbitrary initial distributions and radical correlation effects. Methods for the numerical integration of the associated differential equations on high-speed electronic digital computers are given and their accuracy is examined. Several applications are suggested.
On the Use of Nonintegral Exponents in Elliptical Coordinate Wave Functions, with Special Reference to the Hydrogen Molecule-Ion
Authors: Geller Murray , Ludwig Oliver G.
Published: January 2005

Introduction of arbitrary powers of the elliptical coordinate μ is shown to give a better approximate wave function for the hydrogen molecule-ion than any previous function of comparable complexity. The three-parameter two-configuration functionψ=Nμne−αμ(1+bν2)is found to give an energy of —0.602566 a.u. and an equilibrium internuclear separation of 1.9956 a0 compared with the results for n=0 of —0.602386 a.u. and 1.9966 a0, respectively, and with the exact values of —0.60263 a.u. and 2.0 a0, respectively. This agreement is maintained over a range of internuclear distances.

In the Appendix a discussion is given of various methods for computing kinetic energy integrals, and a special difficulty is pointed out that arises when functions in prolate spheroidal coordinates are employed.
Vacuum Ultraviolet Absorption Spectra of 1,4-Dioxane and 1,3-Dioxane
Authors: Hernandez G. J. , Duncan A. B. F.
Published: January 2005

The spectrum of 1,4-dioxane shows strong absorption regions with intensity maxima at 55 500, 63 000, 69 500, and 72 000 cm—1, and an absorption region whose maxima is obscured by the last two absorption regions. A first ionization potential was located at 76 750 cm—1 (9.52 ev) which agrees with the value determined by electron impact (9.52 ev). The first electronic transition shows considerable virbrational structure, and the analysis of this structure indicates that the upper-state vibrational frequencies are only slightly changed from those of the normal state. The other electronic transitions form a possible Rydberg series which converges to the first ionization potential.

1,3-dioxane shows an absorption region with a maximum at 62 500 cm—1, and another very strong continuous absorption region beginning at about 67 500 cm—1. There is no apparent discontinuity in the region of the ionization potential. The electronic spectrum of 1,3-dioxane showed no vibrational structure.
Effect of Adsorption on Acoustic Boundary-Layer Losses
Authors: Parker J. G.
Published: January 2005

A theory accounting for the effect of surface adsorption of molecules on losses occurring in acoustic boundary layers has been developed. Results of this theory show that such losses can be a sizable fraction of losses due to viscosity and thermal conductivity. Interpretation of recently obtained sound-absorption measurements in H2, He, Ne, N2, CO, O2, and Ar by this means permits direct determination of adsorption times for these gases. Comparison of these results with existing data is not conclusive, since most adsorption measurements have been carried out at temperatures near that of liquid air whereas the data reported here was obtained at room temperature. In addition, it is almost certain that water vapor caused considerable contamination of the adsorbing surface.
Carbonyl Stretching Frequencies of Some Partially Fluorinated Esters
Authors: Radell Jack , Harrah Larry A.
Published: January 2005

The carbonyl stretching frequencies of 19 esters of perfluorinated normal acids and 17 esters of partially fluorinated normal alcohols were measured with a precision of 0.5 cm—1. The carbonyl stretching frequencies of the fluorinated esters were found to be consistently higher than the carbonyl stretching frequencies of the corresponding unfluorinated esters and dependent on the amount and position of the fluorine substituents. The behavior of the carbonyl stretching frequency as a function of fluorine position and number can be generalized with the following equation for the acid moiety: νc=0=ν0+15nα+4.07nβ+1.88nγ+0.8nδ,where ν0 is the carbonyl stretching frequency of the unfluorinated ester and nα, nβ, etc., are the numbers of fluorines on the α, β, etc., carbons in the acid segment. The carbonyl stretching frequencies in the esters with fluorine substitution in the alkyl segment is given by νc=0=ν0+7.97nβ′+1.78nγ′+1.83nδ′+nε′,where νc=0 has its previous significance and nβ′, nα′, etc. are the number of fluorines on the β, α etc. carbons of the alkyl chain.
Entropies, Heats of Sublimation, and Dissociation Energies of the Cesium Halides
Authors: Scheer Milton D. , Fine Joseph
Published: January 2005

The vapor pressures of the crystalline cesium halides have been measured in the 700–900°K temperature range. The salt vapor effusing from a Knudsen effusion cell was accurately collimated into a molecular beam with a well-defined cross-sectional area. Beam intensities were determined from the positive ion currents produced by dissociation of the halide and ionization to Cs+ on a tungsten surface at 1700°K. From the experimental vapor pressures and heats of sublimation, the crystal entropies, dissociation energies, and heats of sublimation at 298°K were computed using available spectroscopic and thermal data.
Consistency and the Fifth Virial Coefficient for a Hard-Sphere Gas
Authors: Cole G. H. A.
Published: January 2005

The modified superposition approximation g(3)(r, s, t)=g(2)(r)g(2)(s)g(2) (t)[1+X1n+X2n2] (where g(3) is the triplet distribution, g(2) the pair distribution, n the number density, and (r, s, t) are the particle separation distances) is used in conjunction with the Born-Green-Yvon equation of the classical theory of fluids in the calculation of the fifth virial coefficient E for a gas of hard spheres. The values of E derived directly from the virial theorem and alternatively from compressibility arguments are reconciled through a suitable choice of X2, the present note forming a sequel to an earlier paper by the present author concerned with the fourth virial coefficient. On the assumption Xi=constant it is found for hard spheres that X1=0.1014b and X2=—0.0424b2 (b=four times a molecular volume) ensures consistency as far as the fifth virial coefficient. The consistent value of E under this approximation is +0.0242b4. The validity of the arguments is considered.
Magnetic Resonance of Strongly Coupled Nuclear Spin Systems. I. Refined Analysis of Complicated NMR Spectra
Authors: Arata Yoji , Shimizu Hiroshi , Fujiwara Shizuo
Published: January 2005

A method which is useful for a refined analysis of the high-resolution NMR spectra is presented. The method is based on the method of least squares. Before refinement of molecular constants, it is necessary to make a rough assignment of multiplet lines in a spectrum. Then the spectrum will be analyzed systematically with high precision. The ways to find a rough assignment are also discussed briefly. Although the method is applicable to any spin system, examples of analysis are shown by the spectra of three spin systems, the vinyl protons of acrylic acid, ethyl acrylate, and vinyl sulfonic acid. From these results, the method appears to be suitable for an analysis of the spectrum which is composed of superposed lines.
Determination of the Molecular Structures of CF3NO2 and CBr3NO2 by Electron Diffraction
Authors: Karle I. L. , Karle J.
Published: January 2005

The structure of the halopicrins is of particular interest since these compounds are not very stable. Of interest also is the orientation of the threefold group at one end of the C–N bond with respect to the —NO2 group at the other end. The quantitative sector-microphotometer method in electron diffraction was employed for studying the structures of bromopicrin and fluoropicrin. In both molecules, the —CX3 group and N–O bond have the expected values for bond lengths and angles. On the other hand, the C–N distance is very long, 1.59 A in CBr3NO2 and 1.56 A in CF3NO2; the ONO angle has values of 134° and 132°, respectively; the —CNO2 group is not planar; and the molecule assumes a staggered configuration similar to that found in ethane compounds (with one position vacant).
Chemical Processes Subsequent to n—π* and π—π* Transitions of Pyridine N-oxide and 2-Picoline N-oxide
Authors: Hata Norisuke , Tanaka Ikuzo
Published: January 2005

The gaseous photolysis of pyridine N-oxide was carried out by irradiating with the 3261 A (Cd) or 2537 A (Hg) resonance line which corresponds to the absorption due to an n—π* or a π—π* transition of this substance, respectively. The main product was pyridine in both cases. However, there exists a remarkable difference in the relation between the quantum yield of pyridine produced and the temperature. In the case of 3261 A irradiation the quantum yield of pyridine increases steeply at temperatures greater than 80°C, which means that an activation energy would be required for the production of pyridine. On the other hand, the quantum yield of pyridine produced at 2537 A irradiation was nearly independent of the temperature. The activation energy necessary for the production of pyridine in the case of 3261 A irradiation is about 11.9 kcal mol—1, which was estimated from the temperature-dependence of the quantum yield of pyridine. The chemical processes succeeding to an n—π* or a π—π* transition of pyridine N-oxide were interpreted under the assumption that the excited molecule dissociates to pyridine and atomic oxygen in a predissociative manner, in which a triplet state crossing with the first excited state exists as a short-lived intermediate.

The gaseous photolysis of 2-picoline N-oxide was also carried out by irradiating it with the 3261 or 2537 A resonance line. It was found that 2-picoline N-oxide undergoes a photochemical rearrangement to isomerize to 2-pyridinemethanol at 3261 A (n—π* transition) and a fission of N→O bond to produce 2-picoline at 2537 A (π—π* transition).
Intensity Sum Rule for NMR
Authors: Gioumousis George , Swalen J. D.
Published: January 2005

The general NMR intensity sum rule ∑ kIj0k= ∑ iIij0+2Fz(j0)is proved. The sum on the left is the sum of the intensities of all the transitions to the state j0 (νj0←k), the sum on the right is the sum of the intensities of all the transitions from the state j0 (νi←j0), and the third term is twice the z component of the total spin of this state j0.
Ligand Field Splitting of d Orbitals in Eight Coordinated Complexes of Dodecahedral Structure
Authors: Randić Milan
Published: January 2005

The splitting and the order of d orbitals in a dodecahedron (D2d) is deduced from the known order of these orbitals in a cube, considering the effect of the distortion of the cube into the dodecahedron on individual d orbitals. The most stable orbital is dxy and it is interesting to note that this orbital is not used in dodecahedral d4sp3 hybridization. The ligand field calculations for different distorted cubic environments support the qualitative discussion.
Cylindrical Approximation and the α—β Quartz Transition
Authors: Hughes A. J. , Lawson A. W.
Published: January 2005

Pippard's cylindrical approximation to the thermodynamics of a λ-point transition is applied to the α—β quartz inversion. Mayer's data on the thermal expansion and on the elastic constants of quartz, coupled with Moser's specific heat data, permit two independent estimates of (dT/dP)λ. The value of (dT/dP)λ derived from the thermal expansion and elastic constant data agrees to within 2.5% with Yoder's experimental value.
Nuclear Magnetic Resonance Spectrum of B11 in Lesserite
Authors: Pennington K. S. , Petch H. E.
Published: January 2005

The quadrupolar splitting of the B11 nuclear magnetic resonance signal in a single crystal of lesserite, the monoclinic dimorph of Mg2B6O11·15H2O, has been investigated in a magnetic field of 6345 gauss. The spectra obtained as the crystal was rotated in turn about three mutually perpendicular axes held normal to the magnetic field were interpreted on the basis that the 12 B11 sites per unit cell belong to three distinct types with the four sites of each type related by the symmetry of point group 2/m. The electric quadrupole coupling constants, eqQ/h, and asymmetry parameters η of the electric field gradient tensors at the three unique B11 sites were determined to be eqQ/h406±4 kc/sec270±4 kc/sec2529±10 kc/secη0.397±0.0020.927±0.0020.075±0.003.It has been inferred from the foregoing values that two of the boron atoms in the asymmetric unit of lesserite have tetrahedral coordinations whereas the third has triangular coordination and that the two BO4 groups form with the BO3 group a closed-ring polyion similar to that found in colemanite. The orientations of the principal axes of the electric field gradient tensors at the B11 sites have also been determined.
Low-Temperature Solution Spectra of Methylcyclohexane and Benzene. Effect of Oxygen and Carbon Tetrachloride
Authors: Tsubomura Hiroshi , Lang Robert P.
Published: January 2005

Measurements of the absorption spectra of some solutions in the form of a low-temperature glass have been made. The absorption band arising from the interaction between oxygen and methylcyclohexane has been found to increase at low temperature. The remarkable enhancement of the benzene ``MR'' series appearing between the B2u bands upon addition of carbon tetrachloride, as found by J. Ham, has been confirmed, but the intensity falls down largely at a higher temperature.
Electron Spin Resonance of Irradiated Single Crystals of Alanines: Hindered Rotation of the Methyl Group in a Free Radical
Authors: Miyagawa Ichiro , Itoh Koichi
Published: January 2005

Electron spin resonance absorption of irradiated single crystals of alanines has been observed at 9 kMc/sec. dl-Alanine and l-alanine showed the same absorption pattern. When treated with heavy water, l-alanine gave the same hyperfine structure but showed a considerably sharper linewidth. A notable dependence on temperature of the absorption was observed in the range from 110° to 210°K. It was concluded that the reorientation of the methyl group of the radical H3CĊHR is quenched at low temperature. The life time τ of the reorientation was estimated from the absorption pattern, using a modified Bloch equation. The classical theory of rate processes was applied to analyze the relation between τ and temperature. The potentential barrier and the frequency factor for l-alanine were found to be 3.6±0.2 kcal/mole and (10±4)×1012 sec—1, respectively. The same values were obtained for dl-alanine, within experimental error. The direction of each C–H bond of the methyl group was determined by analyzing the hyperfine constant for 77°K. It was also shown that some atoms in the parent molecule in the crystal shift considerably on irradiation.
Theory of Polyhedral Molecules. I. Physical Factorizations of the Secular Equation
Authors: Hoffmann Roald , Lipscomb William N.
Published: January 2005

An LCAO—MO systematization of polyhedral molecules such as BNHN is undertaken. Peculiarities of polyhedral systems, such as inapplicability of nearest-neighbor assumption and increased number of parameters are discussed within the framework of a Hückel type of theory. It is found that inclusion of hydrogen atoms does not affect predictions of closed shells, but is important in determining electronic transitions. Various physical factorizations of the secular equations, such as the in-surface, apex-equatorial, and ring-polar separations are critically examined. A computer program for calculations on molecules of up to 15 atoms is described and used to obtain the energy levels of a variety of polyhedral molecules.
Theory of Polyhedral Molecules. II. A Crystal Field Model
Authors: Hoffmann Roald , Gouterman Martin
Published: January 2005

A crystal field model is developed for finding the molecular orbitals of polyhedra of identical atoms. The valence electrons are taken as moving in a one-electron crystal field set up by an effective nuclear charge centered at each atom. The field is expanded in spherical harmonics. Zeroth-order solutions are found from the spherically symmetric term, while higher terms are treated as a first-order crystal field perturbation. Polyhedra of hydrogen and of boron or carbon are considered. For the latter special attention is given to the identification of out-pointing orbitals, i.e., the orbitals used in bonding. Comparison is made between crystal field and LCAO energy levels. It is shown that they become more alike when, in the latter, α(2s) is made much lower than α(2p).
Effect of Styrene Monomer on the Fluorescence Properties of Polystyrene
Authors: Basile Louis J.
Published: January 2005

Fluorescence spectra and lifetimes have been studied for polystyrene samples having different average molecular weights and different concentrations of residual styrene monomer. The residual styrene monomer is fluorescent and acts as a typical fluorescent solute in a rigid medium. The fluorescence properties of polystyrene were found to be dependent on both the concentration of residual styrene monomer and, to a lesser extent, the average molecular weight.
Studies on the Alternant Molecular Orbital Method. II. Application to Cyclic Systems
Authors: Pauncz R. , de Heer J. , Löwdin P. O.
Published: January 2005

Using the general energy expression for an alternant system with closed-shell structure, obtained in our previous paper on the alternant molecular orbital (AMO) method, a numerical analysis is presented of cyclic systems consisting of 2n=4v+2 electrons moving in the field of 2n[Complex chemical formula]centers. Special attention is paid to the case of large n, when we are essentially dealing with a linear chain with Born-von Karman periodicity condition. The most important result obtained is that the energy depression per electron (a measure for the effectiveness of the method to take into account electron correlation) decreases only slowly with increasing n and approaches a limit in the neighborhood of 0.4 ev. Hence the AMO method is useful even in the case of large systems and may provide a powerful tool for tackling certain problems in solid-state theory. A detailed discussion is given of the various approximations incorporated in our analysis and a critical comparison is made with some related results recently obtained by other investigators.
Thermal Isomerization of Isopropyl-1,1,1-d3 Radicals
Authors: Jackson W. M. , McNesby J. R.
Published: January 2005

The unimolecular isomerization of isopropyl radicals was investigated by studying the thermal decomposition of pure CD3CH2CH3 from 472° to 553°C. Isomerization of CD3CHCH3, was detected by measuring CD2CHD formed from the isomerized radical. The net result of isomerization is reaction (14). (14)CH3CHCH3→[CH3CH2CH2]→C2H4+CH3,(15)CH3CHCH3→CH3CH=CH2+H.

It is found that isomerization of isopropyl up to 500°C proceeds at a rate, relative to decomposition via reaction (15), which can be described by k14/k15≤0.07. A mechanism which produces methyl and ethylene directly without intermediate isomerization gives k14/k15≤0.04 at 500°C. Contrary to other published estimates of k14/k15, the latter shows no downward trend with increasing temperature.
Vibrational Excitons. II. Degenerate Vibrations
Authors: Hexter R. M.
Published: January 2005

The energy of the first vibrational excited state of a molecular crystal is derived in terms of exciton theory, for the special case of an exciton state derived from a doubly degenerate molecular excited state. We also treat the case where the degeneracy is lost due to the anisotropic environment of the molecule in the crystal. From the several allowed values of such energies, the correlation field splittings in such bands are derived in terms of three-dimensional ``chain sums.'' The origin of such splittings in certain cubic crystals is traced to the intermolecular exchange of the sense of vibrational angular momentum. An expression is also derived for ``site splittings,'' observable in solid solutions of molecules in their isotopically substituted modifications. A new interpretation of such splittings is offered. Finally, the effects of isotopic substitution in such crystals are discussed and several rules of isotopic invariance are derived. An appendix is included which treats as an example the vibrational fundamentals of crystal benzene derived from the e1u molecular modes.
Crystal and Molecular Structure of Triethylscarphane
Authors: Margulis T. N. , Templeton David H.
Published: January 2005

The crystal structure of triethylscarphane, the compound formed upon addition of CS2 to P (C2H5)3, has been determined from three-dimensional x-ray diffraction data. The structure is monoclinic, space group P21/n, with a=7.50±0.02, b=11.97±0.02, and c=11.58±0.05 A; β=90.2°, Z=4. The compound is not a loose molecular complex but rather a zwitterion of a quaternary phosphonium derivative of dithioformate, (CH3CH2)3P+–CSS—. The phosphorus atom is bound nearly tetrahedrally to four carbon atoms (three from the ethyl groups and one from the CS2) with bond lengths averaging 1.80 A. The carbon-sulfur bonds average 1.69 A and the S–C–S bond angle is 128.0°. Uncertainties are about 0.03 A for bond lengths and about 2° for bond angles.
Structure of the Hydrogen-Bonded Water Molecule in Crystals
Authors: Chidambaram R.
Published: January 2005

A correlation of the structural data on 15 hydrates obtained by x-ray diffraction, neutron diffraction, and proton magnetic resonance reveals that when a water molecule is hydrogen bonded into a crystal structure and the angle subtended at the donor water oxygen by the acceptor atoms deviates from the vapor H–O–H angle, bent hydrogen bonds are formed in preference to distortion of the H–O–H angle. Theoretical justification for this result is obtained from energy considerations by calculating the energy of formation of bent hydrogen bonds on the basis of the Lippincott—Schroeder potential function model for the hydrogen bond and the energy of deformation of the H–O–H angle from spectroscopic force constants.
Hydrostatics in Various Gravitational Fields
Authors: Li Ta
Published: January 2005

A closed axisymmetric container placed in a gravitational field is partially filled with a liquid. The stable configuration of the liquid—vapor interface is determined by minimizing the sum of the potential energy and the surface energies.

It is found that the Dupré—Young equation is an immediate consequence of the terminal condition of an isoperimetric problem, and that it is valid in all gravitational fields. Because of this fact, the initial radius of curvature of the liquid—vapor interface and the initial value of this interface which appeared as parameters in the solutions of the capillary equation of Gauss—Laplace—Young, derived from the isoperimetric problem, are expressed as functions of the radius of intersection of the interfaces.

The radius of the intersection of the liquid—vapor interface and the vapor—solid interface is evaluated by considering the vapor-to-tank volume ratio. Thus, the stable configuration is unique, once the form of the container, the contact angle, the volume ratio, and the gravitational field are given.
Microwave Investigation of Cyclopentene
Authors: Rathjens George W.
Published: January 2005

The microwave spectra of cyclopentene has been investigated. Q-branch assignments have been made for the ground and the first four vibrationally excited states; R-branch assignments have been made for the ground and first excited vibrational state. B-type transitions only were observed. The dipole moment was determined to be 0.22±.015 debye (ground state). From a consideration of the rotational constants for the ground and first excited state, the Stark effect, the comparative intensities of lines in the vibrationally excited states with similarly assigned lines in the ground state, and comparison of the measured and calculated entropy it is concluded that the potential function for the out-of-plane bending of the carbon skeleton has a double minimum with a low barrier (probably about 200 cm-1 high). In the ground state the expectation value for the dihedral angle between the two skeletal planes is computed to be 22°16′.