bluuebunny/crossref_metadata_2025 huggingface dataset:
Direct Determination of Exciton Interactions for Triplet States of Organic Crystals
Authors: Nieman G. C. , Robinson G. W.
Published: January 2005

A method is described which allows the direct measurement of triplet exciton interactions in organic π-electron crystals. As we have pointed out in earlier papers, rapid triplet—triplet annihilation prevents the observation of emission from the triplet state in pure crystals of these molecules. Use of isotopic mixed crystals which retard the annihilation process, combined with what can be called the method of variation of energy denominators, allows an experimental value of the interaction matrix element to be obtained. Application of these methods to dilute mixed crystals of C6H6 in C6D6, C6H3D3, and C6H4D2 gives 12±1 cm—1 for the nearest neighbor, ``pair'' interaction matrix element in crystalline benzene. This value is in good agreement with an earlier lower limit of 8 cm—1 obtained from excitation-transfer studies in these crystals. The relationship between the matrix element and the triplet exciton band structure in pure crystalline benzene is discussed, and it is noted that the triplet factor group splitting in crystalline aromatics is likely of sufficient magnitude to be easily observed in the absorption spectrum of such systems. Application of the methods to the lowest singlet exciton band of crystalline C6H6 indicates that the commonly accepted analysis of the factor group splitting is probably incorrect. Barring quenching mechanisms, the relatively large triplet exciton interaction allows roughly 1012 nearest-neighbor triplet excitation transfer transitions to occur per triplet-state lifetime in aggregates of these molecules, a fact which should have important bearing on energy transfer in chemical and biological systems.
Trapping and Energy Transfer in Atomic Collisions with a Crystal Surface. II. Impurities
Authors: McCarroll Bruce
Published: January 2005

The influence of surface impurities and internal impurities on (1) atomic condensation on a solid, (2) equilibration of the newly captured atom with the solid, and (3) the accommodation coefficient, are examined through calculations with a one-dimensional semi-infinite analog in the harmonic approximation. The general equation for the semi-infinite lattice (arbitrary composition) and impinging gas atom are specialized to (1) a pure lattice with a surface impurity (variable mass and bonding) and (2) a pure lattice with a defective third atom (variable mass and bonding).

For the surface impurity: a decrease in coupling K1 decreases the condensation efficiency. Decreasing either the mass M1 or K1 decreases the rate of thermalization of a captured atom. There is a maximum in the condensation efficiency when M1 is varied. Light surface atoms do increase the accommodation coefficient.

For the internal impurity: a weakening of impurity bonding decreases both trapping efficiency and rate of thermalization. Light impurities decrease the condensation efficiency, but increase the thermalization rate. The effect of the internal impurity on the accommodation coefficient is negligible.
Metastable Transitions in Mass Spectra of Methane and the Deuteromethanes
Authors: Dibeler Vernon H. , Rosenstock Henry M.
Published: January 2005

The mass spectra of methane and the deuteromethanes have been carefully studied to determine whether any parent-ion metastable transitions occur. The only transition found is CD4+→CD3++D. All other species yield only collision-induced dissociations. Approximate appearance-potential studies indicate that this transition occurs from the CD4+ ion in the group of lowest-lying electronic levels which are produced by Jahn—Teller splitting of the nominally degenerate ground state. Some implications of this unusual isotope effect are discussed.
Time-of-Flight Investigations of Electron Transport in Gases
Authors: Hurst G. S. , O'Kelly L. B. , Wagner E. B. , Stockdale J. A.
Published: January 2005

Electron swarm experiments may be arranged to satisfy the boundary conditions applicable to a one-dimensional time-dependent transport equation. Under such conditions it may be shown that the distribution of the time-of-arrival of individual electrons at a point on a plane which is L cm from another plane releasing electrons at time t=0 may be interpreted in terms of the diffusion coefficient D and the drift velocity w. The integrals of the distribution functions, i.e., the total numbers of electrons arriving, before and after the addition of an attaching gas, are directly related to the attachment coefficient, β. Since, in such experiments, time is a more accessible independent variable than is length, it is not surprising that much more information on the basic character of electron transport in gases is obtained than can be obtained from a Townsend experiment. Results for values of D, and w as a function of E/P are given for C2H4 and CO2.
Pressure-Induced Shifts of Molecular Lines in Emission and in Absorption
Authors: Jaffe J. H. , Friedmann H. , Hirshfeld M. A. , Ben-Reuven A.
Published: January 2005

Pressure-induced shifts of lines in the 2–0 band of HCl have been measured both in emission and in absorption. Within the accuracy of the measurements, no consistent difference between absorption and emission was found. The result casts doubt on the validity of some static theories of line shape in their present form.
Analysis of the Electronic Spectra of Neodymium Ethylsulfate
Authors: Gruber John B. , Satten Robert A.
Published: January 2005

The polarized absorption spectra of single crystals of neodymium ethylsulfate [Nd(C2H5SO4)3·9H2O] have been studied between 11 000 cm—1 and 28 500 cm—1 at 77° and at 4.2°K. From the 77°K polarized absorption spectrum of crystals of different thicknesses, it is possible to identify transitions from all the Stark components of the ground level 4I9/2 to many of the Stark components of excited SLJ levels of the 4f3 configuration. The electronic transitions particularly of the 4I9/2 ground level are reliably singled out from among vibronic transitions. The experimental assignment based on selection rules and the number of transitions observed is further verified by a comparison of the experimental levels with the ``free-ion'' spectrum predicted on the basis of the parameters F2=331.33 cm—1, F4=47.956 cm—1, F6=5.313 cm—1, and ζ=880.11 cm—1.

A first-order crystalline-field splitting calculation based on the parameters B20=58.4 cm—1, B40=—68.2 cm—1, B60=—42.7 cm—1, and B66=595 cm—1 gives a predicted splitting to within a mean deviation of 4 cm—1.
Photolysis of Aqueous Nitrite Solution Containing Mercuric Salts
Authors: Shinohara Kenichi , Shida Tadamasa , Saito Nobufusa
Published: January 2005

Photolysis of aqueous sodium nitrite plus mercuric salt solutions has been studied with a high-pressure mercury lamp. The irradiation of mercuric salt solution does not give any noticeable amount of mercurous salt whereas the admixture of sodium nitrite and mercuric salt does.

Two possible explanations are suggested for the reduction of mercuric salt; one is that the absorption of light quantum by nitrite ions induces electron transfer from the ions to water molecules in the hydration shell and that the expanded electron of the excited ions reduce mercuric to mercurous. An alternative is that nitrite ions are excited to their low-lying electronic states in which they can reduce mercuric salts directly.
Raman Spectral Studies of Aqueous Solutions of Selenic Acid
Authors: Walrafen G. E.
Published: January 2005

Relative integrated Raman intensities of aqueous solutions of selenic acid have provided concentrations of the species H2SeO4, HSeO4—, and SeO42—. When water is added to supercooled selenic acid at 25°C, the molecular H2SeO4 concentration, [H2SeO4], which is approximately 18 mole liter—1 in the pure acid, decreases rapidly and approaches zero, as the stoichiometric concentration of selenic acid, CH2SeO4, approaches 11–12M. Simultaneously, the HSeO4— concentration, [HSeO4—], increases, but it falls below the stoichiometric water molarity CH2O as dilution progresses. When CH2SeO4 = CH2O = 14.5M, [HSeO4—]<CH2O, indicating that the reaction H2SeO4+H2O = HSeO4—+OH3+ is incomplete. With further dilution, [HSeO4—] attains a maximum value of about 12.9 mole liter—1, at CH2SeO4 = 13.5M, and near CH2SeO4 = 11–12M, where [H2SeO4]≈0, the absence of intense characteristic Raman lines of SeO42— indicates that [H2SeO4—]≈[OH3+]. Below CH2SeO4 = 11–12M, Raman lines of SeO42— appear, as [HSeO4—] continues to decrease. When CH2SeO4 has decreased to approximately 4.2M, [SeO42—] attains a maximum value of about 0.91 mole liter—1, and the concentration at which [SeO42—] is maximal, compares favorably with the concentration corresponding to a maximum in the electrical conductivity, CH2SeO4 = 3.7M.

Fundamental vibrational frequencies of H2SeO4, HSeO4—, and SeO42— have been assigned according to structures of C2v, Cs, and Td symmetry, respectively, and those assignments are compared with vibrational assignments of the closely related species H2SO4, HSO4—, and SO42—. Other comparisons between Raman spectra of nearly pure selenic and sulfuric acids, however, reveal additional frequencies at 932 and ∼1200 cm—1, respectively, produced by intermolecular vibrations. Such additional vibrations suggest the existence of extended, strongly hydrogen-bonded networks, in which symmetric vibrations of the SeO2 or SO2 groups of individual H2SeO4 or H2SO4 molecules are out-of-phase in neighboring molecules. In addition, another frequency of aqueous solutions of selenic acid at ∼800 cm—1, obtained from careful analysis of band contours, presumably is also produced by intermolecular vibrations between OH3+ and HSeO4—, in accordance with the low electrical conductivity and the high viscosity of solutions in which those ions are predominant.
Continuous Representations in the Statistical Theory of Electronic Energies
Authors: Golden Sidney , Handler George S.
Published: January 2005

The use of continuous bases of representation other than a plane-wave basis is considered in the theory developed originally by Thomas and Fermi. The bases considered here are the sets of eigenfunctions of Hamiltonians corresponding to a particle subjected to a field of force which varies inversely as the cube of the distance to some fixed point. Variation of the strength of the interaction varies the basis continuously. Calculations of the energy of the hydrogen atom is carried out, with results that are appreciably closer to the quantum-mechanical result than is obtained with the original Thomas—Fermi theory. Numerical results suggest the possible existence of a statistical analog of the Rayleigh—Ritz variation principle.
On the Kinetic Theory of Dense Fluids. XIV. Experimental and Theoretical Studies of Thermal Conductivity in Liquid Ar, Kr, Xe, and CH4
Authors: Ikenberry Lynn D. , Rice Stuart A.
Published: January 2005

In this paper we report experimental and theoretical studies of the thermal conductivity of liquid Ar, Kr, Xe, and CH4, in the temperature range 90°—235°K and the pressure range 1–500 atm. It is found that: (a) The magnitude, the temperature dependence, and the pressure dependence of the thermal conductivity all decrease in the following order: CH4, Ar, Kr, Xe. (b) The gross behavior of the coefficient of thermal conductivity is the inverse of the behavior of the self-diffusion coefficient: κ increases (whereas D decreases) as the pressure increases along an isotherm and κ decreases (whereas D increases) as the temperature increases along an isobar. (c) The statistical theory of Rice and Allnatt leads to easily interpreted analytic formulas for the coefficient of thermal conductivity. (d) The theory of Rice and Allnatt leads to predictions in quantitative agreement with experiment.

The importance of accurate pair correlation functions, the relative roles of strong repulsive and soft attractive potentials, and implications of the Rice—Allnatt theory are briefly discussed.
Interpretation of Ion Yields in Binary Mixtures
Authors: Klots Cornelius E.
Published: January 2005

A formal interpretation of ion-yield measurements in binary gaseous mixtures is given in terms of net constituent stopping powers averaged throughout the prevailing degradation spectrum. Subsequent inelastic bimolecular collisions as a source of ionization are not considered. Previously observed regularities in ion yields are consistent with the notion of a typical degradation spectral distribution, a function only of the radiation source. ``Deviations'' from additive-mixture laws then stem from an oversimplified concept of additivity. An application to the energy-partition problem in radiation chemistry follows from the formalism.
Effect of Electric Field Strength on the Gamma-Radiation-Induced Conductance of Liquid Alkanes
Authors: Freeman G. R.
Published: January 2005

The γ-radiation-induced conductance of liquid alkanes has been studied as a function of electric field strength, irradiation dose rate, and temperature over wide ranges. The conductance at fields below about 102 V/cm seems to be governed by electrode processes, but is not understood. The conductance at fields between about 102 and 103 V/cm was explained earlier [G. R. Freeman, J. Chem. Phys. 39, 978 (1963)]. A theory developed by Onsager has been extended to explain the results at fields greater than 103 V/cm. It appears that the number of electrons that escape their parent ions or spurs increases markedly with increasing field strength at high fields, but is nearly independent of temperature.
Ion—Molecule Reactions in Gaseous Ammonia
Authors: Derwish G. A. W. , Galli A. , Giardini-Guidoni A. , Volpi G. G.
Published: January 2005

Ion—molecule reactions in gaseous ammonia have been studied up to 0.065 Torr in the ion source of the mass spectrometer. Besides the primary ions NH3+, NH2+, NH+, N+, the following secondary ions NH4+, N2H5+, N2H4+, N2H3+, N2H2+, and N2H+ have been observed. Appearance-potential data and pressure-dependence studies have allowed the parent—daughter relationship and the cross sections of the pertinent reactions to be determined.
Low-Temperature Limiting Behavior of Gas Imperfections Due to Gas—Solid Interactions
Authors: Hansen Robert S. , Murphy James A.
Published: January 2005

An asymptotic form for the low temperature limiting behavior of the gas imperfection due to gas—solid interaction is derived. When ln{T−12lim lim P→0[(NkT/P)−V]}is plotted against 1/T it is shown that the plot must approach linearity at low T, and expressions for calculating the deviations of the plot from its limiting tangent at higher temperatures are presented. The slope of the limiting tangent depends only on the depth of the minimum in a plot of potential energy for gas—solid interaction against distance (and not on the shape of the potential energy curve). The intercept (at 1/T=0) of the limiting tangent depends principally on the surface area of the solid and the curvature of the potential energy plot at its minimum; neither of these quantities can be inferred from the intercept unless the other is known. The inference of potential energy forms from gas imperfection data is briefly discussed in the light of the asymptotic form developed.
Internal Conversion from Upper Electronic States to the First Excited Singlet State of Benzene, Toluene, p-Xylene, and Mesitylene
Authors: Braun Charles L. , Kato Shunji , Lipsky Sanford
Published: January 2005

The variation with excitation wavelength of the fluorescence efficiencies of some alkyl benzenes has been studied from 2700 to 1600 Å. Measurements have been made in both liquid (pure and dilute solution) and vapor phases. For pure liquids the internal conversion efficiency βλ from upper electronic states to the first excited singlet state has been found to be significantly less than unity and to increase in the order benzene, toluene, p-xylene, mesitylene when comparisons of βλ are made at comparable excitation wavelengths. Solvent effects on βλ have been noted. No emission is observed from any alkyl benzene studied in the vapor phase for excitations beginning on the long-wavelength side of the second absorption band and extending to shorter wavelengths.

Dissociation, internal conversion to the ground state, and intersystem crossing to a triplet state are considered as mechanisms for the disappearance of the upper electronic singlet states. Measurements of the benzene-sensitized phosphorescence of biacetyl indicate that if the disappearance mechanism involves upper-level intersystem crossing to the triplet manifold, then the triplets so produced do not efficiently internally convert to the lowest triplet state.
Studies with a Single-Pulse Shock Tube. II. The Thermal Decomposition of Perfluorocyclobutane
Authors: Lifshitz Assa , Carroll H. F. , Bauer S. H.
Published: January 2005

The thermal decomposition of perfluorocyclobutane was studied behind reflected shocks in a single-pulse shock tube over the temperature range 1040°—1200°K. Mixtures of approximately 1% to 1.5% of perfluorocyclobutane in argon were used. The reaction products were analyzed by vapor-phase chromatography. The first-order rate constants obtained at high temperatures are slightly higher than the values deduced from an Arrhenius extrapolation of the low-temperature data; however, the activation energy is the same. The rate constant is: kuni∞=2.1×1016 exp[—74.3×103/RT].
Evaporation Mechanism and Vapor Composition
Authors: Jepsen D. W. , Somorjai G. A.
Published: January 2005

A number of substances are known to evaporate simultaneously into monomers, dimers, and higher polymeric species in the gas phase. For many of these systems the evaporation is expected to be limited by a surface reaction which precedes desorption. A method is given for determining from experiments whether the various species are evaporated independently. The experiments which will define the evaporation mechanism measure the variation of the evaporation rates with the size of the orifice of the evaporation chamber.
Energy Levels of Yb3+ in Garnets
Authors: Wood D. L.
Published: January 2005

The absorption and fluorescence of Yb3+ in yttrium gallium garnet and yttrium aluminum garnet have been investigated to locate the levels of the ground manifold 2F7/2. From the temperature dependence of absorption in the gallium compound, it is concluded that the levels lie at 0, 112, 308, and 550 cm—1. For the aluminum garnet, the fluorescence spectrum can be interpreted in terms of a ground manifold with levels at 0, 140, 490, and 620 cm—1.
Antiferromagnetism of UO2·2H2O
Authors: Pankey Titus , Senftle Frank E. , Cuttitta Frank
Published: January 2005

Magnetic susceptibility measurements have been made on UO2·xH2O for x=1.78 to x=2.13, and from 77° to 375°K. As the value of x decreased the susceptibility increased. Both these data and structural arguments imply that the formula of this compound is U(OH)4 rather than the dihydrate form. Based on this concept the data have been corrected for diamagnetism and also small amounts of UO2 and H2O which were present. The molar susceptibility of U4+ in U(OH)4 is nearly an order of magnitude less than in other uranium compounds, and it is suggested that this is probably due to superexchange between adjacent uranium atoms through intervening oxygen atoms.
Fragmentation of the Excited Parent Ions, [CH3Kr82]+ and [CH3O18]—, Following the β— Decay of CH3Br82 and the β+ Decay of CH3F18
Authors: Carlson Thomas A. , White R. Milford
Published: January 2005

The relative abundances of the fragment ions that result, respectively, from the β— decay of CH3Br82 and β+ decay of CH3F18 have been measured with a specially designed mass spectrometer. Following the β— decay of CH3Br82, only about 0.4% of the parent ion, CH3Kr+, remained intact, as was anticipated from the rather large recoil energy. The most abundant ion observed was CH3+, 89%. A variety of other ions were also formed and their production is discussed in terms of excitation resulting from a sudden change in nuclear charge. The investigation of the fragment ions formed in the decay of CH3F18 marks the first time a molecule undergoing positron decay has been so studied. The following negative ions were detected: CH3O—, O—, and H—. A large abundance of positive ions, however, was also observed. The origin of these positive ions is critically discussed; and calculations of the probabilities for electron shakeoff following both positron and negatron decay are given for several atomic systems.
Rate of Exchange of Halide Nuclei with Mercury (II) in Aqueous Solution
Authors: O'Reilly D. E. , Schacher G. E. , Schug K.
Published: January 2005

Linewidths ΔHms of the I127 nuclear magnetic resonance of water solutions of KI in the presence of varying amounts of HgII have been measured at temperatures in the range 273° to 373°K. At constant [I—], ΔHms depends linearly on the concentration of HgII: ΔHms=kms[HgII], where kms ranges from 1.9×103 G M—1 at [I—]=4.0M to 3.7×105 G M—1 at [I—]=0.005M (300°K). By means of the modified Bloch equations the results may be interpreted as due to a rapid exchange of iodine nuclei among the species I—, HgI42—, and HgI3(OH2)—. Broadening of the I127 nuclear magnetic resonance is produced by relatively short relaxation times of I127 in the mercury complexes; T2(I—)=1.7×10—4 sec, T2(HgI42—)=1.1×10—7 sec (300°K). Biomolecular rate constants for the following exchange reactions have been obtained: HgI42−+I−→ lim k1I−+HgI42−,HgI3(OH2)−+I−→ lim k2I−+HgI3(OH2)−,HgI3(OH2)−+I−→ lim k3H2O+HgI42−.At 300°K, k1=8.8×107M—1 sec—1, k2=5.7×109M—1 sec—1, and k3=7.1×108M—1 sec—1, ΔE1‡=1.8±0.6 kcal mole—1.

The rates appear to be diffusion limited and may be interpreted by an appropriate solution of the Smoluchowski diffusion equation. Similar but less extensive measurements have been made on KBr solutions containing added HgBr2. Again exchange appears to be diffusion controlled and T2(HgBr42—) is much shorter than T2(Br—).

The relatively small value of k1 is attributed to a negative entropy of activation associated with dielectric polarization of the solvent by the ions involved.

The observed relaxation rate of I127 in HgI42— combined with an estimate of the quadrupolar coupling constant of I127 in solid K2HgI4 allows an estimation of the rotational correlation time τc of HgI42— in solution, which at 25°C is equal to 1.4×10—11 sec. This time is a factor of six shorter than estimated from the Debye expression for τc.
Raman Spectrum and Vibrational Assignment for Molten Thallous Nitrate
Authors: Janz G. J. , Kozlowski T. R. , Wait S. C.
Published: January 2005

The Raman data for TlNO3 (mp 206°C) in the pure molten state are: 1036 (10, p), 1328 (3.3, dp), 1383 (3.9, dp), and 1637 (2.5) cm—1, and two relatively low frequencies, 708 (1.3) and 813 (1.7) cm—1. The results are examined in light of the vibrational assignments for D3h and C2v point group symmetries in solid-state nitrates, and for D3h symmetry for related nitrates in the molten state. An assignment of the Raman activity of molten TlNO3 based on retention of D3h symmetry is advanced; the appearance of the Raman ``forbidden'' frequencies (v2) and the loss of degeneracy (v3) are attributed to cationic environmental effects in this molten salt.
Role of Hydrodynamic Interaction in the Diffusion of n-Alkanes in Carbon Tetrachloride
Authors: Dewan R. K. , Van Holde K. E.
Published: January 2005

The diffusion coefficients of a series of normal paraffins in carbon tetrachloride have been determined by the Rayleigh interferometric method. The dependence of the frictional coefficient on chain length has been examined in terms of a theory which takes into account the hydrodynamic interaction between segments of the diffusing molecule. If average intersegment distances are calculated on the basis of simple models, values for frictional coefficients are predicted which are in good agreement with the experimental results.
Radial Limit in the Configuration-Interaction Method for the 1 1S State of the Helium Isoelectronic Sequence
Authors: Davis H. L.
Published: January 2005

Using the configuration-interaction method with only radial configurations, precise radial limits are obtained for the ground state of the helium isoelectronic sequence for atomic numbers 1 thru 20. All matrix elements required in the calculation are shown to be obtainable from sums over integers, which eliminates all necessity of any multiple precision arithmetic in the computer calculation. Also, when the atomic number is varied, considerable saving in computer time is achieved by noticing that all Hamiltonian matrix elements are expressible in the form ZηA+η2B+ηC, where Z is the atomic number, η a nonlinear variational parameter, and A, B, and C are sums independent of Z and η.
Electron Spin—Spin Interaction in Higher Molecular Spin Multiplets
Authors: Higuchi Jiro
Published: January 2005

The electron spin—spin interaction in molecular spin multiplets was investigated by classifying the three types, that is n—π, π—π, and n—n interactions. The n—π interaction is usually much greater than the others because of the large atomic contribution which arises from the orbitals being perpendicular to each other. On the other hand, the other types come from only the interatomic interaction. In a multiplet state larger than triplet, the D and E values in general appear as arithmetical averages among the interactions concerned. As an example, the numerical calculation was carried out for two series of m−C6H4(CH)m(CH2)n[m+n=2] and 1,3,5−C6H3(CH)m(CH2)n[m+n=3].
Equilibrium Polymerization under Pressure: The Case of Sulfur
Authors: Eisenberg Adi
Published: January 2005

A previously derived theory of equilibrium polymerization is generalized to take into account the effect of superposed hydrostatic pressure, and the results are applied to the equilibrium polymerization of sulfur. It is shown that the transition which at atmospheric pressure occurs at about 160°C is shifted with pressure toward lower temperatures; at ∼850 atm it intersects the melting line, so that above that pressure sulfur melts to a liquid of high viscosity consisting of S8 rings and diradical terminated chains. The effect of pressure on the equilibrium degree of polymerization and the equilibrium S8 concentration is also discussed.
Testing of Diatomic Potential-Energy Functions by Numerical Methods
Authors: Cashion J. K.
Published: January 2005

An accurate and efficient numerical method of solving the radial Schrödinger equation for a diatomic molecule has been employed in two tests relating to approximate potential functions. First, quantitative estimates have been made of the errors in the approximate eigenvalue equation derived by Pekeris for the rotating Morse oscillator. Secondly, as an example of testing a potential function for which no analytic solution is known, the eigenvalues of the Clinton potential have been compared with those of the Morse and with experiment.
Distribution of Dielectric Relaxation Times in Glycerol— and Butanediol-1,3—n-Propanol Mixtures
Authors: McDuffie G. E. , LaMacchia J. T. , Conord A. E.
Published: January 2005

Dielectric relaxation times and their distribution have been measured in associated—associated mixtures of glycerol—n-propanol and butanediol-1,3—n-propanol. Measurements were made at temperatures selected for each concentration so as to give approximately constant relaxation times as a function of concentration. All mixtures exhibited one main relaxation process with a distribution of times of the Davidson—Cole form. The distribution parameter β increased only slightly over the concentration ranges of 0 to 67 mole % n-propanol in the butanediol mixture and 0 to 75 mole % n-propanol in the glycerol mixture. For concentrations above 67 and 75 mole % n-propanol, β increased rapidly to unity as a function of concentration. This behavior of the distribution of dielectric relaxation times is indicative of the influence of structural formation on the dielectric process in these liquid mixtures and demonstrates that the structure is characteristic of the pure glycerol and butanediol-1,3 for concentrations of n-propanol between zero and the values necessary for saturation of the diol and triol molecules. Above 67 and 75 mole %, the structure rapidly takes on the characteristic of the pure n-propanol.
Statistical Mechanical Theory of Double-Layer Structure and Properties
Authors: Buff Frank P. , Stillinger Frank H.
Published: January 2005

The general cluster theory of inhomogeneous fluids is applied to the determination of ion and mean potential distributions in the interfacial region between electrolytic solutions and metallic electrodes (specifically mercury), as well as in colloidal suspensions. The relevant electrostatic problem involving distinct inner and outer Helmholtz regions is solved in closed form. Summation of the linearized cyclic clusters appropriate to dilute solutions demonstrates for the first time the limitations of local Debye—Hückel activity corrections in the method called ``local thermodynamic balance.'' An explicit adsorption isotherm formalism results from proper treatment of cluster vertices confined to the inner Helmholtz plane; this permits proper deduction of the ``discreteness-of-charge'' effect, as well as nonelectrostatic ion size effects in this plane. It is furthermore shown that accounting for ion size to lowest order in the diffuse layer necessarily contradicts the local thermodynamic balance approach. The systematic cluster theory formulation of the colloid stability problem also suggests hitherto unused corrections to the relevant double-layer free energies.
PbO Solid Electrolyte Voltaic Cell
Authors: Laws Kenneth L.
Published: January 2005

When lead is anodized in sulfuric acid at a constant ``half cell'' potential of 1.21 V with respect to hydrogen, an oriented film of tetragonal lead monoxide forms on the surface. If electrical contact is made to the dried surface of the resulting PbO, an open circuit voltage of about 0.5 V is found to exist between this contact and the lead substrate. The current is a nonlinear function of the voltage between the surface contact and the lead. The short-circuit current and open-circuit voltage depend on the atmosphere over the cell; the former is of the order of 1 μA in air saturated with water vapor, dropping by about four orders of magnitude after several days in vacuo. As the cell is dried, these quantities become increasingly dependent on the intensity of visible illumination, the current rising by as much as three orders of magnitude under intense illumination, and the voltage rising by about 0.2 V. The resistance of the cell to steady current flowing in a direction opposite to normal discharge is smaller than the discharge resistance, and varies only slightly with atmospheric conditions. The capacitance of the cell as measured at high frequencies corresponds to that expected for a parallel plate capacitor of thickness equal to the thickness of the cell. At lower frequencies, the capacitance is greater. A theory for the mechanism of the cell involves a diffusion of oxygen vacancies through the PbO, with the oxidation of lead to lead monoxide at the Pb/PbO interface furnishing the energy for the cell.
Transpiration and Mass Spectrometric Studies of Equilibria Involving BOF(g) and (BOF)3(g)
Authors: Hildenbrand Donald L. , Theard Lowell P. , Saul Albert M.
Published: January 2005

The reaction of BF3(g) with B2O3(l) was studied by the transpiration method in the temperature range 600° to 1100°K. Results indicate the reaction to be BF3(g)+B2O3(l)=(BOF)3(g).ΔH298° was found to be 4.2 kcal, and leads to ΔHf298°=—566.8±1 kcal/mole for (BOF)3(g).

The vapor above mixtures of MgF2 and B2O3 contained in a Knudsen cell was analyzed with a mass spectrometer and was found to contain BF3(g), (BOF)3(g), and BOF(g) in the range 980° to 1230°K. From studies of the temperature dependence of appropriate ion intensities the heat of the reaction (BOF)3(g)=3BOF(g)was derived as 131 kcal at 1125°K. Use of low ionizing electron energies was required to avoid fragmentation effects. The heat of formation of BOF(g) at 298°K was calculated to be —144±3 kcal/mole.
NMR Study of the Alkali Hexafluorophosphates' Dynamic Structure
Authors: Miller Gerald R. , Gutowsky H. S.
Published: January 2005

The fluorine nuclear magnetic resonance spectra of the sodium, potassium, rubidium, and cesium hexafluorophosphates were studied between 77° and 400°K. It was found that in each of the salts the PF6—ions are reorienting about the octahedral axes at random, or nearly so, for temperatures of 200°K and above. The broadening of the fluorine resonance in these solids at lower temperatures indicates that the ease with which the PF6— groups reorient increases with increasing size of the alkali metal cation, so that for CsPF6 the fluorine resonance is still narrow at 77°K. A quantitative study of the potential barriers to PF6— group reorientation was discouraged by the discovery that the fluorine line shapes and linewidths are remarkably sensitive to the physical state and, in the case of RbPF6, the thermal history of the sample. These effects are attributed to crystal imperfections which lower the potential barriers to PF6— group reorientations and decrease the size of domains in which there is a cooperative ``freezing out'' of the reorientations. Thus, in the region of changing linewidth, we postulate domains with frozen-out PF6— groups and others with reorienting groups. In samples which should have relatively low imperfection concentrations and where such domains should be large, we find distinguishable broad and narrow components in the fluorine resonance, with one growing at the expense of the other as the temperature is changed. This two-phase behavior disappears in finely powdered samples, in which high concentrations of imperfections were probably introduced by the mechanical grinding. Fluorine line-shape studies reported previously for solid CF4 are reinterpreted in terms of a similar two-phase, cooperative process for the freezing out of the CF4 reorientations.
NMR Study of the Protolysis Kinetics in Simple Amino Acids. II. Sarcosine (the Zwitterion Form)
Authors: Sheinblatt M.
Published: January 2005

The mean lifetime of the amino group τ of aqueous solutions of sarcosine in the zwitterion form was measured using the NMR technique at 21°±1°C. The zwitterion can participate in the following exchange reactions: CH3NH2+CH2COO−+H2O⇌ lim kICH3NHCH2COO−+H3+O,CH3NH2+CH2COO−+OH−⇌ lim kIICH3NHCH2COO−+H2O,CH3NH2+CH2COO−⇌ lim kIIICH3NHCH2COOH (intramolecular),CH3NH2+CH2COO−+CH3NH2+CH2COO−⇌ lim kIVCH3NHCH2COO−+CH3NH2+CH2COOH (intermolecular),CH3NH2+CH2COO−+CH3NHCH2COO−⇌ lim kVCH3NHCH2COO−+CH3NH2+CH2COO−,CH3NH2+CH2COO−+CH3NHCH2COOH⇌ lim kVICH3NHCH2COO−+CH3NH2+CH2COOH.From the experimental results, i.e., the dependence of 1/τ on 1/aH+ and the concentration of the amino acids, the following rate constants were determined: kV=1,5×108 (sec−1 M−1),  kII=4×1010 (sec−1 M−1),kI[H2O]+kIII=80 (sec−1),and kIV+(kVI/K4)=145 (sec−1 M−1).

Discussing and comparing the above rate constants with the rate constants for similar reactions enables one to estimate the value of each of the rate constants given as a sum.
Fluorescence of Naphthacene Vapor
Authors: Williams R. , Goldsmith G. J.
Published: January 2005

The absorption spectrum of naphthacene vapor is similar to that in solution. There is an absorption band with pronounced vibrational structure running from about 5000 to 3500 Å and a second stronger band from 2700 Å to shorter wavelengths. We have examined the fluorescence spectrum of the vapor at low pressures, such that molecules have no collisions during the lifetime of the excited state. By selective excitation with either the 3650 Å line or the 2537 Å line of the mercury lamp it is possible to excite molecules into either the first excited singlet state or into the second excited singlet state. The fluorescence emission appears to be from the first excited singlet state in both cases even though the molecules suffer no intermolecular collisions in the excited state.
NMR Shift and Diffusion Study of Electrolytes in 50% Dioxane—Water Mixtures
Authors: Fratiello Anthony , Douglass Dean C.
Published: January 2005

High-resolution chemical shift measurements were carried out on electrolytic solutions in 50% dioxane—water mixtures. Whereas the water proton resonance position was displaced significantly by the addition of electrolyte, the dioxane signal in all mixtures remained unperturbed. Further, the results, particularly those obtained with chloride solutions of the small or highly charged Be, La, and Th ions indicated that strong selective solvation of cations by the water was occurring. This conclusion was substantiated by differences in the dioxane and the water linewidths observed in several solutions, including those of paramagnetic salts.

Self-diffusion coefficients of dioxane in these electrolytic mixtures were also measured by the nuclear magnetic resonance spin-echo technique. The observed diffusion data could be interpreted solely on a hydrodynamical basis, again indicating that no significant interaction was occurring between dioxane and the added electrolyte.
Geometry of the Alkaline-Earth Dihalides
Authors: Wharton L. , Berg R. A. , Klemperer W.
Published: January 2005

It has been shown by the deflection of beams of alkaline-earth dihalide molecules by inhomogeneous electric fields that the following compounds have permanent electric dipole moments and are therefore assumed bent: BaF2, BaCl2, BaBr2, BaI2, SrF2, SrCl2, CaF2. No polarity was observed for the following compounds investigated: CaCl2, CaBr2, SrBr2, SrI2. The absence of deflection of beams of BaCl2 by inhomogeneous magnetic fields shows that this molecule has no electronic magnetic moment and hence is in a singlet ground state.
C13–H and X—H Coupling Constants for Compounds of the Type X(CH3)4
Authors: Smith George W.
Published: January 2005

From high-resolution proton magnetic resonance experiments, absolute magnitudes of JC13–H and JX–C–H have been determined for compounds of the type X(CH3)4, where X=Si, Ge, Sn, and Pb. The JC13–H values yield the s characters of the carbon orbitals in the C–H and C—X bonds as well as the Juan—Gutowsky s character affinity ΔX. Rough calculations of JX–C–H based on the Fermi contact term give widely varying results depending on the value of the effective charge used. A straight line correlation of JX–C–H with n3 can be explained crudely on the basis of the Fermi contact term.
Study of Two-Center Integrals Useful in Calculations on Molecular Structure. III. A Unified Treatment of the Hybrid, Coulomb, and One-Electron Integrals
Authors: Ruedenberg Klaus , Roothaan C. C. J. , Jaunzemis Walter
Published: January 2005

The problem of the two-center hybrid integrals is solved in a general way for Slater-type atomic orbitals with integral effective quantum numbers. No other restrictions are placed upon effective quantum numbers and effective nuclear charges. The integrals are expressed linearly in terms of one type of auxiliary functions. A method for finding the coefficients is given, and the latter are computed for all cases involving orbitals with quantum numbers 1 and 2. The auxiliary functions are discussed in detail, and methods given for their computation. The treatment developed for the hybrid integrals is shown to be applicable also to the two-center Coulomb integrals and to the one-electron integrals.
Kinetic Theory of Nonspherical Molecules
Authors: Curtiss C. F.
Published: January 2005

A modification of the Boltzmann equation is described in which the rotational motion of nonspherical molecules is considered classically. This Boltzmann equation leads to equations of continuity, motion, and energy balance similar to the equations applying when the molecules are spherical. An additional equation of change arises, however, because of the conservation of angular momentum in collisions. (When the molecules are spherical, this equation is redundant.) Associated with the additional equation of change, there appears an additional ``macroscopic variable'' related to the local density of angular momentum due to the rotational motion of the molecules and an additional flux vector representing the flux or transport of this angular momentum. The Boltzmann equation is solved by a perturbation method similar to the Chapman-Enskog first approximation, and expressions are obtained for the various flux vectors and transport coefficients. Although the equations of change apply under more general conditions, the present treatment is restricted to molecules which may be idealized as rigid nonspherical bodies in which the center of mass is a center of symmetry.
On Chromic Isomerism in Dianthrone and its Analogs
Authors: Harnik E.
Published: January 2005

Two possible ways in which intramolecular overcrowding in dianthrone can be relieved are shown to lead to two stable, interconvertible molecular configurations, separated by a potential barrier. The two molecular configurations are briefly described. The height of the potential barrier is estimated, and found to agree well with that observed between the two isomers—referred to as chromic isomers—responsible for the thermochromic behavior of dianthrone. It is therefore suggested that the two molecular configurations described are identical with the two chromic isomers, and that this model applies also to analogous compounds. Some observed phenomena are discussed in support of the proposed model.
High-Resistivity Nickel Ferrites—the Effect of Minor Additions of Manganese or Cobalt
Authors: Van Uitert L. G.
Published: January 2005

Nickel ferrite, as ordinarily prepared, has a dc resistivity of 104 to 106 ohm-centimeters. It has been found that by incorporating small amounts of manganese or cobalt, the resistivities can be increased to 1010 or 1011 ohm-centimeters. Presumably, replacing Fe++ or Ni+++ with Mn or Co ions eliminates the easy conduction paths otherwise provided by the former ions. Further work is required to elucidate the exact mechanism.
Absolute Infrared Intensities of Vibration Bands in Ammonia and Phosphine
Authors: McKean D. C. , Schatz P. N.
Published: January 2005

The absolute absorption intensities of the fundamental vibration bands in ammonia and phosphine have been measured. Normal coordinates are calculated for each of the vibrations and the intensities interpreted in terms of bond moments μ and their derivatives ∂μ/∂r.

Values of ∂μ/∂r for the NH and PH bonds in the A1 mode are 0.6 and 1.2 D/A, respectively; in the E mode the corresponding values are 0.2 and 0.8 D/A.

Values of the vibrational bond moments found are 1.0 D (A1) and 0.5 D (E) for the NH bond; 0.7 or 0.5 D (A1) and 1.2 or 0.6 D (E) for the PH bond.

The relation of these vibrational bond moments to the molecular dipole moment and the moment (μu.p.) of the unshared pair of electrons is discussed in detail. After corrections have been applied for changes in magnitude and direction of μu.p. during the vibrations, the results for NH3 are compatible with the following static moments: μNH∼0.7D(H+),μu.p.∼0.7D.The data for PH3 are less internally consistent. ``Likely'' moments, taken from the A1 bending vibration, are μPH∼0.2(H+),  μu.p.∼0.2D.
Microwave Dielectric Constant Measurements
Authors: Magnuson D. W.
Published: January 2005

An improved microwave cavity technique for measuring dielectric constants was used to determine the molar polarization, dipole moment, and nonideality of UF6, freon-114, C4Cl3F7, and C6H6. Nonideality parameters were calculated for ClF3 from previous data.
Free Radicals by Mass Spectrometry. IX. Ionization Potentials of CF3 and CCl3 Radicals and Bond Dissociation Energies in Some Derivatives
Authors: Farmer J. B. , Henderson I. H. S. , Lossing F. P. , Marsden D. G. H.
Published: January 2005

The vertical ionization potentials of CF3 and CCl3 radicals, as measured by electron impact, are 10.10±0.05 and 8.78±0.05 v respectively. From the appearance potentials of the CF3+ and CCl3+ ions from derivatives, the heats of formation of CF3 and CCl3 radicals were found to be —117±2 kcal/mole and +13.4±3 kcal/mole respectively, assuming that no excess energy was included in the appearance potentials. From this data and other heats of formation the following bond dissociation energies (in kcal/mole) have been evaluated: D(CCl3−H)=88.9±3D(CCl3−F)=102±7D(CCl3−Cl)=67.9±3D(CCl3−Br)=49.5±3D(CF3−H)=103±4D(CF3−F)=121±4D(CF3−Cl)=83±3
Electrodiffusion : A Fluctuation Method for Measuring Reaction Rates
Authors: Mysels Karol J.
Published: January 2005

A new approach to the problem of measuring rapid ionic reactions is proposed. It is based on the fact that if a dynamic equilibrium system involves a species changing between two ionic forms at a rapid rate, the times spent by the individual particles in the two forms fluctuate randomly. In an electric field this produces a random walk corresponding to an electrically induced diffusion coefficient. The extent of this electrodiffusion is correlated with the rate of the reaction. It is shown that in principle it is feasible to measure reaction rates down to half-lives of the order of ten milliseconds, and that the use of alternating current, and particularly of reversing direct current, offers distinct advantages.
Growth and Some Properties of a Large Single Crystal of Cadmium Selenide
Authors: Heinz D. M. , Banks E.
Published: January 2005

Large single crystals of cadmium selenide have been grown under high pressures. A 17 gram crystal has been prepared from pure starting materials. This crystal was found to contain a large excess of cadmium, probably varying in concentration through the length of the crystal. Samples cut from the crystal had low resistivities of about 10—2 ohm-centimeters. Hall coefficients indicated that the current carriers were electrons in concentrations of 1017 to 1018 cm—3. The resistivity-temperature curves were characteristic of degenerate semiconductors. Intrinsic conductivity was not observed between —170°C and +100°C.
Characteristic Infrared Bands of Monosubstituted Amides
Authors: Miyazawa Tatsuo , Shimanouchi Takehiko , Mizushima San-ichiro
Published: January 2005

Infrared spectra of various monosubstituted amides and the corresponding deuterated compounds have been measured in the gaseous, liquid, and crystalline states and in solutions. From the experimental results, the bands characteristic of the amide structure have been determined. Furthermore, from the comparison with the spectra of related substances and by the application of the product rule, the assignments of these characteristic bands have been made. The observed change of frequencies of these characteristic bands with change of state confirms this assignment.
Derivation of the WLF Equation for the Mobility of Molecules in Molten Glasses
Authors: Bueche F.
Published: January 2005

A previous theory for the mobility of molecules in glasses near the glass temperature has been extended in an effort to deduce the semiempirical relation proposed by Williams, Landel, and Ferry. By focusing attention upon the free volume, one is able to derive their relation in a straightforward fashion subject to approximations valid near the glass temperature. The interpretation of the constants which WLF proposed for their relation is shown to be correct.
Analysis of the Near Ultraviolet Absorption Spectrum of Pyridine N-Oxide Vapor
Authors: Ito Mitsuo , Mizushima Wataru
Published: January 2005

The near ultraviolet absorption spectrum of pyridine N-oxide vapor was studied under a medium dispersion, and the vibrational analysis was made for the discrete band system near 3300 A. The electronic transition of this system is interpreted as an allowed A1–B2 transition arising from the excitation of a 2p nonbonding electron of the oxygen atom into the unoccupied π orbital.
Use of Interpolation Theory in the Analysis of Gas Adsorption Isotherms. III. Application to Low-Temperature Data
Authors: Honig J. M.
Published: January 2005

To furnish a concrete illustration of the interpolation method, the adsorption of helium on charcoal and of neon on glass in the liquid hydrogen temperature range is analyzed by use of this theory. The interpolation method yields results which are consistent with information on the adsorption data available from other sources.