bluuebunny/crossref_metadata_2025 huggingface dataset:
Type II radio emission predictions: Sources of coronal and interplanetary spectral structure
Authors: Knock S. A. , Cairns Iver H.
Published: January 2005

We extend a model for type II radio bursts to investigate emission from the quiet corona, as well as the emission relating to structures in the corona and interplanetary medium. The most notable effect for the quiet corona is the weakening or disappearance of emission near a peak in the heliocentric Alfvèn speed profile. By inserting various structures into the coronal and interplanetary plasma, most observed type II features are produced. Specifically, multiple‐lane events, differing frequency drift rates, emission which turns on and off, and narrowband and broadband emission can be produced.
Integrated Absorptances of Spectral Line Groups in the 2.7-μ Bands of Hot Water Vapor, Including Effects of Centrifugal Distortion
Authors: Maclay G. Jordan
Published: January 2005

Integrated absorptances of two groups of H2O lines, centered at 3504 cm−1 (principal transition, 11−11←12−12) and 3990 cm−1 (principal transition, 14−14←13−13), were calculated and measured. By matching the calculated and experimental integrated absorptances, we determined the band strength Sν of the asymmetric stretch vibration (ν3) and a vibration—rotation interaction parameter c, where S = Sr (1—cm), and S and Sr are the true and rigid rotator line strengths, respectively. The calculated and measured integrated absorptances at 1273°K agreed to within ±10% when we took Sν as 243±24 cm−1/atm·cm at 273°K and c as 0.0433. Using these parameters, the experimental integrated absorptances for the two groups of lines were successfully predicted to within an average of ±7% for temperatures between 637° and 1630°K.

The value of c determined provides the first quantitative estimate for the intensity perturbation due to the vibration—rotation interaction in the ν3 fundamental of H2O. It predicts that, neglecting the population, a P-branch line and R-branch line with the same J and τ will not have approximately equal intensities (as the rigid rotator predicts), but that for J ≈ 10 the P-branch line will have three times the intensity of the corresponding R-branch line.
Electron Spin Resonance of Cu2+ Ions in Aqueous Solution
Authors: Fujiwara Shizuo , Hayashi Hisaharu
Published: January 2005

Relaxation of ESR of Cu2+ ions is investigated experimentally in aqueous solution. Dependencies of line-widths on Cu2+ concentration, temperature, anion species, and field strength are examined. It is shown that the mechanism via spin—orbit coupling is the main source of relaxation.
Ion—Ion and Ion—Neutral Interactions in Solution and Measurements of Dielectric Constants
Authors: Marcus R. A.
Published: January 2005

Data on dielectric constants of electrolyte solutions are used to evaluate directly the r−4 term in the asymptotic expression for the free energy of interaction of two ions in solution for large separation distance r. Use is made of the fact that for large separations each ion is in a uniform field due to the other, and that information about ions in uniform fields is obtainable from measurements of dielectric constants. For a Z:Z electrolyte, for example, the r−4 term is found to be Z2e2δ/8πε0r4, assuming the effect of overlapping solvent structures to be of shorter range; ε0 is the dielectric constant of the solvent and δ is the measured decrement in dielectric constant per unit concentration of added electrolyte. A similar result obtained when one of the particles is uncharged, δ now referring to the decrement observed when the neutral is added to solution. Typical values of the term are given for various substances using the data on δ's. This determination of the r−4 term permits some evaluation of ion—image force theories.
Excitation of Electronic Levels of Sodium by Vibrationally Excited Nitrogen
Authors: Starr Walter L.
Published: January 2005

The excitation of electronic states of sodium by vibrationally excited nitrogen N2‡ has been demonstrated experimentally. The N2‡ was produced in the afterglow of a microwave discharge in flowing N2. Identification of N2‡ as the source of the sodium excitation was accomplished by the selective removal of N2‡ from the afterglow by deactivation with N2O and by observation of the concurrent disappearance of sodium line emission. It is concluded that the observed excitation is representative of a general phenomenon whereby the electronic states of atoms can be excited by the transfer of vibrational energy from diatomic molecules. The results verify the generally assumed mechanism for the quenching of sodium resonance radiation by nitrogen.
Abstraction of Hydrogen Atoms by Energetic Recoil Tritium Atoms: Correlation with C–H Bond-Dissociation Energies in Hydrocarbons
Authors: Root J. W. , Breckenridge W. , Rowland F. S.
Published: January 2005

The yields of HT from ``hot'' abstraction reactions by energetic tritium atoms reacting with various substances RH have been measured in a large excess of C2D4. The energetic tritium atom fluxes are reasonably similar in such systems and permit comparison of absolute HT yields from different R—H bond types. A more accurate comparison is possible when the HT yields are normalized to the yields of either the hot abstraction or substitution reactions with C2D4. The hot HT yields so measured from hydrocarbons show an excellent correlation with the bond-dissociation energies of the C–H bonds involved, with higher yields from weaker bonds. The abstraction of H from CD3CH2CD3 was favored by approximately 1.4, per bond, over H from CH3CD2CH3.

No significant differences were observed in the DT/C2D3T ratios from reaction with C2D4 in the various mixtures with different substances. A preference of 1.27±0.02 was observed for the abstraction of H from C2H4 vs D from C2D4. No isotopic molecule difference was observed between the energetic addition reaction of tritium atoms to the olefinic position in C2H4 vs C2D4.
Single-Particle Theory for Systems at High Densities. I. Characteristic Reduction Parameters for the Mie—Lennard-Jones Pair Interaction Potential from Zero-Point Crystal Data
Authors: Hillier Ian H. , Islam M. Serajul , Walkley John
Published: January 2005

The energy and length reduction parameters for a 12:6 pair-potential are characterized from the consideration of zero-point crystal data. The crystal is considered to be represented by a single-particle anharmonic Einstein model. This anharmonic potential is considered to be spherically symmetric and is developed according to the cell theory of Lennard-Jones and Devonshire. No further approximations to the form of this potential are required in the evaluation of the energy eigenvalues from the wave equation. Both the Wentzel—Kramers—Brillouin approximation and a more exact finite difference method of evaluating the energy eigenvalues are discussed. The systems examined are argon, neon, deuterium, hydrogen, and helium.
NMR Determinations of Barriers to Internal Rotation in Halogen-Substituted Ethanes
Authors: Newmark Richard A. , Sederholm C. H.
Published: January 2005

The theory of Kaplan and Alexander for exchange in nuclear magnetic resonance (NMR) systems has been applied to exchange between three species with any number of nuclei of spin ½, in which all the nuclei in each species are exchanged by the interconversion. A set of explicit equations for the density matrix elements in this case is written down. Computer programs have been written to solve the equations in the two and three spin cases. The results enable the calculation of NMR spectra of highly coupled nuclei undergoing exchange. Absolute reaction rate theory has been used to express the rates of exchange in terms of activation energies. This has been combined with the Kaplan—Alexander theory to determine the free energies of activation for internal rotation in several halogenated ethanes, CFCl2–CFCl2, CF2Br–CCl2Br, CF2Br–CFBr2, CF2Br–CFBrCl, CFClBr–CFClBr, and CF2Br–CHBrCl. Spectra were calculated assuming limiting values for the transmission coefficient, k≪1, k=1. The first case implies free rotation occurs when a molecule is excited to sufficient energy to exceed the barriers. Alternatively, the second case implies that deactivation of the rotational mode occurs in a time comparable with the rotational frequency. The experimental results on CF2Br–CCl2Br can only be explained by the second possibility. The barriers are discussed in terms of the distortion necessary to form the activated complex in which the substituents are eclipsed.

The low-temperature spectrum of the three rotamers of CF2Br–CHBrCl shows two large vicinal HF coupling constants (18 cps) and four small ones (less than 3 cps). The assignment of the rotamers made assuming that the low barrier observed between two of the rotamers does not involve eclipsing two large halogens indicates that the large coupling constants are trans and the four others are gauche coupling constants.
Theory of Branching Processes and Statistics of Rubber Elasticity
Authors: Dobson G. R. , Gordon M.
Published: January 2005

Recent efforts to reformulate statistical theories of polymeric systems in terms of the theory of branching (``cascade'') processes, are here extended to calculations of statistical parameters for the theory of rubber elasticity, viz., the number and mean length of various forms of active network chains. New simple results are given for random f-functional polycondensation; it is shown that such systems are of interest in rubber elasticity studies in the region just after the gel point, where the concentration of active network chains varies rapidly with conversion, while the mean length of these chains diverges at the gel point. General exact formulas are derived for the random cross linking of arbitrary primary distributions, without assuming that the mean primary chain length is necessarily large; examples are worked out for uniform (homodisperse) chains, random, self-convoluted random, or Poisson primary distributions. Calculations are extended also to the cross-polymerization type of vulcanization reaction attributed to the cure of polybutadiene with peroxides. The results suggest reasons for differences in technical performance observed with such rubbers.
Observations of the Triplet State in Phthalocyanines
Authors: Kosonocky W. F. , Harrison S. E. , Stander R.
Published: January 2005

The triplet-state lifetime of metal-free phthalocyanine has been found to vary from 10−6 sec at room temperature to 150×10−6 sec at 77°K. Decay from the first excited state proceeds via the triplet state. Excitation by a giant-pulse ruby laser completely empties the ground state. Luminescence is quenched in metallic phthalocyanines by the extremely rapid intersystem crossing.
Electronic Structure of CH+
Authors: Moore Patricia L. , Browne J. C. , Matsen F. A.
Published: January 2005

Theoretical potential curves for the lowest 1Σ+, 1Π, 3Π, and 3Σ+ states of CH+ are given. Slater-type orbitals were used as a basis for all wavefunctions. The largest wavefunction used was a 37-term valence bond configuration-interaction wavefunction for the 1Σ+ state. The ground state was established to be 1Σ+ with a rationalized binding energy, DeR, of 3.3 eV. [DeR=E(atoms, calculated) — E(molecules, calculated).] A positive lower bound, DeLB, of 0.4 eV was found for the 1Σ+ state. [DeLB=E-(atoms, experimental) — E(molecule, calculated).] Estimates for the spectroscopic constants of the 1Σ+ states are given. A stable 3Π state lying, about 1 eV above the ground state, was found. Douglas and Herzberg and Douglas and Morton both noted the shallowness of the lowest experimental 1Π state potential curve and the anomalous nature of the vibrational level progression of this state. This effect is probably due to the fact that the stability of the lowest 1Π state results from interaction of the C+(2P) + H(2S) curve with the C(1D) + H+ curve.
Photoionization-Efficiency Curves. II. False and Genuine Structure
Authors: Nicholson A. J. C.
Published: January 2005

Specific examples are given of artifacts in photoionization-efficiency curves that result from the use of a discrete-line light source. A comparative technique is used to distinguish this false structure from genuine structure marking energy levels above the ionization potential (I.P.). More accurate I.P.'s than previously available are given for HCl, CH3Cl, CH3NO2, CH3CN, C2H4, C3H6, C2H2 and new values for CH4, CD4, C2H6, C3H8.
Theory of Moderately Concentrated Polymer Solutions
Authors: Yamakawa Hiromi
Published: January 2005

The transition between the theories of the thermodynamic properties of dilute and concentrated polymer solutions is investigated using the random-flight model with explicit consideration of segment—segment interactions. It begins with a qualitative discussion of the transition. Supposing the individual segments, instead of the entire polymer molecules, to be solute molecules, a general expression for the osmotic pressure π is derived by the method of Green. Then the apparent second virial coefficient Γ defined by Γ=π/RTc2−1/Mc, where c is the concentration and M the polymer molecular weight, is evaluated by a coupling-parameter method. The evaluation consists of solving differential equations which can be derived approximately from the Kirkwood integral equations for the distribution functions. The result is expressed as a function of c and α, where α is the linear expansion factor of the polymer molecule at finite concentrations. Thus, α is also evaluated as a function of c, though the expression is incomplete at very high concentrations. For good solvent systems, it is predicted that as α is decreased to unity with increasing concentration and then becomes independent of concentration, Γ increases first rapidly and then gradually, passing through the transition region. This prediction is in fairly good agreement with experiment for polyisobutylene in cyclohexane. For poor solvent systems, the theory is invalid except at low concentrations.
Effect of Exchange Forces on Rotational Lines Broadened by Rare Gases
Authors: Krishnaji  , Srivastava Shyam Lal
Published: January 2005

A theory for the molecular collision cross section due to the exchange forces has been developed here following the Anderson—Tsao—Curnutte approach. The width of pure rotational lines of HCl broadened by rare gases has been theoretically calculated using the method developed here. The experimental and theoretical collision cross sections and half-intensity half-linewidths are compared, and in most cases they agree reasonably well.
Theoretical Studies on the Unimolecular Reactions of Polyatomic Molecule Ions. I. Propane
Authors: Vestal Marvin L.
Published: January 2005

This paper describes calculations on the unimolecular reactions of propane molecule ions using the quasiequilibrium theory of mass spectra. The invalid classical approximation to the number of states of a collection of harmonic oscillators, used in earlier calculations, is replaced for these calculations by an improved continuous approximation described previously. The results of the calculations are compared with experimental data obtained by electron-impact ionization, photoionization, and charge-exchange ionization. The variations in the mass spectra with temperature and with energy of the impacting particles are included in the calculations and comparisons. The quasiequilibrium theory in its improved form is found to be a satisfactory approximation for propane. A number of the apparently diverse features of the measured mass spectra of propane are shown to be consistent with the theory.
Study of Collision Narrowing by Comparison of Molecular-Beam and Gas-Phase Nuclear Resonance Spectra
Authors: Crapo L. M. , Flynn G. W.
Published: January 2005

The second moments of molecular-beam nuclear resonance curves are compared through a simple motionnarrowing theory with linewidths from gas-phase NMR data for CF4, SiF4, SF6, CH3F, CF3H, and CH2F2 at 300°K. From this comparison the average number of collisions necessary for these molecules to change their angular momentum is estimated to be on the order of three.
Structure and Partition Function of Liquid Water. I. Examination of the Model of Némethy and Scheraga
Authors: Vand V. , Senior W. A.
Published: January 2005

The Némethy and Scheraga model for the thermodynamic properties of liquid water is compared with the experimental results of Buijs and Choppin. It is shown that the two sets of data do not agree and an explanation for the discrepancy is suggested.
Microwave Spectrum and Barrier to Internal Rotation in Methylsilylacetylene
Authors: Kirchhoff William H. , Lide David R.
Published: January 2005

The microwave spectrum of CH3CCSiH3 shows a complex fine structure caused by internal rotation with a very low potential barrier. The major part of this structure can be explained on the basis of completely free internal rotation. However, small perturbations are found which suggest that the barrier may not be identically zero. Subject to reasonably firm assumptions, an upper limit of 3 cal/molecule can be placed on the barrier height. The theory for treating this type of spectrum is developed, and some implications of the results are discussed.
Electronic Ground State and Wavefunctions for Scandium Monoxide
Authors: Carlson K. Douglas , Ludeña Eduardo , Moser Carl
Published: January 2005

Approximate wavefunctions for ScO have been calculated by the method of Roothaan to establish the ground-state assignment of the molecule. Experimental analysis leads to a 4Σ ground state, but this assignment has been questioned. The wavefunctions have been calculated with a limited basis in the matrix Hartree—Fock approximation at three internuclear distances about the minimum in the binding-energy curve. Basis functions of Slater type were selected to include effects of distortion and polarization. Preliminary and final calculations at every stage of computation yielded a 2Σ+ ground state of configuration which is largely σ2π4σ. No other states were found to be near degenerate with this in the region of equilibrium separation reported for the experimental 4Σ ground state. It is concluded from this and discussions of possible refinements to the present calculations that 2Σ+ is the ground state of the molecule. It seems reasonable that the observed band structure can be explained as arising from a 2Σ+ ground state with a large hyperfine splitting, possibly owing to the fact that at equilibrium separation ScO is approximately Sc2+ (4s2S) O2− (1S). Ground-state parameters calculated here are De≥6.5 eV, re=1.615 Å, ωe=1373 cm−1, compared with the experimental values De=6.9 eV, re=1.668 Å, ωe=971.55 cm−1 reported for the apparent 4Σ state.
Spectrum of the Iodine Crystal. II
Authors: Schnepp O. , Rosenberg J. L. , Gouterman M.
Published: January 2005

The absorption spectrum of single and oriented crystals of iodine has been investigated in the wavelength region 7000–3000 Å. Four strongly polarized bands and one weakly polarized absorption band have been observed, all of which are polarized in the ac plane of the crystal. All of the absorption bands are approximately 1000 cm−1 wide. The crystal-band theory for iodine given by Rosenberg has been extended, and the effects of exchange and of spin—orbit coupling have been qualitatively considered. Three models are discussed with varying relative importance of spin—orbit and crystal energies. These models are correlated, and the strong crystal force model is used to interpret the experimental observations.
Semiclassical Calculation of Rotational Excitation
Authors: Lawley K. P. , Ross John
Published: January 2005

In the preceding article the Schrödinger equation and its solution are developed for the problem of translation—rotation energy exchange in a representation of rotor functions separately quantized along the moving interparticle axis. The quantum-mechanical time-dependent differential equations for the coefficients in this representation are obtained by the method of variation of constants with a time-dependent potential calculated from a classical trajectory and a symmetrized, initial relative kinetic energy. These equations are solved numerically for a limited number of basis functions, with intermultiplet transitions neglected, for some atom—diatomic systems. The isotropic part of the potential is taken to be a Lennard-Jones (12, 6) potential, with parameters appropriate for the cases K–HBr, Cs–HBr, and Li–HBr. For the present exploratory calculations the anisotropic part is assumed to be proportional to the inverse sixth power of the interparticle distance and to have P2 symmetry. Probabilities of inelastic collisions along given trajectories and total inelastic cross sections are calculated for the j=0→2, 2→4, 0→4, and 1→3 transitions. The total cross section for the 0→2 transition in the case representative of K–HBr is 5.74 Å2 for a reasonable estimate of the anisotropy of the assumed potential. A test calculation is made for the system He–H2 and agreement is found to 20% with Roberts' first-order distorted wave calculation in which the translational motion is treated quantum mechanically. The effect of intermultiplet transitions is examined and it is estimated that their neglect may incur an error in the total cross section of about 50%.
ESR Investigation of the Dynamical Behavior of Hydrogen Atoms in CaF2
Authors: Welber Benjamin
Published: January 2005

The techniques of ESR are employed to investigate the motion of H atoms in the lattice of CaF2. It is found that the atoms are quite stable against motion at temperatures below 100°C but migrate readily through the lattice at temperatures >114°C. The character of the initial decrease in intensity of the spectrum seems to be ``bimolecular.'' Later stages are exponential, and are governed by an activation energy of 1.2 eV.
Microwave Spectrum and Barrier to Internal Rotation in Trifluoronitromethane
Authors: Tolles W. M. , Handelman Eileen Tannenbaum , Gwinn William D.
Published: January 2005

The microwave spectrum for CF3NO2 has been observed for the J = 1→J = 2 through the J = 4→J = 5 transitions. Some 35 lines in these transitions are assigned, and the Stark effects for three of these were studied quantitatively and interpreted. A discrepancy in the Stark effect of a 4→5 transition can be accounted for by properly adjusting the sixfold barrier to internal rotation. The parameters used to obtain the best fit for the spectrum are the following: B + C = 4917.4±0.4 Mc/sec, B — C = 453.9±5 Mc/sec, A (NO2) = 13205±150 Mc/sec, A (CF3) = 5700 Mc/sec (assumed), V6 = 780 000 Mc/sec = 74.4±5 cal/mole. The dipole moment obtained from the Stark-effect measurements is 1.44±0.03 D.
Molecular Constants of Cesium Chloride by the Molecular Beam Electric Resonance Method
Authors: Luce R. G. , Trischka J. W.
Published: January 2005

The electric resonance method of molecular beam spectroscopy was used to observe the CsCl spectra arising from transitions of the type J,mJ→J,mJ′, where J is the rotational quantum number and mJ the electric quantum number. The following transitions were identified and studied : 2,0→2,1;3,0→3,1;4,0→4,1;4,1→4,2; and 5,1→5,2. An analysis of the spectra for several values of the electric field intensity gave the following molecular constants for the ground vibrational state of Cs133Cl35: μ0=10.46±0.14 debye; A0=(385±9)×10−40 g cm2; B0=(72.7±1.7)×10−3 cm−1; r0=(2.88±0.03)×10−8 cm. μ0 is the electric dipole moment, A0 is the moment of inertia, B0 is the rotational constant, and r0 is the internuclear distance. If μ is assumed to be proportional to the internuclear distance, and if the potential function is assumed to be a cubic, then the vibration-rotation constant αe is calculated to be (0.53±0.08)×10−3 cm−1. From measurements of line widths it was possible to set upper limits on the quadrupole interaction constants of Cs and Cl; viz, |eqQ/h|Cs⩽4 mc/sec and |eqQ/h|Cl⩽3 mc/sec.
Electron Traps in the Thallium-Activated Potassium Chloride Phosphor
Authors: Johnson Peter D. , Williams Ferd E.
Published: January 2005

The effects of activator concentration, added impurities, infrared stimulation, and temperature of excitation on the thermoluminescence of KCl:Tl permit the identification of the two principal trapping levels as the 3P00 and 3P20 states of isolated Tl+. The energy of activation necessary to fill these metastable states, following excitation to the 3P10 and 1P10 states, is provided by the polarization energy. The concentration of traps simultaneously filled is limited primarily by re-excitation of metastable Tl+. F and V centers are created by multiple excitation of Tl+. These interpretations are quantitatively correlated by a configuration coordinate model and are shown to be in accord with the band theory.
The System NaCl–H2O at Supercritical Temperatures and Pressures
Authors: Copeland C. S. , Silverman J. , Benson S. W.
Published: January 2005

Apparatus and techniques are described for the sampling of one phase of a liquid-vapor equilibrium system at high temperatures and pressures. These have been applied to the system NaCl–H2O in the supercritical region. Where the experimental ranges overlap, the present data are in reasonable agreement with that of previous workers. From the data obtained it has been possible to construct partial phase diagrams of the NaCl–H2O system and to calculate partial molal volumes of NaCl. The partial molal volumes of NaCl in steam are the largest partial molal volumes ever reported (order of magnitude of −2 liters) and indicate extensive solvation of the solute molecules in the vapor solution.
Crystal Structure and Lattice Energy of Orthorhombic Hexachloroethane
Authors: Sasada Yoshio , Atoji Masao
Published: January 2005

As a part of an investigation of the crystal structures of hexachloroethane, the orthorhombic phase of hexachloroethane has been investigated by x-ray methods. The unit cell, of dimensions a=11.56A,  b=10.18A,  and  c=6.42A,contains four molecules. The space group is D2h16—Pnma. The two- and three-dimensional Fourier series were calculated and atomic coordinates determined. Detailed discussions have been given for the lattice energy and molecular interaction of this crystal.
Substituted Methanes. XI. Potential Constants for CBr3Cl
Authors: Meister Arnold G. , Voelz Fred L.
Published: January 2005

A new set of potential constants has been obtained for CBr3Cl using the Wilson FG matrix method and a potential energy function containing all possible second degree terms. These constants are in better agreement with those determined for CBr2Cl2, CBr2ClH, CBr2ClD, and CCl3Br than the set given previously.
Dielectric and Ultrasonic Relaxation in Glycerol
Authors: Litovitz Theodore A. , Sette Daniele
Published: January 2005

Measurements of dielectric and ultrasonic relaxation in glycerol are compared over a frequency range of 7.5 to 37.5 megacycles and over a temperature range from 20°C to − 25°C. Reduced dielectric and ultrasonic constants when plotted against viscosity at a constant frequency of 30 megacycles appeared quite similar. The imaginary (or loss) part of the reduced constants exhibited a peak at the same viscosity. Both phenomena exhibited a departure from a single relaxation time theory. This deviation of the dielectric phenomena from the simple theory was attributed in the usual manner to a distribution of relaxation times. The striking similarities in the behavior of the dielectric and ultrasonic phenomena suggests an intimate relation between the two. Thus, if a distribution of relaxation times exists for the dielectric, it should in all probability exist in the ultrasonic process.

Both shear and compressional viscous processes are associated with the acoustic phenomena. It was concluded that if any difference exists in the shear and compressional viscous relaxation times, its effect is masked by a probable distribution in relaxation times for each process.

Calculations indicated that the natural ``rotational jump'' time in glycerol is between ½ and 4 times the ``translational (or viscous) jump'' time.
Conditions for the Formation of Hydrogen Bonds
Authors: Fyfe W. S.
Published: January 2005

The conditions necessary for the formation of hydrogen bonds are suggested to be asymmetry of nonbonding electron pairs and small size of hydrogen bonded atoms. Conditions for symmetry of such bonds are discussed.
On the Temperature Dependence of the Optical Absorption of β—Ag2S
Authors: Lehovec Kurt
Published: January 2005

The shift with temperature of the absorption edge for β-Ag2S was measured on a Ag2S ingot and a Ag2S sheet prepared by tarnishing of Ag in sulfur vapor. The measurements indicate a shift in energy of about −1.2 to −1.9×10−3 ev/degree. This value is used to explain the abnormally high value of the numerical factor in front of the exponential term in the expression of conductivity vs temperature. If the change in absorption with temperature is due to the decrease in lattice extension, one should expect a decrease in conductivity with increasing pressure of (1/σ·dσ/dp)∼−0.42/T (T in degrees Kelvin, p in atmospheres). In the course of this study the linear expansion coefficients of β-Ag2S (15.2×10−6 per degree) and of α-Ag2S (37.5×10−6 per degree) have been measured.
Intramolecular Carbon Isotope Effects in the Decarboxylation of Malonic Acid and Bromomalonic Acid
Authors: Yankwich Peter E. , Stivers Edward C.
Published: January 2005

The intramolecular isotope effects in the decarboxylation of C13 and C14 carboxyl-labeled malonic and bromomalonic acids have been determined. The observed C13 effects are in agreement with the results of other investigators; the C14 effects are in partial agreement with earlier published results of one of the authors. The ratio of C14 to C13 effects is found to be near 3.6.
Absorption Coefficients of Gases in the Vacuum Ultraviolet. Part II. Nitrous Oxide
Authors: Zelikoff Murray , Watanabe K. , Inn Edward C. Y.
Published: January 2005

Absorption coefficients of N2O in the region 1080–2100A have been measured. Four continua were observed with maxima at 1820, 1450, 1285, and 1080A having f values of 0.0015, 0.0211, 0.367, and 0.1, respectively. The strongest absorption band in the ultraviolet lies at 1178A with an absorption coefficient of 3010 cm−1 at its maximum. A number of new bands were observed, and some of them classified. Some of the continua have been interpreted in terms of possible dissociation processes, and a potential energy diagram is presented.
Studies on the Photovoltaic Effect. III
Authors: Levin Irvin , Wiebush Joseph R. , Bush Martin B. , White Charles E.
Published: January 2005

Further studies in the ultraviolet region between 4000 and 2500A indicate that the magnitude of the photopotential derived from a photoactive substance in solution is dependent on the absorption of the solution. Aliphatic and aromatic alcohols, hydroxy acids and phenols produce practically no photopotentials between 3000 and 8000A. The photovoltaic behavior of 38 organic halides has been studied. Methyl iodide produced the highest photopotential of any of the compounds used. The normal halides other than the iodides were inactive. In general the iso, secondary, and tertiary halides were more active than the corresponding normal halides. Results on 89 compounds other than halides are listed.
Microwave Spectrum and Molecular Structure of Trichloro Germane
Authors: Venkateswarlu Putcha , Mockler Richard C. , Gordy Walter
Published: January 2005

From measurements of the pure rotational transitions in trichloro germane, the rotational constants B0 (in megacycles/sec) for the various isotopic modifications of the molecule were found to be: 2172.75 for HGe70Cl335, 2169.26 for HGe72Cl335, 2165.84 for HGe74Cl335, 2063.74 for HGe70Cl337, 2060.43 for HGe72Cl337, and 2057.20 for HGe74Cl337. The calculated structure from the above data for the molecule in the ground state is: dGeH=1.55±0.04A, dGeCl=2.1139±0.0010A, and ∠ClGeCl=108°17′±12′. Rotational lines for the molecule when it is in the two excited GeCl3 deformation vibrations are also measured and the corresponding molecular structures calculated.
The Photolysis of Mercury Dimethyl in the Presence of Hydrocarbons
Authors: Rebbert Richard E. , Steacie E. W. R.
Published: January 2005

Mercury dimethyl was photolyzed in the presence of various hydrocarbons between 28°C and 251°C. The activation energies in kcal per mole for reactions of the type CH3+RH→CH4+Rare: 2-methyl propane−7.4; 2,3-dimethyl butane−6.8; n-butane−8.6; cylcohexane−8.3; 2,2-dimethyl propane−10.4; and toluene−7.3, where it is assumed that the activation energy for the reaction 2CH3→C2H6is zero. The collision theory steric factors are less than 10−3 for all these reactions.

The agreement of the above results with those obtained from the photolysis of acetone is noted.
Studies of Ionization Efficiency. Part III. The Detection and Interpretation of Fine Structure
Authors: Morrison J. D.
Published: January 2005

The effect of the spread in energy of the ionizing electron beam on the resolution of structural details in ionization efficiency curves has been evaluated, and the possibility of its removal by analytical methods is discussed. It has been shown that the first and second derivatives of the ionization efficiency possess useful properties, and that, when certain assumptions are made about the shape of the ionization probability function for a single process, a new method of measuring ionization potentials can be devised.

Correlation techniques have been employed to enhance materially the signal-to-noise ratio in the output from the ion collector. Detailed measurements of the ionization efficiencies for the inert gases have been made, and the assumptions referred to are justified.

It is shown that the ionization efficiencies for some molecular ions can be correlated with their vacuum ultraviolet and near x-ray spectra. It is found that competition occurs between all possible processes of excitation and ionization at each level of energy. The higher-energy levels of molecules can be studied and, in principle, an unequivocal assignment of bond dissociation energies from mass spectrometric data is possible.
Relationships between Kinetics and Acoustic Phenomena in Equilibrium Systems
Authors: Manes Milton
Published: January 2005

In a reacting (one-phase, one-reaction) system close to equilibrium, each variable (for example, composition, volume, temperature) approaches its equilibrium value at a rate proportional to its displacement from equilibrium. All the first-order rate constants in a particular state are identical. One can therefore characterize any system at equilibrium by a single relaxation time. When the relaxation of a chemical reaction gives rise to absorption and dispersion of sound, the thermal and dilatational contributions to the relaxational compressibility are necessarily in phase with each other and with the chemical reaction. A known but hitherto limited equation for the propagation of sound has been generalized to combine all such contributions for any system, irrespective of reaction mechanism, so that the propagation of sound may be described in terms of the instantaneous compressibility, the static compressibility, and the relaxation time. The relaxation time is a rather simple function of composition, temperature, and the rate laws for the forward and reverse reactions; it can be expressed for any postulated pair of rate laws. Therefore, measurement of the relaxation time of a (single) chemical reaction at different equilibrium compositions and temperatures yields kinetic information. The relationships derived here may be applied under certain conditions to acoustic studies of very fast reactions
The Reaction of Cyclobutane with Hg 6(3P1) Atoms
Authors: Kantro D. L. , Gunning H. E.
Published: January 2005

The reaction of cyclobutane with Hg 6(3P1) atoms has been studied in a static system at 30.10±0.01°C, over the pressure range from 2–250 mm. The primary products of the reaction are hydrogen, n-butylcyclobutane, and a saturated C8H14 product which is assumed, from kinetic and mass spectral evidence, to be cyclobutylcyclobutane. In addition, prolonged exposure produced a saturated C12H22 product which is probably a dicyclobutylbutane.

The quantum yields of pressure decrease (φP) hydrogen formation (φH2) and cyclobutane consumption (φC) all reach constant maximum values at cyclobutane pressures greater than approximately 100 mm. These values are φC=0.53, φH2=0.10, and φP=0.16. From the simple stoichiometry of the reaction the quantum yields of n-butylcyclobutane (φBC) and cyclobutylcyclobutane (φC2) formation were calculated. From the data φBC=0.16 and φC2=0.10.

The following mechanism was found to be consistent with the observed characteristics of the reaction: cyclo C4H8+Hg 6(3P1)→cyclo C4H7+H+Hg 6(1S0),H+cyclo C4H8→cyclo C4H7+H2,2 cyclo C4H7→dicyclo C8H14,2 cyclo C4H7→cyclo C8H14,H+cyclo C8H14→cyclo C8H15,cyclo C8H15+cyclo C4H8→cyclo C4H7+cyclo C8H16,where dicyclo C8H14 represents cyclobutylcyclobutane; cyclo C8H14, cyclobutylbutene; cyclo C8H15, cyclobutylbutyl radicals; and C8H16, n-butylcyclobutane. The cyclobutylbutene is considered as an intermediate in the formation of the stable n-butylcyclobutane product.
The Methyl Alcohol Molecule and Its Microwave Spectrum
Authors: Ivash Eugene V. , Dennison David M.
Published: January 2005

The theory of hindered rotation in methyl alcohol developed by Burkhard and Dennison has been extended to include the second-order Stark effect as well as a detailed discussion of K-type doubling. It has been applied to an interpretation of the microwave spectrum of normal methanol and of two isotopic molecules, C13H3O16H and C12H3O18H3 recently measured by Hughes, Good, and Coles. A very convincing fit between the predicted and observed lines is obtained which serves to determine many of the molecular constants, as well as providing a substantial number of self-consistency checks.

The height of the potential barrier (on the assumption of a sinusoidal potential) is found to be 374.8 cm−1. The CH distance in the methyl group cannot be obtained with any accuracy from the present data but is consistent with the CH distance in methane, namely, 1.093A, and has been taken to have this value. The remaining dimensions are, however, well determined and are: OH distance=0.937A, CO distance=1.434A, COH angle=105°56′, HCH angle=109°30′. The symmetry axis of the methyl group passes between the H and O of the hydroxyl group and lies at a distance of 0.079A from the oxygen. The above values for the barrier height and molecular dimensions do not differ much from those found by Burkhard and Dennison but are believed to be considerably more accurate.

Using the molecular constants, the positions of all the observed microwave lines which can be identified have been calculated. In every case the agreement is good. Those discrepancies which do exist are of an order of magnitude which can be ascribed to higher-order effects not included in the present theory.

The Stark effect, both first and second order, has been computed for all identified lines. In all but one or two cases the agreement with experiment is found to be very satisfactory.
Surface Migration of Water Molecules in Ice
Authors: Murphy E. J.
Published: January 2005

This paper continues the discussion of data given in a previous paper on the second term in the ``local conductivity'' of ice. It is inferred that the H2O molecules in internal surfaces are engaged in a special kind of random walk, in which the molecule is always attached to the surface by one chemical bond. This is described as bipedal random walk. It occurs with an activation energy of 5.2 kcal/mole (0.23-electron volt per molecule). On the other hand, molecules which jump up into field-free space and return to the surface have to acquire an energy of 11.5 kcal/mole (0.5 ev/molecule). The ratio of the corresponding Boltzmann factors is about 10−5 at 0°C and about 10−8 at −100°C; this implies that the dominant mode of diffusion in internal surfaces in ice is bipedal random walk.

The migration of a water molecule on an ice surface is a special type of diffusion process. The general formulas of the theory of stochastic processes and diffusion become available for the description of the diffusion of water molecules in a surface if the appropriate expression for the diffusion constant D is substituted in the formulas. A new procedure is used to calculate D from the Einstein relation. Instead of using the direct-current conductivity, the second term of the local conductivity is used. The expression for the diffusion constant derived from the model for local conductivity is DL=3.5×10−4 exp(−5.2×103/RT) cm2/sec, where the activation energy 5.2×103 cal/mole, is derived from the second term in the local conductivity of ice. This leads to a rather explicit model of the diffusion process: it may be described as bipedal random walk of the water molecule by the breaking of one bond at a time with an activation energy of 0.23-electron volt associated with each step.

It is pointed out also that the water molecule on an internal surface has a polarizability characteristic of the surface structure.
The Fundamental Absorption Bands in the Infrared Spectrum of Stibine and Deuterated Stibine
Authors: Haynie W. H. , Nielsen H. H.
Published: January 2005

The four fundamental bands in the infrared spectrum of stibine and the two high-frequency bands in deutero-stibine have been measured. These bands have been sufficiently well analyzed to permit the determination of the size and the shape of the molecule. It has been possible, moreover, to correct the band centers for anharmonicity so as to estimate with considerable accuracy the values of the normal frequencies. The constants arrived at for the molecule are as follows: the SbH distance r0=1.71A, the H–Sb–H angle α=91° 30′, the normal frequencies for stibine ω1=1988.9, ω2=795.9, ω3=1974.5, ω4=844.7, and for deutero-stibine the values ω1*=1409.4, ω2*=568.5, ω3*=1403.5, and ω4*=599.5 cm−1 are obtained.
Electronic States of Diatomic Molecules: The Oxygen Molecule
Authors: Fumi Fausto G. , Parr Robert G.
Published: January 2005

A scheme is proposed for the computation of electronic energy levels of diatomic molecules with fair accuracy and minimum labor. The theoretical LCAO MO method including configuration interaction is employed. However, the number of configurations considered is kept small; the energies of the asymptotic dissociation products for the various states are taken from atomic data in the manner of Pariser; the calculation of the interaction energies is simplified by the neglect of overlap in all terms and by the neglect of differential overlap in the electronic repulsion terms; and certain core parameters are fitted empirically. The first application is made to the oxygen molecule, using one empirical parameter. The vertical excitation energies from the ground state to the 1Δg, 1Σg+, 3Σu+, and 3Σu− states are computed as functions of distance between 1.16A and 1.63A, and they agree with the observed values within 0.2 ev; excitation energies to the unobserved 1Σu−, 3Δu, 1Δu, and 1Σu+ states are also computed. The results are in substantial accord with a previous more involved calculation by Moffitt. A justification of the proposed scheme is presented which makes use of the orthonormalized atomic orbitals of Löwdin.
The Distribution of Solute in Crystals Grown from the Melt. Part I. Theoretical
Authors: Burton J. A. , Prim R. C. , Slichter W. P.
Published: January 2005

The incorporation of solute elements into single crystals of germanium grown from the melt is examined in terms of a simple model. The theory takes account of the contribution of solute transport in the melt, owing to diffusion and fluid motion, to the over-all process of impurity incorporation during steady-state crystallization. The analysis is extended to treat the transient inclusion of solute which results when the composition of the melt is abruptly changed.
A Study in the Mechanics of Crystal Growth from a Supersaturated Solution
Authors: Krueger G. C. , Miller C. W.
Published: January 2005

An experimental investigation of the concentration field during crystallization is made using an improved modification of W. F. Berg's interference technique. Na2S2O3·5H2O is crystallized at 23°C; concentrations between 40 percent and 55 percent. Graphing the positions of the growing faces versus time indicates, in all cases, a uniform rate of growth with occasional abrupt changes. These discontinuities were, in general, correlated with changes in the perfection of the growing face, the disappearance of a region of poor growth being associated with a decrease rate, whereas the appearance of an imperfection led to a higher rate. A minimum of concentration is observed near the face center, corroborating previous investigations with NaClO3. A diffusion coefficient of 1.26×10−5 cm2/sec was calculated for Na2S2O3 corresponding to 0.80×10−5 cm2/sec extrapolated from J. D. R. Scheffer's data.

There is no strict correlation between maximum, minimum, or average concentration at a crystal face and its rate of growth. It appears that the variations in concentration revealed by interferometer maps are to be interpreted as a consequence of solution depletion occasioned by the crystal's growth.
The Temperature Dependence of the Mutual Diffusion Coefficient for Four Gaseous Systems
Authors: Strehlow Roger A.
Published: January 2005

Diffusion coefficients have been measured for the systems He—A, H2—A, H2—nC4H10, and H2–SF6 over the temperature range 13°C to 150°C. The values were determined by a point concentration analysis, while diffusion proceeded at one end of a Loschmidt-type cell. The analysis was made with a hot-wire technique and utilized the large difference in thermal conductivity to indicate concentration. The generalized equations for calculating D from an experiment with a Loschmidt-type cell are given as well as an analysis of the errors involved in calculating D from these data.

The data were used to calculate binary force constants for the Lennard-Jones 6–12 potential. In the system SF6–H2 these are ε/k=320°K and (r0)12=3.25A. The other three systems fit the theory very poorly. The middle temperature value was about 5 percent low relative to the theoretical curve through the high and low data point. The difficulties of calculating Lennard-Jones force constants from experimental viscosity or diffusion data are discussed.
Fractionation of the Carbon Isotopes in Decarboxylation Reactions. VI. Comparison of the Intermolecular Isotope Effects of a Pair of Isotopic Isomers
Authors: Bigeleisen Jacob , Wolfsberg Max
Published: January 2005

Theoretical considerations show that malonic acid −2C14 should decarboxylate precisely twice as fast as the isotopic isomer malonic acid −1C14 liberates C14O2. The calculations are supported by the experimental data of Ropp and Raaen. It is shown that these experiments are consistent with a C14 isotope effect twice that of the C13 one.
The Proton Magnetic Resonance in Natural Rubber
Authors: Gutowsky H. S. , Meyer L. H.
Published: January 2005

The proton magnetic resonance has been observed in natural rubber from liquid nitrogen temperature to room temperature. The absorption line widths show two regions of change. With rising temperature, the first change in width starts at about 155°K, and we assign it to the onset of CH3 group rotation. The second, larger change to a narrow line, starts at about 225°K and is assigned to the onset of segmental motions. The latter change coincides with the second-order transitions observed in various physical properties and provides a direct confirmation of the cause of the transition. Samples cured 30, 60, and 90 minutes were investigated, and it was found that curing has a larger effect on the line width changes at lower temperature than at higher temperature. The inferred greater effect of curing upon CH3 group motions than upon segmental motions suggests that cross linking is not the primary mechanism of vulcanization. Rubber stretched 70 percent was found to have the same resonance absorption as unstretched samples.