bluuebunny/crossref_metadata_2025 huggingface dataset:
Solutions of Alkali Metals in Polyethers. I
Authors: Cafasso Fred , Sundheim Benson R.
Published: January 2005

Potassium, rubidium, and cesium have been found to dissolve in 1,2-dimethoxyethane and some of its homologs to give blue, electrically conducting solutions. Although sodium alone is insoluble, it is carried into solution by solvents already containing potassium. Approximate values for the solubilities and electrical conductivities are given at several temperatures. The optical absorption spectra for the region 300 mμ to 2.5 μ and the results of electron paramagnetic resonance studies are reported. Many features of these solutions clearly parallel those of the corresponding solutions of alkali metals in liquid ammonia or in amines. The properties of rubidium solutions are distinctly different from those of the other alkali metal solutions.
Theory of Bose-Einstein Fluids, Statistical Mechanical Treatment of the Thermodynamic Properties of Liquid Helium
Authors: Baldursson Steingrimur , Mayer Joseph E. , Aroeste Henry
Published: January 2005

A formal development of the difference in thermodynamic properties of a Bose-Einstein and a hypothetical Boltzmann system is presented. The treatment is valid for any thermodynamic phase of the two systems, including the liquid phase to which it is intended to apply. The formal equations show the change in activity of the liquid-gas and crystal-liquid transitions for the two systems. A transition, which we identify with the lambda transition in liquid helium is predicted. By reasonable choice of a reduced mass parameter the lambda line can be correctly located. The nature of the lambda transition is related to the behavior at its singularity, of a series, the nth coefficient of which is a defined integral of functions of coordinates of n molecules. The simplest assumption which can be made to permit integration does not lead to the correct order of the transition.
Mass Spectrometric Study of Alkali Hydroxide Vapors
Authors: Schoonmaker Richard C. , Porter Richard F.
Published: January 2005

A mass spectrometer has been used to analyze the vapors effusing from the orifice of a Knudsen cell containing pure and mixed alkali hydroxide condensed phases. Monomeric and dimeric species are detected in all cases except for LiOH in the temperature range 650–900°K. Thermochemical data are reported for the reactions 2MOH(g)=M2(OH)2(g),and M2(OH)2(g)+N2(OH)2(g)=2MN(OH)2(g),where M and N represent constituent alkali metals. The analogous behavior of the vaporization processes of alkali fluorides and hydroxides is discussed.
Absorption Spectrum of UF4 and the Energy Levels of Uranium V
Authors: Conway John G.
Published: January 2005

The absorption spectrum of U4+ has been observed from 2000 A to 8μ. All the terms that can arise from two f electrons have been found. Terms have been assigned to all the absorption peaks. The radial integral, F2, is found to be 206 cm—1 and the spin-orbit coupling ζ5f is 1870 cm—1.
Further Studies of the Pyrolysis of Dimethyl Ether
Authors: Benson Sidney W. , Jain D. V. S.
Published: January 2005

The pyrolysis of dimethyl ether has been investigated over the pressure range 35 to 400 mm Hg and the temperature range 750 to 820°K in a quartz flask. The results confirm the previous designation of an initial 32-order rate relative to Me2O but yield an activation energy of 55.6 kcal. This can be explained if it is assumed that CH3OCH2 is an important chain breaker and that the reaction CH3OCH2→CH3+CH2O is an energy transfer process in its second-order region. The small catalysis provided by added N2 and CH4 is supporting evidence for this. Further evidence comes from the observed rate of exchange of deuterium gas with Me2O which is now in good accord with calculation.

Values of the rate constants for CH3 radical attack on H2 and D2 are in good agreement with those extra-polated from much lower temperatures. Some new values of rate constants are reported as well as new estimates of frequency factors and activation energies for various chain steps. There is some evidence for heterogeneous disappearance of H atoms at the wall, including a temporary inhibition observed in KCl-coated vessels. Small amounts of added O2 have little effect on the rate while C2H4 is a very powerful inhibitor. At 780°K, chain lengths vary from 21 at 25 mm Hg to 84 at 400-mm Hg pressure. They decrease slowly with increasing temperature.
Ligand Field Theory and the Absorption Spectra of MnCl2 and MnBr2
Authors: Pappalardo R.
Published: January 2005

Optical absorption spectra of MnCl2 and MnBr2 at room temperature and 78°K are reported and discussed. Parameters of electrostatic interaction and internal field are derived. Koide and Pryce's formalism to compute transition probabilities is extended to 4T levels. Many properties of the absorption spectra are nicely explained by the ligand field theory.
On the Trapping of Free Radicals of Oxygen and Chlorine
Authors: Benson Sidney W. , Anderson Kenneth H.
Published: January 2005

Gas mixtures of Cl2 (∼2 mm Hg) and O2 (∼50 mm Hg), when exposed to light in the near ultraviolet and then trapped at liquid N2 temperatures, yield a solid Cl2 matrix, which on warming to room temperature liberates small quantities of O2 in excess of that trapped mechanically in the absence of light. It is shown that this excess O2 can be reasonably accounted for in terms of the formation of ClO, Cl2O2, or ClOO. Under the experimental conditions the gas-phase concentration of ClO and Cl are about equal, while Cl·OO/Cl is small. If the source of O2 is Cl·OO it must arise from reaction between Cl and O2 at the cold walls, the gas phase concentration of Cl·OO being negligible. Very small amounts of Cl2O and OClO may be formed in the present system, but these would not produce O2 on warming. Analysis of the flash photolysis experiments on Cl2–O2 mixtures indicates that measurable amounts of OClO would be formed unless there was a very rapid isomerization reaction, ClO+OClO→Cl·OO+ClO.The absence of Cl2O in the flash experiments can be shown to imply a very rapid reaction, Cl+Cl2O→Cl2+ClO,with an activation energy of less than 4 kcal.
3ν3 Band of C12S32S34
Authors: Guenther Arthur H.
Published: January 2005

The 3ν3 band of C12S32S34 at 4556.553 cm—1 has been investigated. The following molecular constants, expressed in cm—1, were obtained: B′+B′′=0.209702,α3=0.000691,B′−B′′=−0.002073,ν0=4556.553,D′=D′′=4B3/ω12=1.12×10−8,r0=1.5544×10−8cm.

It is believed that this is the first resolution and analysis of the rotational structure of C12S32S34 in the infrared region. When the results of this investigation are compared to those of ordinary carbon disulfide, C12S232, they are found to be consistent with the relations governing the effect of isotopic substitution on the molecular constants. The value for the internuclear distance, r0 = 1.5544 A, obtained in this investigation is in good agreement with the value obtained for ordinary CS2, i.e., r0 = 1.5545 A.
Equilibrium in the Exchange of Hydrogen between Arsine and Water
Authors: Zeltmann Alfred H. , Gerhold George
Published: January 2005

The equilibrium constant for the reaction AsH2D(g)+H2O(l)⇌AsH3(g)+HDO(l) has been measured at 25.4° and found to be 1.89±0.02, corresponding to a value in the gas phase of 1.77±0.02. With the known vibrational spectra of AsH3 and AsH3—d3 the gas phase equilibrium constant was calculated at 25.4°, K2=0.777e258/T=1.84.
H3 Activated Complex and the Rate of Reaction of Hydrogen Atoms with Hydrogen Molecules
Authors: Weston Ralph E.
Published: January 2005

The method recently proposed by Sato for determining potential energy surfaces is compared with the semiempirical method of Eyring and co-workers. The two methods are found to be equally empirical. The potential energy surface for the H3 complex has been constructed with the Sato method to give an activation energy which agrees with the experimental value. The H3 complex is found to be linear and symmetrical, with a bond length of 0.93 A and vibrational frequencies of 2108, 877, and 1918i cm—1. Anharmonicity constants for the real frequencies make a negligible contribution to the zero-point energy. A large contribution to the H+H2 reaction from tunneling through the potential barrier is predicted, contrary to experimental data. However, at 1000°K, the calculated pre-exponential factor and ratios of rate constants for isotopic species are in reasonably good agreement with experimental values.
High Frequency Factors in Unimolecular Reactions
Authors: Steel Colin
Published: January 2005

The high frequency factors which are associated with certain unimolecular reactions are discussed in terms of an extended Kassel-type model, in which the critical energy is localized in more than one oscillator.
Color Centers in KI:T1 X-Rayed at Low Temperatures
Authors: Hersh Herbert N.
Published: January 2005

The optical properties of the phosphor KI:Tl have been studied after x-raying at 5 or 78°K. The interactions among the several simultaneously produced centers have been studied by following and correlating changes in luminescent intensity and optical absorption spectra as the crystal is warmed, and an explanation of these effects is offered in terms of retrapping and recombination. Perturbation bands due to the modification of the energy levels of the luminescent center as a result of the interaction with a color center are observed. The major centers produced in the more heavily doped crystals by brief irradiation at low temperatures do not involve vacancies and are identified as an electron center associated with Tl, I2—, and V centers near Tl+. The optical absorption spectrum of I2— consists of bands at 404 and 800 mμ. (The absorption of Br2— in KBr:Tl incidentally has also been identified.) On the basis of certain similarities in luminescence properties, essentially similar effects are proposed for ultraviolet as for x-ray excitation.
Lengths of CC ``Single'' Bonds and Radii of Hybrid Orbitals of Carbon
Authors: Somayajulu G. R.
Published: January 2005

The variation in the CC σ-bond length in hydrocarbons and related compounds has been ascribed primarily to the variation in the covalent radius of the carbon atom with hybridization, resonance effects being considered to be of little importance in the ground states of these molecules. Values for the radii of the hybrid orbitals of carbon have been assigned, and they have been shown to reproduce satisfactorily the lengths of the CC σ bonds in a variety of compounds, both aliphatic and aromatic.
Microwave Spectrum and Internal Rotation of 1-Chloro-2-Butyne
Authors: Laurie Victor W. , Lide David R.
Published: January 2005

The microwave spectrum of CH3C≡CCH2Cl has been investigated in the region from 20–30 kMc. The existence of nearly free internal rotation gives rise to regions of very dense absorption. Transitions of the type ΔJ = 1, ΔK = 0 have been identified for the ground torsional state (m = 0). The ground state spectrum is that of an effective rigid rotor with the rotational constants modified by the internal rotation. Values for the effective rotational constants are 17 631, 1490.55, 1385.06 Mc for the Cl35 species; and 17 329, 1459.76, 1357.26 Mc for the Cl37 species. These rotational constants permit an upper bound of 100 cal/mole to be established for the barrier to internal rotation. A structural analysis indicates that the CCl bond is longer than in CH3Cl.
Abnormal Excitation of OH in H2/O2/N2 Flames
Authors: Kaskan Walter E.
Published: January 2005

The emission from the first four vibrational levels of OH2Σ+ and the concentrations of ground state OH2II have been measured in a series of rich H2/O2/N2 flames held on flat porous burners as a function of distance from the burner. The intensity of emission of each of the bands is proportional to the cube of the concentration of ground state OH, but the constant of proportionality depends on the band and the flame conditions. This dependence, as well as absolute intensity measurements, establish the fact that the radiation is nonthermal.

The dependence of the emission intensity on an integral power of OH strongly indicates that the excited OH is formed as a result of one or more of a set of possible radical recombination reactions. It is shown that in general it is not possible to obtain a unique determination of the excitation mechanism for any band. The only exception to this is that definite evidence for the preassociation reaction, O+H→OH2Σ, v=2, has been obtained. The vibrational distributions of excited OH are shown to be consistent with ``temperatures'' from 3000°K to 5000°K (compared with maximum flame gas temperatures of 1600°K), which is probably to be expected from a reaction with the exothermicity of H+OH+OH→H2+OH*. It is concluded from this and from the general behavior of the data, that this last reaction is most likely responsible for the nonthermal emission of all the bands, with the exception of that specifically known to be due to the preassociation reaction.
Method for the Analysis of Multicomponent Exponential Decay Curves
Authors: Gardner Donald G. , Gardner Jeanne C. , Laush George , Meinke W. Wayne
Published: January 2005

A frequently encountered problem in many branches of science involves the resolution of experimental data into a sum of independent exponential curves of the form f(t)= ∑ i=1nNiexp(−λit),in order to estimate the physically significant parameters Ni and λi. Such problems arise, for example, in the analysis of multicomponent radioactive decay curves, and in the study of the dielectric properties of certain compounds. This paper is concerned with the numerical evaluation of a mathematical approach to the problem. The approach is based on the inversion of the Laplace integral equation by a method of Fourier transforms. The results of the analysis appear in the form of a frequency spectrum. Each true peak in the spectrum indicates a component, the abscissa value at the center of the peak is the decay constant λi, while the height of the peak is directly proportional to Ni/λi. Results obtained on an IBM 650 computer indicate that the method may possess certain advantages over previous methods of analysis.
Infrared Spectra of Vinyl Chloride and Vinyl Chloride-d3
Authors: Narita Shoji , Ichinohe Seiichiro , Enomoto Satoru
Published: January 2005

Vinyl chloride-d3 has been prepared and the infrared spectrum has been obtained in the region from 400 to 4000 cm-1. The spectrum is compared with the that of vinyl chloride. Normal coordinate analyses are made for vinyl chloride and vinyl chloride-d3. A force field of the Urey-Bradley type is used for the planar vibrations, and a modified valence-type potential function is applied to the nonplanar motions. The vibrational secular equations are set up in the GF matrix fashion. The force constants are determined by a least-square process. The force constants established for vinyl chloride are used to calculate the fundamental frequencies of vinyl chloride-d3. Satisfactory results are obtained.
Evidence for a Low-Lying Second Potential Minimum in Hydrogen-Bonded Systems
Authors: Bell Charles L. , Barrow Gordon M.
Published: January 2005

The spectra of phenol-d and p-nitrophenol-d associated with amines in chloroform show, in the region of the stretching fundamental, a band splitting that can be interpreted in terms of a double minimum potential for the proton. For p-nitrophenol and a base as strong as triethylamine, both the infrared and visible spectra show that the associated complex consists of a tautomeric equilibrium between proton transferred and nonproton transferred species. For these systems also, the potential experienced by the proton shows a double minimum. It appears, therefore, that for hydrogen-bonded systems of the type dealt with here in nondissociating solvents the hydrogen-bonding proton will experience a double minimum potential for all strengths of association.
Molecular Transport in Liquids and Glasses
Authors: Cohen Morrel H. , Turnbull David
Published: January 2005

We have derived, by using simple considerations, a relation between the diffusion constant D in a liquid of hard spheres and the ``free volume'' vf. This derivation is based on the concept that statistical redistribution of the free volume occasionally opens up voids large enough for diffusive displacement. The relation is D=A exp[−γv*/vf], where v* is the minimum required volume of the void and A and γ are constants. This equation is of the same form as Doolittle's [J. Appl. Phys. 22, 1471 (1951)] empirical relation between the fluidity φ of simple hydrocarbons and their free volume. It has been shown [Williams, Landel, and Ferry, J. Am. Chem. Soc. 77, 3701 (1955)] that the Doolittle equation also can be adapted to describe the abrupt decrease in molecular kinetic constants with decreasing temperature that accompanies the glass transition in certain liquids. Our result predicts that even the simplest liquids would go through this glass transition if sufficiently undercooled and crystallization did not occur. The problem of transport in actual simple and network liquids also is discussed.

It is shown that data on self-diffusion in some simple van der Waals liquids and liquid metals are described satisfactorily by our relation with v* near the molecular volume for the van der Waals liquids and near the volume of the ion, corresponding to the highest valence state, for the metals.
Strong Coupling in Nuclear Resonance Spectra. III. Systems Containing Many Equivalent Spins
Authors: Waugh J. S. , Dobbs F. W.
Published: January 2005

The spin-coupling problem is discussed for systems of p+q nuclei falling into two groups ApBq where all members of a group are magnetically equivalent. The energies are given explicitly for p=1, arbitrary q, and formulas are given from which the transition intensities can be computed for this case. The results are applied to the proton resonance spectrum of isobutane (p=1, q=9), with the results δCH3—δCH=0.85 ppm, ACH–CH3=6.8 cps.
Heat Capacity of Samarium from 13 to 350°K
Authors: Jennings L. D. , Hill Emma D. , Spedding F. H.
Published: January 2005

Samarium shows anomalies in its heat capacity near 13°K and at 105.8°K. The former has already been shown to be magnetic in origin; it appears certain that the latter is also, although there is only a slight sign of an anomaly in the magnetic data near 105°. The magnetic ordering does not appear to be explicable on the assumption of an isotropic S·S coupling mechanism. The thermodynamic functions are tabulated for the temperature region studied.
Line Shape and f Value in the OH 2Σ+ — 2Π Transition
Authors: Carrington Tucker
Published: January 2005

Line shape and f value in the ultraviolet transition 2Σ+—2Π of OH have been studied by the curve of growth method, and rough direct measurements of line width have been made. The lines Q16, P16, R16, Q216, and S16 fit a curve of growth indicating a collision broadening width of 0.02±0.02 cm-1 at 2600°K and 1 atmos in flame gases of the approximate composition O2 60%, H2O 20%, and CO2 20%. For the Q16 line, the f value is (11.7±4)×10-4. This corresponds to a radiative lifetime for the free molecule of 5.5×10-7 sec, in excellent agreement with the earlier work of Oldenberg.

Brief discussions are given of theoretical limitations on the use of the curve of growth, and of the qualitative factors to be considered in explaining the observed line width.
Polarizabilities and Antishielding Factors of 10 and 18 Electron Closed Shell Atoms
Authors: Burns Gerald
Published: January 2005

Polarizabilities and antishielding factors are obtained for a number of ions that have ten and eighteen closed shell electron configurations. Certain empirical relationships are found so that other polarizabilities and antishielding factors can be deduced. The results using Hartree and Hartree Fock wave functions are also compared.
Determination of Absorption Coefficients from Infrared Dispersion Data
Authors: Kagarise R. E.
Published: January 2005

Liquid dispersion data in the neighborhood of the 14μ absorption bands of CCl4 and the 9μ band of CH2I2 have been analyzed in terms of the Kramer dispersion equation. The so-called oscillator strengths obtained from the dispersion data were found to be in good agreement with those obtained directly from integrated absorption coefficients.

The liquid state absorption coefficients for the 9μ band of CH2I2 are essentially equal to that previously reported for the vapor state. Thus it would appear that the Polo-Wilson ratio of intensities is not satisfied in this case.
Stark Effect at 0.93, 1.18, and 1.5 Millimeters Wavelength: DCl, DBr, and DI
Authors: Burrus C. A.
Published: January 2005

Observations of the Stark effect in the microwave rotational spectra of light molecules have been extended into the sub-millimeter wave region. The Stark shifts of the J=0→1 transition of deuterium chloride at 0.93 mm wavelength, and of deuterium bromide at 1.18 mm have been measured. Values of the molecular electric dipole moment μ, obtained from analysis of the data, are found to be 1.12±0.04 debye for DCl and 0.83±0.02 debye for DBr. An error in the calculation of μ for DI, from measurements at 1.5 mm previously reported, is corrected, and μ for DI is found to be 0.445±0.02 debye.
Optical Spectra of Rare Earth Activated BaTiO3
Authors: Keller Seymour P. , Pettit George D.
Published: January 2005

BaTiO3 has been activated with Pr, Sm, Eu, Dy, or Er ions. The fluorescence spectra were determined at —196°C, —28°C, room temperature, and at 130°C. We looked for crystalline field effects on the energy levels of the rare earths and changes in these effects as the crystallographic phase of BaTiO3 is changed. In particular, we sought changes at the Curie point in going from the ferroelectric tetragonal phase to the cubic phase. The high-temperature data were largely unresolvable and no changes were observed at the low-temperature transitions in going from the tetragonal to the orthorhombic phase in the range of 5 to 13°C and from the orthorhombic to the rhombohedral phase in the range of —70 to —80°C. No crystal field splittings were observed at any temperature, leading to the possible conclusion that the rare earth centers are in positions of either high symmetry or low field strength. The fluorescence data support the hypothesis that the rare earths are present as the trivalent ions and that they can be assigned energy levels and term signatures resulting from the 4fn configuration.
Effect of Argon and Helium on the Thermal Conductivity of the N2O4⇄2NO2 System
Authors: Coffin Kenneth P.
Published: January 2005

The effect of dilution by argon and by helium on the thermal conductivity of the dissociating N2O4⇄2NO2 system was investigated in a hot-wire apparatus. Values of the conductivity were obtained over a pressure range of 0.05 to 1.0 atmosphere at 300°, 320°, and 350°K, (the temperature range where the contribution of the reaction to the conductivity is large). Rigorous calculations of the conductivity were made for the three-component systems. Agreement between experimental and calculated values is generally good. At reduced pressures, experimental results are smaller than the calculated values. A calculation involving reaction rates is shown to predict these low-pressure effects.
Infrared Studies of Crystal Benzene. I. The Resolution and Assignment of v20, and the Relative Magnitudes of Crystal Fields in Benzene
Authors: Swenson C. A. , Person W. B. , Dows D. A. , Hexter R. M.
Published: January 2005

Under the higher resolution available with double pass prism and small grating infrared spectrometers, it has finally been possible to observe splitting of the degenerate fundamentals of benzene in the solid phase. Three components were found for v20 at 1032.6, 1034.7, and 1039.4 cm—1, as predicted by Zwerdling and Halford. These are assigned to the absorptions along the b, c, and a axes, respectively, by a mixed crystal study of benzene-d6 in benzene combined with the polarized work of Zwerdling and Halford. The crystal splitting of v20 was also observed in the benzene-d6 crystal, showing components at 806.5, 808.5, and 812.2 cm—1 assigned to absorptions along the b, c, and a axes, respectively. The magnitudes of the static and correlation fields are thus found to be similar, contrary to the ideas advanced by Zwerdling and Halford, and long accepted intuitively. The effect of temperature on the appearance of the spectrum was studied. An explanation for the changes observed is advanced on the basis of the assignment which is consistent with it, and supports it.
Hyperfine Interaction and Quadrupole Coupling Constant in the Hydrogen Molecule Ion
Authors: Stephen M. J. , Auffray J. P.
Published: January 2005

An accurate calculation has been made of the interaction between the electron spin magnetic moment and a nuclear moment for the ground state of the hydrogen molecule ion. An accurate value of the electric field gradient at the nucleus was also obtained. The values are compared with values from an approximate LCAO wave function. The possibility of observing the paramagnetic resonance spectrum of this molecule is discussed.
On Noncrossing Lattice Polygons
Authors: Rushbrooke G. S. , Eve J.
Published: January 2005

Numerical data on nonselfcrossing closed polygons on simple-cubic and plane-square lattices are presented and discussed in connection with the Monte Carlo investigations of Wall and others on the restricted random walk problems for these lattices.
Participation of Vibration in Exchange Reactions
Authors: Smith Felix T.
Published: January 2005

Exothermic exchange reactions of the type A+BC→AB+C sometimes leave the product AB in a highly excited vibrational state. Simple theoretical considerations related to the description of the molecular collision show that the fraction of the reaction energy available for this vibrational mode is limited by the kinematic factor sin2β, where β is the angle of rotation required to take a coordinate system describing the reactants into one suited to the products, and tan2β=(mB/mA)+(mB/mC)+(mB2/mAmC). In the reaction A+BCD→AB+CD, similar results apply to the newly formed bond AB, and no excitation of vibration in CD is predicted. Although effects to be expected from details of the potential energy surface are ignored, comparison of the kinematic factor alone with experimental results shows excellent agreement.

Applied to the reverse reaction, the theory gives a criterion for predicting the effect on the reaction rate of the distribution of energy between translational and vibrational modes in the collision. In the reaction O3+O2*→O+2O2, it is predicted that the oxygen atom comes preferentially from the vibrationally excited oxygen molecule.

Incidentally, it is shown that the transformation from a properly normalized center-of-mass coordinate system describing the reactants to one describing the products can always be resolved into a sequence of simple rotations.
Vibrational Distribution Functions in Bimolecular Dissociation Reactions
Authors: Shuler Kurt E.
Published: January 2005

The ``ladder climbing'' model of Montroll and Shuler for the dissociation of diatomic molecules is used to evaluate the perturbation of vibrational distribution functions of diatomic oscillators in a bimolecular dissociation reaction. Explicit results are exhibited for the perturbation of initial Boltzmann and δ-function distributions of the oscillators. A limited tabulation of the roots of the Gottlieb polynomials employed in these calculations is presented in the Appendix.
Mean-First-Passage Times and the Collision Theory of Bimolecular Reactions
Authors: Widom B.
Published: January 2005

A general collision theory is outlined for the kinetics of reaction of molecules which are dilutely dispersed in an inert gas, reaction being the result of binary collisions between the reacting molecules and the inert gas molecules. It is assumed that the products of reaction are instantaneously removed from the system. The mean-first-passage time for the transition from reactant to product states is expressed in the classical theory in terms of the solution of an integral equation in which the kernel is the transition probability per unit time between two states of the reacting molecule. As shown by Kim, when a rate constant exists (which is not always the case) it is the reciprocal of the mean-first-passage time. In a one-dimensional system, or in a system of two or three dimensions where the interaction between colliding molecules has a finite range, there exists a finite collision number Z which is independent of the internal state of the reacting molecule. In such a case there is a Liouville-Neumann solution of the integral equation which allows the mean-first-passage time to be expressed as a sum of contributions corresponding to failure to react after no collisions, after one collision, after two collisions, etc.

The equilibrium hypothesis is analyzed and it is seen what the precise nature of that approximation is.

The theory is illustrated with each of two transition kernels, both satisfying the conditions of completeness and detailed balance. The first is a very simple but physically unrealistic one in which the transition probability depends only on the final state but not on the initial state, and here it is found that the equilibrium hypothesis yields the exact rate constant without error. The second illustration uses the previously calculated transition probability for a one-dimensional string oscillator suffering impulsive collisions with particles of mass identical to its own, and counts the oscillator as ``dissociated'' when its energy exceeds a certain critical energy ε*. Here, as is obvious, the equilibrium hypothesis is correct when ε*≫kT, and it is found that in this range the rate constant for dissociation is Z(kT/πε*)12exp(−ε*/kT). It is shown in an Appendix that if instead of just formally calling the oscillator dissociated when its energy exceeds ε*, one actually specifies that the string is then ruptured, the basic transition probability is altered, and the equilibrium hypothesis then yields for the dissociation process the even simpler rate constant Z exp(—ε*/kT).
Vibrational Assignment and Potential Field of Iron Pentacarbonyl
Authors: Pistorius Carl W. F. T. , Haarhoff P. C.
Published: January 2005

The fundamental frequencies of iron pentacarbonyl were assigned using recent vibrational data. The results show that iron pentacarbonyl possesses a trigonal bipyramidal structure. Valency force constants were evaluated for a force field consisting only of the diagonal F-matrix elements.
Proton Magnetic Resonance Study of Lithium Sulfate Monohydrate
Authors: McGrath J. W. , Silvidi A. A. , Carroll J. C.
Published: January 2005

An extended proton magnetic resonance study of lithium sulfate monohydrate is presented. An oddity in the resulting Pake curves appears. Some of the curves show a shift so that they are described by equations of the form, ΔH=2α[3 cos2(φ+φ0) cos2δ−1] +constant shift.

There are two orientations of the hydrated water molecule. For these the direction angles of the proton-proton axes with respect to the crystallographic a, b, and c axes are, respectively, α0=97°, β0=45°, γ0=48°, and α0=74°, β0=38°, γ0=127°. Apparently the hydrogens bond O5— —H–O5–H— —O1, where O5 are neighboring water oxygens and O1 is a sulfate oxygen.

Several possible origins of the shifts in the Pake curves are discussed with limited success. An adequate theoretical explanation is lacking.
Valence Bond Calculation of the Barrier to Internal Rotation in Molecules
Authors: Harris Gilda Maki , Harris Frank E.
Published: January 2005

An approximate calculation of the barrier to internal rotation in ethane was made using a set of covalent valence bond structures involving only s and p orbitals.

The calculated result is sufficiently great that it does not appear that other effects are needed to explain the barrier height.
X-Ray Diffraction Study of Bismuth Polymer in Aqueous Perchlorate Solution
Authors: Levy H. A. , Danford M. D. , Agron P. A.
Published: January 2005

X-ray diffraction study of an aqueous solution of bismuth perchlorate has established the presence of a polymeric species containing six bismuth atoms in octahedral arrangement. The bismuth-bismuth distances are 3.70 and 5.23 A.
Nonequilibrium Kinetics and Chromatography
Authors: Giddings J. Calvin
Published: January 2005

An effort is made here to deal with the complex kinetic processes which determine the structure of component zones in chromatography. The problem is approached by assuming that the various steps are proceding near equilibrium. In order to facilitate the analysis an approximation is made in which each derivative of a concentration is replaced by the derivative of the equilibrium concentration. The latter derivatives are evaluated in terms of the concentration profile. This yields a set of linear algebraic equations from which an equilibrium departure term, ε, can be found for each species. The diffusion of the zone is then obtained as a function of the various ε's.

The simplicity introduced by this method allows one to obtain the zone diffusion term for complex kinetics in contrast to the rigorous theories where only the simplest kinetic schemes have been treated. The results for a simple kinetic example are the same, however, as obtained in the limit of large times by the rigorous methods. The validity of the assumptions made is established independently of this comparison. Various applications of the method are discussed which extend beyond the range of chromatographic analysis.
Overhauser Effect in Asphalt Solutions
Authors: Poindexter Edward H.
Published: January 2005

We have discovered that solutions of asphalt in a suitable solvent will show an Overhauser effect. The effect is qualitatively similar to that in crude oil. It arises from a dipolar interaction between the unpaired spins in the asphaltic free radicals, and the protons of the solvent molecules. The contribution to proton relaxation from the asphalt is a linear function of asphalt concentration. The function relating proton signal enhancement to electron saturating rf field strength is found to vary with asphalt concentration. A plot of enhancement versus electron-stimulating frequency at constant H0 yields a curve similar to the EPR absorption line. The large size of the asphalt radicals does not appear to have any direct significance with respect to the Overhauser interaction.
Lattice Vibrations in Alkali Halide Crystals. I. Lithium and Sodium Halides
Authors: Karo Arnold M.
Published: January 2005

Vibrational frequency distributions for the lithium and sodium halides have been evaluated on the basis of the Born lattice theory by the use of Blackman's numerical-sampling technique. Both room temperature and extrapolated 0°K parameters have been used in the calculation. Specific heats, the corresponding Debye characteristic temperatures, and the moments of the distributions have been evaluated directly from the frequencies. Comparison is made with experimental data and with other theoretical work.
Thermodynamics, Stationary States, and Steady-Rate Processes. II. Migrational Equilibrium in Thermal Fields
Authors: Tykodi R. J. , Erikson Ted A.
Published: January 2005

The thermodynamic method outlined in paper (I) for treating stationary states and steady-rate processes is applied to a discussion of nonisothermal systems. Thermomolecular pressure, thermo-osmotic and thermal diffusion effects are treated in detail.
Thermodynamics, Stationary States, and Steady-Rate Processes. IV. Steady Monothermal Rate Processes
Authors: Tykodi R. J. , Erikson Ted A.
Published: January 2005

The procedure outlined in paper (I) of the series is applied to such steady monothermal rate processes as forced vaporization, diffusion, Poiseuille flow, and chemical reaction. In the case of forced vaporization, numerical values of a coefficient defined in terms of entropy production are computed from the data of Alty pertaining to the vaporization of water and of carbon tetrachloride.
Contribution of Bound, Metastable, and Free Molecules to the Second Virial Coefficient and Some Properties of Double Molecules
Authors: Stogryn Daniel E. , Hirschfelder Joseph O.
Published: January 2005

The second virial coefficient for molecules interacting with a spherically symmetric potential is divided into three parts: (1) a contribution Bb, related to the equilibrium constant for the formation of bound double molecules; (2) a contribution Bm, related to the equilibrium constant for the formation of metastably-bound double molecules; and (3) a contribution Bf, due to molecules which interact but are free to separate after the interaction. Equations are given for determining each of the three parts of the second virial coefficient. A detailed treatment of these three contributions together with numerical tables on a reduced temperature basis is given for the square-well, Sutherland, and Lennard-Jones (6–12) potentials.

The mean lifetimes of metastably bound double molecules are discussed, and numerical values are given for the special case of argon. Tables for computing mean lifetimes in other Lennard-Jones gases are given. It is found that most metastably bound double molecules have mean lifetimes considerably longer than the mean time between collisions at ordinary pressures. Finally, an equation is developed for the number of vibrational levels of a double molecule.
Initial Pressure Dependence of Thermal Conductivity and Viscosity
Authors: Stogryn Daniel E. , Hirschfelder Joseph O.
Published: January 2005

The initial pressure dependence of thermal conductivity and viscosity of gases is considered to arise from molecular association and collisional transfer. Since only the initial pressure dependence is investigated, clusters larger than dimers can be neglected. The effect of dimer formation can be calculated from a knowledge of the equilibrium constant for the reaction 2A⇌A2. The effect of collisional transfer is obtained by a semiempirical modification of Enskog's theory. In the case of thermal conductivity, it is found that at low temperatures molecular association is more important than collisional transfer, while at high temperatures collisional transfer predominates. For viscosity, the initial pressure dependence is due primarily to collisional transfer.

Detailed equations for the initial pressure dependence of both thermal conductivity and viscosity are given in terms of dimensionless groupings which include the intermolecular potential parameters. Tables of these dimensionless groupings as functions of a reduced temperature are given for molecules obeying the Lennard-Jones (6–12) potential. Comparisons between theory and experiment are included. It is found that the numerical results are sensitive to the choice of force constants for the interaction of a monomer with a dimer.
Internal Rotation in Molecules with Two Internal Rotors: Microwave Spectrum of Acetone
Authors: Swalen J. D. , Costain C. C.
Published: January 2005

The theory of internal rotation in molecules is extended to the case of two internal symmetric rotors attached to a molecule with C2v symmetry. The calculation of the internal rotational energy levels and of the interaction with the over-all rotational energy levels is discussed both for the high barrier and the low barrier approximation. The symmetry of the Hamiltonian for a molecule with the acetone structure is considered and the selection rules and relative intensities of the various fine structure components are derived.

The microwave spectra of acetone and of completely deuterated acetone have been measured and assigned. From the rotational constants, the molecular structure has been partially determined. The most probable values of the structural parameters are r0(C=O) = 1.215 A (assumed), r0(C–C) = 1.515±0.005 A, r0(C–H) = 1.086±0.010 A, ∠CCC = 116°14′±1°, and ∠HCC = 110°16′±1°. The angle between the axes of the methyl groups is approximately 3° larger than the ∠CCC.

The dipole moment has been determined to be 2.90 D by a measurement of the Stark effect on the microwave transitions.

Each of the rotational transitions is split into a number of components by the internal rotation. From an analysis of these patterns the barrier height to internal rotation is found to be 274 cm—1 for (CH3)2CO and 258 cm—1 for (CD3)2CO. The difference in the two calculated barrier heights and the errors in the method are discussed.
Generalization of Crystal Field Theory to Include Covalent Bonding
Authors: Jarrett H. S.
Published: January 2005

A potential operator with many of the features of the crystal field potential of Bethe and Van Vleck but which explicitly accounts for any degree of covalent bonding between metal and ligand is derived starting from antisymmetrized molecular orbitals.
Mass Spectrometric and Thermodynamic Study of Gaseous Transition Metal (II) Halides
Authors: Schoonmaker Richard C. , Friedman Alan H. , Porter Richard F.
Published: January 2005

Mass spectrometric and Knudsen effusion techniques have been used to study the vaporization of several transition metal (II) halides. The systems studied include FeI2 and the chlorides and bromides of Cr, Mn, Co, and Ni. The over-all temperature range was between 440 and 700°C. For all systems the monomer is the major vapor species in the temperature range studied. Dimeric species have also been detected in the vapor phase for all systems, except NiCl2 and NiBr2. Vapor pressure data have been combined with mass spectrometric and entropy data to give heats for the dimerization reaction, 2MX2 (g)=M2X4 (g).
Reactions Initiated by β Decay of Tritium. II. The Tritium-Ethylene System
Authors: Yang Kang , Gant Preston L.
Published: January 2005

Because of the β decay of tritium gas, T2→(He3T)++e, the tritium-ethylene system undergoes reactions yielding various tritiated hydrocarbons. From the effects of three experimental variables (T2 conc., γ irradiation, replacing T2 by HT) on the rates of formation of tritiated compounds, we distinguished two types of labeling processes: (a) Recoil labeling:(He3T)++C2H4+(e)→Tritiated compounds,(b) β labeling:T2+C2H4↝ lim eTritiated compounds.Formation of tritiated ethylene involved both processes; its rate was independent of temperature (25°C↔—78.5°C), and not affected by the addition of nitric oxide ([NO]/[C2H4]≃0.05). Tritiated ethane, propane, and n-butane were formed exclusively by the β-labeling process; the rate of formation of these compounds increased with decreasing temperature and nitric oxide almost completely eliminated their production. Probable mechanisms for the recoil and β-labeling processes are discussed.
Calorimetric Heat of Adsorption—Nitrogen on Tungsten
Authors: Kisliuk P.
Published: January 2005

The heat of adsorption of nitrogen on tungsten ribbon has been measured calorimetrically. Up to a coverage of 2.5×1014 molecules/cm2 the heat is sensibly constant at 4 ev/molecule. This is 20% less than the change in enthalpy of nitrogen adsorbed on smilar ribbons determined from quasi-equilibrium adsorption isotherms. The coverage at which the heat departs from its constant value in the present room temperature experiments is twice that at which the change in enthalpy decreases sharply in the high-temperature equilibrium experiments. This is explained in terms of two types of adsorption site for nitrogen atoms on the exposed tungsten crystal planes. A pair consisting of one site of each type is occupied when a molecule is adsorbed at room temperature, but when the temperature is high enough to permit surface migration of nitrogen atoms, the more tightly binding sites are preferentially occupied. At high coverage, where the sticking probability falls to a low value, the calorimetric heat of adsorption depends critically on the microscopic details of the surface structure.
Small Angle X-Ray Scattering from Aluminum Hydroxide Gels. II
Authors: Bale Harold D. , Schmidt Paul W.
Published: January 2005

In a continuation of previously reported work [H. D. Bale and P. W. Schmidt, J. Phys. Chem. 62, 1179 (1958)] a further study of the physical structure of aluminum hydroxide gels prepared by different methods has been carried out, using small angle x-ray scattering techniques. The effects of collimation corrections on some of the earlier data have been calculated, and further experiments have been conducted. Previously, the scattering from the fresh gels was found to be independent of the pH at which precipitation was carried out, and was shown to depend on the concentration and charge of the anion of the aluminum salt from which the gel was precipitated. The present study shows that the anion concentration during precipitation has a much greater effect on the scattering pattern than does the aluminum ion concentration. The scattering from gels prepared under conditions in which no ions were present has also been studied. Scattering data from sols which are made from the gels indicate that the gels can be treated as assemblies of nearly independent particles. All fresh gels are amorphous. No aging effects are observed in gels precipitated at pH 7 from aluminum sulfate. When gels are precipitated at pH 7 from aluminum nitrate, thin boehmite platelets are first formed. After further aging, platelets of gibbsite appear. Values of platelet thickness have been determined. When gels are precipitated from aluminum nitrate and aged at high pH, large bayerite crystals are formed. When the gels are dried, a marked effect is observed on the scattering patterns for the fresh gels, while little change is observed in the scattering from the aged gels. According to the usual interpretation of scattering data, the fresh gels contain some particles or aggregates at least as large as a few hundred Angstroms. Also, a considerable number of the particles must have some dimensions of the order of 25 A or less. The relative importance of the large and small structures in the fresh gels varies with the conditions of preparation. The fresh gel results can be interpreted in terms of a distribution of particles or in terms of an aggregation of small particles.
Total Collision Cross Sections for the Interaction of Atomic Beams of Alkali Metals with Gases
Authors: Rothe Erhard W. , Bernstein Richard B.
Published: January 2005

Total collision cross sections (Q) for the interaction of atomic beams of K and Cs with a number of molecules were measured with an apparatus of 30″ angular resolution. Although absolute determinations of Q are difficult, relative values are readily obtained (±3%). Results are reported as the ratio (Q*) of the cross section for a given molecule to that of argon for the same beam atom. Seventy-seven molecules (of varied complexity and reactivity) were studied with K and 16 with Cs beams. Q* ranged from 0.29 to 2.8.

The data were correlated using the Massey-Mohr theory, assuming an attractive intermolecular potential V(r) = —C/r6. For this case Q=b(C/vr)2/5, where vr is the relative velocity and b a known constant. C was estimated from standard formulas for the London dispersion and dipole-induced dipole forces, using known refraction and dipole moment data. The theoretical values of Q differ by a nearly constant factor from the experimental results; thus values of Q* are predicted with good accuracy. The deviation between Qcalc* and Qobs* was <±3% for 57% (and <±10% for 87%) of the molecules. Most of the large deviations occurred for the light gases.
Crystal Structure of β-Hg
Authors: Atoji Masao , Schirber J. E. , Swenson C. A.
Published: January 2005

The crystal structure of β-Hg, a pressure induced modification of mercury which is the stable form below 79°K, has been determined. Whereas ordinary (α) mercury crystallizes in a simple rhombohedral lattice, β-Hg is found to be a body-centered tetragonal with a=3.995 A, and b=2.825 A at 77°K. Both phases are superconductors. A brief description of the low temperature x-ray cryostat and camera is given. The relation of α-Hg and β-Hg to Pauling's resonating valence bond theory of metals is discussed.
Infrared Spectrum of Crystalline Boron Trifluoride
Authors: Dows David A.
Published: January 2005

Infrared spectra of various mixtures of isotopically substituted boron trifluorides are presented. The samples were studied in the solid state at 83°K, and in the spectral range covering all fundamental vibrations.

Multiplet structures and shapes of the absorption bands show that the crystal structure is not isomorphous with that of boron trichloride and tribromide, and that rather strong intermolecular coupling of vibrations prevails.