bluuebunny/crossref_metadata_2025_split huggingface dataset:
Reactions of Methane with Iodine Activated by Radiative Neutron Capture
Authors: Hornig J. F. , Levey G. , Willard J. E. 
Published: January 2005

About 50 percent of the I128 atoms formed by the I127(n, γ)I128 reaction in gaseous mixtures of 0.2 mm of iodine and 400 mm of methane enter combination as methyl iodide, whereas much less than 1 percent of iodine atoms produced simultaneously by the photochemical dissociation of the iodine do so. By contrast, about 1 percent of the I128 formed by the I127(n, γ)I128 reaction in gaseous mixtures of iodine and ethyl iodide enters organic combination.
The solubility of iodine in pure liquid methane is less than 10−10 m/1 but as much as 3×10−5 m/1 may be dissolved when air has been allowed to condense in the methane. In such solutions I128 from the I127(n, γ)I128 reaction is able to enter organic combination as methyl iodide, ethyl iodide, and higher boiling material.
The Induction Period in Chain Reactions
Authors: Benson Sidney W. 
Published: January 2005

The conditions for the establishment of a stationary state in a system of consecutive reactions can be investigated quantitatively in a sufficient number of cases to permit precise criteria to be formulated generally for the length of the induction period (i.e., prestationary state period) in chain reactions. These are given as functions of the individual rate constants for the separate reactions, the extent of the reaction and the percent of stationary state concentrations achieved. Such relations provide a means for the evaluation of the self-consistency of experimental data with proposed mechanisms and also provide numerical limits on the values of individual rate constants.
Various chain reactions are examined in the light of these criteria. Of the hydrogen-halogen reactions, the H2–Cl2 reaction mechanism does not fulfill the stationary state requirements, and it is probable that many of the discordant results found in this reaction arise from this difficulty.
Intermolecular Potentials for the Systems CO2–CO2 and CO2–N2O
Authors: Amdur I. , Ross J. , Mason E. A. 
Published: January 2005

Experimental values of self-diffusion and mutual diffusion coefficients, in the range −78° to 90°C, have been used to determine the intermolecular potentials for the systems CO2–CO2 and CO2–N2O. It has been assumed that a spherically symmetric potential of the form V (r)=4ε[(σ/r)12—(σ/r)6] may be used and that the dynamics of the diffusion process are adequately described by the classical Chapman-Enskog transport relations, which consider only elastic, binary collisions.
The potential parameters derived from diffusion measurements have been compared with those obtained from measurements of viscosity, compressibility, the critical temperature, and the critical volume. It was not possible, for either system, to obtain a single set of parameters which could satisfactorily reproduce all the gaseous properties. It has been concluded that, for the present systems, the failure is due to one or both of the following: (1) inadequacy of the assumed potential form, (2) importance of inelastic collisions.
The Asymmetric Rotor. X. The Hydrogen Sulfide Spectrum in the 5150 cm−1 Region
Authors: Allen Harry C. , Cross Paul C. , Wilson M. K. 
Published: January 2005

The absorption spectrum of hydrogen sulfide in the region from 5000 to 5250 cm−1 has been measured and the rotational fine structure analyzed. The structure can be accounted for as arising from two vibrational transitions yielding a type A band centered at 5147 cm−1 and a type B band centered at 5145 cm−1. The excited state constants giving the best fit are type A band, A*=10.04, B*=8.68, C*=4.61 cm−1; type B band, A*=10.08, B*=8.68, C*=4.59 cm−1.
The frequencies and rotational band types indicate that these bands are the (nσ, nπ, nδ)=(110) (type A) and the lower component of the resonating pair (020) (200) (type B).
Rotational Isomers of Chloroacetyl Chloride, Bromoacetyl Chloride, and Bromoacetyl Bromide
Authors: Nakagawa Ichiro , Ichishima Isao , Kuratani Kenji , Miyazawa Tatsuo , Shimanouchi Takehiko , Mizushima San-ichiro 
Published: January 2005

The Raman spectra of chloroacetyl chloride, bromoacetyl chloride, and bromoacetyl bromide have been measured in the solid and liquid states. The infrared absorption spectra of these substances have also been measured in the liquid and the gaseous states. From the experimental results it has been concluded that there are two rotational isomers in the liquid and gaseous states and only one of them persists in the solid state. The temperature dependence of the intensity of the infrared absorption in the gaseous state has also been studied, and the energy difference between these two isomers has been found as 1.0±0.1 kcal/mol for bromoacetyl chloride and 1.9±0.3 kcal/mol for bromoacetyl bromide.
The calculation of the normal vibrations and of the product rule has been made for various configurations of rotational isomers, and it has been shown that the more stable form is the trans form (or nearly this one) with regard to the two halogen atoms. The less stable form is considered to have an azimuthal angle between the two carbon-halogen bonds of about 150°.
The Cut-Off Phenomena of Protein Crystallography
Authors: Booth Andrew D. 
Published: January 2005

The well-known paucity of experimentally observed reflections obtained from x-ray studies of protein single crystals, and their tendency to occur in well-marked spherical shells of reciprocal space, are examined quantitatively.
It is shown that, in the case of one protein for which data is available, a simple model with no assumed internal structure gives adequate agreement with experiment.
The addition of simple detail, such as nearest neighbor minimum approach distances, leads to further relations which could be used to produce improved agreement if required.
An Investigation of Certain Solvent Effect in Absorption Spectra
Authors: LeRosen Arthur L. , Reid Charles E. 
Published: January 2005

A study of the solvent effects in the spectra of non-ionic compounds to whose structure a zwitter ion form makes appreciable contribution (particularly in the excited state) has revealed three distinct effects:
1. A shift of absorption bands to greater wavelength with increasing refractive index, as predicted by Kundt's rule. This is ascribed to the effect of electronic polarizability on the zwitter ion structure, and is seen unmixed with the other effects only when the solvents are hydrocarbons or aryl halides.
2. A further shift which appears with most solvents other than hydrocarbons and aryl halides, and is ascribed to orientation of molecules of nonuniform polarizability.
3. The Kuhn-Brockmann effect—a large shift which appears whenever hydrogen bonds between the solvent and solute occur. This is believed to be due to the stabilization of the zwitter ion by the electrostatic nature of the hydrogen bond.
No correlations of the spectra of phenolphthalein, p-rosaniline hydrochloride, or iodine with the properties of the solvent were found.
Comparison of Absorption Spectrum of Uranium Tetrachloride with that of Praseodymium Trichloride and of Uranium Trichloride with that of Neodymium Trichloride
Authors: Sancier Kenneth M. , Freed Simon 
Published: January 2005

The absorption spectra of the following substances were taken at 77°K: crystals of anhydrous uranium tetrachloride, praseodymium trichloride, uranium trichloride, neodymium trichloride, uranium tetrafluoride, and a solution of uranium tetrachloride in a solvent consisting of propyl alcohol, propene, and propane.
The spectra of the ``iso-electronic'' ions U+4 and Pr+3 exhibited a match in wave number of the centers of gravity of the separate absorption groups. The correspondence is especially evident between the spectrum of uranium tetrachloride and that of praseodymium chloride. The uranium tetrafluoride furnished a spectrum resembling the chloride but the separations of the absorption regions were not so clear.
These correspondences between U+4 and Pr+3 lead to term assignments for the basic and activated electronic states of U+4 since those of Pr+3 are known. Thus, the two least stable electrons of U+4 in the basic state and to a good approximation in the excited states lies within the 5f shell.
The interaction of the fields of the environment of the ions in the case of U+4 is greater than in the case of Pr+3 and is especially marked in their 1I6 states. The greater interaction is in agreement with the greater effects of different ionic environments on the spectra of U+4, the greater intensity of the ``forbidden'' transitions and other physical properties.
The correlation of the spectra of U+3 and Nd+3 is less distinct even though the same approach may well be valid in view of their similar color. The areas of absorption are not as distinctly separate and may even overlap.
A new method has been developed for obtaining the absorption spectra of very small anisotropic crystals.
Cyanogen Flames and the Dissociation Energy of N2
Authors: Thomas N. , Gaydon A. G. , Brewer L. 
Published: January 2005

The behavior of cyanogen flames under a variety of conditions has been observed. Because of the relatively high stability of cyanogen, the behavior is considerably different from that of hydrocarbon flames. Because of the high stability of the combustion products, CO and N2, the flame temperature can reach temperatures above 4800°K. Thus the cyanogen-oxygen flame is the hottest natural flame known.
Spectroscopic observations have been made of both the reaction zone and the mantle of completely combusted gases. Rotational and vibrational temperature measurements using the CN violet system have indicated that the reaction zone is not in thermal equilibrium but that the mantle is in thermal equilibrium. Comparison of the calculated flame temperatures based on different heats of dissociation of N2 with the observed mantle temperatures has fixed DN2=9.764±0.005 ev and DCN=8.2±0.2 ev.
The Pyrolysis of n-Propyl-Benzene and the Heat of Formation of Ethyl Radical
Authors: Leigh C. H. , Szwarc M. 
Published: January 2005

The investigation of the pyrolysis of n-propyl-benzene by the ``toluene carrier'' technique revealed that this compound decomposes initially into benzyl and ethyl radicals: C6H5·CH2·C2H5→C6H5·CH2·+C2H5.Ethyl radicals decompose rapidly into ethylene and hydrogen atoms. The hydrogen atoms reacting with toluene produce H2 or CH4. The rate of the initial dissociation process can be measured by the rate of formation of C2 hydrocarbons.
It was shown that the decomposition is a homogeneous, first-order gas reaction. The activation energy was estimated at 57.5 kcal/mole, the frequency factor at 3.1012 sec−1. It appears that the activation energy is equal to D(C6H5·CH2–C2H5). Since the heat of formation of benzyl radicals is known, the estimation of D(C6H5·CH2–C2H5) leads to the value for the heat of formation of ethyl radicals, i.e., ΔHf(C2H5)≈22 kcal/mole.The latter value makes it possible to evaluate various relevant bond dissociation energies, i.e., D(C2H5–H) ≈94±4 kcal/mole.
The Molecular Structure of MoF6, WF6, and UF6 from Infrared and Raman Spectra
Authors: Burke T. G. , Smith D. F. , Nielsen A. H. 
Published: January 2005

This paper is a report of the complete investigation and interpretation of the Raman and infrared spectra of MoF6, WF6, and UF6. The Raman photographs of MoF6 and WF6 exhibit three intense lines in accord with earlier measurements on UF6 in solution. The exploration of the infrared spectra of MoF6 and WF6 from 2–40μ yielded a great many bands for each molecule. Two of these were quite intense in each case and were identified as fundamentals while the remaining weaker ones were identified as overtones and combinations. The infrared spectrum of UF6 was repeated from 2–17μ with substantially the same results as in the earlier work. Extension of this spectrum from 17–40μ was made and three new bands were discovered.
Because of the great similarity of the spectra of these three molecules, an interpretation of the bands was made along lines suggested by Bigeleisen, Mayer, Stevenson, and Turkevich for UF6, that the molecule belongs to the point group Oh and has totally symmetric octahedral structure. It was possible to fit all but five very weak bands into an identification scheme based on this model. The success of this effort is taken to be conclusive evidence in favor of the Oh type symmetry.
Infrared and Raman Spectra of Fluorinated Ethanes. III. The Series CH3–CF3, CH3–CF2Cl, CH3–CFCl2, and CH3–CCl3
Authors: Smith D. C. , Brown George M. , Nielsen J. Rud , Smith Raymond M. , Liang C. Y. 
Published: January 2005

New infrared spectra have been obtained for gaseous CH3–CF3 in the region 20–38μ, and in the region 2–38μ for gaseous CH3–CF2Cl and CH3–CFCl2, and CH3–CCl3 vapor and liquid, by use of LiF, NaCl, KBr, and KRS−5 optics. Raman spectra of gaseous and liquid CH3–CF2Cl and of CH3–CFCl2 and CH3–CCl3 in the liquid state have been obtained with a three-prism glass spectrograph of linear dispersion 15A/mm at 4358A. Depolarization ratios were obtained for all of the stronger Raman bands of the liquids.
The spectra are interpreted, a complete assignment of fundamental frequencies is proposed for each molecule, and thermodynamic functions are calculated for the temperature range 298–600°K and at the boiling point.
The Use of Isotopic Molecules for the Complete Determination of Force Constants. I. Linear Molecules
Authors: Decius J. C. 
Published: January 2005

Equations are developed which show the maximum amount of information which can be obtained concerning the force constants with isotopic linear molecules. It is demonstrated that a unique solution can be found in terms of the expressions Σkλk, Σkλk2, and Σkλk3, where λk=4π2νk2, provided the νk are known for the ``unsubstituted'' molecule and for certain isotopic molecules involving respectively single, double, and triple substitutions; i.e., if ABCD··· is the unsubstituted molecule, isotopic molecules of the types A*BCD···, AB*CD···, etc., A*B*CD···, etc., and A*B*C*D···, etc., are required. More than two isotopic forms (such as A and A*) of any given atom are not required.
For the triatomic molecule, only the singly substituted forms are required (this is also true for the perpendicular vibrations of the tetratomic molecule). It is also found that the force constants of the symmetrical linear molecule may be found using only symmetrical isotopic molecules; the number of these required is naturally less than the number required for an unsymmetrical molecule having the same number of atoms.
Statistical Mechanics of Rubber
Authors: Boggs F. W. 
Published: January 2005

It is shown in this paper that above the second-order transition the partition function of a rubber can be represented to a reasonably good approximation by the product of the partition function of a liquid formed of molecules similar to the chain elements and the partition function of the noninteracting chains divided by the partition function of a perfect gas. In terms of the free energy this means that the free energy of rubber will be equal to the sum of the free energy of the chain network without interactions and that of a liquid formed of the chain elements alone minus the free energy of a perfect gas having the same number of molecules as the rubber has chain elements.
This same procedure has permitted the calculation of the free energy and partial pressure of a rubber solution. This is, however, by no means the only possible application. All the thermodynamic properties of elastomer solvent systems can be obtained.
This is a generalization of the methods previously used in the statistical studies of rubber and rubber solvent mixtures.
The Host Crystal Luminescence of Zinc Sulfide Phosphors
Authors: Bube Richard H. 
Published: January 2005

Effects produced on the host crystal luminescence of zinc sulfide phosphors by increasing the preparation temperature without any additives in the preparation, are compared with effects produced by adding halide in the preparation at a fixed temperature.
Both methods of altering the luminescence properties of the phosphors produce qualitatively the same results on (1) intensification of the host crystal emission for excitation by 3650A ultraviolet and by 6 kv cathode rays, and for phosphors of both cubic and hexagonal crystal structure, (2) glow curves after excitation by 3650A ultraviolet, (3) diffuse reflectivity for light in the wavelength range from 3400 to 4200A, and (4) the variation of the emission intensity during excitation as a function of operating temperature.
Data on the variations, with preparation procedure, of the emission intensity during excitation and of the glow intensity during thermostimulation show that a possible correlation exists between shallow traps and isolated omission defects, and between deep traps and pairs of omission defects; and that a correlation is suggested between luminescence centers and particular perturbed (SZn4) groups in the crystal.
At least a part of the intensification caused by adding halide in the preparation must be attributed to a classical ``flux'' action.
A Molecular Orbital Theory of Reactivity in Aromatic Hydrocarbons
Authors: Fukui Kenichi , Yonezawa Teijiro , Shingu Haruo 
Published: January 2005

In the search for a quantitative correlation between reactivity and electronic configuration of aromatic hydrocarbons, the electron density, at each carbon atom, of the highest occupied π-orbital in the ground state of the molecule is calculated by means of the LCAO method. Comparing the result of such a calculation on fifteen condensed aromatic hydrocarbons with their chemical reactivities, we find that the position at which the electron density is largest is most readily attacked by electrophilic or oxidizing reagents.
It is, therefore, concluded that distinct from other π-electrons the pair of π-electrons occupying the highest orbital, which is referred to as frontier electrons, plays a decisive role in chemical activation of these hydrocarbon molecules. The theoretical significance of this discrimination of the frontier electrons in relation to the chemical activation is discussed.
Infrared and Raman Spectra of Fluorinated Ethanes. IV. The Series CH3–CH3, CH3–CH2F, CH3–CHF2, and CH3–CF3
Authors: Smith D. C. , Saunders R. A. , Nielsen J. Rud , Ferguson E. E. 
Published: January 2005

The infrared spectra of ethyl fluoride and 1,1-difluoroethane vapors have been obtained in the egion from 2 to 38μ, and the spectra of the liquids from 2 to 22μ, with the aid of LiF, NaCl, KBr, and KRS-5 prisms. The Raman spectra of both compounds were studied in the liquid phase with a three-prism glass spectrograph of linear dispersion 15A/mm at 4358A. Depolarization ratios were determined for the stronger bands. The Raman spectrum of 1,1-difluoroethane was also obtained for the gaseous phase.
A complete assignment of fundamental frequencies is proposed for each molecule and used in a detailed interpretation of the spectra and for the calculation of thermodynamic functions over the temperature range 298–600°K and at the boiling point.
Free Radicals by Mass Spectrometry. I. The Measurement of Methyl Radical Concentrations
Authors: Lossing F. P. , Tickner A. W. 
Published: January 2005

A method has been developed for measuring the partial pressure of methyl radicals in thermally decomposing gases, using a modified mass spectrometer. The sensitivity of the instrument to methyl radicals has been determined by decomposing known quantities of mercury dimethyl and di-t-butyl peroxide in a stream of carrier gas and measuring the amounts of the stable products and the net height of the mass 15 peak after correction for contributions from these stable products. Assuming a 100 percent carbon balance, the sensitivity of the instrument to methyl radicals was found to be 0.47±0.07 of the sensitivity to methane under the conditions used. With the present instrument this means that an ion current of 3×10−14 ampere at mass 15 (a peak 1 cm in height) is given by a partial pressure of methyl of 0.02 micron Hg above the leak in the reactor. The rate constants for the decomposition of di-t-butyl peroxide have been measured with this instrument. Combining the values obtained with values from the literature yields a value of E=38 kcal/mole and a frequency factor of 7×1015.
The rate of decomposition of mercury dimethyl was found to be dependent on the pressure of carrier gas in the reactor in the range from 5 to 20 mm. An estimate of the collision efficiency for the recombination of methyl radicals has been made using the partial pressures of methyl radicals measured by the method presented. At 850°C this value of the collision efficiency is 2–3×10−2.
A Mechanical Theory of Spinning Detonation
Authors: Fay James A. 
Published: January 2005

A review of published experimental data and theoretical discussions of spinning detonation reveals that there does not exist a consistent explanation of all the characteristics of such a phenomenon, particularly the dependence of spinning frequency upon tube diameter. In view of this, it is proposed to treat the problem principally from a hydrodynamic viewpoint by considering a possible periodic fluid motion with a characteristic frequency.
It is found that the calculated natural frequencies of vibration of the gaseous products behind a detonation wave agree closely with the measured frequencies of spinning detonation previously published in the literature. An analysis of such vibrations in the light of experimental evidence indicates that the vibratory motion is principally transverse. Of the various possible modes of vibration, the one which is observed depends upon the mixture composition and the tube size.
The observed existence of pressure waves in the wake of a spinning detonation wave is probably due to nonuniform combustion at the detonation front. It is shown how the initiation or cessation of combustion in a plane wave gives rise to compression or expansion waves respectively, and how a nonplanar disturbance excites a transverse vibration of characteristic frequency.
It is proposed that the uneven combustion of the spinning detonation wave is sustained by the heating and cooling effects of the vibratory pressure waves, which are themselves generated by such irregular combustion; i.e., spinning detonation is a self-excited vibratory phenomenon. Its appearance may thus be-attributed to the susceptibility of the reaction rate to the heating or cooling effects of pressure waves.
The Statistical Mechanical Theory of Irreversible Condensation. I
Authors: Reiss Howard 
Published: January 2005

A theory of nucleation, based on statistical mechanics, is presented. The problem reduces to the computation of the multiple occupation, by molecules, of cells, this being accomplished through the evaluation of the configuration integral for a supersaturated assembly. The new theory does not consider the first fragments of the stable phase formed to be spherical liquid drops. In no place (not even at the nucleus) is it necessary to to consider explicitly phase equilibrium between an embryo and the mother phase. The manifold difficulties connected with this point (in view of the small dimensions of typical nuclei) are therefore obviated. Furthermore, it is possible to define an embryo unambiguously, and in such a manner that its energetic properties can, in principle, be computed. This is not possible in the classical theory.
Certain limitations on the application of Einstein fluctuation theory to supersaturated systems are demonstrated.