bluuebunny/crossref_metadata_2025_split huggingface dataset:
Gaseous Detonations. VII. A Study of Thermodynamic Equilibration in Acetylene-Oxygen Waves
Authors: Kistiakowsky G. B. , Zinman Walter G. 
Published: April 2005

The observed detonation velocities in acetylene-oxygen mixtures containing from 5 to 50% acetylene and thermo-hydro-dynamic calculations which assume complete equilibrium to be attained in the Chapman-Jouguet plane agree within 0.5%. This is of special interest because in successive parts of this composition range each of the several reactions, viz. dissociation of excess oxygen, carbon dioxide, water, and hydrogen becomes the main endothermic process. Temperatures may be calculated from the detonation velocities which agree with the theoretical equilibrium values to better than 1% over the range from 3000 to 4500°K.
In acetylene-oxygen mixtures containing 53 and 55% of the former, the observed detonation velocities agree with equilibrium calculations only when it is assumed that undersaturated carbon vapor, taken to be in equilibrium with unburned acetylene, has 170 Kcal as its heat of sublimation.
The velocities in mixtures containing from 60 to 70% acetylene agree quite well with calculations assuming homogeneous equilibrium. However, supersaturation of carbon vapor with respect to the solid must be assumed.
In mixtures containing 71% acetylene a sudden rise in detonation velocity is observed partway down the tube. The final velocity, as well as the constant velocities in still richer mixtures, are consistent with calculations assuming complete equilibrium, including solid carbon.
The discontinuity observed with 71% mixtures is interpreted as the overtaking of the Chapman-Jouguet plane of the primary detonation wave by a secondary shock wave developed by the delayed precipitation of carbon. It is suggested that because of the dependence of the delays of nucleation on the degree of supersaturation of a vapor, high velocities corresponding to complete equilibrium could be observed with leaner mixtures also, if detonation velocities were measured far enough from the point of initiation.
Far Ultraviolet Absorption Spectra of Ethylene and Ethylene-d4
Authors: Wilkinson P. G. , Mulliken R. S. 
Published: April 2005

The absorption spectra of ethylene and ethylene-d4 have been reinvestigated in the 1500 A to 2050 A region, using the first order of the Harrison 21-foot vacuum spectrograph. Vibrational constants of the C=C stretching vibration in the R (first Rydberg) state were determined to be: C2H4, ω20=1381.5 cm—1; x220=—11.2 cm—1; C2D4, ω20=1306.8 cm—1; x220 —8.2 cm—1; and (tentatively) in the V state: C2H4, ω20=852 cm—1; x220=—1.9 cm—1; C2D4, ω20=797 cm—1; x220=—1.8 cm—1. Newly observed fine structure in the v′—0 stretching vibration progression in the long wavelength part of the V←N transition of C2D4 is tentatively attributed to a torsional oscillation. The 0—0 bands of the V←N transition, though too weak to be seen, were estimated to lie near 2500 A. The probable dissociation of ethylene into CH2 radicals in the V←N continuum is discussed.
The torsional frequency in the R state was redetermined as 141 cm—1 (C2D4) and 236 cm—1 (C2H4), decreasing somewhat with increasing stretching quantum number. An attempt has been made to fit the corresponding vibrational levels, for both isotopes, to those calculated for a torsional oscillator-rotator using a potential function of the form V=12V0(1+cos2θ). Rough agreement is obtained for a reasonable barrier height of about 790 cm—1. (Values of 650 cm—1 for C2D4 and 920 cm—1 for C2H4 are obtained when the two isotopes are treated separately.) The anomalous isotope effect and intensities in the R←N twisting bands are tentatively attributed to perturbation of the R state levels by V state levels and/or the departure of the twisting potential from the simple cosine form. These views are encouraged by the fact that a higher Rydberg state shows similar twisting bands but with much less anomalous isotope effect and intensities.
Internal Pressure of Carbon Tetrachloride between —7° and 70°
Authors: Benninga Harm , Scott Robert L. 
Published: April 2005

Measurements of (∂P/∂T)V of carbon tetrachloride at ten different temperatures between —7° and 70°C yield an equation for the internal pressure (∂E/∂V)T=3346[1—2.97×10—3(t—25)—12.6×10—6(t—25)2] atmospheres.
Comparison with the cohesive energy density (ΔEv/V) confirms previous observations (Hildebrand and co-workers) that the ratio of the internal pressure to the cohesive energy density is approximately unity and further shows this ratio to be remarkably constant over the entire 77° range of temperature.
The experimental data on the internal pressure are in marked disagreement with the predictions of ``free-volume theory'' (Lennard-Jones and Devonshire, Hirschfelder and co-workers).
On the Determination of Absolute Intensities from Single- and Multiple-Path Absorption Measurements
Authors: Penner S. S. , Aroeste H. 
Published: April 2005

The physical principles involved in conventional absolute intensity measurements are reviewed. Experimental difficulties rule out the use of extrapolation techniques for some spectral transitions. For this reason it is of interest to re-examine the possibility of using total absorption measurements, in conjunction with the curves of growth, for making intensity estimates. Extrapolation methods yield results which are independent of spectral line shape. Use of the curves of growth, on the other hand, implies the assumption that the line contour can be described by combined Doppler and Lorentz broadening.
The curves of growth permit a unique correlation between total absorption and f-value either for spectral lines with pure Doppler broadening or for pure collision broadening. Furthermore, a simple experimental procedure can be devised for estimating both the absolute intensity and the spectral line profile on the basis of single-path and multiple-path absorption measurements. The suggested procedure involves absorption measurements for optical densities (path lengths) under conditions in which the integrated fractional absorption is a relatively sensitive function of spectral line shape. Representative calculations referring to utilization of the proposed method have been carried out for spectral lines belonging to the 2Σ→2II transitions, (0,0)-band, of OH, and also for lines belonging to the fundamental vibration-rotation spectrum of CO.
Thermal Diffusion in Polymer Solutions
Authors: Emery A. H. , Drickamer H. G. 
Published: April 2005

Thermal diffusion measurements have been made on a series of solutions of polystyrene as follows: (1) Five molecular weights (10 000 to 336 000) in toluene; (2) 136 000 molecular weight in o-xylene, styrene, ethyl benzene, dioxane, and pyridine; (3) Styrene dimer in toluene and styrene; measurements were also made on some binary monomeric mixtures.
The thermodynamic property X∂μ/∂X describes adequately the concentration dependence of the thermal diffusion ratio α. It appears that that portion of the motion of the polystyrene molecule in dilute and somewhat concentrated solutions which is segmental involves 10—13 chain atoms in the moving segment. The results seem consistent with Kauzmann and Eyring's picture for motion of long chain molecules.
Extended Interpretation of the Boltzmann-Maxwell Equation (A Theory of Nonstationary Random Processes)
Authors: Koga Toyoki 
Published: April 2005

Usual theories of statistical mechanics of nonuniform state stand on the assumption of approximately stationary random processes. Generally speaking, this assumption is not reasonable when the state concerned deviates considerably from thermal equilibrium. For a system in such a state, it is difficult not only to define but also to observe a complete set of gross variables. In this case the deviations of the actual future values of the gross variables from their expected future values cannot be neglected.
A new method of coarse-graining is proposed as available to such a state. As a concrete example of system we take a gas. We get a coarse-grained function 〈f〉D by averaging the fine-grained probability function of one molecule over a series of observations made on the system on different occasions where at each observation the system is initially in a common macroscopic state as determined by our incomplete set of initial conditions. It is shown that 〈f〉D satisfies the Boltzmann-Maxwell equation. The equation is valid even when the state concerned deviates considerably from thermal equilibrium and the random processes are not stationary. In this situation, however, the interpretation of the equation is different from the usual one; i.e., the equation predicts not the result of an individual observation of the gas concerned but the result obtained by averaging over a series of observations made repeatedly on different occasions on the same gas under a common incomplete set of macroscopic initial conditions where, with the lapse of time from the start, the result of each observation deviates from the others even in the macroscopic sense. For the time being, the theory is given only in the sense of classical mechanics.
An Ultrasonic Investigation of a Chemical Kinetics Problem: The Dissociation of Magnesium Sulfate
Authors: Bies David Alan 
Published: April 2005

New equations for the excess sound absorption per wavelength and the relaxation frequency have been derived. These equations are derived on the assumption that a dissociation process of the type (AB)⇌(A)+(B) is irreversibly perturbed by the sound field due to assumed pressure dependence of the equilibrium. These equations are applied to the problem of excess sound absorption in dilute magnesium sulfate solutions.
By using mixtures of dioxane and water to vary the dielectric constant of the solvent the effect of varying the ion Coulombic interaction forces of the ions in solution has been studied experimentally. This work and the work of other investigators on the excess sound absorption in dilute magnesium sulfate solutions is explained quantitatively.
The specific rates of dissociation and ion association for magnesium sulfate in solutions of water and water-dioxane have been determined. Good agreement is found between values of the mass action equilibrium constant determined by acoustic means and values determined by the usual conductivity method.
The experimental activation energy of molecular dissociation is determined to be 6.5 kcal/mole while the activation energy of ion association is estimated to be 8.5 kcal/mole.
Dielectric Constant of Polar Liquids at High Field Strengths
Authors: Booth F. 
Published: April 2005

A critical examination is given of a simplifying assumption made in an earlier calculation of the functional dependence of the integral dielectric constant of polar liquids on the applied field. It was assumed in this calculation that, for the cavity and reaction fields at all field strengths the usual expressions for low field strengths could be employed. It was pointed out that this simplification is plausible if the static dielectric constant is large compared with the optical dielectric constant. In the present note it is shown that, if it is postulated that the reaction field alone retains its conventional value, then the cavity field is appreciably increased by dielectric saturation. In the case of water the effect is equivalent to an increase of the external field by about 10 percent; a modified relation between the field and the dielectric constant is suggested.
The alteration of the reaction field as a result of saturation, and the effect of this modification on the dielectric constant, are also examined.
Mass Spectrum of Lithium Iodide
Authors: Friedman Lewis 
Published: April 2005

The mass spectrum of lithium-iodide vapor produced from salt heated in an oven in the ion source of an analytical mass spectrometer was investigated as a function of oven temperature. Evidence was obtained for the existence in the vapor of both monomer and dimer. Partial heats of sublimation to monomer and dimer at 0°K were found to be 44.9±0.7 and 45.5±2 kcal respectively. The heat of dissociation of (LiI)2 into gaseous monomers was found to be 44.4±2.2 kcal. The partial heat of sublimation of monomer was used with supplementary thermochemical data to obtain values for the lattice energy and the heat of dissociation of the diatomic molecule.
Appearance potentials for the major ions in the spectrum where determined. Upper limits for the energy of dissociation of the gaseous diatomic molecule were derived from the appearance potentials of Li+ and I+ which were slightly higher than the thermochemical value.
Decomposition of Ammonia Photosensitized by Mercury 6(3P1) Atoms
Authors: McDonald C. C. , Gunning H. E. 
Published: April 2005

An investigation has been made of the mercury—6(3P1)—photosensitized decomposition of ammonia at room temperature, under both flow and static conditions. Nitrogen and hydrogen were produced in the static experiments; hydrazine was an additional product in the flow experiments.
The quantum yield of ammonia decomposition in the flow experiments did not depend on the flow rate but increased in an exponential manner, as the reaction pressure was decreased, from a value of 0.09 at 650 mm toward unity at very low pressures. The quantum yield in the static experiments at high ammonia pressures and at a low extent of reaction was about the same as in the flow experiments at comparable pressures. The static quantum yield decreased when the extent of reaction was increased, when the ammonia pressure was decreased, or when hydrogen was added to the reaction.
The percentage of the decomposed ammonia which was recovered as hydrazine increased from zero at low flow rates to 95 percent at high flow rates. At a fixed flow rate, the hydrazine-to-nitrogen ratio increased, as the ammonia pressure was increased, from zero to a maximum value which was pressure independent at higher pressures. The hydrazine-to-nitrogen ratio increased as the incident intensity of 2537 A radiation was decreased. When ethylene was added to the flow experiments the hydrazine-to-nitrogen ratio was markedly increased. However, when platinum wire was introduced into the irradiated zone, the reaction was found to be unchanged.
A mechanism is suggested which appears to give the best representation of the results.
Vacuum Photolysis of Silver Bromide and Silver Chloride
Authors: Luckey George W. 
Published: April 2005

The quantum yields of halogen production in the vacuum photolysis of silver bromide and silver chloride have been measured at various temperatures, wavelengths, and light intensities. Silver-bromide crystals containing small amounts of copper and cadmium bromide have also been studied. At room temperature, the yields of thick crystals follow the equation, φ=Q(1−e−ka),where Q is the surface efficiency, k is the absorption coefficient, and a is a parameter which is defined below. At room temperature, in the halogen evolution range studied, the value of a for silver bromide is about 0.4 micron and that for silver chloride is about 0.24 micron. The values of Q are usually between 0.5 and 1.0.
The quantum yield of halogen production at room temperature is similar to the yield of a fast wall reaction. Both depend on the diffusion of reactants to the surface. The parameter a is related to the thickness of the diffusion layer. A numerical solution of the diffusion equation by C. A. Duboc has shown that a=1.154D12k14k114Io14,where D is the diffusion coefficient of positive holes and electrons, k1 is the recombination coefficient of positive holes and electrons in the silver halide, and Io is the incident intensity of light.
Above a certain temperature, the quantum yields decrease with increasing temperature, the long-wavelength yields increase relative to those at short wavelength and the yields increase with increasing light intensity. These effects are inhibited by the addition of copper bromide to silver-bromide crystals. The decrease in yield at high temperatures is probably caused by the decreased effectiveness of traps. The cadmium results indicate that this decrease is also affected by the ionic conductivity of the crystals. The addition of copper or cadmium ion does not have a large effect on the quantum yields at room temperature. This indicates that positive-ion vacancies in the silver halides are not good positive hole-traps at room temperature. The data and the solution of the diffusion equation indicate that the quantum yield of photoconductivity and photolysis are closely related. Additional measurements of photoconductivity and light-absorption coefficients are needed before the results can be completely interpreted.
Statistical Mechanics of Polymer Solutions. Parts I and II
Authors: Kurata Michio , Tamura Mikio , Watari Tatsuro 
Published: April 2005

Some contributions are made to the refining of the lattice model theory of Flory of chain polymer solutions by introducing the idea used in the recent theory of regular assembly that combinatory factor constructed in terms of multiple site clusters can be properly used to take long-range correlations between a given site and its far distant neighbors into account.
In Part I, the combinatory factors of Flory and others in current use are reconstructed to exemplify the pseudo-assembly method which has been presented by Kikuchi and the present authors for an easy construction of combinatory factors of higher-order approximation for regular assembly, and to give a thorough understanding of the succeeding uses in Part II.
In Part II, a refined theory of chain polymer solutions is developed. The final expressions for the entropy of dilution and the osmotic pressure depend on the flexibility and the degree of branching of the polymer chain, and give a better agreement with observed data even at high dilution.
Infrared Spectrum of SOF2
Authors: O'Loane J. Kenneth , Wilson M. Kent 
Published: April 2005

An investigation of the infrared spectrum of gaseous thionyl fluoride results in the following fundamental assignment: ν1(a′)=1333 cm−1,  ν2(a′)=808 cm−1,  ν3(a′)=530 cm−1.ν4(a′)=(410) cm−1,  ν5(a′′)=748 cm−1,  ν6(a′′)=390 cm−1.
Thermodynamic functions for SOF2 are calculated with the usual assumptions.
Concentration of Nitrogen-15 by Chemical Exchange in a Thermal Diffusion Column
Authors: Spindel W. , Taylor T. I. 
Published: April 2005

A concentration of nitrogen-15 has been effected in a thermal diffusion column under conditions where the gaseous exchange action, N14O2+N15O⇄N15O2+N14O, can contribute to the separative process. The top of the column is fed with NO2 of normal isotopic abundance. Reversible thermal decomposition of NO2 into NO and O2 establishes a radial concentration gradient so that the descending cold stream is predominantly NO2 and the inner hot ascending stream is largely NO and O2. As a result of the exchange reaction, N15 preferentially concentrates in the NO2 and is carried to the bottom of the column. Here the enriched NO2 re-enters the hot rising stream and is again decomposed into NO which undergoes further exchange. This reversible thermal decomposition makes it possible to operate the column without a chemical converter as was needed in the CO–CO2 system.
The over-all isotope separation has been studied in a two-meter column as a function of pressure (0.25 to 1.0 atmosphere), temperature (400 to 700°C) and withdrawal rate (5 to 66 cc atmospheres per day). A maximum over-all separation of 2.6 was obtained at a filament temperature of 685°C and a pressure of 0.5 atmosphere. At a withdrawal rate of 27 cc atmospheres the over-all separation is about 70 percent of this maximum value.
The system is a rather complicated one, and it is not yet possible to completely evaluate the contribution of each separative process that can occur in the column.
On the Adsorption of Oxygen on Tungsten as Revealed in the Field Emission Electron Microscope
Authors: Becker J. A. , Brandes R. G. 
Published: April 2005

The tungsten surface in a field emission microscope is exposed to oxygen gas at a pressure near 5×10—8 mm and the effect of the gas on the field emission is observed. During the first 30 seconds, the emission decreases rapidly, but some regions deactivate more rapidly than others. During the next 12 minutes, the rate of deactivation is much slower, but again the change in activity for some planes is much more pronounced than for others. After the surface is heavily covered, the oxygen is desorbed by glowing the tungsten for one minute at successively higher temperatures.
The chief conclusions are: Oxygen is adsorbed on tungsten in three stages or layers. In the first layer, the bond strength is about 5 electron volts and the oxygen cannot be removed below about 1500°K. In the second layer, the bond strength is about 2.5 ev and the oxygen cannot be removed below about 750°K. These bond strengths depend somewhat on the crystallographic plane. In the third layer, the oxygen forms a variety of molecular complexes with the substrate. These reveal themselves as intensely bright, highly localized groups of spots. Each spot is due to electrons emitted by individual atoms in a molecule. The conditions necessary to observe such adatoms are given.
Shape of the Consolute Curve and its Consequences for the Theory of Binary Liquid Mixtures of Nonelectrolytes
Authors: Kohler F. 
Published: April 2005

The experimental results on the shape of the consolute curve of binary liquid mixtures with components A and B, especially the cubic dependence of the concentration on temperature, imply certain peculiarities in the behavior of the excess free energy of mixing ΔGexc. The term ΔGexc is expressed as W · x(1 — x) ·Ψ (x). Here 2W can be considered as the change in free energy, times Avogadro's number, when z contacts A—A and z contacts B—B are changed into 2z contacts A—B; x is the molefraction of one component, and z the coordination number. Moreover, Ψ(x) is much more sensitive than ΔGexc, and has a theoretical significance, being proportional to the ratio of the number of A—B contacts in the system investigated to their number in a perfect solution if the assumptions of the strictly regular model are regarded as valid.
With the assumption that the system is symmetrical, the consolute curve consists of the points at which the first derivative of ΔGm with respect to x vanishes. If the function Ψ is expressed as a power series in s=2x—1, one also obtains Tc—T, Tc being the critical temperature, as a power series in s. The experimental results on the consolute curves serve now to determine the coefficients of the power series, by which Ψ is given. Two additional assumptions are needed: (1) The coefficients of the high powers vanish in order to make use of the relation Ψ(1) = 1 and (2) the value of ΔGexc for T = Tc and x=0.5 is known approximately. With these assumptions the experimentally established flatness of the consolute curves leads to a curve for Ψ vs x having a double-maximum Ψ being greater than unity for high values of s, i.e., for great dilution of one component. This confirms earlier conclusions drawn from vapor pressure measurements and investigations of the volume change on mixing.
From a molecular point of view one can express this result by saying that the solvation of the diluted component is increased as compared to a perfect solution, even if the mixture is so strongly endothermic as to separate into two phases. The theoretical interpretation is not yet clear.
Absorption Spectra of Iodine and Bromine in the Gas Phase and ``Inert'' Solvents. I. Iodine
Authors: Evans Dennis F. 
Published: April 2005

The strong absorption of iodine dissolved in paraffin hydrocarbons in the region of 2200 A—2600 A is not shown either by gaseous iodine or by iodine dissolved in perfluoroheptane (PFH) or di-perfluorohexyl ether, and is present only to a much smaller extent for iodine dissolved in chloroform.
The interaction of iodine with n-heptane has been studied quantitatively in PFH solution. It is concluded that the above absorption is a charge transfer transition due to a very weak, or possibly collisional type, complex, and is not a solvent shift of the N – V transition of the iodine molecule.