bluuebunny/crossref_metadata_2025 huggingface dataset:
The Experimental Determination of the Intensities of Infrared Absorption Bands. IV. Measurements of the Stretching Vibrations of OCS and CS2
Authors: Robinson David Z.
Published: January 2005

The absolute intensity of the infrared stretching vibrations of the molecules CS2 and OCS have been measured. For CS2, the intensity of ν3 was found to be 7560×1010 cycles sec−1 (cm of vapor at NTP)−1. For OCS, the results were 110 and 7900×1010 for ν1 and ν3. A normal coordinate analysis of the stretching vibrations of OCS was carried out to obtain ∂μ/∂r for the bonds and to compare them with those for CS2 and the previously obtained results for CO2. The results for a reasonable value of the interaction constant were 6.7 and 4.3×10−10 esu for the CO and CS bonds, while in CO2 and CS2 they were 6.0 and 5.6×10−10 esu. The bearing of these results on the amount of resonance in OCS is discussed. Arguments are presented which suggest that, in spite of the electronegativity difference between oxygen and sulfur, resonance in OCS is not markedly different from that in CO2 and CS2.
Overlap and Bonding Power of 2s,2p-Hybrid Orbitals
Authors: Mulliken Robert S.
Published: January 2005

A classification and nomenclature for 2s−2p hybrid AO's (atomic orbitals) of any degree of hybridization is proposed, and the concepts of cohybrids, antihybrids, and orthohybrids are defined. Overlap integrals S as follows are computed and tabulated as a function of the hybridization coefficient and the interatomic-distance parameter for the case of two like first-row atoms: S(hβ, hβ; ρ), S(hβ, hoβ; ρ), and S(1s, hβ; ρ). (See also Figs. 1 and 2.) Here hβ denotes any 2s−2p hybrid, and hoβ the corresponding orthohybrid. Slater AO's were used, and also, for selected ρ values for the case of C–C bonds, SCF AO's.

In connection with this work, and extending fragmentary tables given in a previous paper, complete tables from ρ=3 to ρ=14, for the case of two like atoms, are given for the overlap integrals S(1s, 2s), S(2s, 2s), S(1s, 2pσ), S(2s, 2pσ), S(2pσ, 2pσ), and S(2pπ, 2pπ) using orthogonalized Slater 2s AO's, and carbon SCF 2pσ and 2pπ AO's.

Tables of Slater-AO overlap integrals S(1s, hβ) are given as a function of β for the radicals FH, OH, NH, and CH at their equilibrium distances, also similar tables based on SCF AO's for the case of C–H bonds of lengths 1.12, 1.09, and 1.06A. (See also Fig. 3.)

The various tables and figures show that ``a little hybridization goes a long way''; that is to say, a small amount of s character in a pσ AO, or of pσ character in an s AO, causes a large change in S. Applications of this fact to problems of chemical binding are briefly suggested. These will be developed in a following paper. (Also see Note added in proof at end of this paper.)
Discrete Energy Levels Associated with the Lennard-Jones Potential
Authors: Kilpatrick John E. , Kilpatrick Myra F.
Published: January 2005

The radial wave equation for two particles with a Lennard-Jones relative potential energy, in the reduced form, −(Rψ)′′+25b2(R−12−R−6)Rψ=−λ2Rψ, has been examined for discrete eigenvalues by both variation and perturbation theory. The largest eigenvalue, λ0 (corresponding to the lowest energy level), has been followed, as a function of b, until it disappears into the positive energy continuum. A short table of λ0 and λ1 has been computed.
The Dipole Moments and Structures of a Series of Alkyl Polysulfides
Authors: Woodrow Carroll C. , Carmack Marvin , Miller John G.
Published: January 2005

The dipole moments of n-hexadecyl mono-, di-, tri-, and tetrasulfides at 30°C are 1.47, 2.00, 1.63, and 2.16D, respectively. These values provide evidence in favor of non-branched sulfur chains in the polysulfides and are also in accord with fixed non-planar configurations for these chains. It is possible that the disulfide exists as mixture of two non-superimposable mirror-image forms, the trisulfide as a mixture of one highly polar form together with a pair of nearly non-polar enantiomorphs, and the tetrasulfide as a mixture of three different pairs of enantiomorphs, all three pairs being polar.
The Quantum Mechanics of Assemblies of Interacting Particles
Authors: Green H. S.
Published: January 2005

The quantum mechanics of fluids at moderately high and very low temperatures is investigated by the extension of a method due to Wigner. The fundamental equation satisfied by the phase space distribution function is solved, on the basis of classical statistics, by two different methods, and quantum corrections for thermodynamical equilibrium are obtained. It is shown that the effective molecular interaction becomes very weak near absolute zero. An estimate is made of the zero-point energy. Corrections due to quantum statistics are obtained.
The Role of a Positive Column in the Reduction of Current Due to External Light in an Electrodeless Discharge
Authors: Agashe V. V.
Published: January 2005

The discharge current in a cylindrical tube (45 mm in diameter and 45 mm in length) with external electrodes decreases on exposure to external light. An attempt has been made to determine the contribution to the reduction in current, by the different regions of the discharge tube, by exposing equal volumes of the discharge tube, one after another, from one electrode to the other. In the studies of Hg vapor discharge, the intensity and the source of the irradiation are changed and the pressure of Hg vapor is kept constant, while in the studies of Cl2 discharge, the intensity and the frequency of irradiation are kept constant and the pressure of Cl2 is changed from 3 mm to 70 mm of Hg. The results show that the reduction in current is maximum when the positive column of the discharge tube is exposed to external light. It has been suggested that a few more electrons in the positive column are lost by the formation of negative ions under the influence of external light. This reduces the average velocity of negatively charged particles and is probably responsible for the observed decrease in current.
The Variation of Atomic Polarizabilities in Molecular Vibrations
Authors: Matossi Frank
Published: January 2005

The depolarization factor of Raman lines of totally symmetric vibrations can be calculated in agreement with the general concepts of the polarizability theory of the Raman effect and with the concept of mutual interaction of dipoles if it is assumed that the polarizability of an atom depends on the interatomic distances in a molecule. When the totally symmetric species contains more than one vibration, the vibrational patterns, and thus the force constants, are among the factors that determine the depolarization. The results of the theory are evaluated for linear diatomic and triatomic molecules. The utilization of the method for checking force constants and molecular structures is pointed out.
The Infrared Spectra of Propane and Its Symmetrical Deuterium Substituted Analogs
Authors: McMurry H. L. , Thornton V.
Published: January 2005

The infrared spectra of 2,2-dideuteropropane, 1,1,1,3,3,3-hexadeuteropropane, and octadeuteropropane are presented, together with that of propane for comparison. Complete assignments are proposed for the frequencies of the vibrations belonging to species A1 and B1, and partial assignments for the vibrations belonging to species B2, in these molecules. They show that some low frequency vibrations (below 1350 cm−1) in the deuterium substituted molecules cannot be described adequately in terms of simple group motions. The results suggest that this is true also for the corresponding vibrations in propane.
Brownian Motion in a Gas of Noninteracting Molecules
Authors: Green Melville S.
Published: January 2005

The Brownian motion of a hard spherical particle in a gas whose molecules interact only with the particle but not with each other is considered from three points of view. (a) The generalized Fokker-Planck equation for the process is derived by the classical method of Lord Rayleigh. (b) The hypothesis of the phenomenonlogical theory of Brownian motion that the distribution of changes of momentum of the particle is normal is investigated with some mathematical rigor. (c) The formula for the friction constant recently given by Kirkwood is applied to this case. It is found that the plateau value in this formula exists in this case and that the value obtained agrees with Rayleigh's method. The hypothesis of the phenomenonological theory is found to be justified for times long enough for many collisions to have taken place. The theoretical formula for the friction constant is compared with Millikan's data for the friction constant for oil droplets in air at low pressures. It is found to agree with Millikan's data with respect to the form of the dependence on density and temperature. The theoretical values for hard spheres are somewhat lower than the data for oil droplets.
Rotational Isomerism in Oxalyl Chloride (ClOC–COCl)
Authors: Saksena B. D. , Kagarise R. E.
Published: January 2005

The Raman spectrum of liquid and the infrared absorption spectrum of liquid and gaseous oxalyl chloride have been investigated. The effects of dilution in benzene and of temperature upon the spectra were also studied. A tentative assignment has been made of all fundamental frequencies. From temperature intensity measurements in the Raman effect, the value of ΔH for the reaction C2h oxalyl chloride—C2v oxalyl chloride was found to be 2.8 kcal/mole. It is suggested that the high value of the depolarization factor for Rayleigh scattering indicates planar structure.
The Ultraviolet Spectrum of Oxalyl Chloride
Authors: Saksena B. D. , Kagarise R. E.
Published: January 2005

The ultraviolet spectrum of oxalyl chloride in the liquid and vapor phases has been investigated in the region 380–280 mμ. The spectrum of the vapor shows considerable structure and progressions of 70, 390, 940, 1380, and 1420 cm−1 are observed. The liquid spectrum in this region shows several maxima having small extinction coefficients. Beyond 280 mμ the extinction coefficient increases rapidly.
Nucleation in Very Rapid Vapor Expansions
Authors: Kantrowitz Arthur
Published: January 2005

In the Volmer theory, sub-critical droplets (embryos), with vapor pressure greater than their surroundings, nevertheless, grow statistically, because they exist in sufficiently greater numbers than neighboring larger droplets. Thus the formation of nuclei against the thermodynamic barrier presupposes the presence of very large numbers of embryos of all sizes.

An approximate lower bound for the time (nucleation time) required for the formation of this system of embryos can be calculated readily by (1) neglecting the thermodynamic barrier which impedes their formation; (2) assuming that when droplets contain a certain supercritical number, Γ, of molecules they grow very rapidly because their vapor pressure is considerably lower than their surroundings; (3) assuming that the formation of the embryo system begins when the vapor first becomes saturated. The equation for the rate of formation of embryos then reduces to the heat conduction equation yielding a simple solution. The lower bound sought is found to be inversely proportional to the fourth power of the degree of supercooling. Comparison with the experiments of Wegener and Smelt indicates that in some nozzle expansions the occurrence of nucleation is determined by this process.

On this theory the thermal accommodation coefficient which determines the heat transfer and especially the accommodation coefficient for growth, which determines the probability of a molecule sticking to the surface, play a much more prominent role than they do in the Volmer steady-state theory. Comparison with experimental time lags for the condensation of H2O in air at −30 to −60°C gives the order of magnitude of the accommodation coefficient for growth as 5×10−4.
Thermal Analysis of the System PbBr2–PbO
Authors: Knowles L. M.
Published: January 2005

A thermal analysis of the system PbBr2–PbO proved the existence of four compounds intermediate between PbBr2 and PbO, namely PbBr2·PbO, PbBr2·2PbO, PbBr2·3PbO, and PbBr2·7PbO. The compound PbBr2·PbO was unstable above 497°C whereas the others were stable at their melting points. Pure PbBr2·PbO·H2O (or Pb(OH)Br) was prepared and was found to decompose into PbBr2·PbO at temperatures above 150°C. This work offers an explanation for the discrepancies among data reported in the literature for the melting point of lead bromide.
Gaseous Detonation. I. Initiation of Detonation
Authors: Mooradian A. J. , Gordon W. E.
Published: January 2005

By means of piezoelectric gauges, a study has been made of the development of detonation from a shock wave propagated into a mixture. With a sufficiently strong shock, detonation above the stable velocity is immediately established which decays smoothly to the steady state. When the shock is weaker than required for detonation the phenomena which ensue depend upon the strength of the shock wave and the nature of the medium. A zone of combustion, accompanied by a build-up of the pressure, develops in the wake of the shock front. This may lead to a smooth acceleration of the latter until detonation is established; shock waves may be formed which overtake the front and cause detonation; or the initial shock may decay without detonation. The hydrodynamic properties of the medium are particularly important in determining the sequence of events. Composition and pressure limits are observed beyond which detonation cannot be initiated in any case. Near these limits there is always ``spin'' in the detonation, which appears on the pressure records as a periodic oscillation of the pressure for some distance behind the wave front. In these experiments the initiating shock wave was produced by a detonating mixture such as 2H2–O2 contained behind a Cellophane diaphragm. The strength of the shock wave was very much increased when this mixture was diluted with hydrogen.
The Statistical Mechanical Theory of Transport Processes. V. Quantum Hydrodynamics
Authors: Irving J. H. , Zwanzig Robert W.
Published: January 2005

This paper is concerned with certain extensions of a formal technique devised by Wigner for handling problems in quantum-statistical mechanics, especially to problems in quantum-mechanical transport processes. The approach is to find the closest possible analogy between classical and quantum-statistical mechanics, so that the extensive work in classical statistical mechanics can be utilized. This analogy is attained with the Wigner distribution function, with which averages of dynamical variables in quantum mechanics may be calculated by integrations in phase space. We will first state some basic properties of distribution functions in classical statistical mechanics, and then state the corresponding properties of the density matrix in quantum mechanics. We will define and discuss the Wigner distribution function, show that it has the desired averaging properties, and obtain the analog of the Liouville equation satisfied by this function. We will derive the analog of the Liouville equation in reduced phase space, and then obtain the equations of hydro-dynamics from quantum-statistical mechanics.
Paramagnetic Resonance Absorption of Microwaves
Authors: Lancaster Forrest W. , Gordy Walter
Published: January 2005

Paramagnetic resonance absorption in approximately a hundred salts in the powder form, containing atoms of the iron and rare earth groups and organic as well as inorganic radicals, has been investigated. The frequencies employed range from 9000 to 50,000 Mc/sec. Exchange interaction which affects markedly the line widths and shape was found to be of wide occurrence even in ions separated by large organic radicals. The results indicate that paramagnetic resonance is a promising new method of investigating the orbital properties of these organic radicals. Evidence has been found in copper acetate for the simultaneous transition of electrons in neighboring ions with the absorption of a single quantum.
Metal-Solution Potentials of Nickel in Foreign Ion Solutions
Authors: MacGillavry D. , Singer J. J. , Rosenbaum J. H.
Published: January 2005

Metal-solution potentials of nickel in foreign ion solutions were investigated. It was found that nickel may show stationary potentials in potassium hydroxide and phosphate buffer solutions, if oxygen was excluded. The stable potentials were reversible with respect to a change of pH. It was noted that nickel was unable to displace hydrogen from a 0.1 M phosphoric acid solution; nickel dissolved only on admission of air. The possibilities of interpreting the observed potentials are discussed.
The Vibration Spectra and Electric Moments of Azomethane, N–N′ Dimethylhydrazine and Acetaldazine
Authors: West W. , Killingsworth Robert B.
Published: January 2005

The investigations reported here on azomethane, CH3·N=N·CH3, N–N′ dimethylhydrazine, (CH3)HN·NH(CH3), and acetaldazine (CH3)HC=N–N=CH(CH3) were carried out primarily to obtain information on the general form and some of the structural properties of these molecules, which are of a type whose chemical behavior with respect to thermal and photodecomposition is of considerable current interest. The properties examined have included the Raman spectra, with the state of polarization of the stronger lines, in the liquid state, and the electric moment in solution of the three compounds; the infrared absorption spectrum of azomethane vapor has also been investigated to the degree possible with the resolution ordinarily obtained from a rocksalt prism spectrometer.
The Infrared Absorption of the OH Group of Phenol
Authors: Gordy Walter , Nielsen Alvin H.
Published: January 2005

The fundamental vibrational band of the OH group of phenol appearing in the region of 3μ has been studied for solutions of different concentrations of phenol in benzene, bromobenzene, nitrobenzene, dioxane, and ethyl acetate. The band appears at the same position, 2.96μ, for the concentrated solutions in all the solvents. In dilute solution in benzene and bromobenzene it appears at 2.79μ. The band at 2.79μ is attributed to the OH of single molecules, while that appearing at 2.96μ in the more concentrated solutions is thought to be due to associated OH. In dilute solutions in the oxygenated solvents the band appears at wavelengths longer than 2.79μ and is more intense than for the corresponding solution in benzene or bromobenzene. These results are regarded as evidence that the oxygenated solvents form weak additive compounds with the phenol by sharing the proton of the OH group.
Raman Spectra of Benzene and Isotope Effect
Authors: Cheng H. C. , Hsueh C. F. , Wu Ta-You
Published: January 2005

A faint line accompanying the strong line in the region of 990 cm—1 is observed in the Raman spectra of benzene, chlorobenzene, bromobenzene, toluene and cyclohexane. The relative intensities of the weak 984 cm—1 line and the strong 992 cm—1 line of benzene are measured to be in the ratio 6 : 100. This together with an approximate theoretical estimate support the suggestion that the weak line is due to molecules in which one of the carbon atoms is an isotope of mass 13. The exceedingly low intensity of the corresponding faint line in cyclohexane seems to point to a nonplanar structure. Similar study on the 944 cm—1 line in C6D6 is suggested.
The Diffusion of Hydrogen Through Nickel
Authors: Post C. B. , Ham W. R.
Published: January 2005

The diffusion of hydrogen through commercial and very pure anode nickel has been studied in a precision manner throughout the temperature interval 1100° to 150° Centigrade. It was found that the diffusion rates vary in a perfectly regular manner throughout this region, except for a discontinuity at the Curie point, namely near 360°C.

A very exact agreement with the formula R = ATzpy ×exp (—b/T) was found in all cases. After long heat treatment with hydrogen the value of y in the above equation for anode nickel becomes +0.50±0.01 with the possible exception of a region within 3° of the Curie point. All the nickel used had isotherms whose slope at the start of observations was a maximum in the Curie region and markedly greater than 0.5, but which approached 0.5 as the heat treatment, ordinarily considered as having a decarburizing effect, progressed.

The magnetic transition as shown by diffusion is abrupt, the isobars below the Curie region being quite as straight as above. There is always a sudden drop in the value of b as calculated from the simple equation R = A exp (—b/T) at the Curie point, the value changing in the purest nickel from 6600 to 5800 with rising temperature. No systematic breaks appear in the isobars at high temperatures, such as found in pure iron, but nevertheless the value of z indicates that the diffusing hydrogen possesses appreciable energy within the lattice.

The Curie region shows marked hysteresis, and is similar to the Curie region of pure iron in this respect.

Existing theories of ferromagnetism seem to require modification, inasmuch as the Curie transition in nickel appears to take place about as abruptly as the body-centered-face-centered transition in iron. The loss of magnetism at the Curie transition is essentially an atomic phenomenon and should not be associated primarily with conditions in aggregates of atoms or atomic domains. During the transformation for a finite time, there appears to be an additional electron in the valence shell of some nickel lattice points.

A possible description of the process of the change from the ferromagnetic to the paramagnetic condition in the transition elements is that an electron is moved from the 3d shell to one of the 4 levels, followed more or less quickly by a drop of another 4-level electron back to such a 3d level as to result in the pairing of electron spins in the 3d shell.
Calculations of the Lower Excited Levels of Benzene
Authors: Goeppert-Mayer M. , Sklar A. L.
Published: January 2005

The energy of the first excited levels of benzene is calculated by the method of antisymmetrized molecular orbitals. The results predict two weak bands, due to forbidden electronic transitions, at λ = 2500 and λ = 2100 and a strong band at λ = 1500. No empirical data except the carbon-carbon distance in benzene were used.
Infra-Red and Raman Spectra of Polyatomic Molecules. IV. Allene
Authors: Linnett J. W. , Avery W. H.
Published: January 2005

The infra-red absorption spectrum and the Raman spectrum of allene were examined. In the infra-red nine bands were observed at 4200, 2960, 2420, 1980, 1700, 1389, 1165, 1031 and 852 cm—1 and in the Raman effect there were ten individual shifts of 3062, 2992, 2858, 1956, 1684, 1430, 1069, 838, 705 and 353 cm—1. With the aid of heat capacity data it was possible to assign values to the frequencies of all the eleven fundamental modes of vibration of allene. The assignment accounted for all the features of the Raman and infra-red spectra. Calculations were made of the free energy, the entropy and the heat capacity and expressions for the first two, as functions of temperature, derived.
Calculation of the Frequencies of the Symmetrical Modes of Vibration for Molecules with Various Types of Symmetry
Authors: Bernstein H. J.
Published: January 2005

The secular equations for the frequencies of the symmetrical modes of vibration for molecules with various types of symmetry have been developed. The types of symmetry considered include a center of symmetry, and twofold, threefold, and fourfold axes of symmetry. Application to the problem of the configuration of oximes indicates that acetoxime has the following structural formula:     CH3  –  –126∘    C=N−OH.  –  –    CH3.
The Negative Bands of N14 – N15
Authors: Wood R. W. , Dieke G. H.
Published: January 2005

The negative bands of nitrogen were photographed with a mixture which contained about 15 percent of N15. The 0→0, 1→0 and 0→1 bands of the N14 – N15 molecule were analyzed. Their position is within the limits of experimental errors where the elementary theory of the isotopic shifts predicts them. The bands do not show any intensity alternations and there are no perturbations at the places where the corresponding bands of ordinary nitrogen have them.
A Kinetic Approach to the Theory of Conductance of Infinitely Dilute Solutions, Based on the ``Cage'' Model of Liquids
Authors: Polissar Milton J.
Published: January 2005

Attention is called to the disparity between the hydrodynamic model of an electrolytic solution and its physical counterpart. The ``cage'' theory of liquids is reviewed, and some of its equations developed with the purpose of bringing to the surface the underlying assumptions. A quantitative comparison is carried out between the behavior of an ion subject to Brownian motion and that of the placidly moving ion of the hydrodynamic theory. The conclusion is drawn that the tremendous difference between the two models casts doubt upon the validity of the hydrodynamic equations. The possibility is mentioned that the hydrodynamic theory, while giving fortuitously approximately correct values of ionic radii, may still be incorrect in its theoretical implications. Stress is laid on the desirability of a kinetic theory of electrolytic conductance. An approach to a kinetic theory is made, based on the cage model of liquids. In this method, the ionic migration is considered as the cumulative effect of a feeble, sporadic, but directed perturbation of the violent but random Brownian movement. The method leads to an experimentally substantiated relation between the diffusion and the conductivity of an electrolyte. It offers a plausible explanation of the high temperature coefficient of the slow-moving ions. For the ions of an infinitely dilute aqueous solution of potassium chloride, the method yields the following data: Heat of activation for a cage-to-cage jump, 4230 calories; frequency of cage-to-cage jumps, 1.12×1011 sec.—1; frequency of oscillation within the cage, 8.3×1013 sec.—1; average number of oscillations in each cage, 740.
Molecular Interaction in Mixed Monolayers II. Unstable Mixtures with Unsaturated Acids
Authors: Florence Robert T. , Harkins William D.
Published: January 2005

This investigation concerns the effect of the form of a molecule, with otherwise identical composition and structure, on its binding to the acidic or basic water of the subphase and to the molecules of the film itself. The binding to the water by the carboxyl group should be approximately the same for stearic acid and for the unsaturated acids, oleic and elaidic acid, with the double bond in the middle of the hydrocarbon chain. By compression of the film oleic acid may be squeezed out practically completely, from a mixed monolayer in which a saturated long chain alcohol, acid, or amine is the other constituent. Thus the energy of binding of the oleic acid to the other molecules in the film is weaker than that between the saturated molecules. However, earlier work in this laboratory has shown that the presence of the double bond does not decrease, but very slightly increases, the attraction between molecules.

Thus it seems to be the shape of the molecule which reduces the energy of binding of oleic acid in the film. Oleic acid is a cis form, so a nine carbon atom chain R2 is bent backward with respect to the other 9C chain R1 which ends in the carboxyl group. It may be assumed that the whole molecule is free to rotate, with the carboxyl group in contact with the water, and that the group R2 is free to vibrate or ``flagellate.'' Thus the oleic acid molecule would occupy a larger area than a saturated acid and this increased distance together with a lessening of the length of the contact between this and the other molecules in the film, decreases greatly the energy of binding. Space models of oleic and elaidic acid have been used in the study of these relations.

By a greater straightening of the chain, as in the transcompound, elaidic acid, the energy of binding should become intermediate between that of oleic and stearic acid, and much above that for oleic acid. On this basis compression should segregate elaidic acid slightly from the mixed film, but by no means completely, and this is what the experiments demonstrate.
Statistical Mechanics of Condensing Systems. IV
Authors: Harrison S. F. , Mayer Joseph E.
Published: January 2005

It is shown that the theoretical equations of the preceding paper lead to the prediction that, in a finite density and temperature range above the temperature of disappearance of the meniscus, a range of microscopic densities are equally stable, and in a sealed bomb different densities may be observed at a given temperature and average density. The densities observed in various parts of the bomb will depend in a predictable way on its previous history. This is in agreement with the published results of O. Maass on systems in the neighborhood of the critical point.
The Ultraviolet Absorption of Simple Hydrocarbons IV. Unsaturated Cyclic Hydrocarbons in the Schumann Region
Authors: Carr Emma P. , Stücklen Hildegard
Published: January 2005

The absorption spectra of cyclohexene, cyclopentene, 1–3 cyclohexadiene and benzene have been examined in vapor phase in the region λ = 2300–1600A. The electronic excitation responsible for the first group of bands in this region is practically independent of the cyclic structure of the molecule since the wave number of the first band agrees closely with that obtained for olefins having the same arrangement of hydrogen-atoms around the double bond. Characteristic vibrational frequencies and different electronic levels have been identified.
The Isotope Effect in the Vibration Spectrum of CCl4
Authors: Wu C. K. , Sutherland G. B. B. M.
Published: January 2005

The fine structure in certain of the Raman lines of CCl4 observed by Langseth and interpreted by him as being due to a lack of symmetry in the four carbon valencies has been shown to be accountable for as a purely isotopic effect. Rosenthal's general theory of the isotope effect in molecules of this type has been applied to the case of CCl4 in an attempt to differentiate between two types of potential function which have been proposed for this molecule. The fine structure patterns predicted on the different theories have been worked out. Unfortunately the existing experimental data are not sufficiently good to allow a decision to be made as to which is the better function.
A Simple Method for Determining the Polarization of Raman Lines
Authors: Edsall John T. , Wilson E. Bright
Published: January 2005

A simple method is described for determining qualitatively the polarization of Raman lines. The incident light is polarized by means of ``Polaroid.'' One of the arrangements used permits very high intensity of incident illumination. A brief statement of the theory of the method is given, and experimental data on acetic acid, acetone and ethanol are presented.
The Unimolecular Decomposition of Gaseous Chloropicrin
Authors: Steacie E. W. R. , Smith W. McF.
Published: January 2005

The decomposition of gaseous chloropicrin has been investigated in the temperature range 138 to 170°C at pressures from 6 to 20 cm. The reaction is homogeneous and unimolecular, the rate constants being expressed by the equation k=4.90×1015e−37670/RT sec.−1.The products of the reaction are phosgene, nitrosyl chloride, nitric oxide, and chlorine, as represented stoichiometrically by the equation CCl3NO2=COCl2+NOCl↓ ↑  NO+12Cl2.There is, however, evidence to show that at least part of the nitric oxide and chlorine are formed otherwise than by the decomposition of nitrosyl chloride.
Determination of Intermolecular Forces from the Joule-Thomson Coefficients
Authors: Hirschfelder J. O. , Ewell R. B. , Roebuck J. R.
Published: January 2005

The energy of interaction between nonpolar molecules is determined inductively from a study of the experimental Joule-Thomson coefficients. These coefficients have been measured very accurately for some substances, and in these cases our method of analysis is preferable to other methods which utilize less accurate data. It follows from classical statistical mechanics that: μ0=(−2πN/Cp0) × ∫ 0∞r2[1−(1−E(r)/kT) exp (−E(r)/kT)]dr.Here μ0 and Cp0 are the Joule-Thomson coefficient and specific heat at constant pressure, respectively, both extrapolated to zero pressure; N is Avogadro's number; k is Boltzmann's constant; and E(r) is the energy of interaction of two molecules separated by a distance r. This integral is evaluated using the Lennard-Jones form for the potential energy, E(r) = — cr—6+lr—s. Here c, l, and s are varied so as to give the best agreement with the experimental μ0. The numerical tables required for these analyses are given. Helium and argon are studied in detail. The necessary quantum corrections are made for helium and shown to be negligible for argon. The Joule-Thomson studies of Roebuck and Osterberg are found to be in accord with other PVT measurements. It is shown that all substances having a mutual potential energy of the Lennard-Jones form with the same value for s, satisfy the theorem of corresponding states. Consequently, at low pressures, the Boyle point, TB, is proportional to the Joule-Thomson inversion point, TI, and TB=0.532TI. This relationship is verified in the case of N2.
Infra-Red Absorption Bands in the Spectrum of Deutero-Formaldehyde
Authors: Ebers Earle S. , Nielsen Harald H.
Published: January 2005

The spectrum of deutero-formaldehyde in the infra-red has been studied from 2.0μ to 13.0μ and seven absorption bands have been found. With these data and the data on the spectrum of the ordinary formaldehyde available it has been possible, making use of the product relations of Redlich, to identify with considerable certainty the fundamental frequencies of the H2CO and D2CO molecules, respectively, as: ν1 = 2780 cm—1, ν2 = 1750 cm—1, ν3 = 2875 cm—1, ν4 = 1503 cm—1, ν5 = 1278 cm—1, ν6 = 1165 cm—1, and ν1′ = 2056.4 cm—1, ν2′ = 1700 cm—1, ν3′ = 2160.3 cm—1, ν4′ = 1106.4 cm—1, ν5′ = 990.2 cm—1 and ν6′ = 938.0 cm—1. With this identification the valence force constants for the formaldehyde molecules have been computed.
The Mercury Photosensitized Hydrogenation of Ethylene, Ethylene-d4 and Partially Deuterized Ethylenes
Authors: Jungers Joseph C. , Taylor Hugh S.
Published: January 2005

The hydrogenation of ethylene, ethylene-d4 and partially deuterized ethylene photosensitized by excited mercury to λ = 2537A has been studied. It has been found that the rate of hydrogenation of the deutero-compound is more rapid than that of ethylene under comparable conditions. With excess hydrogen, the rate is independent of the ethylene pressure. The data obtained indicate that butane is the important product together with small amounts of ethane relatively more abundant in the case of ethylene-d4. Negligible amounts of methane are formed. The suggested mechanism involves the reactions H+C2H4 = C2H5 followed by C2H5+C2H5 = C4H10 and to a lesser degree, C2H5+C2H5 = C2H6+C2H4. At low hydrogen concentrations, or in absence of hydrogen, a photosensitized polymerization occurs, faster with ethylene than with ethylene-d4. The slower rate of polymerization of the deutero-compound may be explained on the basis of zero-point energy differences between C2H4 and C2D4 in their reactions with free radicals to yield more complex radicals.
The Temperature Variation of Diffusion Processes
Authors: Taylor Hugh S.
Published: January 2005

The Eyring concept of holes in liquids and his theory of absolute reaction rates indicate that diffusion coefficients should vary exponentially with temperature. Data in the literature indicate that this is true. It is shown that empirical observations concerning the relation between diffusion velocity and its temperature coefficient, hitherto generally assumed to be linear, are readily explained upon the basis of holes in liquids as a controlling factor. As with viscosity, in liquids containing hydrogen bonds relatively high activation energies of diffusion are found. Data for small diffusing molecules should not show a constant diffusion-viscosity product as required by the Stokes-Einstein relation at constant temperature, but a product varying within restricted ranges with the dimensions of the solvent molecules. Data already available tend to confirm this conclusion.
Nonadiabatic Reactions. Chemiluminescence
Authors: Evans M. G. , Eyring H. , Kincaid John F.
Published: January 2005

It is pointed out that chemiluminescent reactions are necessarily nonadiabatic, since emission of radiation can only occur by transition from an upper to a lower potential energy surface. The restriction imposed by the second law of thermodynamics on the photon yield is, [open phi]⩽ΔF/E,where [open phi] is the ratio of quanta evolved to molecules reacted, ΔF is the free energy decrease in the reaction, and E is the energy of the photon emitted. Upper potential energy surfaces are reached either by activation by radiation, which may be that of a black body at the temperature of the reaction, or by the ``crossing'' of potential energy surfaces. From Audubert's data on the radiation produced by the thermal decomposition of sodium azide approximate surfaces which account for the observations are constructed.
Electric Moments of the Methyl and Ethyl Alcohol Molecules
Authors: Stranathan J. D.
Published: January 2005

The dielectric constant of methyl alcohol vapor has been measured at 14 temperatures between 25.0°C and 206.0°C. At each temperature measurements were made at an average of 23 different pressures ranging from zero to near saturation. The slope, obtained by least squares, of the resulting (K—1)/(K+2) versus pressure curve gives one point on the Debye line. The 14 such points fall accurately on a straight line whose equation as obtained by least squares, and after making proper allowance for probable errors of calibration, is: [(K−1)/(K+2)]RT/p′=(7.72±0.15)+(17,730±71)/T. Using recently established values of the Boltzmann gas constant and Avogadro's number, this yields a value (1.706±0.005)×10—18 e.s.u. for the electric moment of the methyl alcohol molecule. Taking the sum of the electronic and atomic polarization as 8.6 leads to an electric moment of (1.688±0.006)×10—18. The mean (1.698±0.005)×10—18 is taken as the electric moment of the methyl alcohol molecule. Data on ethyl alcohol previously published by Knowles have been recalculated, using a least squares treatment throughout, and making a minor correction to the value used for the absolute zero of temperature. The data conform to the equation [(K−1)/(K+2)]RT/p′=(13.06±0.20)+(17,725±87)/T, wherein probable errors of calibration have again been allowed for. This yields a moment (1.706±0.006)×10—18. Taking the sum of electronic and atomic polarization as 13.6 leads to a moment (1.696±0.008)×10—18. The mean (1.702±0.007)×10—18 is taken as the electric moment of the ethyl alcohol molecule.
The Effect of Temperature on the Atomic Distribution in Liquid Potassium
Authors: Thomas C. D. , Gingrich Newell S.
Published: January 2005

X-ray diffraction patterns of liquid potassium at temperatures of 70°C, 200°C, 295°C and 395°C have been obtained, using Mo Kα radiation. Three peaks appear in each pattern, and with increasing temperature, the peaks become somewhat less pronounced. The first, and most intense, peak appears at a scattering angle of 10° 36′ in the 70°C case, and it appears at 10° 16′ in the 395°C case. Fourier analysis applied to the above two cases gives the atomic distributions at these temperatures. In the 70°C distribution curve, the maximum of the first peak occurs at 4.64A, that of the second peak at 9.0A, and after this, the distribution rapidly becomes random. In the 395°C distribution curve, the maximum of the first peak occurs at 4.8A, that of the second at 9.2A, and beyond this the distribution becomes random more rapidly than in the 70°C case.
Raman Spectra of Hydrogen and Deuterium Sulfides in the Gas, Liquid and Solid States
Authors: Murphy George M. , Vance John E.
Published: January 2005

Raman spectra have been obtained for H2S and D2S as gas, liquid and solid. Only one frequency has been obtained in the gas and liquid although three are permitted by the selection principles. In the solids, a single line and a close doublet have been obtained. With the available infra-red and Raman data, it is not possible to make quantitative calculations of isotope effect, force constants, angle or anharmonic factors.
The Solid-Liquid Equilibrium in Argon
Authors: Rice O. K.
Published: January 2005

The method of investigating the equilibrium between solid and liquid phases, outlined in a previous paper, has been applied to argon. (In this method the intersections of the curves for the thermodynamic quantities T(∂S/∂V)T and (∂E/∂V)T+P, plotted as functions of the volume, are used to determine the conditions of equilibrium of the system.) Curves are found for the functions (∂S/∂V)T and (∂E/∂V)T, assumed dependent on volume and independent of temperature, which can reproduce with reasonable accuracy most of the melting parameters of argon at high pressures. The significance of these curves is discussed.
The Entropy of Ethyl Alcohol from Molecular Data and the Equilibrium in the Hydration of Ethylene
Authors: Schumann S. C. , Aston John G.
Published: January 2005

The entropy and free energy of ethyl alcohol gas have been calculated from the molecular data at several temperatures on the basis of (a) free internal rotation, (b) restricted rotation (with potentials; about C–C bond=3000, C–O bond=10,000 calories). The latter values are in perfect agreement with those from the third law and from the equilibrium data on the hydration of ethylene.
The Vibrational Spectrum and Thermodynamic Properties of Nickel Carbonyl
Authors: Crawford Bryce L. , Cross Paul C.
Published: January 2005

The infra-red absorption spectrum of nickel carbonyl has been measured in the gas phase from 4 to 23μ, and in the liquid phase from 1 to 8μ. Normal coordinate treatments of both the square and tetrahedral models of the AB4C4 molecule have been applied to the infra-red and Raman data; the results give further evidence of the tetrahedral structure of nickel carbonyl. An analysis of the vibrational spectrum has been made, based on the tetrahedral model, and has been applied to the statistical calculation of the entropy, heat capacity, and free energy function.
Vibration Spectra and Molecular Structure V. Infra-Red Studies on Light and Heavy Acetic Acids
Authors: Herman R. C. , Hofstadter R.
Published: January 2005

The infra-red absorption spectra of CH3COOH and CH3COOD between 1 and 15.5μ have been obtained with a rocksalt prism spectrometer. The association of CH3COOD has been studied and a value of the heat of dissociation obtained. Positions of the hydrogen and deuterium bonded O–H–O and O–D–O frequencies are given. Making certain assumptions, a value for the shorter O–H and O–D distances in the dimer rings is found to be 1.07A.
The Infra-Red Absorption Spectrum of Methyl Alcohol
Authors: Borden Avis , Barker E. F.
Published: January 2005

Using a grating spectrometer having a KBr foreprism the spectrum of methyl alcohol vapor was studied in the region from 2.5 to 26μ. This molecule has bands at 3683, 2978, 2845, 2054, 1477, 1455, 1340, 1034.18 cm—1 and a very broad band extending from 860 to beyond 380 cm—1. These bands are typical perpendicular and parallel bands and indicate that the molecule is only slightly asymmetric.

From the fine structure of the 1034.18 cm—1 parallel band and from certain assumptions about the structure of the molecule the two largest moments of inertia, A and B, were found to be 35.18 and 33.83×10—40 g cm2, respectively. It was not possible to measure C directly but it was estimated to be approximately 6.8×10—40 g cm2.

The low frequency band is probably due to the vibration of the hydroxyl hydrogen atom perpendicular to the O–H bond and perpendicular to the figure axis of the molecule. The presence of this band indicates that the hydroxyl group is not free to rotate, at least in the ground state. There is evidence of rotation in the structure of the band near the high frequency edge. The spacing increases toward high frequencies and finally there is a group of lines having a spacing of about 40 cm—1 between 600 and 860 cm—1. Since these lines are very weak and occur at such high frequencies it appears that free rotation exists only in states of high excitation. A quantitative study of free rotation in a symmetric molecule has been made. This investigation indicates that in a first approximation free rotation should give rise to groups of lines having a spacing of about 40 cm—1 between each group.
Excluded Volume Effect in Polymer Chains
Authors: Smith Richard P.
Published: January 2005

A new Monte Carlo method for the statistical study of the polymer chain excluded volume problem is presented. Random chains which are not allowed to have closed loops of fewer than R links are generated. Results of calculations for diamond lattice chains of up to 5000 links with R up to 1000 are given and discussed. These chain lengths are rather longer than those which have been studied previously. This is possible because (a) volume exclusion applies not to the entire chain, but only to the ``sliding segment'' of R links, and (b) a chain is not rejected when it comes back on itself, but forced not to cross and weighted appropriately. Results closely approximating the correct ones for the completely restricted random walk chain are obtained for R∼100. Results on number of configurations for long chain lengths and ring formation and trapping probabilities are given.
Jahn-Teller Effect in the Eg Vibrational Mode of Hexafluoride Molecules. The Infrared Spectra of RuF6 and RhF6
Authors: Weinstock Bernard , Claassen Howard H. , Chernick Cedric L.
Published: January 2005

The infrared spectra of RuF6 and RhF6 are reported and are interpreted in terms of a regular octahedral structure, point group Oh. The spectrum for RuF6 shows fewer bands than any of the known hexafluoride molecules, presumably owing to a Jahn-Teller effect. The fundamental vibrational frequencies (cm−1) for RuF6 are v1=675, v3=735, v4=275, v5=262; for RhF6, v1=634, v2=595, v3=724, v4=283, v5=269, and v6=192; for RuF6 v2 is estimated to be 573. A broad band arising from an electronic transition in RuF6 is also observed with maxima at 1950 and 1400 cm−1. The symmetry requirements for a Jahn-Teller effect in a regular octahedral hexafluoride molecule are summarized. The evidence for a Jahn-Teller effect in the Eg mode for hexafluoride molecules is reviewed. An analogous effect is not observed for the F2g mode although it is symmetry allowed. Comparison of band widths for (v1+v3) and (v2+v3) permits the following estimates of the Jahn-Teller splittings (cm−1) for the Eg mode: TcF6=80, ReF6=25, and OsF6=54. RhF6, like IrF6, does not show a Jahn-Teller effect of comparable magnitude, presumably because of the ``spin character'' of its Γ8 electronic ground state. The corresponding effect for RuF6 is relatively larger and cannot be evaluated in this way because the band (v2+v3) is so broadened as to make it extremely difficult to characterize.
Rigorous Basis of the Frenkel-Band Theory of Association Equilibrium
Authors: Stillinger Frank H.
Published: January 2005

By means of the general theory of the classical grand ensemble, the complete formal relations for pressure and number of molecules in an open system, as a function of activity, are derived without approximation within the scheme of the Frenkel-Band equilibrium cluster theory of association. The physical clusters, defined geometrically by overlap of spheres drawn about each molecule, are not regarded as statistically independent, but their mutual exclusion property gives rise to free energies of formation work for cavities necessary to contain those clusters. A connection is established between these free energies and a suitable generalization of the Mayer irreducible cluster sum. The appropriate modification of the theory to include external forces (such as the gravitational field) is displayed. A rigorous expansion of molecular distribution functions in terms of physical (rather than Ursell-Mayer) cluster integrals is also presented.