bluuebunny/crossref_metadata_2025 huggingface dataset:
On the Stability of Gas Bubbles in Liquid-Gas Solutions
Authors: Epstein P. S. , Plesset M. S.
Published: January 2005

With the neglect of the translational motion of the bubble, approximate solutions may be found for the rate of solution by diffusion of a gas bubble in an undersaturated liquid-gas solution; approximate solutions are also presented for the rate of growth of a bubble in an oversaturated liquid-gas solution. The effect of surface tension on the diffusion process is also considered.
Rotation-Vibration Spectra of Diatomic and Simple Polyatomic Molecules with Long Absorbing Paths V. The Spectrum of Isocyanic Acid
Authors: Reid C.
Published: January 2005

The spectrum of isocyanic acid has been examined in the photographic infra-red using a 21-ft. grating spectrograph and path lengths up to 500 m. The rotational structure of several bands has been analyzed and the energy levels and moments of inertia determined. With their help the coarse rotational structure of two of the fundamentals has also been analyzed. The molecular parameters fitting best our data and published electron diffraction results for the C–N and C–O bond distances are: r(H–N)=1.000A, ≰ H–N–C=125.5°.
Rotation-Vibration Spectra of Diatomic and Simple Polyatomic Molecules with Long Absorbing Paths VI. The Spectrum of Nitrous Oxide (N2O) below 1.2μ
Authors: Herzberg G. , Herzberg L.
Published: January 2005

The photographic infra-red spectrum of N2O has been investigated with absorbing paths up to 4500 m atmos. Thirty-four absorption bands have been found of which twenty-three have been measured and analyzed in detail. Improved vibrational constants ωi0 and Xik have been determined which give a fair representation of all the bands. The remaining deviations which are outside the present limits of error are due to the effect of Fermi resonance between ν1 and 2ν2.

Precise values of the rotational constants Bv1v2v3 have been determined for almost all vibrational levels involved in the observed bands. For the lowest vibrational level the six most accurately measured bands yield B000=0.419125 cm−1. In this case also the rotational constant D000 representing the influence of centrifugal stretching has been determined: D000=0.193×10−6 cm−1. The value of B000 is larger by 0.000091 than that derived from microwave data. From the Bv1v2v3 values the following values for the rotational constants αi have been obtained, α1=0.00170  α2=−0.00022  α3=0.00339.These values allow the determination of the rotational constant in the equilibrium position Be=0.42145 cm−1 from which the moment of inertia in the equilibrium position is found to be Ie=66.397×10−40 g cm2. The deviations of the individual Bv1v2v3 values from those obtained from the formula Bν1ν2ν3=Be−α1(ν1+12)−α2(ν2+1)−α3(ν3+12) are appreciably larger than would correspond to the errors of measurements and must be ascribed to the effect of the Fermi resonance.
Molecular Orbital Calculations of the Lower Excited Electronic Levels of Benzene, Configuration Interaction Included
Authors: Parr Robert G. , Craig David P. , Ross Ian G.
Published: January 2005

The lower excited π-electron levels of benzene are calculated by the non-empirical method of antisymmetrized products of molecular orbitals (in LCAO approximation) including configuration interaction. All configurations arising from excitation of one or two electrons from the most stable configuration are considered, and all many-center integrals are retained. The results are in better agreement with experiment and valence-bond calculations than those obtained previously by Craig in a calculation neglecting many-center integrals. Configuration interaction is found to change the order of the 1B1u and 1E2g states but leave unchanged the order of the 3B1u and 3B2u states, in agreement with the assignments 1A1g—3B1u and 1A1g—1E2g for the experimental bands at 3.8 and 6.2 ev.
The Admittance Concept in the Kinetics of Chromatography
Authors: Rosen J. B. , Winsche Warren E.
Published: January 2005

Chromatographic processes with linear kinetics can be represented by a system admittance for the case where the influent concentration varies sinusoidally. The admittance has been obtained for a variety of assumed rate controlling mechanisms and is shown to depend strongly on the type of kinetics obeyed by the system. The results indicate experimental techniques for determining the kinetics of these processes. Representative results obtained with an electronic analogue computer are presented for a case of non-linear kinetics.
On the Ultrasonic Absorption in Binary Mixtures of Unassociated Liquids
Authors: Sette Daniele
Published: January 2005

Measurements of absorption coefficient were carried out in a binary mixture formed by two unassociated liquids having similar absorption coefficients. The curve absorption coefficient versus mole fraction has a minimum at an intermediate concentration. A theoretical interpretation of experimental results is presented.
Kinetics of the Isotopic Exchange Reaction between Carbon Monoxide and Carbon Dioxide
Authors: Norris T. H. , Ruben S.
Published: January 2005

The rate of the exchange reaction between carbon monoxide and carbon dioxide has been studied, using C14 as a tracer. The reaction, whose velocity in a quartz vessel is convenient for study between 800 and 900°C appears to follow the rate law: Rate = k(pCO)0.73(pCO2)0.85. The apparent activation energy is 77 kcal. The reaction is accelerated by added nitrogen but not argon. Packing increases the rate only slightly, giving no indication of a primarily heterogeneous reaction. However, this observation is considered questionable.

The present conclusions differ somewhat from those derived by Brandner and Urey from a similar investigation. Re-examination of these authors' data seems to resolve the apparent inconsistencies. It is concluded that their proposed reaction mechanism is invalid; however, their conclusion of heterogeneity seems more acceptable.

A probable mechanism appears to be a bimolecular exchange between the two reactants adsorbed on the catalytic surface. The acceleration by nitrogen or, as observed by Brandner and Urey, by hydrogen or water is then possibly to be ascribed to ``promotion'' of the catalyst by surface adsorption of these substances.
Intramolecular Reaction in Polycondensations. II. Ring-Chain Equilibrium in Polydecamethylene Adipate
Authors: Jacobson Homer , Beckmann Charles O. , Stockmayer Walter H.
Published: January 2005

Decamethylene adipate polymers prepared in the absence of solvent undergo a reversible decrease in solution viscosity when heated for long times in chlorobenzene. This phenomenon is shown to be due to ester interchange reactions which establish equilibrium between ring and chain molecules. Quantitative agreement with the equilibrium theory of the previous paper is obtained if the effective length of a chain link is taken as 4.5±0.2A, which is of the order of magnitude to be expected from hindered rotation and steric effects. Measurements of ring-chain equilibrium thus appear to offer a useful method for characterizing the stiffness of relatively short and flexible chains.
Kinetics of the Reaction of Atomic Hydrogen with Acetylene
Authors: Dingle J. R. , Le Roy D. J.
Published: January 2005

A study has been made of the rate of recombination of atomic hydrogen in the presence and in the absence of the homogeneous catalyst, acetylene. The recombination in the absence of acetylene has a negative temperature coefficient and an order between one and two. The acetylene catalyzed recombination was found to be first order in atomic hydrogen and first order in acetylene, with a rate constant of 1.34×10−14 cc molecules−1 sec.−1 at 17°C. The effect of temperature on the reaction corresponded to a collision theory activation energy of 1.5 kcal./mole and a steric factor of 4×10−4.
The Separation of the Rotational Coordinates from the N-Particle Schroedinger Equation
Authors: Curtiss C. F. , Hirschfelder J. O. , Adler F. T.
Published: January 2005

By group theoretical arguments, it can be shown that a wave function, ψμL, for a system of N particles corresponding to a total angular momentum quantum number, L, and a quantum number, μ, referring to the z component of angular momentum may be written as a sum of terms: ψμL=Σs DL(R)μs*χsL.The DL(R)μs are the representation coefficients for the Lth irreducible representation of the three-dimensional rotation group, and are functions of the three coordinates specifying the orientation of the system of particles in space. The χμL are functions of the 3N−6 coordinates specifying the relative configuration of the N-particle system. The set of coupled differential equations for the functions, χμL, is obtained explicitly. The special case of the three-particle system is discussed in detail. The present treatment is more directly usable than the previous discussions since the basic equations do not involve implicit relationships between the variables.
Rotational Isomerism and the Vibrational Spectrum of 1,2-Dibromoethane
Authors: Neu John T. , Gwinn William D.
Published: January 2005

An assignment of the vibrational frequencies of CH2BrCH2Br and CD2BrCD2Br has been made. The Raman spectra of these compounds have been redetermined using the new ``Toronto''-type mercury arcs. It was possible, in the case of CH2BrCH2Br, to obtain a number of combination and overtone bands which were of assistance in the assignment. The liquid phase infra-red spectra of both compounds have been redetermined with greater resolution and spectral range than had been previously reported. The solid infra-red spectra of the same compounds were also determined in order to separate bands due to the trans isomer from those due to the skew isomer. Evidence for the C2 symmetry of the high energy form has been given.
The Infra-Red Spectra of N15N14O16 and N14N15O16. Some Thermodynamic Properties of the Isotopic N2O Molecules
Authors: Bigeleisen Jacob , Friedman Lewis
Published: January 2005

The three fundamental frequencies of N15N14O16 have been studied in the infra-red. One stretching frequency and the bending frequency in N14N15O16 have similarly been investigated. The bending frequencies in N15N14O16 and N14N15O16 are found to be in good agreement with calculations from the product rule. Some slight changes are made in the force constants for the stretching vibrations in N2O. The stretching frequency ω3 in N14N15O16 provides a good independent check on the force constants.

The partition function ratios for isotopic exchange reactions involving nitrogen and oxygen in N2O are calculated. The isomerization equilibrium N15N14O16=N14N15O16 has been calculated over the temperature range 273.16°—1000°K. A correlation is drawn between the structures of the isotopic isomers, N15N14O16 and N14N15O16, and the isomerization equilibrium.
The Vibrational Spectra and Structure of Inorganic Molecules. III. The Infra-Red Spectra of Nitrosyl Chloride and Nitrosyl Bromide from 2.0 to 25μ
Authors: Burns W. G. , Bernstein H. J.
Published: January 2005

The infra-red absorption spectra of nitrosyl chloride and nitrosyl bromide vapors have been examined from 400 to 5303 cm−1, and the spectra explained on the basis of three fundamentals at 1799, 592, and 332 cm−1 for NOCl and 1801, 542, and 265 cm−1 for NOBr. The force constants and the amplitudes for the fundamental modes were calculated for a central force system. The P—R separation of the predominantly parallel bands and the spacing of rotational bands in one partially resolved mainly perpendicular band in the NOCl spectrum were found to be in good accord with the electron diffraction data for the dimensions of the molecule. Thermodynamic functions for the gases were calculated from 298° to 1500°K. The calculated values of S298° for both gases are in good agreement with the experimental values.
The Multiplicity Forbidden Absorption Bands in the Spectrum of Pyridine
Authors: Reid C.
Published: January 2005

The two singlet-triplet transitions of pyridine have been studied using very long optical paths. The first of these, a π-electron transition, which was previously observed in the liquid phase only as a region of continuous weak absorption at the long wave end of the main absorption system, has been observed in the gas phase as a well-defined band system between 3000 and 3300A with a maximum molar absorption coefficient, ε=0.10.

The sixty observed bands have been fitted into a vibrational scheme which suggests that the transition responsible for them is allowed by symmetry.

The second transition which involves the non-bonding pair of electrons on the nitrogen atom was observed previously as a low temperature phosphorescence emission. Attempts to observe this transition in absorption using very long paths in the gas phase were unsuccessful, but it has been observed weakly using an optical path of 45 cm of liquid pyridine.
Nuclear Magnetic Resonance Line Shape for a Triangular Configuration of Nuclei
Authors: Andrew E. R. , Bersohn R.
Published: January 2005

The nuclear resonance line shape observed in solids can often be accounted for quantitatively and (in the absence of quadrupole effects) may provide information concerning the orientation and internuclear distances of dipolar nuclei. As an example of this method, the line shapes for a rigid and rotating triangular configuration of such nuclei are calculated and compared with recent experiments.
Size Effect in Low Temperature Heat Capacities
Authors: Montroll Elliott W.
Published: January 2005

It has been shown by Bolt and Maa that the distribution of normal modes of vibration of an elastic continuum is given by Aν2+B(S/V)ν+0(1) where A and B are numerical constants and S/V is the ratio of the surface area to the volume of the continuum. When this result is applied to the theory of the vibrational heat capacity of a solid at low temperatures, the Aν2-term yields the well-known T3 law and the B(S/V)ν-term leads to a contribution proportional to T2. About 0.5 to 10 percent of the heat capacity of non-metallic powders and materials with a domain structure can be attributed to the T2 term at 1°K. The importance of the surface term increases with decreasing temperature.

It is well known that at low temperatures the electronic contribution to the heat capacity of a metal is proportional to the temperature. In a system of very small metallic particles, the proportionality constant is increased by a quantity proportional to (S/V⅔)n−⅓ where n is the number of conduction electrons in the metal.
Kinetics of Heterogeneous Nucleation
Authors: Turnbull D.
Published: January 2005

Consider a phase transition α⇄β. Stable β-embryos can be retained in the temperature range of α-stability in cavities of suitable extraneous solids present in the system. Retained β-embryos may nucleate the α→β-transformation in the range of β-stability.

Using these concepts a theory for the effect of thermal history upon the kinetics of phase transformations is proposed. The kinetics of heterogeneous nucleation in the absence of retained embryos is discussed.
Quantitative Determination of Extinction Coefficients in the Vacuum Ultraviolet: Divinyl Ether
Authors: Harrison Anna J. , Gaddis Charlotte L. , Coffin Esther M.
Published: January 2005

A method of determining the molar extinction coefficients of organic compounds in the vapor phase in the vacuum ultraviolet has been developed. Measurements made with a fluorite spectrograph on flowing vapor samples of divinyl ether show a precision of 3 to 8 percent and satisfactory agreement with measurements made from 2360 to 2100A with a Beckman DU spectrophotometer. The absorption spectrum of divinyl ether is completely free from fine structure. The extinction coefficient increases rapidly from a value of 10 at 42,400 cm−1 to a maximum of 15,900 at 49,200 cm−1 and decreases to a minimum value of 4000 before beginning to rise again at 56,700 cm−1. The oscillator strength of the band is 0.45.
The Thermal Stabilization and Sintering of Gold Smoke Deposits
Authors: Harris Louis , Jeffries David , Siegel Benjamin M.
Published: January 2005

Gold smokes made by evaporation in an inert gas atmosphere are initially in a thermodynamically unstable state. A theory based on diffusion of vacant sites to the surface of the crystallites has been developed to describe the process by which the deposit approaches equilibrium. Measurement at different temperatures of the change of resistance associated with the loss of vacant sites gives a value of 23.5 kcal./g atom for the activation energy of this process.

When heated above 100°C the deposits sinter rapidly and undergo pronounced changes in optical properties. However, a gold smoke deposit can be stabilized, by heat treatment at 70°C, so that sintering proceeds at an appreciably slower rate.
Some Studies in Molecular Orbital Theory I. Resonance Structures and Molecular Orbitals in Unsaturated Hydrocarbons
Authors: Longuet-Higgins H. C.
Published: January 2005

The predictions of qualitative resonance theory, as to the electronic structures of unsaturated hydrocarbons, are analyzed in terms of LCAO molecular orbital theory. The following results are proved for ``alternant'' hydrocarbons, that is, hydrocarbons containing no odd-membered unsaturated rings:

(1) The number of unpaired electrons present in the ground state is at least as great as the number of carbon atoms having a deficiency of valence bonds in any principal resonance structure.

(2) With a few special exceptions, these odd electrons are distributed over just those atoms which have a deficiency of valence bonds in one or more of the principal resonance structures.

(3) In singly charged hydrocarbon anions or cations the ionic charge is located on just those atoms which bear charges in the various principal resonance structures.

It follows that enumeration of the principal resonance structures of a hydrocarbon molecule or ion gives much valuable information as to its electronic structure; and in particular, an alternant hydrocarbon possessing no normal Kekulé-type structure must have a paramagnetic ground state, and behave as a radical or multiradical.

These results do not depend on the neglect of overlap, or the assumption of a constant carbon-carbon resonance integral.
The Effect of the Electrostatic Polarization of the Solvent on Electronic Absorption Spectra in Solution
Authors: Bayliss Noel S.
Published: January 2005

Regarding the solvent as a continuous dielectric medium, it is shown that its effect on the Franck-Condon absorption of light by solute molecules must be expressed in terms of the electronic polarization part of its dielectric constant, K = n2. Using methods based both on quantum theory and on classical dispersion theory, it is shown that the red shift of absorption in solution depends directly on f, the oscillator strength, and inversely either on a3 (a is the radius of the spherical solute molecule) or the polarizability α. The expression Δν(cm−1)=const. (f/νa3)[(n2−1)/(2n2+1)] with two possible values of the constant, and alternatively with the substitution of α for a3, is tested on experimental data for isoprene, benzene, bromine, and iodine. Good quantitative agreement is obtained for the (V, N) transitions of isoprene and benzene. If the strong ultraviolet absorption of bromine and iodine solutions is regarded as the displaced (V, N) transition, the quantitative agreement is poor, although qualitatively in accordance with the theory. The weak λ2600 system of benzene, and the visible continua of bromine and iodine, show the expected smaller Δν with smaller f, although quantitative comparison with theory is prevented by the superposition of other solvent effects which become important in weak absorption bands.
The Interchange of Translational and Vibrational Energy in an Asymmetric Molecular Potential Field
Authors: Castellan Gilbert W. , Hulburt Hugh M.
Published: January 2005

Reflection coefficients are calculated for a matter wave in a parabolic channel and in a square channel, each channel closed at one end by a vertical plane tilted slightly from the normal to the axis of the channel. The number of collisions necessary to dissipate one quantum of vibrational energy is given in terms of λ=tanθ, where θ is the angular deviation of the plane end from the normal to the axis of the channel. Comparison with the data from measurements on sound dispersion shows good agreement for N2O and CO2. The temperature dependence of the average probability of transition per collision is compared with data for Cl2 and a mixture of Cl2 and CO.
The Microwave Spectra of Isotopic Methyl Chloride
Authors: Matlack G. , Glockler G. , Bianco D. R. , Roberts A.
Published: January 2005

The rotational transition J=0→J=1 of the isotopic species C13H3Cl, C12H2DCl, and C12HD2Cl have been investigated by microwave absorption. The data have been used to obtain the ground state dimensions of the methyl chloride molecule. The effects of zero-point vibration are rather large, and do not permit very accurate results for the dimensions of the methyl group: C–H=1.103±0.006A, ≰ H–C–H=109.8°±0.5°.
Hindered Rotation in Methyl Alcohol with Note on Ethyl Alcohol
Authors: Halford J. O.
Published: January 2005

The potential barrier to the internal rotation in methyl alcohol is recalculated from the entropy with the aid of new molecular dimensions generously provided by Burkhard and Dennison. The barrier calculation is examined for temperature dependence and checked for reliability by recalculation with the Clapeyron equation substituted for parts of the data. The result is 1600±700 cal./mole, which includes the new spectroscopic barrier of Burkhard and Dennison at 326 cm−1. Within the range covered by the result, a residual entropy up to 0.50 cal./mole deg. is possible, and the retention of 0.46 e.u. by the crystal is consistent with a reasonable simple assumption about the distribution of hydrogen bonds.

It is suggested, by analogy, that the barrier to the hydroxyl group rotation in ethyl alcohol should be about 1000 cal./mole.
Critique of the Free Volume Theory of the Liquid State
Authors: Kirkwood John G.
Published: January 2005

A deduction of the free volume theory of the liquid state from the general principle of statistical mechanics and certain well-defined approximations is undertaken. The Gibbs configuration integral is expressed as a sum of integrals corresponding to single and multiple occupancy of the cells of a reference lattice. The integral corresponding to single occupancy is evaluated with the approximate probability density, expressed as a product of functions of the coordinates of individual molecules, which leads to minimum free energy under the restraints of constant temperature and volume. The minimization of the free energy gives an integral equation for the probability density within each cell of the lattice. A first approximation of the solution of this equation yields a partition function identical with that of the Lennard-Jones-Devonshire free volume theory.
Second-Order Transitions and Mesh Distribution Functions of Cross-Linked Polystyrenes
Authors: Ueberreiter Kurt , Kanig Gerhard
Published: January 2005

To the definition of the state of ``liquid with thermally fixed structure'' is added that of ``liquid with chemically fixed structure.'' Polystyrene is combined with increasing proportions of divinylbenzene. The resulting space network is represented analytically by means of the definition of a mesh width. The second-order transition temperatures of these copolymers are determined from V—T curves. They obey a function where the constant 586[Me·T] characterizes the stiffening of the polystyrene by the addition of divinylbenzene. These polystyrene space networks are capable of being thermally activated up to a critical mesh width of 4 C atoms. The mesh widths are of varying sizes, the distribution is called the ``polydictiality.'' The mesh distribution function can be obtained from the V—T curves. The capacity of the space network to be thermally activated ceases fairly suddenly. This can be understood from a function of the capacity to be activated. The experimentally determined mesh distribution functions are expressed by means of a Gauss error curve. The width of this curve, about 1.7, is in surprising agreement for all copolymers. This means that approximately 50 percent of all meshes lie around the average mesh width with a variation of ±2 meshes. The method can be applied to all cross-linked high polymers.
The Moments of Inertia of Molecules with Internal Rotation
Authors: Torkington P.
Published: January 2005

The moments of inertia of some typical molecules with one internal rotational degree of freedom are obtained for all possible configurations; also the directions of the axes of least and greatest inertia. The dependence on the values of the structural parameters is discussed and illustrated.
Near Infra-Red Pleochroism. I. The Perturbed O–H and the C–H Modes in Polyvinyl Alcohol
Authors: Glatt L. , Webber D. S. , Seaman C. , Ellis J. W.
Published: January 2005

Pleochroism in O–H···O–H bands and > CH2 bands of polyvinyl alcohol is studied in the 0.6–3.7μ-region, using a quartz recording spectrograph in the 0.6–2.7μ-region and a high dispersion grating instrument with a selenium polarizer in the 2.5–3.7μ-region. Weak pleochroism in the fundamental ν(O–H) bands suggests that either some of the conclusions drawn from x-ray determinations may be in error or that there may be appreciable departure of the positions of the H atoms from the O–O lines. Dichroic bands caused by bound water are also found in this region, complicating interpretation and perhaps explaining discrepancies between this work and that of Elliott, Ambrose, and Temple. Evidence is presented for the presence of ``free'' carbinol O–H units in the crystalline regions of well-dried specimens. Pleochroic bands at 2941 cm−1 and 2906 cm−1 are tentatively assigned to > CH2 νa and νs fundamentals, respectively.
The Photovoltaic Behavior of Organic Substances in Solution
Authors: Levin Irvin , White Charles E.
Published: January 2005

A number of organic compounds have been studied for a comparison of photovoltaic behavior and fluorescent properties. No definite correlation could be found between visual fluorescence and the photovoltaic response. The photopotentials were measured by using a platinum point as the irradiated electrode connected to a vacuum tube electrometer. The irradiated electrode is assumed to act as a collector in the ``space charge'' of the photoactive molecules. Both positive and negative photopotentials were obtained. Compounds possessing a carbonyl group adjacent to an aromatic nucleus invariably produced a positive photopotential.
Mean Lifetime of the Fluorescence of Acetone and Biacetyl Vapors
Authors: Kaskan W. E. , Duncan A. B. F.
Published: January 2005

The effects of pressure, temperature, and exciting intensity on the lifetime of fluorescence of acetone and biacetyl vapor have been investigated. The pressure dependence of the lifetime in acetone was interpreted in terms of the formation of double molecules, and part of the temperature dependence was interpreted in terms of the formation of double molecules. The lifetime in biacetyl was found to be independent of pressure at a constant temperature, but dependent on temperature. The effect of oxygen on the lifetime in biacetyl was explained by assuming a simple Stern-Volmer mechanism for quenching. The lifetimes of fluorescence in both acetone and biacetyl were found to be dependent on the incident intensity. This effect was explained by assuming that the fluorescing molecules of both compounds were quenched by the products of photochemical decomposition.
On the Thermodynamic Relation between Surface Tension and Curvature
Authors: Koenig Frederick O.
Published: January 2005

From the Gibbs theory of surface tension general equations are deduced for the change of surface tension with curvature in the system having an arbitrary number of components but no insoluble surface film. For the special case that the surface layer is spherical, the equations are shown to be reducible, by an appropriate choice of auxiliary Gibbs surfaces, to a simple form identical with that recently found by Tolman for the system of one component. Some of the consequences of physical interest following from the equation for the spherical surface layer are pointed out.
The Vibrational Spectrum of Tetrachloroethylene
Authors: Bernstein H. J.
Published: January 2005

The infra-red spectrum of C2Cl4 through long paths has been obtained in the region 2.5–25μ. As many combination tones as possible were observed. An assignment of the fundamentals has been made which interprets satisfactorily 16 lines in the Raman spectrum and 24 bands in the infra-red spectrum.
The Intrinsic Viscosity, Translational and Rotatory Diffusion Constants of Rod-Like Macromolecules in Solution
Authors: Riseman Jacob , Kirkwood John G.
Published: January 2005

A theory of the intrinsic viscosities, translational and rotatory diffusion constants of rod-like macromolecules in solution is developed on the basis of a rigid-chain model made up of monomeric elements separated by rigid bonds. The general methods of previous papers are used to take proper account of the hydrodynamic interactions of the monomeric units of the molecule. The theory developed leads to results showing qualitatively, marked similarity to that obtained for cylindrical and ellipsoidal particles. The intrinsic viscosities, translatory and rotatory diffusion constants are shown, as in the case of flexible macromolecules, to be related through a pair of parameters. A method for obtaining the molecular weight of rod-like macromolecules is proposed, based on the combination of intrinsic viscosity and rotatory diffusion constant measurements.
Time Lag in the Nucleation of Supercooled Water Clouds by Silver Iodide Smokes
Authors: Reiss Howard
Published: January 2005

A mechanism is proposed by means of which the time lag in phase transitions initiated by foreign bodies may be calculated. Calculations are performed for silver iodide nucleating supercooled water clouds, and the results are compared with experimental data.
On the Magnetic Properties of Liquid He3
Authors: Goldstein L. , Goldstein M.
Published: January 2005

The object of this paper is to investigate the possibility that liquid He3 might have a tendency toward nuclear ferromagnetism in the approximation where this fluid is considered to be an antisymmetrical collection of atoms having an angular momentum of ℏ/2 and a finite nuclear magnetic moment. In the rather crude approximation where the motion of the individual atoms is described with the help of plane de Broglie waves, the exchange energy, originating in the interatomic mutual potential energy of He3 atoms, favors the parallel alignment of all spins at the temperature of absolute zero. The total energy of the fluid is, however, smaller in the antiferromagnetic configuration because its kinetic energy is smaller than in the ferromagnetic configuration. To the approximation of these studies then, liquid He3 does not show nuclear ferromagnetism. Its nuclear paramagnetism is then discussed.
Vibration Spectra and Normal Coordinate Treatment of Perfluorocyclobutane
Authors: Claassen Howard H.
Published: January 2005

The Raman spectra of gaseous and liquid cyclic C4F8 at room temperature have been obtained and polarization measurements made for the liquid state. The infra-red absorption spectrum of the gas between 2 and 23.1μ obtained by Dr. D. C. Smith of the Naval Research Laborotory is also reported here. A normal coordinate treatment, based on the assumption that the molecular symmetry is D4h, has been made and applied to assign the 23 fundamental vibration frequencies and to evaluate a set of force constants. The observed spectra have been interpreted in detail.
Reactions of Recoil Atoms in Liquids
Authors: Miller J. M. , Gryder J. W. , Dodson R. W.
Published: January 2005

The reactions in liquid phase of the recoil atoms formed in the (n, γ) process are discussed in terms of a model involving energy loss by elastic collisions, dissociation of solvent molecules by impact, and eventual reaction in a liquid cage. Expressions are derived which relate the fraction of the recoil atoms ultimately found in a given molecular species to the composition and properties of the liquid. Previously published data are interpreted in terms of this model.
II. The Effective Methyl Mass and Its Use in Determining the Force Constants and Character of Metallo-Organic Bonds
Authors: Sheline Raymond K.
Published: January 2005

The ``effective methyl masses'' of the Group IV tetramethyl derivatives and the analogous tetramethyl ammonium ion are shown to give a linear relationship when plotted against their respective stretching and bending frequencies. The linear relationships are used to determine ``effective methyl masses'' from Group V trimethyl stretching and bending frequencies and from some Group VI dimethyl stretching frequencies. Then the ``effective methyl masses'' so determined are used in simplified calculations to predict stretching and bending force constants for Groups V and VI methyl derivatives. This procedure is shown to give stretching force constants for dimethyl mercury and dimethyl zinc which are in good agreement with those obtained by Gutowsky on the basis of a less approximate normal coordinate treatment, the average deviation being 1 percent. Finally this large number of new metallo-organic force constants is summarized with existing metallo-organic force constants and the nature of the metallo-organic bond is discussed.
Molecular Motion in Certain Solid Hydrocarbons
Authors: Andrew E. R.
Published: January 2005

An investigation has been made of the variation of the nuclear resonance absorption line width with temperature for four long chain aliphatic compounds and eight aromatic hydrocarbons. The aliphatic compounds are dimorphous; in the lower temperature modification it is concluded that the molecules are rigid at the lowest temperatures, but that an increasing number of molecules rotate about their length as the temperature increases; in the upper temperature modification all the molecules rotate. The naphthalene crystal lattice is found to be rigid up to the melting point. Benzene and anthracene, however, show sharp line-width transitions at about 110° and 190°K, respectively. It is suggested that in benzene this is due to tunnelling or rotation of the molecules about their hexagonal axes. The explanation for anthracene is less clear, but it is suggested that each molecule rotates about its long diad axis. The xylenes, mesitylene, and hexamethylbenzene show internal rotation of the CH3 groups at all temperatures above 95°K. In addition, hexamethylbenzene has a line-width transition over the range 135–210°K, attributed to tunnelling or rotation of the molecules about their hexagonal axes.

A calculation is made of the reduction of the intramolecular contribution to the resonance line second moment caused by rotational oscillation of molecules in a crystal lattice. The effects of certain types of molecular motion on the intermolecular contribution are also calculated.
The Logical Position of the ``Average Bond Energy,'' the ``Dissociation Energy of a Bond,'' and the ``Force Constant''
Authors: Szwarc M. , Evans M. G.
Published: January 2005

The concepts of ``bond dissociation energy'' and ``average bond energy'' are analyzed. A mathematical treatment is suggested which makes it possible in principle to distribute the energy of atomization among the various bonds of the molecule. The relationship between the ``bond dissociation energy,'' ``average bond energy,'' and ``reorganization energy'' is examined in the light of various molecular force fields.
Expansion of the Montmorillonite Lattice on Hydration
Authors: Cornet I.
Published: January 2005

When exposed to water vapor, water, or some non-aqueous solvents, montmorillonitic clays display expansion of their lattices. Assuming that the expansion on hydration is a uni-dimensional swelling phenomenon, a thermodynamic analysis has been made which furnishes quantitative evaluation of interplanar forces. This analysis indicates that for lattice expansions of 3 or 4A from the dehydrated contracted state, the force between montmorillonite lattice layers is substantially constant; but for greater expansions the force diminishes in a complex manner. The analysis also indicates the possibility of determining quantitatively the forces exerted by molecules of solvents which expand the lattice, providing ion exchange does not occur. Problems in determining molecular forces and structure are discussed.
The Determination of Energy Levels from Thermodynamic Data. II. The Heights of Potential Energy Barriers Restricting Intramolecular Rotation
Authors: Blade Ellis , Kimball George E.
Published: January 2005

The uncertainty in the distribution of the energy levels implies a corresponding uncertainty in the shape of the associated potential energy function. The estimation of barrier heights is known to depend upon the shape of the potential, therefore implicitly upon the energy level distribution. We apply these ideas to the restricted rotation problem by introducing a shape parameter into the assumed potential function, and show that the currently accepted barrier height ranges should be widened. On the basis of our modified function, we found the following barrier heights to be consistent with published thermodynamic data: ethane 1550 to 2700 calories per mole; 1,1,1-trifluoroethane 2300 to 8300; methanol 800 to 3000.
Compressibility of Gases at High Temperatures. III. The Second Virial Coefficient of Helium in the Temperature Range 600°C to 1200°C
Authors: Yntema J. L. , Schneider W. G.
Published: January 2005

An apparatus is described for measuring the second virial coefficient of gases up to 1200°C. The method of measurement is based on a modification of an expansion method described previously. Results of measurements of the second virial coefficient of helium at 600°, 800°, 1000°, and 1200° are given.
On the Intermolecular Potential of Helium
Authors: Yntema J. L. , Schneider W. G.
Published: January 2005

Experimental values of the second virial coefficient from 0°C to 1200°C (see preceding paper) were used to test various intermolecular potential functions for helium. A Lennard Jones potential, E(r)=λr−n−μr−m,with m=6 and with n either 9 or 12 could not be made to fit the experimental data over the entire temperature range. The coefficients λ and μ derived from the data showed a marked temperature dependence. The theoretically calculated potentials of Slater and Kirkwood and of Margenau were found to give values of the second virial which were approximately 8.5 percent and 27 percent lower, respectively, than the experimental values. A potential function with exponential repulsion, which gives a more satisfactory fit with the experimental data, was derived empirically. A semi-empirical expression given by Keyes (reference 17) for B as a function of temperature was also compared.
Light Scattering in the Critical Region. I. Ethylene
Authors: Cataldi H. A. , Drickamer H. G.
Published: January 2005

1. In the neighborhood of the critical point, light scattering reveals the presence of four regions: a. A region where the light scattering depends on the inverse fourth power of the wave-length. b. A region of increasing scattering and decreasing dependence on wave-length, beginning about a degree above the critical temperature, and extending about a degree. The maximum scattering in this region is of the order of 100 times the initial value. c. An abrupt decrease in scattering, accompanied by absorption which sets in at a higher temperature for the shorter wave-length. d. A large and erratic increase in scattering, apparently resulting from condensation.

2. The scattering observed upon cooling and heating are identical, provided the temperature does not drop below the temperature for zero scattering or condensation.

3. The wave-length dependence of light scattering is not completely described by any existing theory.

4. Applying the Ornstein-Zernike equation where it is possible, one calculates clusters of about 20 molecular diameters more than a degree above the critical temperature. These clusters increase rapidly with decreasing temperature.
Light Scattering in the Critical Region. II. Ethane
Authors: Babb A. L. , Drickamer H. G.
Published: January 2005

Light scattering experiments have been performed on ethane in the critical region, using apparatus and procedure previously applied to ethylene. The results are qualitatively quite similar to those obtained for ethylene, indicating that no theory so far developed completely describes the phenomenon.
The Primary Quantum Yield of Dissociation of Iodine in Hexane Solution
Authors: Zimmerman Joseph , Noyes Richard M.
Published: January 2005

The primary quantum yield for the photo-dissociation of iodine in degassed hexane at 25° has been calculated from measurements of the mean lifetime of the chains involved in the exchange of iodine atoms with trans-diiodoethylene. The primary quantum yield to an accuracy of ±15 percent is 0.59 at 436 mμ and 0.37 at 578 mμ. The deviation of this quantity from unity is affected both by the ``primary recombination'' of atoms which fail to escape from the original ``cage'' of solvent molecules, and by the ``secondary recombination'' of the original atoms by diffusion during a time which is very short compared to that in which either is apt to encounter an atom from another molecule.

The specific rate constant for the recombination of iodine atoms in hexane solutions has been determined and has been shown to be about one fifth of the rate constant for collision in the gas phase.

The presence of air decreases the rate constant for the photochemical exchange of iodine with diodoethylene by a factor of four and increases the apparent mean lifetime of iodine atoms by a factor of one hundred.
Absorption by H2S Vapor in the Region 3.6μ to 4.5μ
Authors: Noble R. H. , Nielsen H. H.
Published: January 2005

The region near the absorption band of hydrogen sulfide vapor at 3.7μ has been measured with high resolution. The data obtained corroborate some of the previously published work on this molecule. Results were obtained, however, which are difficult to reconcile with a predicted band based on a model of the probable size and shape of H2S.
The Vibrational Spectra and Structure of Inorganic Molecules. I. The Infra-Red Spectrum of F2O from 2.5 to 25μ
Authors: Bernstein H. J. , Powling J.
Published: January 2005

The infra-red spectrum of gaseous F2O has been obtained from 2.5 to 25μ at pressures of 10 mm to 600 mm Hg in a 10-cm cell and at 600 mm Hg in a meter cell.

All three fundamentals have been observed and identified.

The fine structure of a ⊥ band was resolved and gave an estimate of the bond distance and apex angle as 1.38±0.03A and 101.5±1.5°, respectively.

The upper and lower limits of the constants of a quadratic potential function with all possible interaction constants have been obtained.
The Infra-Red Spectrum of N15N14O and the Force Constants of Nitrous Oxide
Authors: Richardson W. S. , Wilson E. Bright
Published: January 2005

The infra-red spectrum of N15N14O has been studied. The observed bands together with those already known for N14N14O provide sufficient data to calculate a reasonable set of force constants for the nitrous oxide molecule. The zeroth-order stretching frequencies for N15N14O and the force constants derived from them are also calculated. In the observed frequency approximation the N–N, N–O and interaction constants have been assigned the values 17.9, 11.4, and 1.4×105 dynes/cm, respectively. These values are consistent with the picture that N2O is a resonance hybrid of the two (principal) structures N̄=N lim +=O and N≡N lim +–Ō.
Electronic Processes in Zinc Fluoride and in the Manganese-Activated Zinc Fluoride Phosphor
Authors: Crawford James H. , Williams Ferd E.
Published: January 2005

Measurements have been made of the temperature-dependence of electrical conductivity and thermal e.m.f. on ZnF2 and ZnF2:Mn, and of the Hall coefficient and rectifying power at 25°C on ZnF2. Both ZnF2 and ZnF2:Mn are N-type impurity semiconductors. The presence of MnF2 in ZnF2 decreases the electronic conductivity by a factor of about 103, indicating a decrease in the concentration of electron donors by oxidation. A marked dependence of the temperature variation of conductivity on heat treatment has been observed. Contrary to the simple theory, the absolute values of the thermal e.m.f. increase with temperature. From the Hall coefficient and conductance at 25°C of heat-treated ZnF2, a concentration of free electrons of 3×1016 cm−3 and a mean free path of 6.7×10−8 cm are deduced. ZnF2 rectifies in the expected direction.
On the Electrical Conductivity of Violanthrone, Iso-Violanthrone, and Pyranthrone
Authors: Akamatu Hideo , Inokuchi Hiroo
Published: January 2005

Violanthrone, iso-violanthrone, and pyranthrone have electrical conductance to a certain degree. This is due to the molecular structure of these compounds, which are made of the network planes of carbon atoms, and to the assumption that the π-electron contribute to the electrical conduction.

The electrical resistivity of violanthrone, iso-violanthrone, and pyranthrone was measured. The values at 15°C are as follows; 2.3×1010 ohm-cm, 5.7×109 ohm-cm, and 3.9×1015 ohm-cm respectively. The resistivity decreases with increasing temperature in every case, and a good linear relationships is observed between the logarithm of the resistivity and the reciprocal of the temperature. As the activation energy of the electrical conductance, the following values were observed; 0.39 ev, 0.375 ev, and 0.53 ev respectively. The values for violanthrone and iso-violanthrone suggest that they can be assumed to be intrinsic semi-conductors.
The Statistical Mechanical Theory of Transport Processes. IV. The Equations of Hydrodynamics
Authors: Irving J. H. , Kirkwood John G.
Published: January 2005

The equations of hydrodynamics—continuity equation, equation of motion, and equation of energy transport—are derived by means of the classical statistical mechanics. Thereby, expressions are obtained for the stress tensor and heat current density in terms of molecular variables. In addition to the familiar terms occurring in the kinetic theory of gases, there are terms depending upon intermolecular force. The contributions of intermolecular force to the stress tensor and heat current density are expressed, respectively, as quadratures of the density and current density in the configuration space of a pair of molecules.
Light Scattering Investigation of the Structure of Polystyrene
Authors: Outer Paul , Carr Clide I. , Zimm Bruno H.
Published: January 2005

Using light scattering, the mean square molecular radius and length of a number of samples of polystyrene have been measured as a function of solvent and temperature. Molecular weights, intrinsic viscosities, and ``osmotic second virial coefficients'' have also been determined on many of the samples. From the data it may be concluded: (1) that polystyrene molecules are extended and stiffened by steric interactions of the phenyl groups; (2) that the molecules are largely unbranched; (3) that the heat of dilution is negative in some solvents, contrary to the usual situation in hydrocarbon systems; (4) that the osmotic second virial coefficient depends strikingly on molecular weight for a given solvent; (5) that there is a good correlation between this coefficient and the mean square radius at a given molecular weight; (6) that the intrinsic viscosity is strictly proportional to a power of the molecular weight over the molecular weight range from 2,000 to 2,000,000, but that deviations occur at lower molecular weights; (7) that the intrinsic viscosity and mean square radius are functions of solvent at high molecular weights but not at very low molecular weights. Theoretical concepts necessitated by these observations are discussed briefly.