bluuebunny/crossref_metadata_2025 huggingface dataset:
Rotational Constants of GeH3D and GeHD3
Authors: Lindeman Louis P. , Wilson M. Kent
Published: April 2005

The analysis of the rotational structure of the Ge–D stretching fundamental of GeH3D yields the following values: B′′=1.957,  B′′−B′=0.0142±0.0017,  ν0=1520.4±0.2 cm−1.A similar analysis of the Ge—H stretching mode in GeD3H yields for this molecule: B′′=1.665,  B′′−B′=0.0128,  ν0=2112.4±0.2 cm−1.The germanium-hydrogen distance obtained under the assumption that it is unchanged by isotopic substitution is 1.529±0.003 and 1.525±0.005 in GeH3D and GeHD3, respectively.
Dielectric Properties of Wool-Water Systems at 3000 and 9300 Megacycles
Authors: Windle J. J. , Shaw T. M.
Published: April 2005

The dielectric constant ε′ and dielectric loss ε″ for wool-water systems have been determined at frequencies of 3000 and 9300 Mc by a cavity resonator method. The water content of the wool fibers was varied between 0 and 14 percent of the weight of the dry wool. The upper limit of 14 percent is approximately one-half the amount of water wool will absorb in a saturated atmosphere at 25°C. The increased dielectric loss in the systems studied and the resultant attenuation of microwave power prevented measurements from being made at water contents in excess of approximately 14 percent.

The results of the measurements show that both ε′ and ε″ increase with increasing water content. The results have been analyzed in terms of a sorption theory proposed by Cassie which shows that the water sorbed by wool consists of localized water which is intimately bound to polar sites in the wool and mobile water which constitutes the remainder sorbed. The dielectric constant of the localized water is found to be 5.8 at both frequencies. This result compares favorably with the microwave dielectric constant of irrotationally bound water obtained by Buchanan et al. from studies of protein hydration. It has been found that ε′ and ε″ of the mobile water are less than for liquid water if the dielectric properties of the wool are assumed to be unaffected by water sorption. The alternate assumption (in which ε′ and ε″ for the mobile water are set equal to those of liquid water) is discussed.
Tables of Statistical Electron Distributions for Atoms with Degree of Ionization Zero to Four and of the Corresponding Electrostatic Potentials
Authors: Thomas L. H.
Published: April 2005

The potential and electron density in statistical distributions for atoms according to Dirac's equation and Jensen's boundary conditions are given as functions of radial distance on a logarithmic scale for neutral atoms and for singly charged positive ions, at uniform interval of a parameter γ. A simple interpolation only is required to obtain them for any particular atomic number. The values of the separate terms in the energy of the distribution are also given.

Tables at a closer interval in radial distance and for positive ions up to charge four can be obtained from the Watson Laboratory, free of charge. They are also available on punched cards.
Investigation of Rotational Isomers with Ultrasound
Authors: Karpovich John
Published: April 2005

Sound absorption measurements in organic liquids have revealed relaxation processes in some cyclohexane derivatives, cyclohexene, methyl formate, ethyl acetoacetate, acetic anhydride, and methyl benzoate. Additional absorption measurements have been made in the relaxation regions of formic acid, ethyl formate, methyl acetate, and ethyl acetate.

A study of cyclohexane derivatives and other similar ring molecules has led to the identification of the mechanism responsible for the relaxations in these liquids. The relaxation phenomena are attributed to the disturbance by the sound wave of equilibria between rotational isomers. The restricted rotation occurs about the single bonds in the ring during the conversion from one chair configuration to another.

The relaxation in cyclohexene is caused by the disturbance of the equilibrium between pseudochair and boat configurations, again involving rotation about single C–C bonds.

The relaxations in esters of the carboxylic acids are attributed to rotational isomers which arise from rotation about C–O bonds.

Infrared absorption bands at about 1160 and 1185 cm-1 in the formates and acetates are identified with rotational isomers of the type postulated for the relaxations in these liquids.
Statistical Mechanical Derivation of Onsager's Equation for Dielectric Polarization
Authors: Harris Frank E. , Alder Berni J.
Published: April 2005

The assumptions necessary in deriving the equation for the dielectric polarization in the absence of short-range interactions between the molecules, as represented by the Onsager equation, are made explicit. The equation derived by Harris and Alder for the general case of dielectric polarization of polar liquids is seen to involve an approximation not previously stated. The latter equation, when reduced to the limit represented by the Onsager equation, becomes identical to it when a further simplification is introduced.
Raman and Infrared Spectra of CF3Br and CF3I
Authors: Edgell Walter F. , May Charles E.
Published: April 2005

The Raman spectra of CF3Br and CF3I have been obtained at —100°C and —40°C, respectively. The infrared spectra of both compounds have been obtained at 30°C, and some measurements have been made at 160°C. The observed frequencies were assigned to the fundamental modes of vibration, their combinations and differences. The frequencies were interpreted in correlation with other CF3X molecules in terms of the pertinent ``natural'' frequencies of vibration.
Magnitudes of Barriers in Intramolecular Rotation
Authors: Luft N. W.
Published: April 2005

By applying symmetry considerations to intramolecular torsional barriers the over-all barriers are resolved into contributions from the interactions of individual change distributions (i and k). This makes it possible to classify internal potential barriers and calculate their heights and shapes if the Fourier coefficients Cvik are known. Some figures, mainly C3ik values, were obtained from experimental barriers others can be estimated by theoretical methods. The Lennard-Jones potential with n = 12 and m = 6 appears to be altogether unsuitable for describing barriers of internal rotation, but a simple repulsive potential V = anR-n with n∼5 furnishes a reasonable approximation.
Configurational Interaction in Simple Molecular Orbital Theory
Authors: Moffitt W.
Published: April 2005

The application of simple MO theory in the interpretation of electronic spectra is investigated. Certain simple theorems are derived and their applications, particularly with respect to configurational interaction in the polyacene series, are discussed. The potentialities and difficulties of this approach are enumerated, and it is concluded that the theory should only be used with caution.
Ionization and Dissociation by Electron Impact; Methylene, Methyl, and Methane
Authors: Langer A. , Hipple J. A. , Stevenson D. P.
Published: April 2005

The appearance potentials of C+, CH+, and CH2+ in the mass spectra of methylene, methyl, and methane are found to be mutually consistent and when combined with the spectroscopic value of the ionization potential of the carbon atom (11.26 ev) lead to 15.5±0.5 ev/molecule for the heat of atomization of methane. This value (15.5) when further combined with the heat of formation of methane (—0.78 ev/molecule) and the dissociation energy of H2 (4.48 ev/molecule) yields 5.76 ev/atmos or 133 kcal/mole for the heat of sublimation of graphite.

The set of appearance potentials confirmed the spectroscopic value for the heat of dissociation of CH+ (3.6 ev/molecule) and yield the following additional energetic quantities: D(CH2–H) = 3.75±0.3 ev/molecule, D(CH–H) = 3.99±0.3 ev/molecule, D(CH3+–H) = 1.34±0.1 ev/molecule, D(CH2+–H) = 5.54±0.2 ev/molecule, and D(CH+–H) = 3.37±0.2 ev/molecule. Earlier determinations of Iz(CH4), Iz(CH3) and D(CH3–H) are confirmed (within the experimental error) and the ionization potential of the methylene radical, Iz(CH2), is found to be 11.75±0.1 ev/molecule.

Combination of the appearance potentials of CH2+ in the methane and diazomethane mass spectra gives 46±6 kcal/mole for the heat of formation of diazomethane.
Free-Electron Network Model for Conjugated Systems. V. Energies and Electron Distributions in the FE MO Model and in the LCAO MO Model
Authors: Ruedenberg Klaus
Published: April 2005

A comparative study is made of the LCAO MO model (including overlap) and the FE MO model. Energies and electronic distributions are examined and the concepts ``atom population'' and ``bond population'' are analyzed. A close correspondence is found to exist between the two theories.
Magnetic Behavior of the System CoO–MgO at Elevated Temperatures
Authors: Elliott Norman
Published: April 2005

The magnetic susceptibilities of solid solutions of CoO and MgO have been measured at elevated temperatures. The data fit a Curie-Weiss law ξ = C/(T+Θ) with C = 3.23±0.04. Θ varies linearly with the mole fraction of CoO. The magnetic measurements indicate that CoO has an antiferromagnetic ordering of spins of the first kind below the Curie point.
Force Constants for F2CO and Thermodynamic Properties for F2CO and FClCO
Authors: Lovell R. J. , Stephenson C. V. , Jones E. A.
Published: April 2005

A set of force constants for F2CO has been calculated using the observed fundamental frequencies and a potential function consisting of valence force interaction terms and an additional term involving an interaction between the oxygen and fluorine atoms. The large values obtained for the interaction constant and the angle deformation constants were related to interaction forces between the terminal atoms.

Also included in this paper are calculations of the thermodynamic properties of F2CO and FClCO.
Statistical Interpretations of Unimolecular Reaction Rates
Authors: Johnston Harold S. , White James R.
Published: April 2005

Consistency theorems are derived from the general Lindemann theory of unimolecular reaction rates; one can make several general statements about the signs of the slopes and curvatures of plots of observed rate constants against a function of the pressure. Observed rate constants and simple combinations of observed rate constants are interpreted in terms of Tolman's distribution function, the distribution of molecules which react. Moments of the ratio of rate constant for decomposition to that for deactivation by collision, ci/bi, can be found at any pressure. By means of Schwarz's inequality one can find several dimensionless quantities which provide consistency tests with respect to the statistical interpretations and which provide a check against a wrong assignment of the high- or low-pressure limit. These methods are used to examine the data for cyclobutane, cyclopropane, nitrogen pentoxide, and nitrous oxide. Previous interpretations given to the data on the last two cases are revised. The average detailed rate constants for molecules which react are estimated using an approximate relation.
Vibrational Spectra of CF2 = CHD and CF2 = CD2
Authors: Edgell Walter F. , Ultee Casper J.
Published: April 2005

A method has been devised to prepare CF2 = CD2 and CF2 = CHD. The infrared spectra of the gaseous compounds and the Raman spectra of the liquids have been determined. The observed frequencies have been assigned to the fundamental modes of vibration and to overtones and combinations. The torsional frequency has been estimated as ca 720 and ca 520 cm—1 in CF2 = CH2 and CF2 = CD2, respectively. The overtone of the torsional frequency interacts with the CH2 or the CD2 deformation fundamental and this is the cause of the anomalous results with the product rule.
Effect of Intermolecular Interactions between CH Frequencies on the Infrared Spectra of N-Paraffins and Polythene
Authors: Stein R. S. , Sutherland G. B. B. M.
Published: April 2005

A systematic study has been made of the infrared absorption band near 725 cm—1 which arises from the rocking vibration of methylene groups in n-paraffins and in polyethylene. In unoriented crystals of n-paraffins, this band exhibits two components of equal intensity below the transition point; above the transition temperature and in the liquid state only the higher frequency component is found. In solid cold-drawn polyethylene the two components are of unequal intensity, the low frequency component being the stronger; in liquid polyethylene only the lower frequency component is found. Studies were made of polyethylene in various states of crystallinity and orientation, using both polarized and unpolarized radiation. The results obtained can be consistently interpreted, if the higher frequency component is attributed to crystallites in the polyethylene and the lower frequency component is assumed to be due partly to the crystalline and partly to the amorphous form of the polyethylene. It is concluded that the doubling of this frequency arises from some interaction between methylene groups which is peculiar to the crystalline state of long chain n-paraffins below their transition points.
Nuclear Magnetic Resonance in Liquids under High Pressure
Authors: Benedek G. B. , Purcell E. M.
Published: April 2005

The work reported here is an application of free precession or ``spin echo'' techniques in nuclear magnetic resonance to a study of the properties of liquids under high pressure. The proton relaxation time T1 was measured as a function of pressure, over the range 1 to 10 000 atmospheres, for six liquids: water, n-pentane, n-hexane, toluene, ethyl iodide, and methyl iodide. In addition to the relaxation time, the normalized values D(P)/D(1) of the self-diffusion constant were measured as a function of pressure for water and methyl iodide.

In each liquid T1 decreases with increasing pressure. However, comparison of the observed variation of T1 with pressure with Bridgman's data on the variation of viscosity η with pressure shows in all cases (except that of methyl iodide for which no viscosity data are available) that T1 is not simply proportional to 1/η, but instead T1η increases with pressure. Similarly, for water and methyl iodide, the diffusion constant D varies in such a way that T1/D increases with pressure. For water the Stokes-Einstein relation Dη = cT is obeyed within the errors of observation. The behavior of T1 can be understood if one assumes that the dominant relaxation mechanism involves intramolecular fields, whose correlation time is determined by the rotational freedom of the molecule, and that compression of the liquid inhibits migrational freedom more drastically than rotational freedom.

The necessity of making the present measurements has led to the discovery that BeCu, a heat treatable alloy, makes a very satisfactory high pressure, non-magnetic bomb which might well be used for other magnetic investigations under high pressure.
Nuclear Quadrupole Resonances in Bromobenzene Derivatives
Authors: Bray P. J. , Barnes R. G.
Published: April 2005

The pure nuclear quadrupole resonance frequencies of the Br79 isotope are given for a number of previously unreported bromobenzene derivatives. The resonance frequencies of the Br81 isotope in these and other previously reported compounds are compared with the electron density in the vicinity of the carbon atom to which the bromine is bonded.
Microwave Spectrum of 1,1-Difluoroethane
Authors: Solimene N. , Dailey B. P.
Published: April 2005

The spectrum of 1,1-difluoroethane has been investigated over the region 18 000 Mc to 38 000 Mc with a conventional Stark-modulation spectrometer. This molecule is a moderately asymmetric rotor of the oblate type with components of its dipole moment along the A and C axes. About 30 lines have been identified with the aid of the Stark effect and an approximate model for the molecule. The analysis yields the following rotational constants: A=9491.95 Mc; B=8962.65 Mc; C=5170.43 Mc; x=0.75504. The barrier hindering internal rotation has been determined as (1.25±0.20)×103 cm—1 from intensity ratio measurements of the torsional frequency.
Emission Bands of NO in the Vacuum Ultraviolet Region Excited in the NO Afterglow
Authors: Tanaka Yoshio
Published: April 2005

The emission bands of the NO molecule excited in an impure afterglow were studied in the vacuum ultraviolet region. The abrupt cutoff at a certain ν′ value was observed in the β, γ, and δ bands and also the non-appearance of the ε, and β′ bands was confirmed. An explanation for these observations was attempted in connection with the dissociation energy of the NO molecule and with the mechanism of the afterglow.
Substituted Methanes. XVIII. Vibrational Spectra of C13H3I
Authors: Bernstein Richard B. , Cleveland Forrest F. , Voelz Fred L.
Published: April 2005

Raman (liquid) and infrared (liquid and gas, with KBr and NaCl prisms) spectra have been obtained for two mixtures of C13H3I (9.3 and 61 atom percent) and C12H3I, and from these the vibrational spectrum of C13H3I has been deduced. In the Raman spectrum, only v3(a1)—the C–I stretching frequency—could be resolved from the C12H3I lines; the isotopic shift was — 17.7±0.5 cm—1. In the infrared spectrum (gas), five isotopic shifts were obtained; they were: v1(a1) — 10±3, v2(a1) — 5.5±1.0, v3(a1) — 16.1±1.0, v5(e) — 4.4±0.8, and v6(e) — 3.7±0.3 cm—1. For the remaining fundamental, v4(e), the shift was obtained by use of the Redlich-Teller product rule; the value was — 9.4±2.3 cm—1. Analysis of the perpendicular bands yielded, with the aid of microwave data, values of the rotational constants, Coriolis interaction constants, and band origins for the v6(e), v5(e), and v4(e) bands of C12H3I and C13H3I, though the values for the v4(e) band of C13H3I are incomplete and are only estimated values since the sub-bands were not resolved in this case.
Influence of Solvent upon the Energy Difference between Rotational Isomers
Authors: Wada Akiyoshi
Published: April 2005

The energy difference between the rotational isomers of the gauche- and trans-forms of 1,2-dichloroethane in various solutions have been calculated by use of a modified Onsager's reaction field. The following assumptions have been employed in the calculation: first, the cavity of the solute molecule is spheroidal; second, the dipole moment of the molecule is composed of two point dipoles which are placed at the foci of the spheroidal cavity, the focal distance being taken as equal to the distance between the contact points of the carbon and chlorine atoms in the dichloroethane molecule. The change of energy difference between rotational isomers by solvents thus computed has been found to be in close agreement with the experimental observations, that is, those obtained by infrared absorption measurements as well as dipole moment.
The Dielectric Constant of Supercritical Steam
Authors: Fogo James K. , Benson Sidney W. , Copeland Charles S.
Published: April 2005

A description is given of the method used to measure the dielectric constant of steam at densities between 0.2 and 0.4 g/cc in the temperature range 377 to 395°C. Smoothed values of the dielectric constant are tabulated at 378, 383, 388, and 393°C for densities from 0.1 to 0.5 g/cc.
Wavelength Shifts in the near Ultraviolet Spectra of Fluorinated Benzenes
Authors: Sponer H.
Published: April 2005

Results on wavelength shifts of the 0,0 bands in the near ultraviolet absorption spectra of a number of fluorinated benzenes are presented, and a brief discussion in terms of the inductive effect and the migration effect is added.
The Kinetics of Phase Transitions Involving Dimer Reactions
Authors: Frisch H. L. , Willis C.
Published: April 2005

Kinetic theory of phase transitions in which embryos of the new phase may grow or diminish by the acquisition or loss of monomer and dimer is presented. The error committed in neglecting the latter is shown to be negligible except in systems in which a large fraction of the old phase is present in the form of dimer.
Inter- and Intramolecular Energy Transfer Processes. 3. Phosphorescence Bands of Some Carcinogenic Aromatic Hydrocarbons
Authors: Moodie Margaret M. , Reid C.
Published: April 2005

The triplet-singlet emission spectra of a number of carcinogenic hydrocarbons are recorded together with the corresponding spectra of their 1,3,5-trinitrobenzene complexes. A new explanation of the complex spectra is given, involving a radiationless transition from an ionic ``charge transfer'' state to a triplet state complex.
The Librational Heat Capacity of Ice and of Heavy Ice
Authors: Blue R. W.
Published: April 2005

Interpretation of the heat capacities of crystals is difficult when polyatomic molecules or ions are involved, owing to the variation with temperature of the translational heat capacity, arising from intermolecular vibrations, in the same regions in which rotational and vibrational heat capacities are also varying with temperature. It is shown how translational and rotational heat capacities may be studied separately in the case of ice where the heat capacities of both H2O and D2O have been measured. Moments of inertia are nearly doubled by substitution of D for H, while the molecular weight is increased by only ten percent. Thus the effect of isotopic substitution is relatively large on the rotational heat capacity as compared to the translational heat capacity.
Dielectric Properties of Hydrogen Halides. II. Hydrogen Chloride
Authors: Swenson Richard W. , Cole Robert H.
Published: April 2005

Dielectric constant and loss measurements have been made for liquid and solid hydrogen chloride in the temperature range 63—190°K and frequency range 20 cps to 106 cps. The dielectric constants of the liquid and disordered solid phase stable above 99°K are described quite accurately by Onsager's equation. Below 99°K a slight dispersion with activation energy of 2.6 kcal/mole is found with dielectric constants in the range 3.7—4.3. Special precautions against sample inhomogeneity were necessary; these and various residual effects are discussed.
The Electronic Spectra of Cata-Condensed Hydrocarbons
Authors: Moffitt William
Published: April 2005

It is shown how the main features of the spectra of cata-condensed hydrocarbons may be explained on the basis of a very simple model. This, so-called perimeter model was used, in its free-electron variant, by Platt in order to classify the spectra. In this note, a more quantitative version is formulated which enables calculations to be made; it may be considered as an approximation either to an antisymmetrized molecular orbital treatment or to the method of atoms in molecules.
The Velocity of Sound in Water as a Function of Temperature and Pressure
Authors: Smith A. H. , Lawson A. W.
Published: April 2005

The velocity of sound in water has been measured by an ultrasonic echo technique in the temperature range from — 12°C to 129°C under hydrostatic pressures varying up to 9600 kg/cm2. Even at the highest pressures the temperature dependence of the velocity of sound is found to be abnormal. In contradiction to certain previous results, the temperature at which the velocity of sound is a maximum is found to increase with increasing pressure. The behavior of the sound velocity is discussed in the light of recent theories concerning the structure of water. The internal consistency of the data with existing pressure standards is also analyzed.
Statistical Thermodynamics of Associated Solutions
Authors: Barker J. A. , Smith F.
Published: April 2005

Thermodynamic data for the solutions chloroform+benzene, acetone+chloroform, ethanol+chloroform, ethanol+acetone, and ethanol+ether are discussed in the light of a model for associated solutions which has been described previously. The theory in its original form, previously found satisfactory for solutions of alcohols in nonpolar solvents, proves satisfactory for the first two of these systems. To interpret the data for the remaining more complicated systems it is necessary to generalize the model to allow for interaction free energies which depend on temperature (presumably because of changes in vibration frequencies). The necessary generalization of the theory is described, and a consistent set of interactions for the ethanol systems is derived. The generalized theory should apply, with the limitations inherent in lattice theories, to most nonaqueous associated solutions.
Relation between Bond Length and Stretching Frequency for the Carbonyl Group
Authors: Margoshes M. , Fillwalk F. , Fassel V. A. , Rundle R. E.
Published: April 2005

A plot is shown of bond length vs stretching frequency of the carbonyl group in a series of compounds containing this group. For bond lengths ranging from 1.13 to 1.31A, the average distance of the points from a smooth curve is 0.013A.
Some Ions of High Kinetic Energy in Mass Spectra of Polyatomic Molecules
Authors: Mohler Fred L. , Dibeler Vernon H. , Reese Robert M.
Published: April 2005

When the lighter-fragment ions of hydrocarbons and hydrocarbon derivatives are recorded with low-ion accelerating voltages, one observes satellite peaks on the high-mass side of the main peaks that come from ions with a fairly homogeneous high kinetic energy. Observations of the satellite peaks of CH3+ ions in mass spectra of 13 hydrocarbons and CH3CF3, are reported. The kinetic energies range from 1.5 to 3.4 ev and the relative intensities have a wide range of values but are less than the main peak except in benzene. The appearance potential of the satellite peak is roughly 30 volts in most cases while the main peak is observed above 20 volts. These high-energy ions are ascribed to doubly charged molecule ions that dissociate into two singly charged fragments. The kinetic energy of the pair of fragment ions is in most cases nearly equal to the Coulomb energy of two ions at a distance equal to the greatest distance between valence electrons in the molecule.
Markoff Random Processes and the Statistical Mechanics of Time-Dependent Phenomena. II. Irreversible Processes in Fluids
Authors: Green Melville S.
Published: April 2005

The procedures developed in a previous paper of the same main title are applied to the specific case of irreversible processes in fluids. The gross variables are chosen to be a finite number of the plane-wave expansion coefficients of the local particle, momentum and energy densities. As an example, the gross variables describing the local particle density are ∑ i=1Nexpik·xi,where pi and xi are the momentum and position of the ith molecule and N the total number. k runs over a finite number of values which are all small compared to the reciprocal mean distance between molecules. The phenomenonological equations are derived and expressions are given for the viscosity, diffusion, and heat conductivity in terms the autocorrelation coefficients of certain phase functions. These expressions are supposed to be valid for both liquids and gases. They are shown to coincide with the Chapman-Enskog expressions for dilute gases.
The Infrared and Raman Spectra of Carbon Suboxide
Authors: Rix H. D.
Published: April 2005

The infrared spectrum of C3O2 has been studied in the vapor phase from 2.2 to 20μ with a Perkin-Elmer double-pass spectrometer, and the Raman spectrum has been photographed in the liquid phase. A comparison of the Raman with the infrared spectrum shows definitely that the molecule has a center of symmetry as is required for the linear structure commonly assumed. However, the infrared spectrum cannot be explained on the assumption of a linear model; the envelopes of the principal absorption bands as well as those of the weaker combination bands have the wrong shape. It appears rather that the oxygen atoms are bent out of line with the carbons in a plane zig-zag configuration. From the rotational structure of one of the combination bands the O–C–C angle is computed to be approximately 158°.
The Microwave Spectrum of Hydrogen Peroxide
Authors: Massey J. T. , Bianco D. R.
Published: April 2005

Nine absorption lines of H2O2 and some one hundred absorption lines of D2O2 and HDO2 have been observed in the microwave frequency region using a flow system for sampling to overcome the decomposition of the peroxide at low vapor pressure. An analysis of the microwave spectrum of H2O2, using a symmetric top approximation, reveals that it is necessary to invoke hindered internal rotation to explain the experimental data. Using a sinusoidal approximation for the hindering potential yields a barrier height of about 113 cm—1. From the Stark effect calculations, a value of dipole moment of 2.26 debye units is obtained. Some limiting conditions on the values of the molecular parameters are discussed.
Ionic Components of Charge in the Electrical Double Layer
Authors: Grahame David C. , Soderberg Barbara A.
Published: April 2005

The rate of change with concentration of the capacity of the electrical double layer on mercury has been measured. From this there have been calculated Γ+, the excess of cations in the double layer, and Γ—, the excess of anions. The latter has been subdivided into η—d, the excess of anions in the diffuse double layer, and η—i, the excess of anions in the inner part of the double layer. From these data it has also been possible to evaluate ψ0, the potential of the outer Helmholtz plane.

It is found that fluoride ion remains unadsorbed on mercury at all potentials investigated, including potentials anodic to the e.c.max. Other anions are strongly adsorbed (chemisorbed) when the mercury is positively charged, and sometimes even when it is negatively charged. The ``hump'' in the capacity curves of salts of such anions as chloride, bromide, acetate, and nitrate, are found to be present in curves of C—, the capacity attributable to anions alone. No chemisorption of monatomic cations could be detected.

The kinetic theory of the diffuse double layer with constant dielectric constant is found to fit the experimental results within the expected accuracy. This fit extends to electrolytes of the 1:2 and 2:1 types also.

A new method of evaluating salt adsorption at the potential of the electrocapillary maximum (e.c.max.) is described and results are given. Likewise a new method of determining C+ at the e.c.max. is described and used.
A Microwave Investigation of the Ionization of Hydrogen-Oxygen and Acetylene-Oxygen Flames
Authors: Shuler Kurt E. , Weber Joseph
Published: April 2005

The ionization of premixed hydrogen-oxygen and acetylene-oxygen flames burning at atmospheric pressure was studied by a microwave method. The attenuation of electromagnetic radiation by the flames was employed to determine the free electron concentration. To obtain a high sensitivity for these measurements, a microwave bridge operating slightly off balance was employed, with the flames positioned between two electromagnetic horns in one of the bridge arms. This method permits the determination of electron densities down to about 5·108 electrons per cm3 at atmospheric pressure.

In interpreting the data obtained in this study it was found necessary to take a quantitative account of the ``background ionization'' resulting from the presence of alkali salts as contaminants in the air and the flame gases. After the appropriate background measurements and corrections were made, it was found that the ionization of the hydrogen-oxygen flames and of lean and stoichiometric oxy-acetylene flames was thermal and agreed well with the electron concentration values obtained from equilibrium calculations using the adiabatic flame temperatures. A complete equilibration and equipartition of the internal energy for H2–O2 flames is indicated by the good agreement between the effective ionization temperature and the rotational, vibrational, and electronic temperatures determined previously.

The background corrected ionization of the rich acetylene-oxygen flames (C2H2/O2=1.5/1 to 4/1) was found to be higher by a factor of 10 to 100 than that calculated for a purely thermal flame ionization. This can very plausibly be accounted for on the basis that the high electron concentration in these rich hydrocarbon flames is primarily due to the thermal evaporation of electrons from the carbon atom aggregates (soot particles) formed in these flames. A calculation showed that a work function of 8.5 ev for the small carbon particles in the flame accounts well for all the observed electron concentrations. This value stands in a reasonable relationship to the ionization potential of gaseous carbon atoms (11.265 ev) and the work function of graphite (4.35 ev).

It is suggested on the basis of these results that the ionization in hydrogen-oxygen and acetylene-oxygen flames, at least as far as the hot combustion gases are concerned, is an equilibrium process which can be accounted for by purely thermal considerations. Whether or not this holds true also for the reaction zone proper must remain open to question for the present, since the measurements described here pertain by necessity to an ionization density averaged over a rather extensive region of the flame.
The Near Ultraviolet Absorption Spectrum of Para-Difluorobenzene Vapor
Authors: Cooper C. Dewey
Published: April 2005

The vapor spectrum of p-difluorobenzene was obtained with a Bausch and Lomb Littrow spectrograph. The band at 36 843 cm—1 is assigned as the 0,0 band of the Ag—B3u electronic transition. Ground-state frequencies of 452, 860, and 1259 cm—1 with the corresponding excited-state frequencies of 408, 819, and 1250 cm—1 are assigned to totally symmetric vibrations. Also, an 841-cm—1 frequency is assigned to the ground state of a totally symmetric vibration. Many of the bands that are temperature dependent are shown to result from a transition that involves a 248-cm—1 ground-state vibration. This 248-cm—1 frequency is assigned as a β1g fundamental. Most of the prominent bands are assigned to progressions or combinations of the above frequencies. The unusually large spectral shift produced by the two para-positioned fluorines is discussed.
Electronic Structure, Infrared Absorption, and Hall Effect in Tellurium
Authors: Callen Herbert B.
Published: April 2005

An analysis of the band structure of tellurium is based on the symmetry properties of a drastically simplified model of its crystal structure. These symmetry considerations lead to suggestions of the physical mechanisms underlying a variety of experimental facts in this material.
Proton Magnetic Resonance Spectrum of Ammonia and the Interactions Involved in Hydrogen Bond Association
Authors: Ogg Richard A.
Published: April 2005

High-resolution proton magnetic resonance spectra are presented for the liquid and vapor states of ammonia. The vapor spectrum displays the expected spin-spin interaction multiplet structure. This is likewise found in the liquid state, provided the ammonia is rigorously anhydrous. A trace of water results in the appearance of a single resonance—an effect attributed to chemical exchange of protons. A marked shift of resonance between the liquid and vapor states is found, interpreted as decreased shielding in the liquid state. This effect, not observed for the non-polar substance propane, is discussed in connection with so-called ``hydrogen bonding.''
Random Walk with Semiadsorbing Barrier
Authors: Goodrich Frank C.
Published: April 2005

The problem of random walk in the presence of a semiadsorbing barrier is formulated and discussed. The results are applied to a study of the kinetics of adsorption in colloidal systems.
The Viscoelastic Properties of Plastics
Authors: Bueche F.
Published: April 2005

A general method has been devised to predict the viscoelastic behavior of plastics. A simplified model of the molecule is assumed and its general motion is treated by the method of normal coordinates. General equations have been developed such that when the manner of application of external forces to the molecule is known, the molecule's general behavior may be found in a convenient and straightforward fashion.

This method has been used to obtain theoretical curves for the viscoelastic behavior of cross-linked polymers subjected to sinusoidal forces. Also, the similar problem for linear material has been solved together with the creep and stress relaxation problems. It is shown that the temperature-time superposition procedure of Ferry and Tobolsky has a firm theoretical basis. In general, the theoretical curves appear to agree with the limited experimental data available. The method is also applied to the case of dilute solutions and comparison is made with the result obtained by Rouse using a different approach.
Free Radicals by Mass Spectrometry. V. The Ionization Potentials of Methyl, Allyl, and Benzyl Radicals
Authors: Lossing F. P. , Ingold K. U. , Henderson I. H. S.
Published: April 2005

The ionization potentials of methyl, allyl, and benzyl radicals have been measured directly by electron impact. The values found were methyl 9.95±0.03 ev, allyl 8.16±0.03 ev, and benzyl 7.73±0.08 ev. The radicals were produced by thermal decomposition of suitable compounds in a mass spectrometer designed for the study of free radicals. Reactions of the radicals after formation led to the expected dimers, but the disproportionation reactions were found to be negligibly slow.
Schlieren Studies of the Critical Region
Authors: Palmer Howard B.
Published: April 2005

The critical regions of ethane, carbon dioxide, and xenon have been studied, using a Schlieren optical system. The material to be studied was confined in a thermostatted high pressure cell having optically flat windows, and placed in the test section of the optical system. At temperatures over a range of about two degrees, in the critical region, refractive index gradients within the cell were determined as a function of height along the cell. From these data were calculated the density distribution, the pressure distribution, and the shapes of the pressure-volume isotherms at the various temperatures. The technique permitted detailed study of the isotherms over a narrow range of pressures, too small to be observed by usual experimental methods. Extensive visual observations were made throughout the course of the experiments. Particular attention was devoted to the question of the equilibrium state in the critical region and the process of equilibrium attainment.
Absorption Intensities of the Isomeric Pentenes in the Vacuum Ultraviolet
Authors: Semenow Dorothy , Harrison Anna J. , Carr Emma P.
Published: April 2005

Quantitative measurements of the absorption spectra of the six isomeric pentenes in vapor phase have been made in the region 45 000—65 000 cm—1. The maximum of the intense band (N→V) is the same for 1-pentene, cis-2-pentene, and 2-methyl-2-butene, with one, two, and three alkyl substituents, respectively. The results show that in a series of hydrocarbons, where the molecular weight is unchanged and the number of alkyl groups is the only variable, the position of the N→V maximum is not a function of the number of alkyl substituents. From the standpoint of methyl substituents, there is no shift between cis-2-pentene with one methyl group and 2-methyl-2-butene with three. In the absence of such a shift, spectral evidence in support of hyperconjugation in the substituted ethylenes is lacking.

The N→V maximum for trans-2-pentene is less intense and at somewhat longer wavelength than for the cis-isomer. The greatest shift in this band is with 2-methyl-1-butene, where the two alkyl groups are on the same carbon atom. These results indicate the importance of molecular shape in determining the energy of the N→V transition in the monoolefins.

The positions of the shallow bands (N→R) on the long wave side of the N→V band are in substantial agreement with earlier measurements and confirm the conclusion that the energy of this transition is dependent on the number of alkyl substituents on the carbon atoms of the double bond. The possibility of other Rydberg bands on the short wave side is discussed briefly. Oscillator strengths for the N→V band are given for the six pentenes; these vary from 0.26 in 2-methyl-1-butene to 0.45 in cis-2-pentene but their value for testing theoretical predictions is doubtful because of the overlapping of different electronic transitions.
Structural Investigations by Means of Nuclear Magnetism. III. Ammonium Halides
Authors: Gutowsky H. S. , Pake G. E. , Bersohn R.
Published: April 2005

The proton magnetic resonance absorption has been measured in NH4Cl, NH4Br, and NH4I crystal powders from —195°C to room temperature, and for NH4Cl to 200°C. Line width transitions were found at —144, —171, and about —198°C in the chloride, bromide, and iodide, respectively. The N–H distance in the ammonium ion was determined to be 1.035±0.01A from the second moments of the broad, low-temperature absorption lines observed in NH4Cl and NH4Br, with allowance for broadening by modulation effects and narrowing by zero-point torsional oscillations. The relatively narrow room temperature line shapes are consistent with the broadening estimated for inter-NH4+ interactions, the intra-NH4+ interactions averaging to zero over the hindered rotational motions of the NH4+ ions. No appreciable line shape changes were found at the λ temperatures. An electrostatic calculation is made of the potential barriers to rotation of the NH4+ ion giving values comparing favorably with experimental inferences. The results clarify the motions which narrow the absorption line at low temperatures and emphasize the dynamic aspects of the order-disorder process.
Proton Magnetic Resonance in an Ammonium Chloride Single Crystal
Authors: Bersohn R. , Gutowsky H. S.
Published: April 2005

The nuclear resonance absorption spectrum has been calculated theoretically for a tetrahedral 4-spin system, with I of ½, for orientations in which the external magnetic field coincides with a two- or three-fold symmetry axis of the tetrahedron or with a tetrahedral edge. Comparison of the theoretical results with the proton resonance observed at —195°C in a single crystal of ammonium chloride demonstrates that the NH4+ ion is oriented with the N–H bonds pointed essentially towards corners of the unit cube. An N–H distance of 1.032±0.005A is determined from the low-temperature second moments of the resonance line with the applied magnetic field in the (1,0,0) and (1,1,0) directions. At room temperature, the anisotropy of the resonance results from inter —NH4+ interactions, with intra —NH4+ interactions averaged to zero by hindered rotational motions; free rotation of the ammonium ions does not occur. A small decrease with temperature of the second moment of the resonance line at the λ-point agrees with the order-disorder model for the transition. The motion of the NH4+ ion is discussed.
Scattering of High-Velocity Neutral Particles. II. Helium-Helium
Authors: Amdur I. , Harkness A. L.
Published: April 2005

Total collision cross sections have been measured for helium atoms, with energies between 500 and 2100 ev, scattered in room temperature helium. Measurements were made with two detectors of different geometric aperture, 13.4 and 0.96 minutes. In order to obtain meaningful potential energy information from such results, it is necessary to determine effective apertures by taking into account beam shape, intensity distribution, and for the case where the beam is wider than the detector, scattering to the detector from external regions of the beam. Potential energy functions have been derived from the cross sections obtained with the two detectors. The functions agree within a factor of about 1.3 as compared with 0.17 when geometric apertures are used directly. The results from both detectors have been represented by an average function, namely, V(r)=7.55×10−12/r5.94 ergsfor values of r between 1.27A and 1.59A.

The potential energy information obtained from the present experiments is in agreement with theoretical calculations of P. Rosen and H. Margenau within the uncertainty of such calculations. The information also appears to be consistent with that derived from measurements of gaseous compressibility and viscosity, for values of r between 1.90A and 2.30A.
Kinetics of the Fast Gas Phase Reaction between Ozone and Nitric Oxide
Authors: Johnston Harold S. , Crosby Harvey J.
Published: April 2005

The rate of reaction between ozone and nitric oxide was followed optically at —43 and —75°. The reaction appears to be elementary bimolecular NO+O3=NO2+O2and the rate constant is k=0.8×1012e−2500/RT cc mole−1sec−1.

The pre-exponential factor for this reaction is compared with those of six other elementary gas phase reactions of the type X+Y=Z+W+···involving the oxides of nitrogen for which the energies of activation were higher. For this series of similar reactions the molecular complexity of the reactants is about constant (five or six atoms), and there appears to be no systematic difference in pre-exponential factor between the fast and the slow reactions.
Use of Electron Repulsion Integral Approximations in Molecular Quantum Mechanics
Authors: Barker Roland S. , Eyring Henry , Thorne Charles J. , Baker Don A.
Published: April 2005

Straightforward theoretical calculation for molecular systems using eigenfunctions built up from atomic orbitals and employing actual and approximate methods for the evaluation of certain integrals have recently been widely applied with considerable success. Most of these calculations have evaluated the difficult multicentered electron repulsion integrals by use of an approximate formula suggested by Mulliken, in terms of Coulombic and overlap integrals. Previous work has indicated the general utility of this relationship. Here, direct numerical comparison is made of actual and approximate values of the multicenter 1s orbital integrals. The comparisons indicate that this approximation of integrals is moderately accurate over a wide range of internuclear configurations. Direct calculations of the energy of the linear triatomic hydrogen complex molecule with this approximate integral formula disclose that the total binding energy obtained by the two procedures is different by several kcal/mole. However the energy variation with internuclear separations obtained from the approximate calculations has its minimum very near that obtained using actual integrals. This indicates that energy minimization by variation of the parameters included in the trial eigenfunction may be accomplished using these approximate integrals. Single calculations may then be made using these ``best'' parametric values.
Approximation of Molecular Orbitals in Diatomic Molecules by Diatomic Orbitals
Authors: Wallis Richard F. , Hulburt Hugh M.
Published: April 2005

The constants necessary for the specification of the exact wave functions of the homonuclear one-electron diatomic molecule have been tabulated for a range of relatively large internuclear distances. A method for determining upper and lower bounds of the constants is presented. The energy of the hydrogen molecule has been calculated for the ground state using the one-electron two-center wave functions as molecular orbitals. The results of a similar calculation by Hylleraas have been confirmed and extended. It is found that the best results are obtained if the effective nuclear charges for the molecular orbital of one electron are different from the effective nuclear charges for the molecular orbital of the second electron. Somewhat less satisfactory results are obtained if the effective nuclear charges are the same in both orbitals. The application of diatomic orbitals in the calculation of the properties of other diatomic molecules is discussed. Calculations of energy appear to be prohibitively laborious; calculations of electric dipole moments and transition probabilities may be feasible.
Infrared Absorption Spectra of Aqueous HF2—, DF2—, and HF
Authors: Jones Llewellyn H. , Penneman Robert A.
Published: April 2005

Strong infrared absorption bands of KHF2 appear at 1233 cm—1 and 1473 cm—1 in the solid, and are observed at 1206 cm—1 and 1536 cm—1 respectively, in H2O solution. Corresponding values for KDF2 are 888 cm—1 and 1045 cm—1 in the solid, and 873 cm—1 and 1102 cm—1 in D2O solution. In saturated KHF2 and in KHF2 solutions containing excess HF, there appear new, broad absorption bands attributed to polymeric species, e.g., H2F3—. The HF2— ion is observed in concentrated aqueous HF; in addition, there is a strong absorption at 1820 cm—1 which is not shifted in D2O-HF mixtures.