bluuebunny/crossref_metadata_2025 huggingface dataset:
The Infrared Absorption Spectrum of the Deuterium Sulfides
Authors: Nielsen Alvin H. , Nielsen Harald H.
Published: January 2005

The spectra of HDS and D2S have been investigated under high dispersion using a grating spectrometer. An absorption band at 9.0μ in HDS has been identified as ν2 and has an average spacing of the rotation lines of about 6.85 cm—1. In D2S bands were located at 3.75μ, 5.0μ and 10.7μ which have line spacings of 4.8 cm—1, 5.0 cm—1, 5.0 cm—1 and may be identified as ν1+ν2, ν3 corresponding to a similar identification in H2S. As in H2S, ν2 appears to have a Q branch while ν3 does not. If this is actually so, ν2 must arise from a vibration of the electric moment parallel with the axis of least moment of inertia and ν3 from a vibration along the middle axis. Since ν2 is a vibration parallel with the symmetry axis of the triangle then this axis must be identified with the axis of least moment of inertia. This argument supports the acute angled model suggested by Sprague and Nielsen, and the evidence is interpreted to favor a vertex angle of 85° instead of the 110° angle of Bailey, Thompson and Hale.
The Infrared Absorption of Various Solutions of Acetic Acid
Authors: Gordy Walter
Published: January 2005

The characteristic vibrational band associated with the C=O group of acetic acid has been studied as a function of concentration of acetic acid in benzene, in carbon tetrachloride, and in isopropyl ether. The effects of benzene and carbon tetrachloride on the band were approximately the same. In both solvents the band became sharper, its intensity was increased, and its center was shifted to the longer wave-lengths. For concentrations of acetic acid as low as 6 percent the shift amounted to 0.15μ. Although in isopropyl ether solution there was a measurable shift of the band to the longer wave-lengths, the shift was small compared to that observed for benzene and carbon tetrachloride solutions. It is suggested that the changes in the C=O acetic acid band are likely due to variations in the polymerization of the acetic acid as the concentration is varied. However, the position of the band does not approach that for the vapor state in any of these solvents. Ethyl acetate was also studied in benzene and in isopropyl ether; no shifts could be detected in the C=O band.
The Emission of Visible Light from Cavitated Liquids
Authors: Chambers Leslie A.
Published: January 2005

Emission of visible light from a number (14) of pure liquids and from some aqueous and nonaqueous solutions occurs during cavitation by intense sound waves of 8900 c.p.s. The intensity of the visible components of the radiation varies directly with the numerical product of viscosity (in poise) and dipole moment (in Debye units) and inversely with the temperature. In the case of polar solutes in nonpolar solvents the intensity varies with the concentration of the dipole. The light originates in cavitated areas or at the surface of the cavities, and is therefore proportional to the amount of cavitation, and in consequence, to the acoustic power input.
The Effect of Radiation on Oil Drops
Authors: Stenstrom Wilhelm , Vigness Irwin
Published: January 2005

Oil drops on a water surface increase their diameter when they are irradiated with β-rays, x-rays, or ultraviolet rays. The growth of the diameter depends on the amount of exposure to the radiation. Curves showing the increase of diameter with time have been made. If oil in a closed container is irradiated with x-rays, and drops from such irradiated oil are placed on a water surface, the drops spread and reach a limiting size after a few hours. The experiments made are of a preliminary nature and are intended to demonstrate the general nature of the phenomena.
Reactions in the System Containing Nitrogen Dioxide, Carbon Monoxide and Oxygen; NO3 as an Intermediate in the Classical Trimolecular Oxidation of Nitric Oxide
Authors: Calhoun G. M. , Crist R. H.
Published: January 2005

The kinetics of some reactions in the system containing carbon monoxide, oxygen, and nitrogen dioxide have been studied over the temperature range from 658° to 800°K. It has been shown that the reaction is heterogeneous for the lower pressures of nitrogen dioxide and homogeneous for pressures above 10 mm. The homogeneous portion of the reaction appears to include the oxidation of nitric oxide and the oxidation of carbon monoxide by ``oxides'' of nitrogen. A bimolecular reaction involving nitric oxide and oxygen has been studied. Evidence is presented which indicates that the oxidation of nitric oxide involves two consecutive bimolecular reactions instead of the classical termolecular mechanism.
Bimolecular Association Reactions
Authors: Kimball George E.
Published: January 2005

By means of classical vibration theory a method is developed for estimating the mean lifetimes of the unstable molecules formed by the reaction of two polyatomic radicals. It is shown that these lifetimes are usually long in comparison with the time between collisions, except for the very simplest radicals. Approximate lifetimes for a number of these unstable molecules are given. From these values the orders of the corresponding association reactions may be predicted.
A Theoretical Study of Magnetic Cooling Experiments
Authors: Hebb M. H. , Purcell E. M.
Published: January 2005

The experimental results obtained by several investigators on the magnetic cooling method are investigated in the light of (1) the electric crystalline fields acting on the magnetic ions of the paramagnetic salts used in the experiments, and (2) the magnetic dipole-dipole coupling between these ions. These two factors produce anomalous specific heats and departures of the magnetic susceptibility from Curie's law at temperatures below 1°K with which the magnetic method is concerned. Thus the empirical Curie temperature, proportional to the reciprocal of the susceptibility, deviates from the true Kelvin temperature in this region. By the methods developed and discussed in the preceding paper by Van Vleck, numerical calculations of the specific heat and susceptibility have been performed for several salts. The experimental specific heat measured on a Curie scale has been corrected to the Kelvin scale and compared with the calculated results. Fairly good quantitative agreement is obtained, although there is some uncertainty as to the effect of (2) on the susceptibility and hence on the relation between the empirical and Kelvin temperature scales.
The Free Energy of Diatomic Carbon Vapor
Authors: Gordon A. R.
Published: January 2005

An equation for the rotational state sum for a 3Π molecule with intermediate a—b coupling is derived from Budó's expression for the rotational energy, and is used to compute the free energy of diatomic carbon vapor. Previous calculations of the equilibrium between C2 and C in the vapor are discussed, and a revised equation for the equilibrium constant is obtained.
Internal Volume and the Entropy of Vaporization of Liquids
Authors: Rice O. K.
Published: January 2005

An effective internal volume, Ve, of a liquid is defined by the equation ΔS = R ln Vv/Ve, where ΔS = entropy of vaporization, and Vv = molal volume of the vapor in equilibrium. A condition for equilibrium is found which gives ΔS in terms of Ve/V and dVe/dV, where V is the actual molal volume of the liquid. The experimental data are considered in the light of this relationship, and the reason for the approximate validity of Trouton's or Hildebrand's rule is discussed. The nature of the relation between the internal and actual volume and its connection with the specific heat of the liquid is considered. Finally suggestions are made in way of explanation of the fact that entropies of vaporization of associated liquids are practically invariably high.
Studies on Glass XV. The Viscosity and Rigidity of Glucose Glass
Authors: Parks George S. , Reagh John D.
Published: January 2005

By an electromagnetic torsion method, in which glucose glass threads were substituted for the phosphor-bronze suspension in a d'Arsonval galvanometer, the rigidity and viscosity of glucose glass have been measured between 12° and 37.5°C. The rigidity values were fairly constant around 2.5 (1010) dynes per cm2 between 12° and 30° but decreased rapidly above the latter temperature. The viscosity values ranged between 1015 and 1010 poises. These values decreased rapidly with rising temperatures but also depended greatly on the previous history of the glass threads, i.e., the extent to which the threads had been annealed and the amount of previous working to which they had been subjected. This finding suggests the existence of a series of glassy states for a substance such as amorphous glucose.
A Thermal Conductivity Method for the Determination of Isotopic Exchanges in the Simpler Gaseous Molecules
Authors: Trenner Nelson R.
Published: January 2005

A simple high pressure thermal conductivity gauge of good mechanical stability, freedom from poisoning effects and high accuracy has been described in detail. Its physical characteristics have been studied and optimum conditions for operation indicated. Its applicability to a wide variety of analyses is discussed and specific data quoted for those of the isotopic isomers of the lower aliphatic hydrocarbons and the hydrogens. Methods of direct calibration for the latter substances are indicated as well as a technique for their separation and purification. The theory of the gauge is developed and compared with experimental observations on the hydrogen isotopes.
On the Fundamental Frequencies of CH2, CHD, CD2, CHCl, CDCl, and Cis and Trans C2H2D2 and C2H2Cl2
Authors: Wu Ta-You
Published: January 2005

A valence force treatment of the groups CH2, CHD, CD2, CHCl, CDCl is given. The relative dependence of the three fundamental frequencies calculated for each group on the deformation force constant is used as a guide in correlating these frequencies with the three individual modes of vibration of the group. On the basis of this calculation, an assignment of the fundamental frequencies of cis, trans and asymmetric C2H2D2 calculated by Manneback and Verleysen is given. Also from the data on the degrees of depolarization of the Raman lines of cis C2H2Cl2 and trans C2H2Cl2, intensity and selection rules in Raman effect and infrared absorption, an assignment of the fundamental frequencies of these isomers is suggested.
The Energy States of Crystalline Pr2(SO4)3·8H2O
Authors: Spedding F. H. , Howe J. P. , Keller W. H.
Published: January 2005

The absorption spectra of Pr2(SO4)3·8H2O were photographed when the salt was at 20°K, 78°K, 105°K, 169°K, 200°K and 300°K. At least three low lying excited levels were found to exist beside the basic one and they appear to be located at 110, 235 and 500 cm—1 above the basic state. They are therefore in fair agreement with the calculations of Penney and Schlapp and with the field constant D for the rare earth sulphates which was determined spectroscopically for Nd and Er. A very strong coupling of vibrational states with the highly excited energy states seems to occur as the absorption bands consist of hundreds of closely spaced lines.
Energy States in Solids With Particular Reference to NdCl36H2O
Authors: Spedding F. H. , Hamlin H. F.
Published: January 2005

The absorption spectra of NdCl36H2O has been photographed at 78°K, 169°K and 200°K. Two low lying excited states were found, located at 62 and 250 cm—1 above the basic state. These three levels presumably arise from a splitting of the basic state of Nd+++(4J9/2) in a predominantly cubic field. The over-all splitting is slightly smaller than that which was found for the sulphate, and the relative splitting is slightly different. The differences reflect the change in crystal field which is brought about by the break in the homologous series of the hydrated chlorides of the rare earths between Nd and Pr.
The Normal Vibrations and the Vibrational Spectrum of C2H6
Authors: Howard J. B.
Published: January 2005

An investigation is made of the vibrations, frequencies and selection rules of C2H6, which is assumed to have an internal rotational degree of freedom subject to a restricting potential of an arbitrary magnitude. Making use of the fact that the total potential energy of such a molecule is invariant under a reflection in a plane perpendicular to the threefold symmetry axis, a set of vibrational selection rules is obtained which is more complete than that of Teller and Topley who made use only of the invariance of the potential energy under operations of the point group D3. The vibrational selection rules are found to be essentially the same for all degrees of restriction of the internal rotation except for the rules governing the appearance of the degenerate frequencies in the Raman spectrum, so that even in the limit of free rotation only one type of degenerate vibrational frequency is active in the infrared spectrum. A normal coordinate treatment based on a three-constant potential function of the valence force type is found to give a set of frequencies in good agreement on the whole with the observed frequencies. The fundamental region of the vibrational spectrum seems to afford no conclusive evidence for or against free internal rotation.
The Rotation-Vibration Spectrum of C2H6 and the Question of Free Internal Rotation
Authors: Howard J. B.
Published: January 2005

If there were free internal rotation in C2H6 the rotational structure of certain perpendicular type infrared bands would be very different from that for the customary symmetrical top molecule without internal rotation. To account for the fact that this difference is not observed it is necessary to assume that there is a potential difference of at least 2000 cal. (700 cm—1) between the two symmetrical forms of C2H6 differing by an internal rotation of 2π/6. A potential of this magnitude corresponds to an internal torsion vibration of 230 cm—1. The above conclusion is based upon a dynamical treatment of C2H6 in which it is assumed that vibration, over-all rotation, and internal rotation subject to a restricting potential may occur simultaneously. An approximate form of the Hamiltonian expression obtained is H=12{(Px−px)2/A+(Py−py)2/A+(Pz−pz)2/C+(Pγ−pγ)2/C+ ∑ pk2}+V, where γ represents the angle of internal rotation. The rotational selection rules are determined and it is found that under ordinary circumstances the internal rotation when free is inactive in the infrared rotation-vibration spectrum. However, when there is accidental degeneracy of certain pairs of twofold degenerate vibrational levels, the internal rotation becomes active in the infrared bands for these vibrations. In such a case of accidental vibrational degeneracy, which is approximated to by at least two sets of vibrations in C2H6, the rotation-vibration frequency for the infrared bands involves the quantity (h/4π2)[(K±K′)(1−ζ)/C–K/A] if the internal rotation is free; K and K′ are the quantum numbers of over-all and internal rotation about the threefold symmetry axis and ζ is a quantity depending on the angular momentum of vibration. The observed rotational spacing, however, is well reproduced by a frequency containing instead the quantity (h/4π2)K[(1−ζ)/C−1/A], which is to be expected if C2H6 is an ordinary symmetrical top molecule without internal rotation.
Thermodynamic Functions for Molecules Having Restricted Internal Rotations
Authors: Pitzer Kenneth S.
Published: January 2005

The partition function is considered for molecules having restricted internal rotations, and expressions are obtained which are reasonably accurate for most actual molecules. Tables are presented which list the contributions of a single restricted rotational degree of freedom to the entropy, energy, free energy, and heat capacity.
The Rotation and Vibration of Linear Triatomic Molecules
Authors: Weinberg Alvin , Eckart Carl
Published: January 2005

The rotation and vibration of a linear molecule cannot be treated by the method of rotating axes if it contains more than three atoms. The definition of the axes for the triatomic case may be based on the fact that the three atoms always determine a plane. The relation of this definition to that for the nonlinear molecules is discussed, and the appropriate normal coordinates are introduced. The wave equation of the problem is derived and its approximate solution is discussed. The fact that the Eulerian angles do not enter into the zero- and first-order terms of the Hamiltonian makes it possible to calculate some of the second order terms of the expression for the energy values with complete generality. These are the terms that arise from the rotation and from the coupling between the rotation and vibration. They are found to be ℏ2[J(J+1)−l2]/2A+C,where A is the value of the moment of inertia at equilibrium, and C=[ℏ2(V2+1)/2A]{s2(V1+12)[(ω1/ω2)+(ω2/ω1)] +c2(V3+12)[(ω3/ω2)+(ω2/ω3)]}−ℏ2/2A.In this expression, the V's are the vibrational quantum numbers and the ω's are the natural frequencies. The index 2 refers to the perpendicular vibration. The quantities c and s are determined by the potential energy function and are related by c2+s2=1. For symmetric molecules, X – Y – X, their values are c=1, s=0. If the natural frequencies are commensurable, the derivation ceases to be valid, but it appears likely that the result is essentially the same in this case.
The Heat Capacities of Benzene, Methyl Alcohol and Glycerol at Very Low Temperatures
Authors: Ahlberg J. E. , Blanchard E. R. , Lundberg W. O.
Published: January 2005

The design and operation of a low temperature vacuum calorimeter which is internally cooled from 13° to 2°K is described. The principle employed is that of adiabatically expanding cooled helium gas from a small pressure chamber, located inside the calorimeter can. The heat capacities of crystalline benzene and methyl alcohol and crystalline and glassy glycerol have been measured down to 3°K. New values of the entropies of these substances at various temperatures have been calculated. Below 9°K the heat capacity of glassy glycerol is 100 percent larger than that of crystalline glycerol. The glassy form apparently has 4.64 units of entropy at the absolute zero.
On the Role of Dipole-Dipole Coupling in Dielectric Media
Authors: Van Vleck J. H.
Published: January 2005

The mathematical treatment of dipole-dipole coupling in my previous article on magnetism applies with but little modification to the electric case. Because of fluctuation effects, the use of the usual Lorentz local field E+4πP/3 and of the Clausius-Mossotti formula cannot be justified except as a first approximation valid at low density. Consequently one need not accept the C-M prediction that polar liquids should exhibit the electric analogue of ferro-magnetism. A Gaussian approximation, or better still, a formula based on Onsager's field would never allow ferro-magnetism. Consequently the hypothesis of hindered rotation, as in the theories of Fowler and Debye, may not be necessary to explain the absence of spontaneous polarization, as well as the non-occurrence of much saturation curvature in strong applied fields. It is a weakness of their theory that this hypothesis cannot consistently be employed both for such purposes and to explain discontinuities in dielectric constants and specific heats at lower temperatures (e.g., 100° in HCl). It is surprising that the Clausius-Mossotti formula works so exceedingly well as it does in nonpolar liquids, since it is theoretically valid at high densities only for an artificial model of harmonic oscillators which cannot be regarded as an accurate representation of the induced polarization. The calculations of Kirkwood on the translational fluctuation effect, causing deviations from the C-M expression in gases, are extended to include polar molecules, and agree adequately with recent measurements of Keyes and collaborators on NH3.
Spectroscopic Studies of the Hydrogen Bond I. A Photometric Investigation of the Association Equilibrium in the Vapor of Acetic Acid
Authors: Badger Richard M. , Bauer Simon H.
Published: January 2005

The association equilibrium in the vapor of acetic acid has been studied by photometric measurement of the intensity of a narrow O–H band at λ9750 which appears to be characteristic of the single molecules. The results are in reasonable agreement with vapor density measurements, indicating that the association is at least largely due to hydrogen bond formation and that two hydrogen bonds are formed in the majority of the double molecules. An O–H absorption characteristic of the double molecules could not be observed in the vapor state, due to insufficient path length, but in the liquid and in carbon tetrachloride solutions a broad band was found with maximum around λ10,100. It is suggested that the spectroscopic criterion for the presence of hydrogen bonds is not the disappearance but rather the shift and modification of the O–H absorption.
The Ultraviolet Absorption Spectrum of Benzene
Authors: Kistiakowsky G. B. , Solomon Arthur K.
Published: January 2005

The variation of the ultraviolet absorption spectrum of benzene with temperature has been studied. From the Boltzmann distribution function two fundamental frequencies of the normal state are deduced. One is best identified with the Raman frequency of 404 cm—1, whereas the other is possibly the 605 cm—1 vibration, but may be somewhat lower. The significance of these findings for the interpretation of the ultraviolet spectrum of benzene is discussed.
The Vibration-Rotation Energy Levels of Polyatomic Molecules III. Effect of Centrifugal Distortion
Authors: Wilson E. Bright
Published: January 2005

The effect of the centrifugal distortion on the individual rotational energy levels of semirigid asymmetrical rotator molecules is calculated by an approximate quantum-mechanical treatment. A secular equation is obtained which reduces to the Wang equation when the molecule is rigid and which can be factored to the same extent as the Wang equation. It is shown that the numerical coefficients which occur are identical with those which enter the classical treatment of this problem, if the assumption is made that the vibrational wave functions are harmonic oscillator functions.
The Molecular Structure of P4O6, P4O8, P4O10 and As4O6 by Electron Diffraction
Authors: Maxwell L. R. , Hendricks S. B. , Deming Lola S.
Published: January 2005

Molecular structures of P4O6 and As4O6 were determined from electron diffraction data. P4O6 was found to have the symmetry of the point group Td with an angle P–O–P of 128.5±1.5°, and a P–O distance of 1.67±0.03A. In this structure the phosphorus oxygen distances and the phosphorus valence angles were preserved with resulting deformation of the oxygen valence angle. The separation of the arsenic atoms in As4O6 was found to be 3.20±0.05A. Because of the predominant scattering of the arsenic atoms it was difficult to determine the oxygen valence angle, As–O–As. Values of 120°, 127.5° and 140° gave approximate agreement between the observed and calculated positions of maxima. Electron diffraction photographs obtained from P4O10 differ considerably from those found for P4O6. It was not possible to explain all of the features of the P4O10 diffraction pattern by a model having the symmetry of the point group Td and it is thought that the structure might be one of lower symmetry. Data were obtained on P4O8 which indicated that it has approximately the same electron diffraction pattern as P4O10.
The Infrared Absorption Spectrum of Carbon Suboxide
Authors: Lord R. C. , Wright Norman
Published: January 2005

The infrared absorption spectrum of carbon suboxide vapor has been studied under low dispersion in the region from 2μ to 25μ. The vibrational bands observed may be satisfactorily accounted for on the basis of a linear symmetric structure for the carbon suboxide molecule, in agreement with evidence obtained from Raman spectra and from electron diffraction investigations.
Calculation of the Heat Capacity Curves of Crystalline Benzene and Benzene-d6
Authors: Lord R. C. , Ahlberg J. E. , Andrews D. H.
Published: January 2005

The heat capacity curve for solid benzene has been computed with the help of the set of internal frequencies previously proposed by Lord and Andrews. The agreement with experiment is satisfactory over the entire temperature range in which the internal frequencies contribute, indicating that the frequency values are essentially correct. A prediction of the heat capacity of benzene-d6 has also been made.
Molecular Rotation in Crystalline Disubstituted Ethanes
Authors: White Addison H. , Morgan S. O.
Published: January 2005

The dielectric constants and conductivities of ethylene chloride, ethylene bromide, ethylene cyanide, ethylene diamine and ethylene thiocyanate have been measured over a wide temperature range in the solid and liquid states and in the frequency band 1–100 kc. Thermal measurements have revealed hitherto unreported transitions in ethylene cyanide at —38° to —46° and in ethylene bromide at —23° to —25°. The ethylene cyanide molecule rotates about all three axes in the crystal between the transition and melting temperatures. The internal rotational motion of atomic groups about the central C–C bond, which is believed to characterize this molecule in the liquid state, is not observably restricted by solidification. This internal motion is believed to facilitate molecular rotation in the crystal by increasing the time-average symmetry of the molecule. An atomic polarization of about 17 cc below the transition is ascribed to the persistence of some degree of torsional vibration within the molecule even in the low temperature phase of the crystal. In none of the other crystals does the polar form of the molecule rotate below the freezing point nor is there evidence of unusual intramolecular motion except possibly in ethylene thiocyanate. It is probable, however, that the trans form of the ethylene bromide molecule rotates about its long axis between the transition and melting points.
Vibration Spectra and Molecular Structure. III The Infrared Absorption Spectra of Cyclopropane and Ethylene Oxide
Authors: Bonner Lyman G.
Published: January 2005

With a rocksalt prism spectrometer, the infrared absorption spectra of gaseous cyclopropane and ethylene oxide have been mapped in the region 1–15.5 μ. Cyclopropane shows bands at 6250, 4425, 3086, 2525, 2088, 1887, 1739, 1429, 1021, 860, and 671 cm-1, while ethylene oxide absorbs at 6211, 4310, 3891, 3021, 2632, 2304, 2024, 1733, 1626, 1493, 1255, 1134, 862, 804 and 696 cm-1. In addition to these infrared measurements, a redetermination was made of the Raman spectrum of liquid ethylene oxide. Raman lines appeared at 807, 867, 1123, 1269, 1488, 2914, 2958, and 3007 cm-1.
Theory of the Viscosity of Liquids as a Function of Temperature and Pressure
Authors: Ewell Raymond H. , Eyring Henry
Published: January 2005

An equation for the viscosity of a liquid in terms of the energy of vaporization and the molal volume is developed from the reaction rate theory of viscosity due to Eyring. The degree of freedom corresponding to flow is assumed to be a translational one, and the energy of activation for the elementary flow process is assumed to be some fraction, 1/n, of the energy of vaporization. On applying this equation to a large number of normal liquids it is found that molecules possessing spherical symmetry have n = 3, while nonspherical molecules have n greater than 3, usually about 4. It is shown that the ratio ΔEvap/ΔEvis,  where  ΔEvis=R(d ln η)/(d(1/T)),can be taken as an index of the size and shape of the molecule, or more precisely, of the unit of flow in the liquid. The activation energy for flow in liquid metals is a very small fraction of the energy of vaporization, ranging from 1/10 to 1/25, leading to the conclusion that the metal ions flow without their valence electrons. Viscosity data confirm the S8 ring structure for sulfur below 160° and lead to the conclusion that above 250° sulfur probably consists of long chains containing as a rough average about 36 sulfur atoms. In the long chain hydrocarbons the activated configuration for flow is probably a curled up molecule. The structure activation energy of flow in associated liquids due to the hydrogen bond structure is discussed, and viscosity data are used to compute the degree of coordination in liquid water. At high pressures the energy of vaporization in the equation must be replaced by V(pinternal+pexternal). This yields an equation for computing either the internal pressure of a liquid or the viscosity under pressure, if either is known. Using Bridgman's viscosity data, values of the internal pressures of some liquids are calculated from this equation which agree with internal pressures calculated from compressibility data.
Liquid Structure and Energy of Vaporization
Authors: Hildebrand J. H.
Published: January 2005

The equation derived by Hildebrand and Wood for the potential energy of a liquid in terms of its structure, as determined by x-ray scattering, has been tested by the aid of the structures determined by Thomas and Gingrich for potassium at 70° and 395°. The ratio of the energy of vaporization is calculated to be 1.154 while the same ratio as determined by aid of the vapor pressure curve is 1.155. The decrease in the van der Waals a is the same for potassium and benzene for temperature intervals corresponding to equal expansion ratios.
Scattering of Slow Electrons in, and Apparent Electron Affinity of Boron Fluoride
Authors: Seward R. P. , Simons J. H.
Published: January 2005

Slow electron scattering in boron fluoride exhibits a phenomenon similar to that observed in mercury. An inverse fourth-power attraction law is indicated and the apparent electron affinity may be roughly estimated. A possible correlation between electron affinity and bands observed in the spectra is postulated.
The Further Concentration of N15
Authors: Thode H. G. , Urey H. C.
Published: January 2005

A further study has been made on the application of the chemical exchange reaction between ammonia gas and ammonium nitrate in water to the problem of securing high concentrations of the nitrogen isotope of atomic weight 15. The apparatus consists of several glass packed columns filled with efficient packing materials arranged in cascade, such that a smaller second column operates on the product from the first and a third column operates on the product from the second. With this arrangement of columns we have secured 72.8 percent N15 and have produced sufficient quantities of concentrated material to investigate many of the physical properties of N15 and its compounds.
The Blackening of Zinc Sulfide Phosphors
Authors: Gordon Newell T. , Seitz Frederick , Quinlan Frank
Published: January 2005

The process of blackening of zinc and cadmium sulfide phosphors is studied experimentally and theoretically. A survey of the principal experimental facts is given and several new experiments are described. It is suggested that the blackening of the sulfide salts is a two-quantum process in which both positive and negative charges are released from the interior; these charges move to the surface and there produce electrolysis in a film of moisture that is present on the surface when the specimen is in damp air. This picture will explain the known experimental facts concerning the blackening process. The important differences between the blackening of sulfides and the print-out effect in photographic emulsions are discussed.
The Equilibrium Dissociation and Thermodynamic Constants of Nitrosyl Chloride. Comparison with Spectroscopic Data
Authors: Beeson Carrol M. , Yost Don M.
Published: January 2005

Careful measurements of the equilibrium dissociation of nitrosyl chloride into nitric oxide and chlorine have been made in the temperature range 100–220°. Pressure-temperature measurements at 0°-100° on mixtures of nitrosyl chloride and nitric oxide were made and from them the second virial coefficients of nitrosyl chloride gas were calculated. These vary from —389 cm3/mole at 0° to —196 cm3/mole at 100°. The virial coefficients were used to correct the measured equilibrium constants to those for perfect gases. Equations for free energy, entropy and heat content changes accompanying the dissociation were derived as functions of the temperature. The experimentally found entropy changes for the reaction were found to be less than those calculated from spectroscopic data by 3.61±0.3 cal./deg. To attain agreement, the spectroscopic entropy of nitrosyl chloride must be increased by 1.8 cal./deg., and this was attained by assuming that an observed infra-red frequency at 923 cm-1 is a combination, 633+290 cm-1. For the reaction 2NOCl(g) = 2NO(g)+Cl2(g), ΔF°298=9,720±60 cal., ΔS°298=28.0±0.5 cal./deg. ΔH°298=18,060±200 cal. S°298(NOCl)=63.0±0.3 cal./deg.
On the Viscosity of Nonpolar Liquids
Authors: Kyropoulos S.
Published: January 2005

The phenomenon of viscosity drop by flow-orientation (i.e., mechanical orientation in a Couette apparatus) with nonpolar liquids composed of large dissymmetrical molecules points to a marked influence of the dissymmetry of polarizability on this phenomenon and on viscosity in general. In the case of such liquids the molecular forces of interaction are practically confined to the dispersion forces, and there are very definite states of minimum mutual potential energy. This condition results in temporary formation of complexes of higher saturation of those residual fields of force which interact in the phenomenon of viscosity. An analogous case is represented by long chain hydrocarbon molecules with polar head where the dipole forces are eliminated to a great extent, insofar as viscosity is concerned, by association, resulting in a viscosity behavior very similar to that of corresponding paraffins. With small molecules, even small permanent moments tend to suppress the influence of the anisotropy of polarizability of deformation, resulting in a type of complex which is ultimately, even temporarily, more determined by the dipole forces.
Hindered Molecular Rotation and the Dielectric Behavior of Condensed Phases
Authors: White Addison H.
Published: January 2005

The polarizability of a liquid or a collection of randomly oriented single crystals in which polar molecules are unable to move except to rotate from one to the other of two equilibrium orientations separated by an angle β and of potential energies whose difference is E, is α=(μ2/6kT)(−cos β)/cosh2E/2kT,where μ is dipole moment. This model accounts for the reduction of α in solids and liquids from the value μ2/3kT observed in gases, and at the same time provides for anomalous dispersion in terms of discontinuous molecular processes.
The Jahn-Teller Effect and Crystalline Stark Splitting for Clusters of the Form XY6
Authors: Van Vleck J. H.
Published: January 2005

The present article develops the mathematical theory needed in connection with the preceding paper, and with a study of paramagnetic relaxation to appear later. Jahn and Teller have shown that the normal coordinate theory for a molecular cluster such as X·6H2O (X=Ti, V, Cr) is materially different from usual if the X ion is degenerate. Namely, it is impossible to eliminate linear terms in the atomic displacements simultaneously from all substates of the degenerate level. Consequently, stability is achieved only if the degeneracy is lifted, and so the water group distorts itself so that it is not cubically arranged. A calculation is made of the magnitude of the effect, which has an important bearing on magnetic behavior. In order to allow for the disturbing effect of distant atoms, the cluster X·6H2O is not treated as free, but rather as embedded in a trigonal field of force. The Stark splittings in such fields, quite apart from the Jahn-Teller effect, are hence obtained as a corollary.
A Further Study of the Absorption of Aqueous Solutions at 4.72μ
Authors: Barr E. S. , Craven C. J.
Published: January 2005

By the use of a grating spectrometer, the infra-red absorption spectra of aqueous solutions of five inorganic materials (KI, CuBr2, ZnBr2, CdCl2·2H2O, and NaOH) and six organic materials (acetone, CH3COONa, CH3COONH4, cane sugar, C6H5OH, and C2H5OH) were observed in the region of the water band at 4.72μ. The organic materials investigated caused a displacement of the position of maximum absorption to shorter wave-lengths; the inorganic materials apparently caused a shift to longer wave-lengths, but the actual effect on the water band may be masked by other absorption bands in the same region. The concentration-shift relationship was investigated for some of the materials. Size of the solute molecule and the positive ion seemed to be of comparatively little importance.
The Infra-Red Absorption Spectrum of Gaseous Cyanogen, C2N2
Authors: Bailey C. R. , Carson S. C.
Published: January 2005

A discussion of the thermodynamic functions of cyanogen recently appeared in this journal. We therefore think it of interest to describe our re-examination of the infra-red spectrum. The structure of the bands is critical in arriving at a satisfactory assignment of the fundamental frequencies and we have been able to obtain some additional evidence on this question.
The Variation in the Structure of Water in Ionic Solutions
Authors: Stewart G. W.
Published: January 2005

It has been long thought that the presence of ions in an aqueous solution produces a contraction of the water. Here it is shown by x-ray diffraction curves (1) that with concentration of ions there is a lessening of the amount of the 4-coordinated water structure, increasing the density, (2) that the alteration in structure is apparently similar to that produced by increasing the temperature of the water, and (3) that the effect on the water structure is not confined to the shell immediately adjacent to an ion. Further, by the use of fifteen strong electrolytes, selected because of their wide variation in type and also in apparent molal ionic volume, it is shown by measurements on the alteration in the minor diffraction peak (4) that the rate of variation of the liquid structure of the water with ionic concentration has a striking correspondence with the rate of variation of the apparent molal ionic volume. In fact, the alteration in liquid structure seems to have a much more important effect in the apparent molal ionic volume than has an electrostatic theory based on the Debye-Hückel theory.
X-Ray Diffraction in Liquid Ethyl Alcohol
Authors: Harvey G. G.
Published: January 2005

X-ray diffraction patterns of liquid ethyl alcohol have been taken at temperatures of 25°C and —75°C with monochromatic Mo Kα radiation out to values of (sin θ) /λ = 1.2 and Fourier analyses of these curves carried out. The weighted radial atom distribution function shows a number of well-defined peaks. The first of these, at about 1.5A, corresponds to the C–C (1.54A) and C–O (1.43A) distances in the molecule, the two being superposed. This composite peak is completely resolved from the remainder. A peak at about 2.4A may be interpreted as due to the other C–O distance in the molecule. These are the only definite distances, corresponding to permanent neighbors, that would be expected. A most interesting feature is the existence of a peak at about 2.9A corresponding to intermolecular linkage of hydroxyl groups, similar to the situation found in liquid methyl alcohol. The area under this peak shows that each hydroxyl is linked to, roughly, two others, as was also found to be the case for methyl alcohol. Beyond this there are no very definite distances, the density curve rapidly approaching the average density.
The Raman Spectra of Gaseous Substances 1. Apparatus and the Spectrum of Methylamine
Authors: Kirby-Smith J. S. , Bonner L. G.
Published: January 2005

An apparatus is described by means of which the Raman spectra of gases may be obtained at pressures as low as 2–3 atmospheres and with exposure times of 3–6 hours. The fundamentals of this apparatus are a high intensity light source, a large scattering volume and a large aperture spectrograph camera. Nine lines in the spectrum of methylamine have been measured and are compared with previous measurements on the liquid. An interesting feature of this spectrum is the existence of four lines in the region of C–H valence vibrations, where but two are expected. This anomaly is interpreted in terms of a double resonance interaction.
The Nature of the Fusion Process in Argon
Authors: Rice O. K.
Published: January 2005

A brief review is presented of the method previously used of treating the phenomenon of fusion by means of curves for the thermodynamic functions (∂E/∂V)T and (∂S/∂V)T as functions of the molal volume. The curves used by the writer in previous work are shown to be consistent with Bridgman's P-V-T data. The characteristics of these curves are discussed, and the evidence is considered which tends to indicate that fusion involves an order-disorder phenomenon. The applicability of various types of order-disorder theory is critically considered in the light of the available experimental data.
Exchange Reactions of Nitrogen Isotopes on Iron and Tungsten Surfaces
Authors: Joris George G. , Taylor Hugh S.
Published: January 2005

The activities of iron synthetic ammonia catalysts and of tungsten filaments in promoting the reaction between N230 and N228 have been studied in the range from room temperature to 725°C with iron and to 900° on tungsten. In contrast to the exchange reaction of molecular hydrogen isotopes, the exchange reaction of nitrogen molecules is very slow, first measurable above 450°C. The reaction is accelerated by the presence of hydrogen. The evidence indicates that the exchange involves, as the slow process, either the rupture of valence bonds of absorbed molecular nitrogen on the surface or migration of nitrogen atoms over the surface, and that hydrogen accelerates such processes. The temperature coefficient of exchange in a N2 : 3H2 mixture is ∼50 kcal. The data suggest that measurements of the velocity of nitrogen adsorption at ca. 400°C on synthetic ammonia catalysts are measurements of true activated adsorption.
Remarks on the Hole Theory of Condensation
Authors: Kirkwood John G.
Published: January 2005

The hole theory of condensation recently proposed by Cernuschi and Eyring is discussed from the standpoint of the order-disorder theory of critical solution phenomena. It is pointed out that the hole theory predicts critical temperatures which are several times larger than those observed for most nonpolar fluids. This is attributed to the failure of the theory to take adequate account of the lattice vibrational factor in the partition function.
Specific Heat and Double Minimum Problem of NH3
Authors: Haupt R. F. , Teller E.
Published: January 2005

The specific heat of ammonia is calculated in the temperature range from 0°C to 150°C. The effect of the anharmonicity of the 948 cm—1 vibration on the specific heat is very noticeable. Small corrections due to the stretching of the molecule by centrifugal force and the interaction of vibration and rotation are taken into account. The results are in good agreement with measurements of Osborne, Stimson, Sligh and Cragoe.
Partition Functions for Partly Classical Systems
Authors: Wilson E. Bright
Published: January 2005

A method is described for calculating the partition function of systems whose Hamiltonian operator separates into three terms of the following types. The first and second terms are functions of different sets of coordinates while the third is a small coupling term. The energy levels of the first term by itself are widely spaced compared to kT while those of the second are closely spaced. In the result given, the partition function becomes a sum over the widely spaced levels and a phase integral for the contribution of the other levels, as in the case with no coupling term, but here the effect of the coupling term is included in the integral. As an illustration it is shown that the coupling of rotational and vibrational angular momentum in a polyatomic molecule has no appreciable effect on the thermodynamic properties even though it has a marked effect on the energy levels.
The Variation of the Differential Diffusion Constant of Hydrochloric Acid with Temperature
Authors: James W. A. , Gordon A. R.
Published: January 2005

The differential diffusion constant of hydrochloric acid has been determined at temperatures ranging from 10°C to 35°C. At 10° and at 15°, the variation of the diffusion constant with concentration is given by the relation k=k0(1+c∂ lnf/∂c)·(η0/η) only up to about 0.2 normal. The activation energy of diffusion for concentrations less than 0.2N is practically independent of acid concentration; it decreases with increasing temperature, and is of the order of magnitude of the activation energy of viscous flow. For higher concentrations, the activation energy increases with increasing acid concentration.
Line Absorption Spectra of Rare Earth Ions in Crystals
Authors: Meehan E. J. , Nutting G. C.
Published: January 2005

Absorption spectra of the sulfate octahydrates of Er+++, Dy+++, Ho+++ and Tm+++ have been obtained at temperatures ranging from 14°K to 300°K. From the study of the variation in intensity of the absorption lines with temperature, energy levels have been found, in Er+++, at 19, 41 and 86 cm-1 above the normal state. Similar levels have been found in Dy+++ at 22 and 57 cm-1 above the lowest. No such low energy states have been found in Ho+++ and Tm+++.
On the Ellipsoids of Polarization of Bonds and Octets
Authors: Wang Sheng-Nien
Published: January 2005

By using the method of Gunther Sachsse the transverse and longitudinal polarizabilities of bonds and octets occurring in simple organic molecules are calculated from the Kerr constants and the degrees of depolarization of compounds in the gaseous state. The results are more reliable and show more regularities than those calculated by Sachsse from his measurements on solutions.
Phase Transitions
Authors: Mayer Joseph E. , Streeter S. F.
Published: January 2005

H-T and V-P curves for various types of phase transitions are shown. In second-order transitions a discontinuity in the curvature of the free energy occurs. It appears to follow that some change in the system must be occurring in the phase of high heat capacity, and that this change is such that it has gone to completion at the transition, so that an extrapolation of the phase is meaningless. It is shown that it is extremely difficult uniquely to prove, by calorimetric or equation-of-state data alone, the presence of an anomalous first-order transition, in which heat capacity and compressibility approach infinity continuously as the transition is approached. This type of transition can be distinguished by obtaining two phases of differing density in equilibrium, or by sound velocity measurements.

A tentative discussion of phase transitions, based on a suggestion of Frenkel, is given. It is shown that the factors determining the type of transition can be partially unraveled. A positive surface free energy between the phases necessitates a simple first-order transition.

The relation of the Band and Frenkel developments, for an imperfect gas, to the method based on Ursell's development is discussed, and it is shown that the two methods are not identical.
A Method of Obtaining the Expanded Secular Equation for the Vibration Frequencies of a Molecule
Authors: Wilson E. Bright
Published: January 2005

A method is described for obtaining the secular equation for the vibration frequencies of a molecule directly in expanded form, i.e. as an algebraic rather than a determinantal equation. The force constants occur literally and the masses may occur either literally or numerically, as desired. The symmetry may be employed as usual to factor the secular equation. Several methods of obtaining approximate roots are described for which the expanded form is particularly suitable. Finally, an example, the nonlinear general triatomic molecule, is worked out algebraically.