bluuebunny/crossref_metadata_2025 huggingface dataset:
Magnetic Susceptibilities of Praseodymium Oxides
Authors: Rabideau Sherman W.
Published: January 2005

The magnetic susceptibilities of the three oxides of praseodymium, Pr2O3, PrO2, and Pr6O11, have been measured with the faraday magnetic balance over a range of temperatures from 80° to 300°K. The sesquioxide and the dioxide have been found to have moments of 3.55 and 2.48 Bohr magnetons, respectively, and to obey the Weiss modification of the Curie law, χ(T+Δ)=C, over the range of temperatures studied with corresponding values of Δ equal to 55.0° and 104°. A curvature was noted in the plot of 1/χ vs T for the oxide Pr6O11. Thus the Weiss-Curie law does not adequately express the relationship between the susceptibility and the temperature for this oxide. A moment of 2.8 Bohr magnetons was calculated for Pr6O11 from the slope of the above plot between 200° and 300°K.
The Overlap Average and Central Field Approximations
Authors: Mueller Charles R. , Eyring Henry
Published: January 2005

A series of approximations, which achieve a considerable simplification in molecular orbital calculations, is discussed. The method is to replace some of the more complex integrals in some cases by an ``overlap average'' of simpler integrals; in other cases to use a ``central field'' approximation. The effective charge of the central field point source is calculated by application of Gauss' theorem. These approximations are applied to diatomic lithium hydride.
A Seemingly Forbidden Octacovalent Structure
Authors: Duffey George H.
Published: January 2005

About a metal atom in the Ta6Cl12+a-like structure, one cannot set up spd hybrid orbitals directed toward all eight neighboring atoms. One can set up spd hybrid orbitals with four orbitals directed toward neighboring halogen atoms and with four orbitals directed towards the middles of neighboring faces of the octahedron. Using such bond orbitals in the over-all structure and assigning two electrons to each set of overlapping bond orbitals, one gets the value two for a. The degree of overlapping seems favorable.
Infrared and Mass Spectra of Some Deuterium-Containing Derivatives of Propane
Authors: Condon Francis E. , McMurry H. L. , Thornton V.
Published: January 2005

Infrared and mass spectra of 2-deutero−2-propanol (from acetone and lithium aluminum deuteride), 2-chloro−2-deuteropropane (from 2-deutero−2-propanol and concentrated HCl and ZnCl2), 2,2-dideuteropropane (from 2-chloro−2-deuteropropane via the Grignard reagent and D2O), and 2-deutero−2-methylpropane (from t-butylmagnesium chloride and D2O) are presented in comparison with the infrared and mass spectra of the corresponding compounds not substituted with deuterium.
A Study of Metallic Electrodes Prepared by Sublimation
Authors: Bradshaw Benjamin C.
Published: January 2005

The relative electromotive force of zinc crystals deposited from the vapor phase in high vacuum was measured and found to be of the order of 100 microvolts. It is concluded that zinc crystals formed by evaporation of zinc are practically strain free and, as such, are highly suitable where reversible zinc electrodes are needed.
Binding Energy and Dipole Moment of Alkali Halide Molecules
Authors: Rittner Edmund S.
Published: January 2005

A simple theory of alkali halide gas molecules in the spirit of Born-Mayer lattice theory is presented. The molecule is considered to be constituted of ions, each of which is polarized by the electrostatic field of the other. This deformation polarization has two important consequences: (1) the net dipole moment of the molecule becomes appreciably lower than that given by the product of the electric charge e, and the internuclear separation a; (2) the repulsion constants (determined from empirical data) become different from the corresponding constants for the crystal. The theory yields satisfactory results for the binding energy, vibration frequency, and dipole moment, μ, in all instances where necessary data are available. In cases where the internuclear distances are not known experimentally, they are calculated from the theory using experimental binding energies. It is possible to assign to the ions Goldschmidt-like radii, the sums of which reproduce reasonably well both the calculated and the observed internuclear distances. Finally, item (1) above explains why Pauling's criterion for the fraction of ionic character, f=μ/ea, is not a very good measure of ionicity for these completely ionic substances.
The Rate Equation of Ammonia-Synthesis on Iron-Type Catalysts of Different Composition
Authors: Brill R.
Published: January 2005

Investigations on the rate equation of ammonia synthesis on iron catalysts have been carried out. The results agree in a general way with the rate equation of Temkin and Pyzhev. An improvement of this equation is given, which leads to a better agreement between observed and calculated synthesis rates. Experiments carried out at low temperatures show that the rate equation is the same for the three catalysts which have been investigated: (1) pure iron, (2) iron containing 3 percent alumina, and (3) iron containing 3 percent alumina and 2 percent potassium oxide. By means of the improved Temkin and Pyzhev equation a formal explanation can be given for the results obtained by Love and Emmett on ammonia decomposition on a singly promoted iron catalyst between 400 and 450C.
The Effect of Grinding on Particles
Authors: Bradshaw Benjamin C.
Published: January 2005

Although much experimental work has been done on grinding, many well-known facts concerning this process and its effect on particles remain unexplained. The writer postulates that the well-known limiting distribution of particle sizes, which results from long-continued grinding, is dynamic rather than static.
Concerning the Temperature Coefficient of the emf of Reversible Galvanic Cells Operated at Variable Concentration
Authors: Li James C. M.
Published: January 2005

The usual form of the Gibbs-Helmholtz equation such as dΔF/dT=—ΔS is limited in its application to reversible galvanic cells where all variables except temperature, which can change the emf of the cell, keep unchanged when temperature varies. For cells where concentration changes simultaneously with temperature, a form including concentration terms should be used instead. Barieau's idea concerning the confusion in literature is discussed. His ``correct reaction'' is explained and a method for writing this reaction is evaluated in general. It is found that his idea is only useful in certain cases.
Formation of Complexes in Benzene-Oxalyl Chloride Solutions
Authors: Saksena B. D. , Kagarise R. E.
Published: January 2005

Extinction coefficients have been obtained for solutions of oxalyl chloride diluted with benzene, n-heptane, and me-cyclohexane; and for solutions of diacetyl, acetyl bromide, acetyl chloride, α-methyl acrolein, and crotonaldehyde diluted with benzene and n-heptane. It has been possible to correlate the observed data in the infrared, Raman, and ultraviolet spectra of oxalyl chloride-benzene solutions by postulating a complex formation of the type Ar+[COCl]2−.
Studies on the Photovoltaic Effect. II
Authors: Levin Irvin , White Charles E.
Published: January 2005

Benzaldehyde dissolved in alcohol in concentrations less than 0.1 M yields a positive photopotential and in greater concentrations the photopotential is negative. The production of the negative photopotential is attributed to the presence of peroxybenzoic acid. In general, oxygen in the peroxide linkage seems to cause negative photopotentials and oxygen in a carbonyl group yields positive photopotentials. Strong inorganic oxidizing agents produce negative photopotentials. Inorganic reducing agents and salts which are not oxidizing agents yield little or no photopotentials. A polar solvent is necessary for the production of a photopotential. A photopotential-spectrum curve which in general follows the light absorption curve is derived for anthraquinone. High photopotentials can be obtained at wavelengths where light absorption is low if a high intensity light source is used.
The Asymmetric Rotor. IX. The Heavy Water Bands at 2787 cm−1 and 5373 cm−1
Authors: Innes K. Keith , Cross Paul C. , Giguère Paul A.
Published: January 2005

The combination band (110) of the two stretching fundamentals of D2O is reported and analyzed to yield ν0=5373.2 cm−1 and the excited state moments of inertia 1.910, 3.931, and 5.929×10−40 g cm2. The same method of analysis applied to the unsymmetrical fundamental band (100) envelope gives ν0=2787.5 cm−1 and the excited state moments 1.881, 3.876, and 5.843×10−40 g cm2.
Double Refraction of Flow: Numerical Evaluation of Extinction Angle and Birefringence as a Function of Velocity Gradient
Authors: Scheraga Harold A. , Edsall John T. , Gadd J. Orten
Published: January 2005

The method of double refraction of flow in systems containing large asymmetrical molecules gives experimental data which, when interpreted in light of the theory of Peterlin and Stuart, enable one to calculate molecular lengths; information about the polydispersity of the system and about the optical properties of the solute particles may also be obtained from such data. Heretofore, this theory had been developed so that the data could be interpreted only under the limiting condition of low velocity gradient where the degree of orientation of the solute particles is very small. With the aid of the Mark I computer of the Harvard Computation Laboratory, the necessary equations have been solved to provide numerical values over a much wider range of velocity gradients, greatly increasing the usefulness of flow birefringence measurements for the study of macromolecular systems.
The Outer Electron Configuration in Metallic Copper
Authors: Snow A. I.
Published: January 2005

The effect on the atomic scattering factor of metallic copper of the 3d7.754s14p2.25 outer electron configuration, demanded by the Pauling valence of 5.50, is computed. Approximately a 6 percent lowering in intensity of the (111) reflection when compared with the atomic scattering factor computed on the basis of a Hartree-Fock calculation for the 3d104s1 configuration is predicted if the Pauling model is the correct one. Differences for other reflections are also computed. Available intensity data for metallic copper are discussed in the light of these results.
Hydrogen Molecule Energy Calculation by Correlated Molecular Orbitals
Authors: Frost Arthur A. , Braunstein Jerry
Published: January 2005

The electronic energy of the hydrogen molecule was calculated using the correlated molecular orbital wave function ψ=(a1+b1)(a2+b2)(1+pr12),where a1, b1, a2, and b2 are 1s atomic wave functions of electrons 1 and 2 about nuclei a and b, and r12 is the interelectronic distance. The p of the above formula together with z, the effective nuclear charge, used in the explicit definition of the atomic orbitals, are two parameters which are varied in minimizing the energy according to the variation method. The energy minimum was found to be 4.11 ev below the value for complete separation of the nuclei. The minimum occurred at an internuclear distance of 0.71A, and the parameters have the values z=1.285 and p=0.28 in atomic units. The energy is far better than Coulson's best molecular orbital calculation and better than any other two-parameter calculation except for that of Gurnee and Magee.
The Entropy of Aqueous Solutes
Authors: Powell Richard E. , Latimer Wendell M.
Published: January 2005

The standard partial molal entropies of monatomic ions and of non-electrolytes in aqueous solution can be represented by the empirical expressions, for monatomic ions:S̄0=(3/2)R lnM+37–270Z/re2,for non−electrolytes:S̄0=Sint+(3/2)R lnM+10–0.22VM.Here Z is the absolute value of the charge on the ion, re is the effective radius of the ion, and VM is the molal volume.

These expressions can be interpreted in terms of the smoothed-potential type of partition function for the system.
Bond-Bond Interactions in Linear and Angular Molecules
Authors: Duchesne Jules , Burnelle Louis
Published: January 2005

The vibration potential function of several molecules is studied with special emphasis on the bond-bond interaction terms. It is shown that in the case of molecules with localized bonds a satisfactory correlation of the results cannot be obtained without assuming the existence of a maximum in the bond-bond energy curve. This maximum presumably arises from the electrostatic interactions between the bond orbitals. As a result, the bond-bond interaction terms may be either positive or negative, according to the position of the point which represents the equilibrium position of the molecule on the curve. However, this sign seems generally positive, except for molecules with hydrogenated bonds. On the other hand, for molecules with delocalized bonds (resonance), a general law may be formulated for the behavior of these terms when they refer to nonadjacent as well as to adjacent bonds. In those cases, the part played by the electrostatic interactions seems to be dominated by the resonance effects.
The Kinetics of the Reaction H+C2H6=CH4+CH3
Authors: Steacie E. W. R.
Published: January 2005

The production of methane in the reaction between hydrogen atoms and ethane has been investigated by the discharge-tube method. It is found that the reaction H+C2H6=CH4+CH3 proceeds with an activation energy of 8.6 Kcal. (assuming a steric factor of 0.1) in satisfactory agreement with the value of 7.2 Kcal. found by Trenner, Morikawa, and Taylor. The error introduced by methane formation into Steacie and Phillips' determination of the activation energy of the reaction D+C2H6=HD+C2H5 appears to be negligible on the basis of the present results. At present no explanation can be offered of the discrepancy between the results of Trenner, Morikawa, and Taylor, and of Steacie and Phillips for the latter reaction.
Exchange of Deuterium Between Methanol and Water: Vibrations of the Hydroxyl Group in Methanol and Methanol-d: The Entropy of Methanol
Authors: Halford J. O. , Pecherer B.
Published: January 2005

New measurements of the equilibrium in the exchange reaction between methanol and heavy water, in conjunction with data in the literature, are considered in relation to the vibrations of the hydroxyl group, including the torsional degree of freedom. An interpretation is presented which allows for a torsional frequency of 250 cm—1, a value which is shown to be in reasonable agreement with the entropy from thermal data.
The Raman Spectrum of Liquid Diborane
Authors: Anderson Thomas F. , Burg Anton B.
Published: January 2005

The Raman spectrum of B2H6(l) is found to contain an isotopic triplet (v1) 793, 806, 821 cm—1, a broad line (v2?) 1108 cm—1 and a very intense doublet (v3?) 2102, 2523 cm—1 as well as several weaker lines. Abnormally large values for the B–B, C–C, and Si–Si bond force constants in B2H6, C2H6, and Si2H6 suggest that these bonds are compressed in these molecules by forces which may be associated with those which restrict internal rotation. The value of 55.3±1.5 cal./deg. is calculated for the entropy of B2H6(g) at 25°. Combined with the known heat of formation this value leads to a free energy of formation of —30,000±4000 cal. for B2H6(g) at 25°. This large value does not truly indicate high stability, for diborane decomposes easily to form other boron hydrides.
The Variation of the Raman Spectrum of Nitrate Solutions with Cation
Authors: Laird Elizabeth R. , Plesset Frances M.
Published: January 2005

The strong Raman line from solutions of cadmium, silver and lead nitrates has been remeasured at varied concentrations, and the results of Grassmann confirmed, namely that the frequency shift diminishes with increasing concentration for lead and silver, and varies little for cadmium. A qualitative explanation of this behavior and that of sodium nitrate is suggested in the effect of the cations on the structure of water, and attention is drawn to the similar order of these nitrates in x-ray diffraction phenomena.
Temperature Scale and Thermionic Emission from Rhodium
Authors: Wahlin H. B. , Whitney L. V.
Published: January 2005

When rhodium is heated to incandescence in an atmosphere of air or oxygen, a coating forms on its surface. This is shown by a change in the emissivity. When the temperature is increased sufficiently this coating suddenly disappears, and when the temperature is lowered it reappears. This coating is probably an activated adsorption of oxygen, or an oxide of rhodium. It is found experimentally that the temperature and partial oxygen pressure at which the coating disappears are related by the Clausius-Clapyron equation: (d loge P)/dT=L/RT2.P is the partial oxygen pressure, T the absolute temperature, and L the heat of vaporization of the surface. The electron work function of a clean rhodium surface is found to be [open phi]=4.80 volts, and A = 33 amp./cm2/degree2.
The Dipole Moments of Molecules Containing Two Movable Dipoles
Authors: Beach J. Y. , Stevenson D. P.
Published: January 2005

The average dipole moment of a molecule containing two movable dipoles has been calculated as a function of temperature and restriction to internal rotation for three different potential functions. The potential functions used are: (V0/2)(cos φ+1), (V0/π)(π—φ) and V0/π2(π—φ)2, where V0 is the difference in potential energy between the cis and trans forms of the molecule and φ is the angle between the planes containing the dipoles and the axis of rotation. Values of the integral ∫ 0πcos x exp (−bx2)dx are tabulated for values of b ranging from 0 to 2 at intervals of 0.1. The dipole moments of s-dichloro-ethane, 1,2-bromo-chloro-ethane and s-dibromo-ethane as a function of temperature are used with the three potential functions to determine values of V0. The values thus obtained are compared with the values obtained by other methods.
Internal Rotation in Ethylene Chloride
Authors: Beach J. Y. , Palmer K. J.
Published: January 2005

The electron diffraction method of investigation has been used to determine the nature of the potential barrier restricting the rotation about the carbon-carbon single bond in ethylene chloride (CH2Cl–CH2Cl). Assuming that the shape of the barrier is given by a cosine function, the height of the barrier is between 5 kcal./mole and infinity. This potential barrier is compared with the barrier resulting from the exchange repulsions and the electrostatic repulsions of the two ends of the molecule. Eyring's method was used for calculating the exchange repulsions. The repulsions between the chlorine atoms must be calculated differently from the repulsions between hydrogen and chlorine atoms in order to obtain agreement between theory and experiment. Duplicate experiments were done at Princeton and at Pasadena.
The Atomic Distribution in the Allotropic Forms of Phosphorus at Different Temperatures
Authors: Thomas C. D. , Gingrich Newell S.
Published: January 2005

Monochromatic x-ray diffraction patterns of liquid yellow phosphorus, amorphous red phosphorus and amorphous black phosphorus were obtained, using Mo Kα radiation. The effect of temperature upon these patterns was investigated for the first two forms. Analysis of these patterns led to the determination of the atomic distribution curves in each case. The number of nearest neighbors is three for all forms. This is taken as direct proof of the existence of P4 molecules in liquid yellow phosphorus. Comparisons are made of the atomic distribution curves of each form and at the different temperatures for liquid yellow and amorphous red phosphorus.
Competition of Predissociation Processes in the Photolysis of Polyatomic Molecules
Authors: Rollefson G. K. , Burton Milton
Published: January 2005

It is shown that if a photoactivated polyatomic molecule may decompose in more than one way with different products for each path, certain generalizations govern the probability of an activated molecule decomposing by any given path. First, there is a tendency to form those products which require a minimum amount of the activation energy to appear as kinetic energy. This tendency increases with increase in energy of the molecule if the energies at which the different paths become possible are widely separated but the opposite effect is found if the separation is small. The effects of collisions in causing predissociation is shown to be interpretable partially as an alteration of the number of times that the molecule reaches a condition represented by the intersection of two hypersurfaces and partially as a disturbance of the restrictions existing at such crossings. These principles are applied in a discussion of the photolyses of acetone, acetaldehyde, acetic acid, formic acid, and normal butyraldehyde.
The Mechanism of the Photolysis of Deutero-Ammonia
Authors: Burton Milton
Published: January 2005

In order to avoid theoretical objections to the mechanism previously suggested for the photolysis of ND3, a new mechanism is proposed involving competition between two spontaneous predissociation processes in the discrete region. The relative amounts dissociating by the two paths, one yielding atomic hydrogen and the other molecular hydrogen, are shown to be in the approximate ratio 19 : 1 in the primary act. In the diffuse region, the time of decomposition is so short that the reaction is exclusively by the first path.
Infra-Red and Raman Spectra of Polyatomic Molecules. V. Cyclopropane and Ethylene Oxide
Authors: Linnett J. W.
Published: January 2005

The Raman and infra-red spectra of cyclopropane and ethylene oxide have been examined. The infra-red spectra were examined using a potassium bromide prism from 25 to 11μ, a rock-salt prism from 15 to 7μ and a fluorite prism from 8 to 1.5μ. Because of the greater dispersion of fluorite more bands than had previously been observed were resolved in the region in which this prism could be used. The nature, symmetry and selection rules of the vibrations of these two molecules are summarized. It was found possible to make a complete assignment of the fundamental frequencies of cyclopropane which accounts for all the features of the spectra. With ethylene oxide it was only possible to make a partial assignment. The frequencies of the corresponding fundamental modes of vibration of the two molecules are compared. On the basis of the frequency assignment described, values for the free energy, entropy and heat capacity of cyclopropane are calculated between 100° and 1000°K.
A Partial Analysis of Some Infra-Red Absorption Spectra of Organic Molecules in Dilute Solution
Authors: Wulf Oliver R. , Deming Lola S.
Published: January 2005

An attempt is made to resolve into component parts a number of relatively complex infra-red absorption coefficient curves for several OH-containing organic molecules in the region of the first overtone absorption of the OH group. Such analyses suggest certain relations between the structure of the molecule and its effect upon the character of the absorption of the absorbing group.
Wave Functions and Potential Curves for Excited H2
Authors: Coolidge Albert Sprague , James Hubert M.
Published: January 2005

Results on wave functions and energy values for the 1sσ2pσ3Σu and 1sσ2sσ3Σg states of H2, obtained by a variational method, are given. The nuclear separations considered range from 1.3aH to 2.9aH. The errors in the computed energies for the 3Σu state are of the order of 0.001 atomic unit, while the computed energies for the 3Σg state are in general more accurate. Rootmean-square errors in the wave functions are of the order of 2 percent.
Nuclear Spin and Symmetry Effects in the Heat Capacity of Ethane Gas
Authors: Wilson E. Bright
Published: January 2005

The heat capacity of ethane gas has been calculated for a number of values of the internal potential barrier from zero to high barriers. Detailed account of the presence of noncombining species and of the exact nuclear spin statistical weights was taken. It was found that down to temperatures at least as low as 90°K these phenomena are entirely unimportant and that the partition function calculated in the usual way is correct. It is concluded that the observed experimental data are best explained by the assumption of a high restricting potential. Tables of statistical weights for the rotational levels of C2H6 and C2D6 are given.
The Relative Adsorbabilities of Hydrogen and Deuterium
Authors: Wheeler A.
Published: January 2005

The unexpected results of Beebe, Klar and others on the relative adsorbabilities of H2 and D2 on metal surfaces are explained by a statistical-mechanical treatment. By constructing simple partition functions for the adsorbed molecules and atoms, equal adsorption at low temperatures and an inversion temperature at higher temperatures are predicted. Both predictions are fulfilled by the experimental results.
Diffuse Electron Diffraction Patterns
Authors: Burwell J. T.
Published: January 2005

Diffuse electron diffraction patterns taken by reflection have in the past been cited as proof that the polished surfaces of metals are amorphous or very finely crystalline. In the present work it is shown that such patterns can be obtained from a large-grained crystalline surface and hence cannot be due to an amorphous phase but rather to the physical contour of the surface.
The Infra-Red Absorption of Carboxylic Acids in Solution I. Qualitative Features
Authors: Davies M. M. , Sutherland G. B. B. M.
Published: January 2005

The absorption spectra of solutions of acetic, benzoic and trichloracetic acids in carbon tetrachloride have been studied at various concentrations and temperatures in the neighborhood of 3μ, 6μ, and 7μ. At each of these regions is a double band, one component of which is due to the monomeric, the other to the dimeric form of the molecule. The relatively small shift in each case indicates that the molecule is not radically altered on association. The absorptions in the three regions studied were due respectively to the O–H, the C=O and the C–O bonds of the COOH group. It has been possible to make a first estimate of these bond distances in the monomer and dimer, as follows (in A units): O−HC=OC−OMonomer0.9811.1951.298Dimer1.041.2111.285The values for the C=O and C–O distances are in satisfactory agreement with those deduced by x-ray methods for oxalic acid but not with those obtained by electron diffraction for formic acid. The general appearance and the temperature variation of the O–H ``association'' band in these acids appears to be very similar to that of the corresponding band in the alcohols. This is evidence in favor of Badger's explanation of the width of such bands rather than Errera's.
Infra-Red Bands of Methylamine and the Phenomenon of Free Rotation
Authors: Thompson H. W. , Skinner H. A.
Published: January 2005

Two bands in the absorption spectrum of methylamine have been measured in the photographic infra-red. One of the bands shows rotational structure. The bands have been interpreted as involving excitation of the frequencies 3νCH+νCN). The rotational structure of the latter band suggests that it is a perpendicular-type band, and the precise spacing of the Q branches suggests that the molecule behaves approximately like a rigid symmetric top. The inference of hindered internal rotation is in agreement with other independent data.
Kinetics of OH Radicals Determined by Their Absorption Spectrum IV. Pressure Broadening and the Line Spectrum as Background
Authors: Oldenberg O. , Rieke F. F.
Published: January 2005

For the measurement of the concentration of OH radicals the intensity of the absorption spectrum is measured more easily with an emission line background than with a continuous background, provided that the pressure broadening is known. The total broadening of the OH absorption lines at 1473° K and 1 atmos. (⅔O2+⅓H2O) is observed to be 0.58 cm—1; 36 percent of this value is Doppler broadening, the rest is pressure broadening. With this figure, recent intensity measurements of the OH bands by Avramenko and Kondratjew are reinterpreted. The resulting f values of approximately 3×10—4 are in reasonable agreement with our previous measurements. The conditions are discussed under which the simple method using the line spectrum as a background is applicable.
The Energy of the Triatomic Hydrogen Molecule and Ion, V
Authors: Hirschfelder Joseph O.
Published: January 2005

In previous papers, the energy of H3 and of H3+ has been obtained by the variational method for linear configurations. In this treatment we are able to evaluate the difficult three center integrals for nonlinear configurations with the aid of the differential analyzer and to compute the energy of H3 and of H3+ as a function of the angle between the nuclei. The excited states as well as the ground states are considered. Direct comparison of calculated energy values for the equilateral triangle show that the molecular orbital approximation is inferior to the method of homopolar bond functions. The triatomic hydrogen molecule has its lowest energy for linear configurations. The angle dependence calculated by the variational method agrees well with that calculated on the basis of the Eyring semi-empirical scheme. By the theorem of Jahn and Teller there could not be a minimum in the energy for the equilateral triangle, as here the lowest electronic state is doubly degenerate. The triatomic hydrogen ion, H3+, is very stable (when left to itself) and has an energy lower by more than 184. kcal. than two separated hydrogen atoms and a proton. Thus the chemical reaction: H2+H2+→H3++His certainly exothermic by more than 11 kcal. and probably is exothermic by 38 kcal. The triatomic hydrogen ion has a stable configuration corresponding to separation between the nuclei of about 1.79A with the nuclei lying intermediate between a right and an equilateral triangle. The vibration frequencies of H3+ are estimated but their exact value as well as the exact configuration of the stable state are somewhat in doubt. Two of these frequencies should be infra-red active and susceptible to direct experimental measurement.
The Calculation of Bond Strengths from Photochemical Evidence
Authors: Burton Milton
Published: January 2005

When predissociation manifests itself in polyatomic molecules by a sudden broadening of the rotation lines of a discrete absorption spectrum, a close correspondence is to be expected between the beginning of the predissociation region and the strength of the bond involved. This principle is used to calculate the bond strengths of C–C in ethane, acetaldehyde, acetone and free acetyl (values: 72.1, 93.1, 96.5 and — 19.4 kcal., respectively) and of C–H in methane, acetaldehyde O(CH3C−H), formaldehyde and free formyl (values: 94.8, 114.7, 103.3, and 0.1 kcal., respectively), where the bond strength is defined in reference to the state of the molecule at 0°K. Assuming the validity of the method, the bond strength values given are shown to be accurate within 1.0 kcal. The limitations of the method as well as some implications of the results are indicated.
Quadrupole Contributions to London's Dispersion Forces
Authors: Margenau Henry
Published: January 2005

The contribution of terms in R—8 and R—10 to the dispersion forces is expressed by a simple, approximate formula (Eq. (7)) involving only measurable quantities (polarizability, absorption frequency, oscillator strength). The formula is applicable when the dispersion curve of the substance can be represented with the use of a single resonant frequency. Numerical values of the terms in question are calculated for a number of molecules (Table II). Except in the case of the alkalies, where the convergence of the sequence in inverse powers of R fails at distances around 6A, the R—10 term is generally negligible, while the R—8 term contributes appreciably in the region of the van der Waals minimum.
A Spectral Investigation of Glucose Glass
Authors: Cohn Willi M.
Published: January 2005

The spectral transmission of glucose glasses has been investigated over the wave-length region from 3600 to 8000A. Glasses of different thermal history were tested, ranging from white to dark brown in color. The glasses show different transmission values, and shifts of the transmission maximum and the absorption limit at small wave-lengths with increasing caramelization.
The Electron Diffraction Investigation of the Molecular Structures of Ketene and Thiophosphoryl Chloride
Authors: Beach J. Y. , Stevenson D. P.
Published: January 2005

The structures of the gas molecules of ketene and thiophosphoryl chloride have been determined by the diffraction of 57 kilovolt electrons. The interpretation of the photographs was made by the visual method in conjunction with the radial distribution method. The results for ketene are: carbon-carbon distance 1.35±0.02A., and carbon-oxygen distance 1.17±0.02A. The carbon-hydrogen distance was assumed to be 1.07A. The results for thiophosphoryl chloride are: phosphorus-chlorine distance 2.01±0.02A, phosphorus-sulphur distance 1.94±0.03A, and the Cl–P–Cl angle 107±3°. The results are discussed in terms of covalent radii and the resonance of molecules among several electronic structures.
The Photolysis of Acetone in Presence of Hydrogen
Authors: Taylor Hugh S. , Rosenblum Charles
Published: January 2005

The photodecomposition of acetone in presence and absence of hydrogen with light of wave-length >2500A has been studied at temperatures from 70 to 300°C. Up to 160°C acetone alone yields negligible amounts of methane and ethane is the hydrocarbon predominantly produced. The proportion of methane increases rapidly with temperature, the activation energy of its formation in acetone being 8.6 kcal. In presence of hydrogen methane formation is negligible at 70°C, is marked at 160°C and increases rapidly with temperature with an activation energy of this increase equal to 6.4 kcal. At 300°C it represents 75 percent of the ethane-methane product, which shows that photodissociation to methyl radicals is the major, if not exclusive primary process. Analysis of the data indicates that ethane formation is either a wall reaction with zero activation energy or a bimolecular association process of small activation energy. A decrease in ethane formation with increase of temperature is ascribed to a decrease in the stationary state concentration of methyl radicals. An activation energy of the reaction CH3+H2=CH4+H equal to 11±2 kcal. has been deduced. A mechanism to account for quantum yields less than unity in the low temperature range, consistent with primary dissociation into radicals, has been suggested.
The Influence of Salts on the Absorption Spectra of Aqueous Cobalt Chloride Solutions
Authors: Pearce J. N. , Dawson Lyle R.
Published: January 2005

The effects of equal concentrations of the alkali and alkaline earth chlorides and of hydrogen chloride on the absorption spectra of aqueous cobalt chloride solutions have been studied. Solutions prepared both on the molar and on the molal bases were used. In all cases, the absorption bands widen with an increase in concentration of the added salt. The increase in width of the absorption bands varies directly as the ionic charge and inversely as the ionic volume of the added cation. The inadequacy of existing explanations of the well-known color changes in cobalt chloride solutions is discussed and a new explanation is offered.
Interpretation of the Properties of Alkali Halide-Thallium Phosphors
Authors: Seitz Frederick
Published: January 2005

An attempt is made to interpret the properties of alkali halide-thallium phosphors. The experimental basis of this interpretation is the work of Pohl and his numerous collaborators on these substances. It is concluded that the long wave-length absorption peaks of the phosphors which are not contained in the pure alkali halides are to be attributed to the excitation of the thallium ions. These are assumed to be distributed throughout the crystal, replacing alkali metal ions. The structure of the observed peaks is interpreted in terms of the details of the spectrum of Tl+ and the probable effects of crystalline perturbations. The nature of the fluorescent and phosphorescent spectra is then correlated with the behavior of the normal and excited levels during the time after absorption and before optical radiation in which the crystal again comes to mechanical equilibrium. Distinction is drawn between two cases: That in which the excited Tl ion has no thallium ions among its twelve positive ion neighbors and that in which it has one. It is concluded tentatively that excitation to the lowest excited levels, associated with a triplet in the free ion, will give rise to fluorescence in either case, and that excitation to the higher, singlet level will lead to the alternative possibility of phosphorescence in the second case, but not in the first. The theoretical justification of these tentative conclusions involves assuming that the homopolar forces between the excited ion and its neighbors depress singlet excited levels more than triplet excited levels, and that singlets are depressed more when one of the neighbors of a Tl ion is another Tl ion than when none are.
The Mercury Photosensitized Decomposition of Ethane
Authors: Steacie E. W. R. , Phillips N. W. F.
Published: January 2005

An investigation of the mercury photosensitized decomposition of ethane has been made, the products of the reaction being analyzed by low temperature fractional distillation. It is found that by improved trapping methods it is possible to remove butane from the system as formed, and thus the formation of secondary products is entirely inhibited. Under these circumstances the products of the reaction consist exclusively of methane, propane, and butane, the hydrogen and higher hydrocarbons found in previous investigations being secondary products of the propane and butane decompositions. The quantum yield (in terms of ethane disappearing) is approximately 0.2. The suggested mechanism of the reaction is: C2H6+Hg(23P1)=2CH3+Hg(11S0)CH3+C2H6=CH4+C2H52CH3=C2H62C2H5=C4H10CH3+C2H5=C3H8.
Limits of Infra-Red Sensitizing
Authors: Kornfeld G.
Published: January 2005

The competition between the thermal reaction and the photochemical reaction will set a natural limit to the extension of photographic methods into the infra-red region. From plausible assumptions concerning the velocity of the spontaneous reaction of molecules containing an excess of energy, it is concluded that this limit will be found at a wave-length of 2μ.
The Near Ultraviolet Bands of Acetylene
Authors: Woo Sho-Chow , Liu Ta-Kong , Chu T. C. , Chih Wu
Published: January 2005

The present investigation is a part of the program of a series of studies aiming at a satisfactory analysis of the near ultraviolet spectrum of acetylene. The spectrum of C2H2 at room temperature and 300°C was taken with a Bausch and Lomb large quartz spectrograph. The spectrum extends from λ2430A down to the ultraviolet limit of the instrument. More than 1000 bands and lines have been measured. Most of the bands revealed intensification at elevated temperature. Some of them have been partially resolved into rotational lines with alternating intensities. Seven main progressions all with frequency difference ∼1050 cm—1 have been found. Only the bands of three of the progressions showed no intensification at higher temperature. From the differences between these bands, a frequency 580 cm—1 has been observed. Weaker bands on the red side of stronger ones have been proved through temperature variation to be due to transitions from the excited 2v5″(Eg) level in the ground state. Through a tentative assignment, 2v5′=1050 cm—1 and v4′(Eu)=580 cm—1 and the empirical selection rules, all of the bands in the seven progressions can be satisfactorily explained. Other possible assignments and the nature of the electronic transition have also been briefly discussed.
Infra-Red and Raman Spectra of Polyatomic Molecules II. Cis- and Transbutene-2
Authors: Gershinowitz Harold , Wilson E. Bright
Published: January 2005

The infra-red absorption spectra of gaseous cis- and transbutene-2 have been measured with a prism spectrometer from 435 to 4000 cm—1. The Raman spectra of these compounds as liquids have also been obtained. The accepted identification of the high boiling isomer with the cis structure is confirmed by the fact that this compound shows many more coincidences between the Raman and infra-red spectra than the other isomer, as is to be expected if the latter approximates a molecule with a center of symmetry. The observed frequencies below 800 cm—1 are sufficiently different for the two isomers so that it is not safe to assume that both isomers have the same vibrational entropy.
Arrangement of Molecules in a Single Layer and in Multiple Layers
Authors: Germer L. H. , Storks K. H.
Published: January 2005

Electron diffraction studies have been made upon layers of molecules of barium stearate and of stearic acid built upon surfaces by the Langmuir-Blodgett method. Upon clean metal surfaces odd numbers of layers have been built, and investigated by the reflection method; upon thin organic supporting foils even numbers of layers have been built, and investigated by the transmission method. On foils of Resoglaz the molecules are regularly arranged. The hydrocarbon chains of barium stearate molecules form hexagonal arrays with their axes normal to the supporting surface and separated by distances of 4.85A. Stearic acid molecules form crystals of monoclinic form with a=8.27A, b=4.96A, β=70°, the a and b axes lying in the plane of the supporting surface. In built-up films we previously observed a different polymorphic form of stearic acid; a correction to the data on this earlier structure is given here. On a clean metal surface molecules of the first layer stand with the axes of the hydrocarbon chains normal to the surface and the chains closely packed together laterally but irregularly arranged. The precision of alignment of the axes normal to the surface is greater for barium stearate than for stearic acid. In layers on top of the first, molecules of barium stearate and of stearic acid are regularly arranged in the way the same molecules are arranged on organic foils. In the case of barium stearate, the arrangement is random about the surface normal, although large single arrays are often formed; in the case of stearic acid, crystals are built with the axes of the hydrocarbon chains approximately in the plane defined by the surface normal and the dipping direction and pointing upward from the surface. Two applications or continuations of these experiments are suggested. 1. The methods of the experiments can probably be applied to fundamental studies of boundary lubrication. 2. Interpretable diffraction patterns can be obtained from single layers of molecules which are considerably shorter than stearic acid, and comparable in scattering power with films of adsorbed gas; thus studies of films of adsorbed gas can be carried out as soon as adequate vacuum technique is available.
The Mechanism of Formation of Mercury Hydride and Mercury Deuteride. Optical Excitation of Cadmium Deuteride
Authors: Olsen Leonard O.
Published: January 2005

An attempt has been made to secure resonance excitation of HgH by illuminating (1) a mixture of mercury, hydrogen and nitrogen, and (2) a mixture of mercury and water vapor, with the light from a mercury and hydrogen discharge. This discharge emitted a fairly intense HgH spectrum. Weak HgH band radiation was observed which was similar to that secured when the same mixtures were illuminated with a discharge tube which did not emit the HgH radiation. Inability to secure resonance is evidence that the weak band radiation is due to HgH molecules formed in excited states which dissociate after emission. Experimental evidence is presented which indicates that the formation process is Hg63P1+H→HgH2π1/2, 3/2+Δ,where Δ is an energy parameter. Essentially similar results were secured for HgD. Resonance excitation of CdD was observed when a mixture of cadmium and deuterium was illuminated with a cadmium and deuterium discharge.
The Change in Absorption of Water at 4.7μ Due to Solutions
Authors: Plyler E. K. , Barr E. S.
Published: January 2005

A study has been made of the absorption of aqueous solutions of some halogen salts in the region of 4.7μ. It has been found that KF shifts the bands to shorter wave-lengths, while KCl, KBr, and KI shift the band to longer wave-lengths. The effect is explained as due to changes in hindered rotation as produced by the binding forces between the ions and water molecules. The changes in position of the band vary with concentration. The kind of positive ion does not seem to change the effect when the same negative ion is in solution.
The Free Energy and Entropy of Nitrosyl Chloride
Authors: Jahn Francis P.
Published: January 2005

Using the harmonic oscillator rigid rotator approximation to the partition function of nitrosyl chloride, the values of the free energy function, (F0—E00)/T, and the entropy, S0, have been calculated for the ideal gas from 298.1°K to 1000°K at fifty degree intervals. By comparison with the equilibrium data for the dissociation of nitrosyl chloride, ΔE00 is found to be 15,510±53 cal. It is found necessary to assume an electronic weight of four for the ground state. Although the calculated equilibrium constants agree fairly well with experiment, a definite trend in the deviations cannot be satisfactorily explained.
An Improved Calculation of the Energies of Metallic Li and Na
Authors: Bardeen J.
Published: January 2005

The method of calculation used in the present work is a modification of that used by Wigner and Seitz in their original calculations of the energies of metallic Li and Na. The main difference lies in an improved method for the calculation of the Fermi energy. In each polyhedral cell, the wave function of an electron is taken to be of the form ψk=[u0(r)+i(k·x)(v1(r)−u0(r))]exp [ik·x], where u0(r) and v1(r) are radial s and p functions, respectively, which depend only on the distance from the ion in the center of the cell. Both functions are determined explicitly from the differential equations, and the energy of the electron is expressed in terms of the boundary values of the wave function. Values of the Fermi energy, and of the total energy of each metal, are tabulated as a function of the lattice spacing. Calculated values of the lattice constants, heats of sublimation, and compressibilities are in fair agreement with experiment.
Dielectric Absorption in Polar Media and the Local Field
Authors: Cole Robert H.
Published: January 2005

The phenomena of dielectric dispersion and absorption in polar liquids subject to applied high frequency electrical fields are discussed on the basis of a modified Onsager theory for the local field. The results of this theory agree quite as well with experiment as do those from Debye's application of the hypothesis of hindered rotation with which the present work is compared. The application of the modified theory to the static case is also considered. A law of corresponding states is found to exist for the alcohols and an empirical equation proposed by Van Arkel and Snoek for ``normal'' polar liquids is shown to have an explanation in terms of the local field. The desirability of more complete measurements of dielectric constants and absorption as a function of temperature and frequency is stressed.
Theory of the Viscosity of Unimolecular Films
Authors: Moore Walter J. , Eyring Henry
Published: January 2005

The equation for the fluidity of a liquid based on the reaction rate theory of viscous flow is modified to interpret the viscosity data for liquid films. The free energy of activation for viscous flow in the surface films, as calculated from the viscosity data of Harkins and Meyers, and Langmuir and Schafer, is found to be about twice that for flow in the liquid in bulk. This may be explained by the occurrence of various types of association in the liquid films, e.g. lateral association of the surface molecules with one another and vertical association with the solvent (solvation of the polar groups). Equations are given for the pressure and temperature effect on surface viscosity. It is shown how the knowledge of these effects may be used to interpret the structure of the films, and to separate and evaluate the contributions to the free energy of activation due to lateral association, solvation and hydrogen bonds.