bluuebunny/crossref_metadata_2025 huggingface dataset:
The Absorption Spectra of Manganese Fluoride, Zinc Fluoride, and Manganese-Activated Zinc Fluoride
Authors: Parkinson W. W. , Williams Ferd E.
Published: January 2005

Thin films of MnF2, ZnF2, and ZnF2:Mn have been prepared by evaporation, and their optical absorption spectra have been measured from 1500 to 2600A. The absorption coefficient of MnF2 has a maximum of 8.64×104 cm−1 at 1613A, corresponding to an oscillator strength of 0.042; while there appears to be a maximum of lower value at 1470A for ZnF2. An unresolved weaker band at 2050A is also evident for MnF2. For the phosphor, ZnF2:Mn, the absorption coefficient is intermediate between those of ZnF2 and MnF2, but the peak characteristic of the Mn++ activator is shifted to 1666A and the oscillator strength of the transition is increased to 1.2.

The relative excitation spectrum of ZnF2:Mn was determined, and maximum response occurred between 1600 and 1670A, indicating that radiation in the strong absorption band characteristic of the activator is most effective in exciting luminescence. Less efficient excitation occurs to 2200A.

It is concluded that a transition to an excited atomic state of the activator, rather than an electron transfer process, is responsible for the first absorption peaks in MnF2 and ZnF2:Mn.
Infra-Red Absorption Spectra at Low Temperatures
Authors: Walsh A. , Willis J. B.
Published: January 2005

An infra-red absorption cell for use at low temperatures is described. Use of the cell requires no modification of the optical system of the spectrometer. Spectra of several organic substances which are solid or liquid at room temperature have been recorded and the changes in spectrum on cooling to −170°C observed. The results show that there is no systematic narrowing of infra-red absorption bands on cooling from room temperature to −170°C. The narrowing reported by previous workers is not of general occurrence but is restricted to certain compounds which undergo a change of state in this temperature range.
Surfaces of Solids XIX. Molecular Interaction between Metals and Hydrocarbons
Authors: Harkins William D. , Loeser E. H.
Published: January 2005

The energy of interaction between a hydrocarbon and a metal increases rapidly in the order copper, silver, lead, and iron (Fig. 8), and with the value of P/P0. Tables Ia and Ib give the values of the energy at p/p0=1; i.e., at saturation of the vapor. The values of the work of adhesion WA at 25°C for the clean metals are copper 69, silver 77, lead 89, iron 93. For the oxide coated metals the values are only slightly higher (Table Ib). These increase with decrease of temperature. For n-hexane they are essentially the same at 0°C as for n-heptane at 25°C. Isotherms for n-heptane are given for both 25°C and 15°C. Figure 7 illustrates a common phenomenon: a first-order change at 0.02-mm Hg on clean silver.

The method in general use for calculation of the work of adhesion from the adhesion tension is absurd, since for the usual case in which the liquid wets the solid the work of adhesion is given as twice the free surface energy of the liquid. Thus this states that the nature of the solid has nothing to do with the work of adhesion. Unfortunately, all of the books on surface chemistry give this entirely fallacious method of calculation. On this account it is recommended that the use of adhesion tension should be abandoned, since it is one of the most prolific sources of error in Surface Science.
The Surface Tension of Liquid Metals and the Excess Binding Energy of Surface Atoms
Authors: Oriani R. A.
Published: January 2005

By assuming that the cohesive energy of a liquid metal can be expressed as the sum of the pairwise interaction energies of nearest neighbors, and by obtaining the number of effective nearest neighbors for atoms on the surface and in the interior from simple considerations, it is shown that the pairwise bonding energy of surface atoms is greater than that for atoms in the interior of liquid metals. With mercury as the sole exception, this excess bonding energy is a nearly constant 2 percent of the cohesive energy when the liquids are taken as close-packed, but greater variation of this proportion is obtained when the liquids are taken as solid-like in structure.
I. The Infra-Red Spectrum of Tetramethyl Lead and the Force Constants of M(CH3)4 Type Molecules
Authors: Sheline Raymond K. , Pitzer Kenneth S.
Published: January 2005

The infra-red absorption of tetramethyl lead has been measured in the region 2–23μ. A frequency assignment has been proposed. A partial normal coordinate analysis has been made using the fundamental frequencies of this investigation and the data of previous investigators of tetramethyl compounds. Thereby M — C valence-type force constants of all the Group IV tetramethyl derivatives and the analogous tetramethyl ammonium ion have been determined. These force constants are compared with those predicted by the rules of Badger and Gordy and the relationship between bond force constants and atomic parameters is briefly considered.
On the Fluctuation of Energy of Gases in the Bose-Fermi Quantum Statistics
Authors: Széll Koloman
Published: January 2005

The energy fluctuation of monatomic gases is calculated in the Bose-Fermi quantum statistics computing the mean values by the Bose and Fermi distribution functions and on the base of the entropy equation. The obtained results are compared with Fürth's calculations.
The Contribution of the Surface of the Specific Heat of Disperse Systems
Authors: Koppe H.
Published: January 2005

A theory of Brager and Schuchowitzky concerning the contribution of the surface of the specific heat is extended to the interfaces of binary systems.
The Approximate Rate of Exchange between Iodine Atoms and Molecules
Authors: Noyes Richard M. , Zimmerman Joseph
Published: January 2005

The rate constant for the exchange reaction of iodine atoms with iodine molecules in hexane at 25° has been estimated by an indirect method. The rate constant is approximately 1.3×10−13 (atom/ml)−1 sec.−1 or 8×1010 (mole/ml)−1 sec.−1. The energy of activation for the exchange is probably between 2 and 3 kilocalories.
The Mercury Photo-Sensitized Decomposition of Decane in the Liquid State
Authors: Phibbs M. K. , Darwent B. deB.
Published: January 2005

The decomposition of liquid decane photo-sensitized by dissolved mercury to λ2537 has been investigated between 0° and 134°C. The only important products are hydrogen and eicosanes. The initial act is probably the breaking of a C–H bond with the production of a hydrogen atom and a decyl radical. The decyl radicals recombine to form eicosanes without undergoing any detectable disproportionation to form decene and decane. The quantum yield of the production of hydrogen is about 0.10 at 0°C and increases to 0.45 at 134°C. The low quantum yield and its temperature dependence may be due to either an inefficient primary act or to recombination of hydrogen atoms and decyl radicals in liquid ``cages.''
The Asymmetric Rotor. VIII. The Hydrogen Sulfide Band at 6300 Cm−1
Authors: Allen Harry C. , Cross Paul C. , Wilson M. K.
Published: January 2005

The absorption spectrum of hydrogen sulfide in the region 6140 to 6420 cm−1 has been measured and the rotational fine structure analyzed through the use of published energy tables for the rigid rotor and a classical correction for centrifugal distortion. The excited state constants giving the best fit are A* = 10.39, B* = 8.90, and C* = 4.55 cm−1. The band center is located at 6289.5 cm−1.

The value of IC—IA—IB and the strong Q branch, indicating the non-vanishing electric moment derivative to be along the least inertial axis, show the upper vibrational level to be the (111) state.
Markoff Chains and Excluded Volume Effect in Polymer Chains
Authors: Montroll Elliott W.
Published: January 2005

In most of the theoretical work on statistical properties of polymer chains one includes (for mathematical simplicity) configurations which correspond to several monomers located at the same point. Here a mathematical method based on the theory of Markoff chains is used to eliminate short-range excluded volume effects in polymer chains formed on space lattices. Those aspects of the theory of Markoff chains which are important in this problem are briefly reviewed.

If as(s=j—k) is the correlation coefficient between the x component of the position of the jth monomer and that of the kth, then the root-mean-square distance between ends of a chain of degree of polymerization N is proportional to N½ (as N→∞) provided that as→0 more rapidly than A/s1+ε (as s→∞). Here A is a constant and ε is an arbitrarily small positive constant. This condition is satisfied in a chain in which any group of n0 successive monomers do not overlap each other or any monomers in neighboring groups of n0 provided n0≪N.

A detailed analysis of a polymer chain on a square lattice is given.
The Effects of Saturation with Microwaves on Thermal Properties
Authors: Griffing Virginia
Published: January 2005

It is assumed that saturation with microwave is observed because the two states, J and J+1, are statistically filled. Under these conditions the change in the rotational partition function is temperature dependent so that thermal properties of the system could be changed. The changes in the rotational specific heat are calculated for a linear molecule. This effect would produce a change in the specific heat of HCN of about 2 parts in 10,000 if the J=0→1 transition is saturated.
Tetragonal Antiprism Bond Orbitals
Authors: Duffey George H.
Published: January 2005

A set of eight equivalent bond orbitals of tetragonal antiprism symmetry is considered. The orbitals are of type snp3d5−n. The acute angle between the fourfold axis and the maximum in a bond function varies from 66° 49′ to 44° 33′ as the parameter α is varied. The strongest orbitals (with a strength equal to 2.988) arise when n equals 0.9047. These are only slightly stronger than those with n equal to one.
Chemical Kinetics of Bromine Following Neutron Capture
Authors: Williams Russell R. , Hamill William H.
Published: January 2005

The kinetic behavior of Br80 produced by neutron capture has been investigated in gaseous systems containing ethyl bromide, ethylene and hydrogen bromide. The distribution of active bromine between organic and inorganic form has been shown to be principally dependent on the ethylene pressure. A kinetic scheme, incorporating a ``hot atom'' reaction, is postulated and shown to be in agreement with the experimental facts. Additional experimental tests of critical points in the proposed scheme have been successful.
Variations in Absorption Spectrum of the Nitrate Group
Authors: Katzin Leonard I.
Published: January 2005

Lithium, magnesium, calcium, aluminum, manganous, cobaltous, nickelous, cupric, zinc, cadmium and thorium nitrates, and nitric acid, show an absorption in tertiary butyl alcohol solution which is different from that of dilute aqueous solutions of nitrates. The most marked effects are shown by the transition elements with partially completed d shells. The variety of the spectra indicate that a single change, such as the rearrangement of the normally planar nitrate ion into a pyramidal form, cannot account for nitrate spectrum changes.
The Relative Rates of the Reactions of Hydrogen Iodide and Deuterium Iodide with Methyl Iodide
Authors: Newton Thomas W.
Published: January 2005

The relative rates of the reactions of hydrogen iodide and deuterium iodide with methyl iodide were studied by a competitive method at 310° and 250°C. The analysis of hydrogen-deuterium mixtures was accomplished by means of a simple viscometer with an accuracy of 0.5 percent. It was found that hydrogen iodide reacts about 1.4 times as fast as deuterium iodide at both temperatures. These results are discussed in terms of Eyring's theory of absolute reaction rates and a simple model.
Self-Quenching and Sensitization of Fluorescence of Chlorophyll Solutions
Authors: Watson W. F. , Livingston Robert
Published: January 2005

The intensity of fluorescence of solutions of chlorophyll (either a or b) is sensibly independent of concentration, for values less than 2×10−3m. At higher concentrations, the fluorescence decreases with increasing concentration, conforming to the empirical equation, If,max/If=1+4300m2. The absorption spectrum of chlorophyll a is the same at 0.02m as it is for very dilute solutions. These results, as well as the observed temperature coefficient of the fluorescent intensity, indicate that the self-quenching of chlorophyll solutions is not due to the formation of non-fluorescent dimers nor to collisions of the second kind, but is very probably related to the resonance exchange of excitation (16, 17) between an excited and normal chlorophyll molecule.

Measurements of the fluorescence intensity of solutions containing mixtures of chlorophylls a and b indicate that chlorophyll b can sensitize the fluorescence of chlorophyll a, and that the fluorescence of chlorophyll b is more strongly quenched by a than it is by itself.
Thermodynamics and the Canonical Distribution
Authors: Eisenschitz R.
Published: January 2005

The hypothesis is made that the thermodynamic energy and the virtual work done in a reversible process are statistical averages of the corresponding mechanical quantities and that the averages comply with the laws of thermodynamics. These assumptions are shown to be sufficient for deriving the canonical distribution so far as the distribution on the energy scale is concerned.
The Study of Restricted Rotation by Gas Diffraction
Authors: Karle J. , Hauptman H.
Published: January 2005

A probability function has been derived which characterizes the variation of an interatomic distance affected by the restricted internal rotation of a molecule. The probability function takes into account the general vibration of the molecular frame in addition to the internal libration. The theory and practice are developed for determining the values of the parameters in the probability function directly from experiment. In addition the contribution from this probability distribution to the intensity of electron scattering is derived.
Effects of Dielectric Saturation upon the Diffuse Double Layer and the Free Energy of Hydration of Ions
Authors: Grahame David C.
Published: January 2005

The theory of the diffuse double layer is developed for the case of a dielectric of variable dielectric constant. Using experimental data by Malsch, calculations have been made of the properties of the diffuse double layer. It is found that those properties which are experimentally significant are almost unaffected by the onset of dielectric saturation. The Born equation for the free energy of hydration of ions is elaborated to include the effects of dielectric saturation, and it is found that these effects are negligible in the case of the alkali halide ions.
Low Frequency Dispersion in Ionic Crystals Containing Foreign Ions
Authors: Breckenridge R. G.
Published: January 2005

The anomalous electrical response at low frequencies previously observed in pure ionic crystals has been studied in ionic crystals containing foreign ions. Measurements of the dielectric loss at one kc as a function of temperature have been made on four salts with a variety of foreign ions at several concentrations. A number of loss maxima were observed which depended in height on the concentration of the foreign ion and the heat treatment of the crystal; and, in their position on the temperature scale on the nature of the salt and foreign ion. An interpretation of the results in terms of defect pairs of various types is presented.
Periodicity of Some Molecular Properties of Diatomic Hydrides
Authors: Sheline Raymond K.
Published: January 2005

The log of the force constants of the ground electronic states of all available diatomic hydrides is plotted versus the log of the atomic number of the element to which the hydrogens are bonded. A definite periodicity associated with the periods in the periodic table results. This periodicity is used to predict the force constants of ten diatomic hydrides which have as yet not been investigated. A plot of hydride interatomic distance versus the atomic number of the ``united atom'' shows a similar periodicity and strong shell structure and allows the prediction of 13 new interatomic distances for hydrides. These data are interpreted as evidence for the ``united atom'' model for hydrides. Finally plots of the low lying atomic energy states for atoms suggest that the seemingly inconsistent d shell periodicity may be the result of the mixing of energy states and hence a different type of hybridization trend in the d shell.
Magnetic Susceptibilities of Some Ions. Part I. A Study of the Alkaline Earth Salts of Organic Acids
Authors: Prasad Mata , Kanekar C. R. , Walvekar S. P. , Khanolkar D. D.
Published: January 2005

A linear relation between the molar susceptibility (χm) and the number of electrons in the cation has been established for the organic salts of (i) Mg, Zn, and Cd, and (ii) Ca, Sr, and Ba, containing a common anion. This relation has been successfully used to evaluate (a) the susceptibilities of anions in combination with cations of these two subgroups and (b) the susceptibilities of the cations themselves. It has been pointed out that this method of evaluation of ionic susceptibilities enables one to predict unknown cases with considerable accuracy.
Internal Motion and Molecular Structure Studies by Electron Diffraction. II. Interpretation and Method
Authors: Karle J. , Karle I. L.
Published: January 2005

The application of a recently developed objective procedure to the analysis of electron diffraction photographs from more complex molecules is discussed in terms of the further development of the details of some of the theoretical and experimental aspects of the procedure. The topics discussed are the physical significance of measured vibrational amplitudes, the method for drawing a background line, the calibration of photographic plates, and the computation of intensity curves by means of IBM machines.
The Experimental Determination of the Thickness of a Shock Front in a Gas
Authors: Cowan George R. , Hornig Donald F.
Published: January 2005

Equations are developed from which the density profile of a shock front may be calculated from a knowledge of its reflectivity as a function of wave-length and angle of incidence. The reflectivities of shock fronts of shock pressure ratio p2/p1=1.71 have been measured in nitrogen at initial pressure, p1, equal to 85, 68, and 42 lb./in.2. From the change of reflectivity with wave-length, the thickness of the fronts was found to be 1.8×10−5 cm, 2.0×10−5 cm, and 3.2×10−5 cm with an accuracy of twenty-five percent. An independent but less accurate check was provided by the change of reflectivity with initial pressure, yielding a thickness of 1.5×10−5 cm for p1=85 lb./in.2. The weighted mean value, 1.7×10−5 cm, for p1=85 lb./in.2 is significantly greater than that calculated from the theory of Thomas, 1.0×10−5 cm.
The Vibrational Spectra and Structure of Inorganic Molecules. II. Sulfur S8, Sulfur Chloride S2Cl2, Phosphorous P4
Authors: Bernstein H. J. , Powling J.
Published: January 2005

The infra-red spectra from 2–25μ have been obtained for S8 as solid and in CS2 solution; for S2Cl2 as liquid and in CS2 solution; and for P4 in CS2 solution. A satisfactory assignment of the Raman and infra-red spectrum of S8 has been made on the basis of D4d symmetry. The spectrum and valence force calculations are consistent with the C2 structure for S2Cl2, and together with the electron diffraction data exclude the C2v form. The vibrational spectrum of P4 is interpreted unequivocally on the basis of the tetrahedral structure (Td).
Thermal Diffusion in the System Methane-Xenon
Authors: Tung L. H. , Drickamer H. G.
Published: January 2005

Thermal diffusion measurements have been carried out for the system methane-xenon at a temperature 100°C above the critical using two thermal diffusion columns. The results confirm the column theory presented in an earlier paper, and are consistent with the results obtained on the system ethane-xenon.
X-Ray Diffraction by Solid Soaps
Authors: Stosick A. J.
Published: January 2005

Arguments are presented to show that x-ray diagrams obtained by using the powder technique for common soap samples can be interpreted in terms of two kinds of disordering. The first kind of disorder, a stacking disorder of micellar layers, makes the layers optically independent for certain diffraction maxima so that continuous diffraction bands arise rather than discrete maxima. A second kind of disorder within a layer in which long chain ions are randomly oriented with respect to rotation about their long axes causes all but one set of bands to be weak. A consideration of these two disorders permits extensive unification of the results of x-ray diffraction experiments for poorly crystallized soaps. The use of such diffraction patterns for phase studies is subject to severe uncertainties.
Spectral Resemblances between Azulenes and Their Corresponding Six-Carbon Ring Isomers
Authors: Klevens H. B.
Published: January 2005

The spectra of odd-ring compounds, azulene, 1,2-benzazulene, 2-phenyl azulene, and indeno-azulene are compared with those of their corresponding regular isomers, naphthalene, phenanthrene, phenylnaphthalene, and benzfluorene in part from 1730 to 7500A. The five band systems found in the azulenes seem to correspond with respect to intensity, vibrational structure, and sequence to the five found in their corresponding isomers except that the former are shifted to lower frequencies. The lowest frequency band is shifted some 17,000 cm−1 to the red in the azulenes, which accounts for the color observed in these compounds, whereas the four transitions at higher frequencies are shifted about 8000 to 9000 cm−1 as compared with the corresponding regular isomers. Decreases in total oscillator strengths with non-linearity of these planar molecules as compared with the linear compounds (a type of C2v symmetry about the long axis) are noted as has previously been shown in the comparison of anthracene and phenanthrene, and tetracene and 1,2-benzanthracene and chrysene.
Molecular Orbitals for H3+
Authors: Walsh J. M. , Moore R. A. , Matsen F. A.
Published: January 2005

A somewhat more general concept of molecular orbitals than used heretofore is applied to H3+. It is shown to be superior to the Heitler-London approximation, but inferior to the HLSP-plus-ionic-terms treatment of Hirschfelder. Relations between the HLSP and molecular orbital approaches to wave functions are discussed.
Substituted Methanes. II. Vibrational Spectra and Calculated Thermodynamic Properties of Deuterotribromomethane
Authors: Ferigle Salvador M. , Cleveland Forrest F. , Boyer William M. , Bernstein Richard B.
Published: January 2005

Raman displacements, semiquantitative relative intensities, quantitative depolarization factors, and wave numbers and percent transmission for the infra-red bands in the region 400–5000 cm−1 have been obtained for CBr3D. Details about the measurement of the depolarization factors are given. Thermodynamic properties—heat content, free energy, heat capacity, and entropy—have been calculated from the spectroscopic and molecular structure data for eight temperatures from 298.16° to 1000°K.
Statistical Mechanics of Dilute Polymer Solutions. II
Authors: Flory P. J. , Krigbaum W. R.
Published: January 2005

New thermodynamic relationships applicable to dilute solutions of heterogeneous high polymers are derived. The function previously given to express the interaction between two polymer molecules of equal size is modified to include chemically similar polymer molecules differing in size. With the aid of this more general pair partition function the mutually excluded volume for a pair of polymer molecules is easily computed. The osmotic pressure for a dilute solution of a heterogeneous polymer may be expressed in virial form through the application of conventional methods for treating imperfect gases. The second virial coefficient in the series expansion for the osmotic pressure is readily obtained but it is necessary to resort to the hard sphere approximation for estimation of the third coefficient. The third coefficient is much larger than was indicated by earlier theories now known to be inapplicable to dilute solutions, and plots of π/c vs. c must be appreciably curved if the slope is great. Similar expressions are derived for Hc/τ obtained from light scattering measurements.

For a dilute solution of a homogeneous polymer the value of the second coefficient in either the osmotic pressure or light scattering expression is not entirely independent of molecular weight, as predicted by earlier theories. The effect of heterogeneity on the second coefficient in these expressions is investigated for the special case of a dilute solution of two polymers differing only in molecular weight, from which it follows that the ratio of the second coefficients in the light scattering and osmotic pressure relations may be either equal to two, or greater or less than that value, depending on the heterogeneity ratio.

At the critical miscibility temperature Θ, the excluded volume vanishes and the present treatment becomes identical with previous theories. The latter should be valid for all concentrations only at the unique temperature T=Θ. The primary parameters κ1 and ψ1 governing the heat and entropy of interaction between polymer segments and solvent molecules are difficult to evaluate solely from thermodynamic measurements on dilute solutions except at T=Θ.
The Recombination of Iodine Atoms in Solution
Authors: Noyes Richard M.
Published: January 2005

A simple theory involving jumps between lattice sites has been used to treat the recombination of atoms produced in solution by photo-chemical dissociation. The results have been applied to experimental data obtained previously on the photo-dissociation of iodine in hexane at 25°C.

The treatment indicates that if a pair of atoms is separated by one molecular diameter in the dissociation process, then the probability is 0.40 to 0.50 that these atoms will recombine by diffusion in a period of 10−6 second or less. The experimental data for light of 436 mμ indicate that if some of the atoms undergo ``primary recombination'' without escaping from the cage of solvent molecules in which they are formed, then a larger number of atoms must become separated by two or more molecular diameters as a result of the photo-dissociation.

For light of 578 mμ the data and calculations indicate that about 35 percent of the atoms become completely separated and ultimately combine with atoms from other molecules, about 30 percent become separated by a molecular diameter but recombine rapidly by diffusion, and about 35 percent either fail to undergo predissociation or recombine without escaping from the cage of solvent molecules in which they are formed.
Quantum-Mechanical Resonance between Identical Molecules
Authors: Jehle Herbert
Published: January 2005

The process of synapsis of chromosomes in meiosis and the process of self-duplication of genes in mitosis reveal the existence of a highly specific attraction between pairs of large molecules provided they are identical and rigid. We shall investigate the quantum-mechanical behavior of a pair of molecules which interact with each other by means of vibrating electric dipole moments which are thermally excited. Because of resonance between equal frequency modes or commensurable modes of vibration, each one of the molecules shows a statistical preference for certain phase relations between these modes (using the language of the correspondence principle). A pair of molecules interacts strongly if it is an identical pair because of these phase preferences.
X-Ray Dose Determinations with Chloral Hydrate
Authors: Andrews Howard L. , Shore Parkhurst A.
Published: January 2005

The chemical effects of x-rays on aqueous solutions of chloral hydrate (CCl3CH(OH)2) have been studied. The primary reaction is the conversion of the organic halogen to HCl and the resulting changes in electrical conductance have been used for the determination of x-ray dosage. The change in conductance is linear with x-ray dose and independent of dose-rate over a wide range. This compound has been used to determine the total output and depth-dose curves from a high intensity beryllium window x-ray tube.
Molecular Orbital Calculations on Porphine and Tetrahydroporphine
Authors: Longuet-Higgins H. C. , Rector C. W. , Platt J. R.
Published: January 2005

The first three electronic transitions of porphine and the first five electronic transitions of tetrahydroporphine are predicted as simple one-electron LCAO molecular orbital transitions (with overlap included). The electron densities and bond orders in the ground states are also computed. The observed levels are tentatively assigned to the predicted levels with the help of comparisons with spectra of other aza-amine derivatives of conjugated hydrocarbons. Probable degeneracies and polarizations are determined. The blue shift and loss of intensity of the first electronic transition, in going from tetrahydroporphine to the larger conjugated system of porphine, is typical of the change from a ``long-field'' to a ``round-field'' molecule (see previous paper) and is shown to occur in several other ``long-field'' systems when additional conjugated atoms are added at the side of the system.
Optical Rotatory Power of Benzoin
Authors: Kwoh Ting-Chang , Eyring Henry
Published: January 2005

The procedure for calculating the optical rotatory power due to one electron transitions in an asymmetric field is simplified and systematized. The necessary transformations of functions to elliptic coordinates is carried through explicitly and the method of calculation is outlined. Extensive tables and graphs were prepared which greatly simplify the calculations. The method is applied to benzoin and the results are compared with the published experimental results which vary characteristically with the solvent. Representing transitions by eigenfunctions involving changes in more than one electron is the next natural but difficult improvement in this type of treatment.
Kinetics of OH Radicals from Flame Emission Spectra. I. Vibrational Transition Probabilities, Intensities, and Equilibrium in the 2Σ+—2Π Transition
Authors: Shuler K. E.
Published: January 2005

The relative vibrational transition probabilities for the first four vibrational levels of the 2Σ+—2Π system of OH have been calculated. Anharmonic wave functions derivable from the Morse potential function were used and the electronic dipole moment matrix component appearing in this formulation has been evaluated. Relative intensities for the various bands have been calculated under the assumption of thermal equilibrium. Comparison of these calculated values with the data of Dieke and Crosswhite on the oxy-acetylene flame at one atmosphere indicate vibrational equilibrium with a vibrational temperature of ∼3750°K in the outer cone which compares with a rotational temperatue of ∼3000°K. The relationship between vibrational and rotational equilibrium for this case is discussed briefly.
An X-Ray Investigation of the Shapes and Hydrations of Several Protein Molecules in Solution
Authors: Ritland H. N. , Kaesberg Paul , Beeman W. W.
Published: January 2005

The x-ray scattering curves of five proteins in solution have been measured at small angles. The radii of gyration of the protein molecules are determined from the scattering curves. These data together with the known molecular weights, densities, and frictional ratios are used to estimate the axial ratios and hydrations of the molecules. Some possibilities and limitations of the method are pointed out.
The Electroplating of Metallic Selenium
Authors: von Hippel A. , Bloom M. C.
Published: January 2005

The electroplating of metallic selenium from acid baths has been achieved and reduced to practice. The paper discusses in succession the polymorphism of selenium; selenium ions in selenious acid solution; cathodic deposition as the amorphous and metallic phase; the nucleation characteristic and crystal growth of the metallic modification; the properties of various types of plating baths; a selenium-carbon anode for the stabilization of the bath composition; and finally a number of influences affecting the crystallization habit of the deposit. The current density of 200 amp./ft.2 attainable in a well-balanced plating bath compares favorably with standard baths for true metals.
On Lattice Theories of the Liquid State
Authors: Peek H. Milton , Hill Terrell L.
Published: January 2005

The Lennard-Jones and Devonshire theory of the liquid state has been modified by introduction of the quasi-chemical method to allow for both holes in the liquid and an expandable lattice. The essential step is to minimize the free energy with respect to a lattice expansion parameter. On the whole, critical constants obtained in this way are in appreciably better agreement with experiment than those of the Lennard-Jones and Devonshire theory. however, the equilibrium number of holes turns out to be much too small.
Paramagnetic Susceptibilities of Solid Solutions of MnF2 and ZnF2
Authors: Corliss Lester , Delabarre Yvette , Elliott Norman
Published: January 2005

The paramagnetic susceptibilities of solid solutions of MnF2 and ZnF2 have been measured as a function of temperature. The Curie-Weiss law X=C/T+Δ is obeyed by all the solutions examined over the temperature range 76°—295°K. The constant Δ was found to be a linear function of the mole fraction of MnF2. This behavior is consistent with the assumption that the magnetic interaction energy associated with a given ion is proportional to the number of its paramagnetic neighbors.
On the Mass Spectra of Propanes and Butanes Containing C13
Authors: Stevenson D. P.
Published: January 2005

A mass spectrometric method of analysis of C13 enriched samples of paraffins, both with respect to the gross concentrations of —C013, —C113, and —C213 species and the concentration of C13 isomeric species is described, with particular reference to samples of propane−1—C13, propane−2—C13, n-butane−1—C13, n-butane−2—C13, i-butane−1—C13, and i-butane−2—C13 prepared in connection with tracer studies of certain paraffin reactions. With respect to the analysis, the necessary a priori assumptions and a posteriori checks of the assumptions are described.

The relative intensities of certain C1 and C2 ion fragments characteristic of the 75-ev mass spectra of propane—C013, propane−1—C113, and propane−2—C113, and certain C1, C2, and C3 ion fragments characteristic of the 75-ev mass spectra of the six similar butanes are tabulated. The isotope effects on the dissociation probabilities of certain states of the propane and butane molecule-ions are discussed in terms of a simple qualitative model.

Of particular interest is the observation that in the states of C3H8+ which dissociate into C1 ion fragments, and the states of i-C4H10+ which dissociate into C1 or C2 ion fragments the carbon atoms become essentially indistinguishable, and the mass spectra of the isomeric C113 compounds become essentially identical as far as the relative intensities of these fragments are concerned.
Kinetics of the Rapid Gas Phase Reaction between NO, NO2, and H2O
Authors: Wayne Lowell G. , Yost Don M.
Published: January 2005

Using the absorption of light by nitrogen dioxide as a measure of its concentration, the rate of the gas phase reaction NO+NO2+H2O=2HNO2 was measured over a fivefold range of water vapor and nitrogen dioxide concentrations, with nitric oxide greatly in excess. Changes in light intensity were detected by means of an electron-multiplier photo-tube and recorded by photographing the screen of a cathode-ray oscilloscope. Half-times as short as 0.014 sec were observed. The reaction rate was found to depend more strongly upon the concentration of water vapor than upon that of nitrogen dioxide and to be kinetically consistent with a mechanism involving termolecular collisions.

The equilibrium constant of the reaction has been calculated and its order of magnitude experimentally confirmed, and a lower limit has been fixed for the rate of dissociation of nitrogen sesquioxide.
The Free Volume for Rigid Sphere Molecules
Authors: Buehler R. J. , Wentorf R. H. , Hirschfelder J. O. , Curtiss C. F.
Published: January 2005

The free volume is calculated for non-interacting rigid sphere molecules taking into account the exact geometry imposed by the face-centered cubic packing. The size and shape are quite different from that of the inscribed spheres which correspond to the Lennard-Jones and Devonshire approximation. At high densities the equation of state obtained from the exact treatment agrees well with the Eyring or Lennard-Jones and Devonshire equation. When the specific volume is greater than twice the cube of the collision diameters, the molecules are no longer confined to cages formed by neighboring molecules. At these low densities the free volume concept is ambiguous. The equation of state depends upon the shape and orientation of the cells with respect to the lattice positions of the molecules. A particular choice is considered which leads to an equation of state that at low densities is accurate through the second virial coefficient. There are other shapes and orientations of the cells which would lead to other equations of state having this same property.
The Recombination of Methyl Radicals
Authors: Miller D. M. , Steacie E. W. R.
Published: January 2005

An investigation has been made of the rate at room temperature of recombination of methyl radicals by photolysing mercury dimethyl in the presence of nitric oxide and comparing the rates of the reactions CH3+CH3→C2H6and CH3+NO→CH3NO.It is concluded that k1½/k2 is approximately equal to 3×10−5. If Forsyth's value for k2 is accepted, this leads to a collision yield for methyl radical recombination of 4.4×10−5.
The Rate Constant of Ethane Formation from Methyl Radicals
Authors: Gomer Robert , Kistiakowsky G. B.
Published: January 2005

The rotating sector technique has been applied to a determination of the rate constant of methyl radical recombination in the photo-decompositions of acetone and mercury dimethyl, using the small but accurately measurable rate of methane formation as a measure of methyl steady-state concentration. The resulting value of the recombination rate constant is 4.5×1013 (moles/cc)−1 sec−1, with an activation energy of E=0±700 cal regardless of radical source. The determination of this constant permits the evaluation of the rate constants for several other reactions of methyl radicals. It is found that hydrogen abstractions have steric factors of the order of 10−4.
Hexacovalent Bond Orbitals. IV
Authors: Duffey George H.
Published: January 2005

Six equivalent bond orbitals of D3 symmetry are set up. Application of the orthogonality and normalization conditions leads to solutions when the composition is snp1+2md5−n−2m. The coefficients in the angular wave functions are expressed in terms of four parameters. The trigonal prism orbitals and the trigonal antiprism orbitals previously discussed can be obtained on assigning values to some of the parameters.
Analysis of the 774 cm−1 (ν6) Absorption Band of F2CO
Authors: Nielsen Alvin H.
Published: January 2005

The absorption band at 774 cm−1 in F2CO, which has the appearance of a parallel-type band for a symmetric top, has been resolved into its rotational fine structure with a grating. An analysis of the band has been performed and reveals the band center to be 774.40 cm−1 and the average B″ for the two close moments of inertia to be 0.3925 cm−1. The moments of inertia in the upper and lower states are very nearly identical and the coefficient of the (v6+½)2 term in the energy is estimated to be 1.4 cm−1.
Self-Diffusion in CO2 at Moderate Pressures
Authors: Timmerhaus K. D. , Drickamer H. G.
Published: January 2005

Diffusion data are presented for the system CO2–C14O2 over a pressure range from 0.50 to 28.1 atmospheres. Within the accuracy of the data, agreement is obtained with the diffusion theory of Enskog and Chapman, using the Lennard-Jones model.
The Prediction of Isothermal Compressibilities by Light Scattering
Authors: Blosser L. G. , Drickamer H. G.
Published: January 2005

Light transmission measurements have been made on ethane, and on a mixture of methane and propane near the critical point, using the 4050, 4360, and 5460A lines from a mercury lamp. Isothermal compressibilities have been calculated. This appears to be a considerably more accurate method than the use of p-v-t data for the prediction of compressibilities near the critical point.
A Mobile Electron Model for Aromatic Molecules
Authors: Rüdenberg Klaus , Parr Robert G.
Published: January 2005

A three-dimensional mobile electron model for unsaturation electrons in aromatic molecules is described which allows leakage of electrons across rings and takes aromatic atoms explicitly into account. The model contains the free electron model as a limiting case. Applications to the spectra of cata-condensed hydrocarbons are discussed.
Second-Order Transitions and Critical Points
Authors: Price P. J.
Published: January 2005

The thermodynamic formulas, of the Ehrenfest type, applicable to an isolated second-order point on a first-order equilibrium line (e.g., a critical point) are discussed.
The Coulomb Energy of Complex Crystals
Authors: Fisher Edward
Published: January 2005

A method of computing Madelung constants is adapted to the problem of determining the electrostatic energy of complex ionic crystals.
Optical Absorption and Photoconductivity of Amorphous and Hexagonal Selenium
Authors: Gilleo M. A.
Published: January 2005

In amorphous and hexagonal selenium optical absorption and photoconductivity were studied in their dependence on temperature. The absorption edge shifts for amorphous selenium toward shorter wavelengths with decreasing temperature. For a temperature change from 300° to 90°K and a layer thickness of 98μ, for example, a shift from 6600 to 6100A is observed at an optical density of 3; for higher densities (shorter wavelengths) the shift is smaller. It can be shown that this shift is related to the thermal excitation of vibrational levels. At higher temperatures the population of the higher vibration levels increases and the separation of these from the excited state diminishes.

At low temperature (ca 90°K) photoconductivity is observed only after the light quanta exceed 2.5 ev and the absorption coefficient has reached 105 cm−1. Increase of temperature brings about a shift of the photoconductive threshold toward longer wavelengths, paralleling the absorption-edge shift. The absorption coefficient has been followed over the wavelength range 6900 to 2100A; its values at the end points of this range are 1.6×102 and 5.2×105 cm−1, respectively; there is a slight maximum at 2600A where the absorption coefficient reaches 5.6×105 cm−1.

The transformation of amorphous into hexagonal selenium by heat brings about an increase of the optical absorption in the 5000 to 7200A region and the appearance of a distinct hump in the absorption edge at 5200A. Decrease of temperature sharpens the hump and causes a decrease of absorption at all wavelengths in the 4000 to 7200A range except in the vicinity of the hump. In hexagonal selenium photoconductivity is observed at wavelengths as long as 7500A for films 0.5μ thick. A peak in the photoresponse is found where the optical density of these films reaches ca 1 (10 percent transmission). It can be shown that this behavior is to be expected for a bimolecular law of recombination of electrons and holes when their inhomogeneous distribution is taken into account. With decreasing temperature the peak response shifts consequently toward shorter wavelengths with the absorption edge.
Note on the Temperature-Independent Factors of Elementary Reactions
Authors: Steacie E. W. R. , Szwarc M.
Published: January 2005

The ``temperature-independent'' factors of bimolecular and free radical reactions are discussed.
Quantitative Line-Width Measurements in the Infrared. I. Carbon Monoxide Pressurized with Infrared-Inactive Gases
Authors: Penner S. S. , Weber D.
Published: January 2005

Quantitative infrared-intensity measurements on CO pressurized with gases such as H2, He, and A have been carried out at room temperature. For pressures up to 100 psia the experimental absorption measurements are correlated quantitatively by the use of theoretical relations derivable from the dispersion formula. Thus, for a fixed value of the total pressure, the observed absorption is a linear function of the square root of the optical density. Similarly, at constant optical density, the absorption is a linear function of the square root of the total pressure. Using Elsasser's treatment for equally spaced and equally intense rotational lines, lower limits have been determined for the rotational half-widths of CO broadened by various infrared-inert gases.

The determination of rotational half-widths from spectroscopic measurements can be refined by allowing for the variation of integrated absorption per rotational line from one line to another in a given vibration-rotation band. By carrying out numerical calculations, with the rotational half-width treated as a variable parameter, a direct comparison between calculated and observed infrared absorption can be used to determine the rotational half-width δ0 for pressures which are small enough to justify a treatment for nonover-lapping rotational lines. In this manner it was found that (δF)H2 = 0.077 cm−1 atmos−1, (δF)A = 0.040 cm−1 atmos−1, (δO)H2 = 0.063 cm−1 atmos−1. Here the subscripts F and O denote measurements on the fundamental and the first overtone, respectively. The subscripts H2 and A identify the broadening agent used for study.
Thermodynamic Data and Some Notes on the Nature of Adsorbed Helium
Authors: Mastrangelo S. V. R. , Aston J. G.
Published: January 2005

The adsorption isotherms and heat capacities of helium on TiO2 in the rutile crystalline form have been obtained. On the basis of the observed shift in lambda-point with coverage, the behavior of the adsorbed phase has been correlated with the behavior of the bulk liquid and solid under pressure.
Rotational Temperatures of OH in Methane-Air Flames
Authors: Broida Herbert P.
Published: January 2005

Rotational line intensity distributions in emission and absorption of the 0↔0 band of the 2Σ↔2Π transition of OH have been measured in methane-air flames. The number of electronically excited OH radicals in the inner cone greatly exceeds the equilibrium concentration, and the intensity distribution of the high quantum numbers gives a temperature of 5200°K. However, OH radicals in the ground state were in thermal equilibrium at 2000°K. A break in the intensity distribution indicates a two stage combustion reaction. It is suggested that the excessive amount of excited OH is due to its formation in the intermediate reaction steps. Line reversal temperatures using Na, Hg, and OH have been measured in the same flame for purposes of comparison. Also the rotational temperature of excited OH in a methane-oxygen flame was measured.
The Ultraviolet Absorption Spectra of Gaseous Diazomethane and Diazoethane. Evidence for the Existence of Ethylidine Radicals in Diazoethane Photolysis
Authors: Brinton R. K. , Volman D. H.
Published: January 2005

The absorption of gaseous diazoethane begins at about 5400A, increases to a broad maximum of ε=3.5 at 4500A and falls to a minimum of ε=0.15 at 3200A. At wavelengths shorter than 3000A a second region of rapidly increasing absorption is found. The absorption curve of diazomethane is similar in general shape to this curve but shifted somewhat toward shorter wavelengths. The absorption of diazoethane is continuous over its entire region while in the visible region diazomethane shows a number of broad and very diffuse bands from about 4300A to 3200A which probably overlie a continuum. The presence of 2-butene in the photolysis products of diazoethane is explained by the combination of ethylidine radicals formed by the primary photochemical process CH3CHN2+hν→CH3CH+N2.