Large Molecules in Carbon Vapor
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Measurement of Thermal Conductivity by Utilization of the Peltier Effect
A special technique for the accurate measurement of thermal conductivity is discussed. The method involves use of the Peltier heat to maintain a temperature gradient along the specimen. Straightforward measurements allow calculation of the absolute value of the thermoelectric power, thermal conductivity, and electrica…
Infrared spectra of crystalline polysaccharides. II. Native celluloses in the region from 640 to 1700 cm. −1
Abstract The infrared spectrum of uniplanarly oriented valonia cellulose film and the polarized infrared spectra of doubly oriented films of ramie and bacterial cellulose crystallites have been observed in the region from 640 to 1700 cm. −1 . The spectra have been interpreted with the assistance of band assignments in…
Einlagerungsverbindungen mit Alkali‐ und Erdalkalimetallen
Abstract Natrium, Kalium, Rubidium und Caesium können „stufenweise”︁ zwischen die Kohlenstoff‐Schichten des Graphit‐Gitters eingelagert werden. Aus Lösungen der Alkali‐ und höheren Erdalkalimetalle in flüssigem Ammoniak oder organischen Aminen bilden sich mit Graphit Ammoniakate oder Amine von Alkali‐ bzw. Erdalkali‐g…
Nitrogen, A Major Impurity in Common Type I Diamond
Common type I diamonds (as classified by Robertson et al.) have additional absorption in the infrared and ultraviolet. It is shown that the strongest absorption band in the infrared at 7.8 \ensuremath{\mu} and the ultraviolet absorption at 3065 A are proportional to the nitrogen concentration of the crystal. A corresp…
Origin of the Characteristic Electron Energy Losses in Aluminum
The characteristic electron energy loss spectrum of aluminum has been measured by analyzing the energy distribution of 760-, 1000-, 1520-, and 2020-ev electrons scattered by an evaporated specimen through 90\ifmmode^\circ\else\textdegree\fi{}. Twelve loss peaks were observed, made up of combinations of elementary 10.3…
Self-Consistent Field Approach to the Many-Electron Problem
The self-consistent field method in which a many-electron system is described by a time-dependent interaction of a single electron with a self-consistent electromagnetic field is shown to be equivalent for many purposes to the treatment given by Sawada and Brout. Starting with the correct many-electron Hamiltonian, it…
Recombination of Hydrogen Atoms on Various Transition Metal Surfaces
Abstract A study has been made of surface recombination of hydrogen atoms on various transition metals. Hydrogen atoms were produced in the electric discharge tube by use of an alternating current. In order to prevent the reacting gas from reaching the undesired part of the sample, a method which may be called “an eff…
Novel Perturbation Theory in Simple LCAO Treatment of Conjugated Molecules—Method of Perturbed Secular Determinant
A new method of perturbation theory is developed in the simple LCAO MO treatment of conjugated molecules. Several useful equations are derived, giving orbital energy, electron density, and bond order of the perturbed system.
Theoretical Depolymerization Kinetics in Polymers Having an Initial ``Most Probable'' Molecular Weight Distribution
The kinetic equations describing a general chain mechanism of depolymerization are solved at steady state for a polymer having an initial ``most probable'' molecular weight distribution. Chain scission initiation, end group initiation, depropagation, intermolecular chain transfer, and several types of termination are…
Factors Affecting the Non-Newtonian Viscosity of Rigid Particles1
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTFactors Affecting the Non-Newtonian Viscosity of Rigid Particles1Jen Tsi YangCite this: J. Am. Chem. Soc. 1959, 81, 15, 3902–3907Publication Date (Print):August 1, 1959Publication History Published online1 May 2002Published inissue 1 August 1959https://pubs.acs.org/doi/10.10…
Adsorption of polymers: Polystyrene on carbon
Abstract The adsorption of polystyrene from toluene solution on a carbon black has been studied at 25°C. under varying conditions of dryness. The isotherm for adsorption on the relatively dry carbon black exhibited a characteristic steep initial rise as a function of concentration and attained a saturation value. Larg…
High‐Temperature Mechanical Properties of Ceramic Materials: II, Beta‐Eucryptite
High stresses arise in sintered β‐eucryptite (Li 2 O. Al 2 O 2 ‐2SiO 2 ) during cooling from the firing temperature because of its extreme anisotropy of thermal expansion. These stresses cause extensive fracturing of the crystals, resulting in abnormally low mechanical property values at room temperature. During rehea…
Endgroups in tetrafluoroethylene polymers
Abstract The aqueous polymerization of tetrafluoroethylene initiated with ammonium persulfate in neutral or relatively weak acid solutions leads to polymer containing carboxyl end groups. The conversion of this endgroup to the sodium salt and its pyrolysis to the terminal olefin was followed, using infrared absorption…
Dislocation arrangements in aluminium deformed in tension or by fatigue
A comparison has been made of transmission electron microscope observations on polycrystalline aluminium deformed in tension or by fatigue. The dislocation distribution in aluminium deformed in tension, was studied as a function of stress. At stresses up to 3 kg mm−2 the distribution is extremely irregular; at higher…
Dislocation Dynamics at Low Temperatures
A model for low-temperature dislocation motion is developed using the concept of nucleation and growth of kinks in dislocations lying in Peierls potential troughs. The model is compared with existing experimental data.
Über den Leitungsmechanismus oxydischer Halbleiter bei hohen Temperaturen
Die Leitfähigkeit σ oxydisdier Halbleiter in Gegenwart von Sauerstoff wird bei hohen Temperaturen und nicht zu großen Störstellenkonzentrationen nicht allein durch die thermische Abspaltung von Trägern aus den Störstellen, sondern in entscheidendem Maße auch durch eine von der Temperatur T und vom Sauerstoffdruck P O2…
The genesis of carbonate apatites
A portion of the system Na/sub 3/PO/sub n4/-CaCO/sub 3/)-H/sub 2/0 was investigated at low temperatures. The formation of a carbonate apatite by phosphate replacement of calcite in alkaline solutions and the structural positions of the carbonate groups are discussed. Data indicate calcite replacement by low concentrat…
Elimination of the α1α2 Doublet in X-Ray Patterns
The characteristic K-radiation employed in x-ray diffraction consists of the bichromatic wavelengths λ(α1) and λ(α2). In practice the observed diffraction pattern is the superposition of the patterns of the two components. In many cases it is necessary to determine the diffraction pattern for a single wavelength. An a…
On the Dynamic Mechanical Properties of Polymers at Ultrasonic Frequencies in Relation to Their Glass Transition Phenomena
Complex Young's modulus, rigidity and bulk modulus are measured at 33 kc/s, 66 kc/s and 1 Mc/s for polystyrene, polymethyl methacrylate, polyvinyl acetate and phenol resin. In each material, the storage modulus-temperature curve has a discontinuity in the slope, irrespective of frequency and type of modulus, at the gl…