Computer simulation of the carbon diffusivity in austenite

Tracer carbon diffusion in austenite is formulated in terms of a f.c.c. lattice gas model in which carbon interstitials repel at the distance of nearest neighbors. A Monte Carlo method is used to calculate the tracer carbon diffusivity as a function of composition and interaction energy. The computed diffusivities are discussed in relation to the experimentally determined diffusivities and the results of a model investigated by Parris and McLellan.     

Strict convexity of the pressure: A note on a paper of R. B. Griffiths and D. Ruelle

Strict convexity of the pressure of a quantum lattice gas is demonstrated in [1] with the help of a trace condition. An interpretation of that condition is given, and, simultaneously, an extension of the result of [1]. In particular, it is shown that the pressure is a continuous function of the lattice gas density.On leave of absence from the Institut für Theoretische Physik, Universität Göttingen, Fed. Rep. of Germany.     

The influence of water vapour and temperature on depletion of carbon monoxide in D.C. corona discharge

The plasmochemical and/or electrocatalytical reactions of carbon monoxide with water vapour were studied. Dc corona discharge of both polarities at room temperature and temperatures enhanced up to 70°C was applied at pressures close to atmospheric. The reaction products were analysed by IR absorption spectrometry. The main products in the gas phase were CO₂ and CH₄. The reactions are influenced by the formation of a catalytically active surface layer on electrodes. The composition of this layer depends on the polarity of electrode.     

B.R.S. algebras. Analysis of the consistency equations in gauge theory

We compute all possible anomalous terms in quantum gauge theory in the natural class of polynomials of differential forms. By using the appropriate cohomological and algebraic methods, we do it for all dimensions of spacetime and all structure groups with reductive Lie algebras.     

Quasi-free states of the C.C.R.—Algebra and Bogoliubov transformations

We give a complete characterization of quasi-free states (generalized free states) of the C.C.R. algebra. We prove that the pure quasi-free states areall Fock states and that any two Fock states are related through a symplectic automorphism (Bogoliubov transformation). We make an explicit construction of these representations which correspond to primary quasi-free states.Work under contract D.G.R.S.T.Attaché de Recherches au C.N.R.S. This work is part of a Thèse de Doctorat d'Etat presented to the Faculté des Sciences de Marseille in May 1968, under the number A.O.2.323.Aangesteld Navorser van het Belgisch N.F.W.O. On leave from University of Louvain (Belgium).     

Interpretation of S-state ion E.P.R. spectra

Although a considerable body of data exists on the parametrization of the ground-state splittings of S-state ions in crystals, relatively little progress has been made in obtaining a quantitative understanding of the mechanisms which determine these parameters. In the course of summarizing our present understanding, we emphasize the need for making planned experiments explicitly aimed at testing theoretical models, such as those proposed in this article. The variable frequency E.P.R. technique is described in some detail, as it has proved to be particularly useful in this respect.     

Spectrophotometric and E.P.R. study of TCNE charge-transfer complexes

Liquid state charge-transfer complexes formed from the strong acceptor tetracyanoethylene (TCNE) and four donors of like donor properties are studied by spectrophotometric and E.P.R. techniques. If the enthalpy of complex formation ΔH is sufficiently large, the triplet state of the complex ³C will be appreciably populated thermally during complex formation. The E.P.R. signal of the TCNE anion promptly arises because of a dissociation of ³C, reaches a maximum, and then follows second-order decay kinetics. The higher the dielectric constant of the donor, the slower the decay rate. The initial intensity of the E.P.R. signal is proportional to the original TCNE concentration in the donor-solvent. Reversible photoinduced TCNE anions are formed by irradiating the complexes in the charge-transfer band. The relationship between the prompt and photoinduced E.P.R. signals is shown. Singlet-triplet separation energies are estimated.