Concept

Loi d'Arrhenius

Publications associées (119)

Cooperative Jahn-Teller distortion in PrO2

We report neutron diffraction data on single crystal PrO2 which reveal a cooperative Jahn-Teller distortion at TD=120±2 K. Below this temperature an internal distortion of the oxygen sublattice causes the unit cell of the crystallographic structure to beco ...

2004

Mathematical modelling of the unsteady-state oxidation of nickel gauze catalysts

Albert Renken, Lioubov Kiwi

The oxidn. of nickel gauze catalysts by O2 was investigated by transient response methods. Qual. description of the exptl. transient responses have shown that the oxidn. of metallic nickel proceeds in two stages. The first step is a fast dissocn. of gaseou ...

2003

Activated Bond-Breaking Processes Preempt the Observation of a Sharp Glass-Glass Transition in Dense Short-Ranged Attractive Colloids

Giuseppe Foffi, Francesco Sciortino

We study—using molecular dynamics simulations—the temperature dependence of the dynamics in a dense short-ranged attractive colloidal glass to find evidence of the kinetic glass-glass transition predicted by the ideal mode coupling theory. According to the ...

2003

Gasification reactivity of charcoal with CO2. Part II: Metal catalysis as a function of conversion

Rudolf Paul Wilhelm Jozef Struis

The catalytic influence of major metal species found with waste wood (Na, K, Ca, Mg, Zn, Pb, Cu) was studied during the gasification of nitrate salt impregnated charcoal with CO2 at 800degreesC in the kinetically controlled regime. In contrast with literat ...

Elsevier2002

Hetero-Diels-Alder and cheletropic additions of sulfur dioxide to 1,2-dimethylidenecycloalkanes. Determination of thermochemical and kinetics parameters for reactions in solution and comparison with estimates from quantum calculations

Pierre Vogel

Below -60 and without catalyst, 1.2-dimethylidenecyclopentane (16), 1,2-dimethylidenecyclohexane (13), 1,2-dimethylidenecycloheptane (17), and 1,2-dimethylidenecyclooctane (18) add to sulfur dioxide in the hetero-Diels-Alder mode, giving the corresponding ...

2002

Palladium supported on filamentous active carbon as effective catalyst for liquid-phase hydrogenation of 2-butyne-1,4-diol to 2-butene-1,4-diol

Albert Renken, Lioubov Kiwi, Eric Joannet, Chrystèle Horny

Structured palladium catalysts suitable for three-phase reactions have been developed based on woven fabrics of active carbon fibers (ACF) as the catalytic supports. The Pd/ACF were tested in liq.-phase hydrogenation of 2-butyne-1,4-diol showing a selectiv ...

2002

Chlorination of natural organic matter: kinetics of chlorination and of THM formation

Urs von Gunten

The kinetics of the formation of trihalomethanes (THMs) and of chlorine consumption for the chlorination of natural organic matter with an excess of chlorine (50 muM > Cl-2 > 210 muM) was investigated. THM precursors could be divided into a fast and a ...

2002

Transition from strong to weak coupling and the onset of lasing in semiconductor microcavities

Raphaël Butté

Angular-dependent emission spectra are investigated in a strongly coupled InGaAs-GaAs-AlAs-based semiconductor microcavity as a function of excitation intensity and of detuning between the uncoupled exciton and photon modes. Under conditions of nonresonant ...

2002

Fluctuations and Landau-Devonshire expansion for barium titanate

Alexander Tagantsev

The experimentally observed temperature dependence of the quartic coefficients in the Landau-Devonshire expansion for BaTiO3 is naturally accounted for within a proper fluctuation model. It is explained, in particular, why one of the quartic coefficients v ...

2002

Recombination dynamics in GaN/AlGaN quantum wells: The role of built-in fields

Nicolas Grandjean

We present an experimental study of the dynamical screening effect of the built-in field in GaN-based quantum well structures by means of picosecond time-resolved luminescence measurements. Our results clearly show that the recombination dynamics of the ph ...

2001

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