Electron bombardment fragmentation of size selected molecular clusters

(CO₂) _n , (NO) _n and (NH₃) _n clusters are generated in a supersonic molecular beam and size selected by scattering from an He beam. By measurements of angular dependent mass spectra, TOF distributions and the angular dependence of the scattered signal quantitative information on the fragmentation probability by electron impact is derived. The van der Waals systems (CO₂) _n and (NO) _n appear only at masses which are simply multiples of the monomer mass. The preferred cluster ion is the monomer ion for all investigated cluster sizes withn=2 to 4. The fragment pattern for the quasi-hydrogen bonded (NH₃) _n -cluster shows, beside a large number of fragment masses, a preference for protonated ions. The results are explained in terms of simple models based on the structural change from the neutral to the ionized configuration and the fragmentation pattern of the monomer followed by ionmolecule reactions.     

A *-product on SL(2) and the corresponding nonstandard (\mathfrak{s}\mathfrak{l}({\text{2}}))

We obtain Zakrzewski's deformation of Fun SL(2) through the construction of a *-product on SL(2). We then give the deformation of dual to this, as well as a Poincaré basis for both algebras.Aspirant au Fonds National belge de la Recherche Scientifique. Partially supported by EEC contract SC1-0105-C.     

Novel Catalytic Dielectric Barrier Discharge Reactor for Gas-Phase Abatement of Isopropanol

Catalytic gas-phase abatement of air containing 250 ppm of isopropanol (IPA) was carried out with a novel dielectric barrier discharge (DBD) reactor with the inner catalytic electrode made of sintered metal fibers (SMF). The optimization of the reactor performance was carried out by varying the voltage from 12.5 to 22.5 kV and the frequency in the range 200–275 Hz. The performance was significantly improved by modifying SMF with Mn and Co oxide. Under the experimental conditions used, the MnO _x /SMF showed a higher activity towards total oxidation of IPA as compared to CoO _x /SMF and SMF electrodes. The complete destruction of 250 ppm of IPA was attained with a specific input energy of ∼235 J/L using the MnO _x /SMF catalytic electrode, whereas, the total oxidation was achieved at 760 J/L. The better performance of the MnO _x /SMF compared to other catalytic electrodes suggests the formation of short-lived active species on its surface by the in-situ decomposition of ozone.     

Numeric simulation of epoxy cure in molds

Thermodynamic and kinetic parameters have been determined suitable for the numerical simulation of the curing reaction of the epoxy/anhydride based casting resin system Araldite CY 225/HY 225/filler. In particular, the decisive role of the heating rate on the evaluation of the kinetic parameters from dynamic DSC-experiments is discussed.

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Zusammenfassung Mit Hilfe der Mikrokalorimetrie wurden thermodynamische (Reaktionsenthalpien) und kinetische (Arrhenius-Konstanten, Reaktionsordnung) Parameter eines gefüllten Epoxid/Anhydrid-Giessharz-Systems (Araldit CY 225/HY 225/Quarzmehl) bestimmt.Die Eignung dieser Parameter zur praxisrelevanten Simulation der HÄrtungsreaktion in Giessformen wird demonstriert. Es zeigt sich, dass die Heizrate im dynamischen DSC-Experiment bei der Bestimmung der kinetischen Parameter eine entscheidende Rolle spielt.

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We wish to thank Dr. P. Bujard, Ciba-Geigy SA, for the measurement of the thermal conductivity data, and Mrs. Emmi Stoisser for technical assistance.     

Untersuchungen an oxidischen Katalysatoren. XLII. Redoxverhalten des Nickels in NiNa?Y-Zeolithen 4. Einfluß der Zusammensetzung auf die Reduzierbarkeit von Nickel in NiNa?Y-Zeolithen

Studies on Oxide Catalysts. XLii. Redox Behaviour of Nickel in Zeolites NiNa? Y. 4. Influence of Composition on the Reducibility of Nickel in Zeolites NiNa? Y By chemical analysis (reaction with K₂Cr₂O₇) and ESCA investigations we determined the degree of reduction in reduced samples NiNa-Y as function of the mole ratio SiO₂/Al₂O₃ (module), of the Ni²⁺ degree of exchange and the kind of the second cations. (NH₄₊, Ca²+, Co²+, and Nd³+) in the temperature region of 620–770 K. The degree of nickel reduction increases with increasing module, decreasing degree of exchange and decreasing number of Brönsted acidic centres. This behaviour is caused by the influence of the interaction between cations Ni²⁺ and zeolite lattice on the reduction equilibrium.     

Darstellung,Eigenschaften und Schwingungsspektren von K[SbCl5N3], K[SbCl5NCO] und K[SbCl5CN]

Preparation, Properties and Vibrational Spectra of K[SbCl₅N₃], K[SbCl₅NCO] and K[SbCl₅CN]. KaN₃, KNCO and KCN react in liquid SO₂ with stoichiometric amounts of SbCl₅ yielding K[SbCl₅N₃] K[SbCl₅NCO], and K[SbCl₅CN], respectively. NaN₃ and SbCl₅ form Na[SbCl₅N₃] which contains impurities of Na[SbCl₆]. With more SbCl₅ (SbCl₄N₃)₂ is obtained from K[SbCl₅N₃] and (SbCl₄NCO)₂ from K[SbCl₅NCO], [BCl₂N₃]₃ is formed from K[SbCl₅N₃] and BCl₃. The vibrational spectra of the pentachloro-pseudohalo-antimonates can be assigned with a model of C_4v symmetry for the direct neighborhood of the Sb atoms.     

Inclusive ϱ0,K *±(892) andf production in\bar p p Interactions at 12 GeV/c

Inclusive production of ?⁰,K ^*±(892), andf is studied in \(\bar p\) p interactions at 12 GeV/c. The inclusive cross sections for ?⁰,K ^*±(892), andf are found to be 6.7±0.3 mb, 1.0±0.2 mb, and 1.4±0.3 mb, respectively. The differential cross sections are presented as a function of c.m. rapidity, Feynmanx and square of the transverse momentump _T ² . Comparison with the correspondingpp data shows some interesting differences which can be attributed to the \(\bar p\) p annihilation. The results are compared with the predictions of the quark fusion model.     

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