Crossed-beam study of Co+(3F4)+propane: experiment and density functional theory

A pulsed beam of Co+(3F4) crosses a pulsed beam of C3H8 or C3D8 gas under single collision conditions at collision energies of 0.01 eV and 0.21 eV. After a variable time delay t(ext) = 1-8 micros a fast high voltage pulse extracts product ions into a field-free flight tube for mass analysis. Consistent with earlier work, we observe prompt CoC3H6+ +H2 elimination products in 3:1 excess over CoC2H4+ +CH4 products at 0.21 eV on a 2-10 micros time scale. Long-lived CoC3H8+ complexes fragment predominantly back to Co+ +C3H8 reactants and to H2 elimination products on a 6-24 micros time scale. Density functional theory (B3LYP) calculations provide energies, geometries, and harmonic vibrational frequencies at key stationary points for use in a statistical rate model of the reaction. By adjusting two key multicenter transition state (MCTS) energies downward by 4-7 kcal mol(-1), we obtain good agreement with our decay time results and with the cross section versus collision energy of Armentrout and co-workers from 0.1-1.0 eV. B3LYP theory succeeds in finding relative energies of the MCTSs leading to CH4 and H2 in the proper order to explain the different product branching ratio for Co+ (which favors H2 over CH4) compared with its nearest neighbors Fe+ and Ni+ (which favor CH4 over H2).     

Einfaches Verfahren zur Bestimmung des Chloridgehaltes von schwefelsauren galvanischen Kupferb?dern mit Hilfe ionensensitiver Elektroden

Zusammenfassung Die Anwendung einer chloridionensensitiven Elektrode für die direktpotentiometrische Chloridbestimmung in galvanischen BÄdern wird beschrieben und eine genaue Arbeitsvorschrift sowie drei verschiedene Auswerteverfahren angegeben. Die Messungen wurden in einem Bereich von 30–250 mg Cl^– je Liter Badlösung an Modellösungen durchgeführt. Die einzelnen Methoden ergaben eine Standardabweichung von ±2,1 mg bei Verwendung einer Eichkurve, ±2,2 mg beim Standardzusatzverfahren und ±3,6 mg bei der Direktablesung auf einer logarithmisch geteilten Skala eines mV-Meters. Ebenso wurden Messungen an einer Reihe von Badproben durchgeführt.Für wertvolle Anregungen und Diskussionen danken wir Herrn Schwank, Siemens AG, Abt. Informationselektronik.     

Delta-electron emission in fast heavy ion — atom collisions: observations of new phenomena and breakdown of common scaling laws

Double differential cross sections for the emission of Delta-electrons have been measured in fast uranium-rare gas collisions. The well-known Binary Encounter peak reveals unexpected structures for certain observation angles and its intensity increases towards smaller angles, which is in contradiction to results and scaling laws obtained by experiments with light ion impact. The observed dependencies are fairly well described by recent calculations in the framework of IA and CTMC. From systematic experimental as well as theoretical studies we can derive that the potential of the partially stripped projectile ion gives rise to rainbow and glory scattering of the target electron in the field of the projectile. The rainbow scattering is observed in the laboratory frame as pronounced interference structures, whereas the glory scattering is responsible for the steep increase of the cross sections for binary-encounter electrons towards small laboratory ejection angles. The observed effects have a dramatic influence on the commonq ² scaling laws derived from experiments with light ions. Furthermore, since the binary-encounter electrons ejected at forward angles have approximately twice the projectile velocity, these new phenomena have an important influence on the electronic stopping power of heavy ions and therefore have to be taken into account for the investigation of radiation damage by these ions e.g. in biological matter.     

The nickel-catalysed carbonylation of 2-mercaptoethanol

2-Mercapthoethanol undergoes carbonylation in pyridine solution in the presence of oxygen and of [Ni(CO)₃Pyl as a catalyst to give cyclic O, S-ethylelnethiorcarbonate. The isolation of thiolatonickel compound [Ni(SCH₂CH₂OH)₂] by the oxidation of a solution containing [Ni(CO)₃Py] and 2-mercaptoethanol, and its reaction with carbon monoxide to give the cyclic thiocarbonate and [Ni(CO)₃Py] prove that the reaction proceeds in at least two steps.     

Dynamical and thermal aspects of relativistic heavy-ion collisions

Within a covariant BUU-approach we simulate heavyion collisions at various bombarding energies from 400 MeV/u to 1 GeV/u. We evaluate locally the energymomentum tensorT ^v (x), and extract pressures, energydensities and temperatures. The connection of these thermodynamical quantities to experimental observables and their sensitivity to the equation of state is discussed. Furthermore, we investigate the question of local equilibration and evaluate the entropy produced in these reactions.Dedicated to Prof. Dr. P. Kienle on the occasion of his 60th birthday. Work supported by BMFT and GSI Darmstadt