Über lineare Limitierungsverfahren

Ohne Zusammenfassung     

The Oseen drag on a circular cylinder revisited

A scheme is presented to evaluate the drag on an infinite circular cylinder, at rest in a perpendicular uniform stationary flow. This scheme leads already in second approximation to very satisfactory values for the drag coefficient up to Reynolds number R = 10 and probably even up to R = 10².     

Break up of spectator residues at ultra-relativistic energies

The 200GeV/u sulfur beam available at CERN was used to bombard a 1.5 mg/cm Au target. Light nuclei were detected at 60° in the laboratory using a silicon telescope. The shape of the inclusive atomic number distribution of intermediate mass fragments with an atomic numberZ ≥ 2 looks different from the one measured on theO +Au system at the same bombarding energy.     

Oxidative transformations of surface-bound perylene

We report on the covalent attachment of perylene derivatives to silica and indium-doped tin oxide surfaces. The spectroscopic properties of the immobilized fluorophores are studied by steady-state and time-resolved emission spectroscopy. The redox properties of the molecules are examined by electrochemical methods. It was found that the oxidation of perylene in aqueous medium results in the formation of perylenequinones. The transformation proceeds through a number of steps, with monohydroxyperylene(s) being the intermediate species. The final oxidation products are three isomeric forms of the perylenequinone/perylenehydroquinone redox couple. Understanding the mechanism of perylene transformation allows estimation of the concentration of molecules on the surface, and comparison of these results to those for pyrene and anthracene derivatives underscores the generality of this type of oxidative degradation for polycyclic aromatic hydrocarbons.     

Experiments on the viscosity of some symmetric top molecules in the presence of magnetic and electric fields

In order to obtain information on the scalar structure of non-equilibrium polarizations a comparison between the magnetic and the electric field effect on the viscosity of some symmetric top molecules has been carried out. It is shown that the polarization produced in viscous flow is more complicated than assumed so far.     

The broadening and shift of the ratational Raman lines for hydrogen isotopes at low temperatures

Collisional broadening of rotational Raman lines has been investigated for the gases nH₂, nD₂ and HD between 20 and 300 K. For H₂ and D₂ the dependence of the linewidth on ortho-para composition has been investigated. For a number of systems the pressure shift of the Raman lines has also been determined. The experimental results are compared with theory.