Die Abhängigkeit der Lebensdauer des Tl 72 S 1/2-Zustandes von den Anregungsbedingungen in einem Resonanzfluoreszenzexperiment

The lifetime of the Thallium 7² S _1/2-level has been studied by measuring the phase of the modulated intensity of fluorescens light. The lifetime was found between 6.65 and 8.25 nsec depending on the exciting conditions.

     

Hopf Bifurcation and Exchange of Stability in Diffusive Media

We consider solutions bifurcating from a spatially homogeneous equilibrium under the assumption that the associated linearization possesses a continuous spectrum up to the imaginary axis, for all values of the bifurcation parameter, and that a pair of imaginary eigenvalues crosses the imaginary axis. For a reaction-diffusion-convection system we investigate the nonlinear stability of the trivial solution with respect to spatially localized perturbations, prove the occurrence of a Hopf bifurcation and the nonlinear stability of the bifurcating time-periodic solutions, again with respect to spatially localized perturbations.     

A study of a moleculartweezer host-guest system by a combination of quantum-chemical calculations and solid-state NMR experiments

A study of a host-guest system consisting of a naphthalene-spaced tweezer with a 1,4 dicyanobenzene guest molecule is presented. The complex is investigated using a combination of quantum-chemical calculations and solid-state NMR experiments. The advantages of such an approach are illustrated. The focus is on the calculation of (1) 1H NMR and (2) 13C NMR chemical shifts for model fragments of the solid-state structure, (3) the analysis of host-guest interactions important for molecular recognition, and (4) the investigation of the process of a guest molecule rotation. For modeling the solid-state structure, up to three host-guest units are considered and the convergence with respect to the size of the solid-state fragment is investigated.