75 research outputs found
Unconventional MBE Strategies from Computer Simulations for Optimized Growth Conditions
We investigate the influence of step edge diffusion (SED) and desorption on
Molecular Beam Epitaxy (MBE) using kinetic Monte-Carlo simulations of the
solid-on-solid (SOS) model. Based on these investigations we propose two
strategies to optimize MBE growth. The strategies are applicable in different
growth regimes: During layer-by-layer growth one can exploit the presence of
desorption in order to achieve smooth surfaces. By additional short high flux
pulses of particles one can increase the growth rate and assist layer-by-layer
growth. If, however, mounds are formed (non-layer-by-layer growth) the SED can
be used to control size and shape of the three-dimensional structures. By
controlled reduction of the flux with time we achieve a fast coarsening
together with smooth step edges.Comment: 19 pages, 7 figures, submitted to Phys. Rev.
Expected Measurement Accuracies and Limits of Error in a Fabrication Plant for High Enriched Uranium
Synthesis of furano-epothilone D
The total synthesis of furano-epothilone D by a convergent route is reported. The key fragments are available on a large scale to provide sufficient material for biological evaluation. The approach involves a palladium-catalyzed coupling that generates a highly functionalized aldehyde which is connected in a stereoselective aldol reaction to yield the framework of furano-epothilone D. Finally, a macrolactonization provides furano-epothilone D
- …