30 research outputs found
Sedimentology, carbon isotope stratigraphy and micropalaeontology of the Rhaetian Zlambach Formation-Implications for the Dachstein carbonate platform development (Northern Calcareous Alps, Austria)
Dolchmesser, Dolche und Kurzwehren des 15. und 16. Jahrhunderts im Kern-Raum der Hanse - Fortsetzung
Harnische und Waffen des 15. bis 17. Jahrhunderts : Eine Ausstellung auf der Marksburg ...
Lightwave-controlled electron dynamics in graphene
We demonstrate that currents induced in graphene by ultrashort laser pulses are sensitive to the exact shape of the electric-field waveform. By increasing the field strength, we found a transition of the light–matter interaction from the weak-field to the strong-field regime at around 2 V/nm, where intraband dynamics influence interband transitions. In this strong-field regime, the light-matter interaction can be described by the wavenumber trajectories of electrons in the reciprocal space. For linearly polarized light the electron dynamics are governed by repeated sub-optical-cycle Landau-Zener transitions between the valence- and conduction band, resulting in Landau-Zener-Stuckelberg interference, whereas for circular polarized light this interference is supressed
Lightwave-controlled electron dynamics in graphene
We demonstrate that currents induced in graphene by ultrashort laser pulses are sensitive to the exact shape of the electric-field waveform. By increasing the field strength, we found a transition of the light–matter interaction from the weak-field to the strong-field regime at around 2 V/nm, where intraband dynamics influence interband transitions. In this strong-field regime, the light-matter interaction can be described by the wavenumber trajectories of electrons in the reciprocal space. For linearly polarized light the electron dynamics are governed by repeated sub-optical-cycle Landau-Zener transitions between the valence- and conduction band, resulting in Landau-Zener-Stuckelberg interference, whereas for circular polarized light this interference is supressed
Single-Molecule Junctions with Epitaxial Graphene Nanoelectrodes
On the way to ultraflat single-molecule
junctions with transparent electrodes, we present a fabrication scheme
based on epitaxial graphene nanoelectrodes. As a suitable molecule,
we identified a molecular wire with fullerene anchor groups. With
these two components, stable electrical characteristics could be recorded.
Electrical measurements show that single-molecule junctions with graphene
and with gold electrodes display a striking agreement. This motivated
a hypothesis that the differential conductance spectra are rather
insensitive to the electrode material. It is further corroborated
by the assignment of asymmetries and spectral features to internal
molecular degrees of freedom. The demonstrated open-access graphene
electrodes and the electrode-insensitive molecules provide a model
system that will allow for a thorough investigation of an individual
single-molecule contact with additional probes
Gateless patterning of epitaxial graphene by local intercalation
We present a technique to pattern the charge density of a large-area epitaxial graphene sheet locally without using metallic gates. Instead, local intercalation of the graphene–substrate interface can selectively be established in the vicinity of graphene edges or predefined voids. It provides changes of the work function of several hundred meV, corresponding to a conversion from n-type to p-type charge carriers. This assignment is supported by photoelectron spectroscopy, scanning tunneling microscopy, scanning electron microscopy and Hall effect measurements. The technique introduces materials contrast to a graphene sheet in a variety of geometries and thus allows for novel experiments and novel functionalities