Lihua Shao

Macroscopic 3D nanographene with dynamically tunable bulk properties.

Polymer-derived, monolithic three-dimensional nanographene (3D-NG) bulk material with tunable properties is produced by a simple and inexpensive approach. The material is mass-producible, and combines chemical inertness and mechanical strength with a hierarchical porous architecture and a graphene-like surface area. This provides an opportunity to control its electron transport and mechanical properties dynamically by means of electrochemical-induced interfacial electric fields.

Electrochemical Modulation of Photonic Metamaterials

[∗] L.-H. Shao ,[+] M. Ruther ,[+] Prof. S. Linden ,[+] Prof. J. Weissmuller , Prof. M. Wegener Institut fur Nanotechnologie Karlsruhe Institute of Technology (KIT) Postfach 3640, D-76021 Karlsruhe (Germany) E-mail: matthias.ruther@kit.edu L.-H. Shao , M. Ruther , Prof. S. Linden , S. Essig , Prof. K. Busch , Prof. J. Weissmuller , Prof. M. Wegener DFG-Center for Functional Nanostructures (CFN) Karlsruhe Institute of Technology (KIT) D-76131 Karlsruhe (Germany) M. Ruther , Prof. S. Linden , Prof. M. Wegener Institut fur Angewandte Physik Karlsruhe Institute of Technology (KIT) Wolfgang-Gaede-Strasse 1, D-76128 Karlsruhe (Germany) S. Essig , Prof. K. Busch Institut fur Theoretische Festkorperphysik Karlsruhe Institute of Technology (KIT) Wolfgang-Gaede-Strasse 1, D-76128 Karlsruhe (Germany) Prof. S. Linden Current Address: Physikalisches Institut, Universitat Bonn, Nusallee 12, D-53113 Bonn (Germany) [+] These authors have contributed equally to this work

Microstrain in nanocrystalline solids under load by virtual diffraction

We propose a method for computing virtual X-ray diffractograms for nanocystalline materials under uniaxial load based on molecular-dynamics simulation data. While the increase in diffraction microstrain during deformation is generally taken as evidence for the generation of lattice dislocations, our virtual diffraction data show extra microstrain even at small load, before the onset of lattice dislocation activity. We show that the microstrain data have a natural explanation in the elastic response of a heterogeneous medium. The results imply that the conclusions of previous experimental in situ diffraction data for nanocystalline metals may deserve a critical examination.

Electrochemical restructuring of plasmonic metamaterials

Recent electrochemical experiments on gold-based photonic metamaterials have shown reversible optical modulation as well as an irreversible reduction in the plasmonic damping. Here, we systematically study the latter aspect as a possible means of postprocessing plasmonic gold nanoantennae arrays aiming at loss reduction. We characterize the samples by optical spectroscopy, electron microscopy, and atomic-force microscopy. For sub-10 nm gold thicknesses, the measured damping decreases by factors exceeding 3; for 20–30 nm thin structures, the obtained loss reduction still amounts to about 30%.

Electromodulation of Photonic Metamaterials

By applying voltages of about 1V to very thin metal nanostructures via an aqueous electrolyte, we demonstrate reversible modulation of split-ring-resonator resonances by as much as 60 THz at around 300 THz resonance frequency.