Nanosystems Initiative Munich

About: Nanosystems Initiative Munich is a facility organization based out in Munich, Germany. It is known for research contribution in the topics: Quantum dot & Perovskite (structure). The organization has 323 authors who have published 549 publications receiving 24316 citations.

Photocatalytic Nanosheet Lithography: Photolithography based on Organically Modified Photoactive 2D Nanosheets.

Abstract: Harvesting the properties of nanosheets is not only crucial from a fundamental perspective, but also for the development of novel functional devices based on 2D nanosheets. Herein, we demonstrate the processing of organically modified TBAx H1-x Ca2 Nb3 O10 nanosheets into photonic thin films and study their colorimetric sensing properties in response to various aqueous and organic solvent vapors. Building on the enhanced solvent accessibility of TBA-containing nanosheets and their photocatalytic activity under UV irradiation, we develop a new concept for photocatalytic lithography using TBAx H1-x Ca2 Nb3 O10 nanosheets as a negative photoresist to obtain high-fidelity micron-scale patterns of robust inorganic nanosheets. Photocatalytic nanosheet lithography (PNL) therefore adds a new resist-free, resource efficient direct patterning technique to the toolbox of photolithography.

A surface acoustic wave-driven micropump for particle uptake investigation under physiological flow conditions in very small volumes.

Abstract: Static conditions represent an important shortcoming of many in vitro experiments on the cellular uptake of nanoparticles. Here, we present a versatile microfluidic device based on acoustic streaming induced by surface acoustic waves (SAWs). The device offers a convenient method for introducing fluid motion in standard cell culture chambers and for mimicking capillary blood flow. We show that shear rates over the whole physiological range in sample volumes as small as 200 μL can be achieved. A precise characterization method for the induced flow profile is presented and the influence of flow on the uptake of Pt-decorated CeO2 particles by endothelial cells (HMEC-1) is demonstrated. Under physiological flow conditions the particle uptake rates for this system are significantly lower than at low shear conditions. This underlines the vital importance of the fluidic environment for cellular uptake mechanisms.

Diffusion of colloidal rods in corrugated channels.

Abstract: In many natural and artificial devices diffusive transport takes place in confined geometries with corrugated boundaries. Such boundaries cause both entropic and hydrodynamic effects, which have been studied only for the case of spherical particles. Here we experimentally investigate the diffusion of particles of elongated shape confined in a corrugated quasi-two-dimensional channel. The elongated shape causes complex excluded-volume interactions between particles and channel walls which reduce the accessible configuration space and lead to novel entropic free-energy effects. The extra rotational degree of freedom also gives rise to a complex diffusivity matrix that depends on both the particle location and its orientation. We further show how to extend the standard Fick-Jacobs theory to incorporate combined hydrodynamic and entropic effects, so as, for instance, to accurately predict experimentally measured mean first passage times along the channel. Our approach can be used as a generic method to describe translational diffusion of anisotropic particles in corrugated channels.

Gapped excitations of unconventional fractional quantum Hall effect states in the second Landau level

Abstract: We report the observation of low-lying collective charge and spin excitations in the second Landau level at $\ensuremath{ u}=2+1/3$ and also for the very fragile states at $\ensuremath{ u}=2+2/5$ and $2+3/8$ in inelastic light scattering experiments. These modes exhibit a clear dependence on filling factor and temperature substantiating the unique access to the characteristic neutral excitation spectra of the incompressible fractional quantum Hall effect (FQHE) states. A detailed mode analysis reveals low-energy modes at around 70 $\ensuremath{\mu}\mathrm{eV}$ and a sharp mode slightly below the Zeeman energy interpreted as gap and spin-wave excitation, respectively. The lowest-energy collective charge excitation spectrum at $\ensuremath{ u}=2+1/3$ exhibits significant qualitative similarities with its cousin state in the lowest Landau level at $\ensuremath{ u}=1/3$ suggesting similar magnetoroton minima in the neutral excitations. The mode energies differ by a scaling of 0.15 indicating different interaction physics in the $N=0$ and $N=1$ Landau levels. The striking polarization dependence in elastic and inelastic light scattering is discussed in the framework of anisotropic electron phases that allow for the stabilization of nematic FQHE states. The observed excitation spectra provide new insights by accessing quantum phases in the bulk of electron systems and facilitate comparison with different theoretical descriptions of those enigmatic FQHE states.