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Klaus Kern

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Publications associées (299)

Imaging and controlling coherent phonon wave packets in single graphene nanoribbons

Klaus Kern, Yang Luo

The motion of atoms is at the heart of any chemical or structural transformation in molecules and materials. Upon activation of this motion by an external source, several (usually many) vibrational modes can be coherently coupled, thus facilitating the che ...

Nature Portfolio2023

Landing Proteins on Graphene Trampoline Preserves Their Gas-Phase Folding on the Surface

Klaus Kern, Stephan Rauschenbach, Sven Alexander Szilagyi, Hannah Julia Ochner

Molecule-surface collisions are known to initiate dynamics that lead to products inaccessible by thermal chemistry. These collision dynamics, however, have mostly been examined on bulk surfaces, leaving vast opportunities unexplored for molecular collision ...

AMER CHEMICAL SOC2023

Single Skyrmion Generation via a Vertical Nanocontact in a 2D Magnet-Based Heterostructure

Klaus Kern, Marko Burghard, Lukas Powalla

Skyrmions have been well studied in chiral magnets and magnetic thin films due to their potential application in practical devices. Recently, monochiral skyrmions have been observed in twodimensional van der Waals magnets. Their atomically flat surfaces an ...

AMER CHEMICAL SOC2022

Anionic character of the conduction band of sodium chloride

Klaus Kern, Abhishek Grewal

The alkali halides are ionic compounds. Each alkali atom donates an electron to a halogen atom, leading to ions with full shells. The valence band is mainly located on halogen atoms, while, in a traditional picture, the conduction band is mainly located on ...

Nature Portfolio2022

Superconducting quantum interference at the atomic scale

Klaus Kern, Haonan Huang

A single spin in a Josephson junction can reverse the flow of the supercurrent by changing the sign of the superconducting phase difference across it. At mesoscopic length scales, these pi-junctions are employed in various applications, such as finding the ...

NATURE PORTFOLIO2022

Extracting transport channel transmissions in scanning tunneling microscopy using superconducting excess current

Klaus Kern, Markus Etzkorn, Jacob Senkpiel

Transport through quantum coherent conductors, such as atomic junctions, is described by conduction channels. Information about the number of channels and their transmissions can be extracted from various sources, such as multiple Andreev reflections, dyna ...

AMER PHYSICAL SOC2022

Phase Reconstruction of Low-Energy Electron Holograms of Individual Proteins

Klaus Kern, Stephan Rauschenbach, Sven Alexander Szilagyi, Hannah Julia Ochner

Low-energy electron holography (LEEH) is one of the few techniques capable of imaging large and complex three-dimensional molecules, such as proteins, on the single molecule level at subnanometer resolution. During the imaging process, the structural infor ...

AMER CHEMICAL SOC2022

Real-space subfemtosecond imaging of quantum electronic coherences in molecules

Klaus Kern

Tracking electron motion in molecules is the key to understanding and controlling chemical transformations. Contemporary techniques in attosecond science are able to generate and trace the consequences of this motion in real time, but not in real space. Sc ...

Nature Publishing Group2022

Ultrashort Pulse Excited Tip-Enhanced Raman Spectroscopy in Molecules

Klaus Kern, Yang Luo

Vibrational fingerprints of molecules and lowdimension materials can be traced with subnanometer resolution by performing Tip-enhanced Raman spectroscopy (TERS) in a localization of light in the plasmonic nanocavity of the STM enables high spatial resoluti ...

AMER CHEMICAL SOC2022

Berry curvature-induced local spin polarisation in gated graphene/WTe2 heterostructures

Klaus Kern, Marko Burghard, Lukas Powalla

Experimental control of local spin-charge interconversion is of primary interest for spintronics. Van der Waals (vdW) heterostructures combining graphene with a strongly spin-orbit coupled two-dimensional (2D) material enable such functionality by design. ...

Nature Portfolio2022

Identifying the origin of local flexibility in a carbohydrate polymer

Klaus Kern, Stephan Rauschenbach, Sabine Abb

Correlating the structures and properties of a polymer to its monomer sequence is key to understanding how its higher hierarchy structures are formed and how its macroscopic material properties emerge. Carbohydrate polymers, such as cellulose and chitin, a ...

National Academy of Sciences2021

Visualizing the multifractal wave functions of a disordered two-dimensional electron gas

Klaus Kern

The wave functions of a disordered two-dimensional electron gas at the quantum-critical Anderson transition are predicted to exhibit multifractal scaling in their real space amplitude. We experimentally investigate the appearance of these characteristics i ...

AMER PHYSICAL SOC2021

Atomic-Scale Structural Fluctuations of a Plasmonic Cavity

Klaus Kern, Anna Maria Roslawska, Abhishek Grewal

Optical spectromicroscopies, which can reach atomic resolution due to plasmonic enhancement, are perturbed by spontaneous intensity modifications. Here, we study such fluctuations in plasmonic electroluminescence at the single-atom limit profiting from the ...

AMER CHEMICAL SOC2021

Ultrafast Photon-Induced Tunneling Microscopy

Klaus Kern, Yang Luo

Unification of the techniques of ultrafast science and scanning tunneling microscopy (STM) has the potential of tracking electronic motion in molecules simultaneously in real space and real time. Laser pulses can couple to an STM junction either in the wea ...

AMER CHEMICAL SOC2021

Catalyzing Bond-Dissociation in Graphene via Alkali-Iodide Molecules

Klaus Kern, Stephan Rauschenbach, Sabine Abb, Sven Alexander Szilagyi, Hannah Julia Ochner

Atomic design of a 2D-material such as graphene can be substantially influenced by etching, deliberately induced in a transmission electron microscope. It is achieved primarily by overcoming the threshold energy for defect formation by controlling the kine ...

WILEY-V C H VERLAG GMBH2021

All-optical and microwave-free detection of Meissner screening using nitrogen-vacancy centers in diamond

Klaus Kern, Dinesh Kevin Mathais Pinto

Microscopic studies on thin film superconductors play an important role for probing non-equilibrium phase transitions and revealing dynamics at the nanoscale. However, magnetic sensors with nanometer scale spatial and picosecond temporal resolution are ess ...

AMER INST PHYSICS2021

Gigahertz Frame Rate Imaging of Charge-Injection Dynamics in a Molecular Light Source

Klaus Kern, Markus Etzkorn, Anna Maria Roslawska, Abhishek Grewal

Light sources on the scale of single molecules can be addressed and characterized at their proper sub-nanometer scale by scanning tunneling microscopy-induced luminescence (STML). Such a source can be driven by defined short charge pulses while the lumines ...

AMER CHEMICAL SOC2021

Light-matter interaction at atomic scales

Klaus Kern

Light-matter interaction drives many systems, such as optoelectronic devices like light-emitting diodes and solar cells, biological structures like photosystem II and potential future quantum devices. The absorption or emission of light typically occurs on ...

SPRINGERNATURE2021

Low-energy electron holography imaging of conformational variability of single-antibody molecules from electrospray ion beam deposition

Klaus Kern, Stephan Rauschenbach, Sabine Abb, Sven Alexander Szilagyi, Hannah Julia Ochner

Imaging of proteins at the single-molecule level can reveal conformational variability, which is essential for the understanding of biomolecules. To this end, a biologically relevant state of the sample must be retained during both sample preparation and i ...

National Academy of Sciences2021

Local stiffness and work function variations of hexagonal boron nitride on Cu(111)

Klaus Kern, Markus Ternes, Abhishek Grewal

Combined scanning tunnelling and atomic force microscopy using a qPlus sensor enables the measurement of electronic and mechanic properties of two-dimensional materials at the nanoscale. In this work, we study hexagonal boron nitride (h-BN), an atomically ...

BEILSTEIN-INSTITUT2021

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