Publications

@article{,
title = {Toward Plasmonic Tunnel Gaps for Nanoscale Photoemission Currents by On-Chip Laser Ablation},
author = {P Zimmermann and A H\"{o}tger and N Fernandez and A Nolinder and K M\"{u}ller and J J Finley and A W Holleitner},
url = {https://doi.org/10.1021/acs.nanolett.8b04612},
doi = {10.1021/acs.nanolett.8b04612},
issn = {1530-6984},
year = {2019},
date = {2019-02-13},
journal = {Nano Letters},
volume = {19},
number = {2},
pages = {1172-1178},
abstract = {We demonstrate that prestructured metal nanogaps can be shaped on-chip to below 10 nm by femtosecond laser ablation. We explore the plasmonic properties and the nonlinear photocurrent characteristics of the formed tunnel junctions. The photocurrent can be tuned from multiphoton absorption toward the laser-induced strong-field tunneling regime in the nanogaps. We demonstrate that a unipolar ballistic electron current is achieved by designing the plasmonic junctions to be asymmetric, which allows ultrafast electronics on the nanometer scale.},
keywords = {Solid-Solid},
pubstate = {published},
tppubtype = {article}
}

@article{,
title = {Toward Plasmonic Tunnel Gaps for Nanoscale Photoemission Currents by On-Chip Laser Ablation},
author = {P Zimmermann and A H\"{o}tger and N Fernandez and A Nolinder and K M\"{u}ller and J J Finley and A W Holleitner},
url = {https://doi.org/10.1021/acs.nanolett.8b04612},
doi = {10.1021/acs.nanolett.8b04612},
issn = {1530-6984},
year = {2019},
date = {2019-02-13},
journal = {Nano Letters},
volume = {19},
number = {2},
pages = {1172-1178},
abstract = {We demonstrate that prestructured metal nanogaps can be shaped on-chip to below 10 nm by femtosecond laser ablation. We explore the plasmonic properties and the nonlinear photocurrent characteristics of the formed tunnel junctions. The photocurrent can be tuned from multiphoton absorption toward the laser-induced strong-field tunneling regime in the nanogaps. We demonstrate that a unipolar ballistic electron current is achieved by designing the plasmonic junctions to be asymmetric, which allows ultrafast electronics on the nanometer scale.},
keywords = {Solid-Solid},
pubstate = {published},
tppubtype = {article}
}

@article{,
title = {Interchromophoric Interactions Determine the Maximum Brightness Density in DNA Origami Structures},
author = {T Schr\"{o}der and M B Scheible and F Steiner and J Vogelsang and P Tinnefeld},
url = {https://doi.org/10.1021/acs.nanolett.8b04845},
doi = {10.1021/acs.nanolett.8b04845},
issn = {1530-6984},
year = {2019},
date = {2019-02-13},
journal = {Nano Letters},
volume = {19},
number = {2},
pages = {1275-1281},
abstract = {An ideal point light source is as small and as bright as possible. For fluorescent point light sources, homogeneity of the light sources is important as well as that the fluorescent units inside the light source maintain their photophysical properties, which is compromised by dye aggregation. Here we propose DNA origami as a rigid scaffold to arrange dye molecules in a dense pixel array with high control of stoichiometry and dye\textendashdye interactions. In order to find the highest labeling density in a DNA origami structure without influencing dye photophysics, we alter the distance of two ATTO647N dyes in single base pair steps and probe the dye\textendashdye interactions on the single-molecule level. For small distances strong quenching in terms of intensity and fluorescence lifetime is observed. With increasing distance, we observe reduced quenching and molecular dynamics. However, energy transfer processes in the weak coupling regime still have a significant impact and can lead to quenching by singlet-dark-state-annihilation. Our study fills a gap of studying the interactions of dyes relevant for superresolution microscopy with dense labeling and for single-molecule biophysics. Incorporating these findings in a 3D DNA origami object will pave the way to bright and homogeneous DNA origami nanobeads.},
keywords = {Molecularly-Functionalized},
pubstate = {published},
tppubtype = {article}
}

@article{,
title = {Top-Down Synthesis of Nanostructured Platinum\textendashLanthanide Alloy Oxygen Reduction Reaction Catalysts: PtxPr/C as an Example},
author = {J Fichtner and B Garlyyev and S Watzele and H A El-Sayed and J N Schw\"{a}mmlein and W-J Li and F M Maillard and L Dubau and J Michali\v{c}ka and J M Macak and A W Holleitner and A S Bandarenka},
url = {https://doi.org/10.1021/acsami.8b20174},
doi = {10.1021/acsami.8b20174},
issn = {1944-8244},
year = {2019},
date = {2019-02-06},
journal = {ACS Applied Materials & Interfaces},
volume = {11},
number = {5},
pages = {5129-5135},
abstract = {The oxygen reduction reaction (ORR) is of great interest for future sustainable energy conversion and storage, especially concerning fuel cell applications. The preparation of active, affordable, and scalable electrocatalysts and their application in fuel cell engines of hydrogen cars is a prominent step toward the reduction of air pollution, especially in urban areas. Alloying nanostructured Pt with lanthanides is a promising approach to enhance its catalytic ORR activity, whereby the development of a simple synthetic route turned out to be a nontrivial endeavor. Herein, for the first time, we present a successful single-step, scalable top-down synthetic route for Pt\textendashlanthanide alloy nanoparticles, as witnessed by the example of Pr-alloyed Pt nanoparticles. The catalyst was characterized by high-resolution transmission electron microscopy, energy-dispersive X-ray spectroscopy, X-ray diffraction, and photoelectron spectroscopy, and its electrocatalytic oxygen reduction activity was investigated using a rotating disk electrode technique. PtxPr/C showed ∼3.5 times higher [1.96 mA/cm2Pt, 0.9 V vs reversible hydrogen electrode (RHE)] specific activity and ∼1.7 times higher (0.7 A/mgPt, 0.9 V vs RHE) mass activity compared to commercial Pt/C catalysts. On the basis of previous findings and characterization of the PtxPr/C catalyst, the activity improvement over commercial Pt/C originates from a lattice strain introduced by the alloying process.},
keywords = {Solid-Liquid},
pubstate = {published},
tppubtype = {article}
}

@article{,
title = {Phase-matching and Peak Nonlinearity Enhanced Third-Harmonic Generation in Graphene Plasmonic Coupler},
author = {T Wu and Y Luo and S A Maier and L Wei},
url = {https://link.aps.org/doi/10.1103/PhysRevApplied.11.014049},
doi = {10.1103/PhysRevApplied.11.014049},
year = {2019},
date = {2019-01-24},
journal = {Physical Review Applied},
volume = {11},
number = {1},
pages = {014049},
abstract = {Strong nonlinear optical effects generally require giant optical fields interacting with the nonlinear media. Doped graphene hosts electrically tunable plasmons with long lifetimes that interact strongly with light. We investigate a graphene plasmonic coupler and explore two mechanisms to pursue highly efficient third-harmonic generation (THG): (1) phase matching of graphene plasmons at fundamental- and third-harmonic frequencies and (2) peak third-order nonlinear susceptibility of doped graphene. The third-harmonic wave is mainly converted from the evanescent mode of the incident light and the THG efficiency is found to be enhanced by over 10 orders of magnitude compared with a bare monolayer graphene. The significantly enhanced nonlinear optical responses in the graphene plasmonic coupler make this configuration an ideal platform for the development of alternative frequency generators and for signal processing at midinfrared and terahertz frequencies.},
keywords = {Solid-Solid},
pubstate = {published},
tppubtype = {article}
}

@article{,
title = {Cobalt-Catalyzed Electrophilic Aminations with Anthranils: An Expedient Route to Condensed Quinolines},
author = {J Li and E Tan and N Keller and Y-H Chen and P M Zehetmaier and A C Jakowetz and T Bein and P Knochel},
url = {https://doi.org/10.1021/jacs.8b11466},
doi = {10.1021/jacs.8b11466},
issn = {0002-7863},
year = {2019},
date = {2019-01-09},
journal = {Journal of the American Chemical Society},
volume = {141},
number = {1},
pages = {98-103},
abstract = {The reaction of various organozinc pivalates with anthranils provides anilines derivatives, which cyclize under acidic conditions providing condensed quinolines. Using alkenylzinc pivalates, electron-rich arylzinc pivalates or heterocyclic zinc pivalates produces directly the condensed quinolines of which several structures belong to new heterocyclic scaffolds. These N-heterocycles are of particular interest for organic light emitting diodes with their high photoluminescence quantum yields and long exciton lifetimes as well as for hole-transporting materials in methylammonium lead iodide perovskites solar cells due to an optimal band alignment for holes and a large bandgap.},
keywords = {Molecularly-Functionalized},
pubstate = {published},
tppubtype = {article}
}