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Author: Bergues, Boris × Has files: Yes ×

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    Few-cycle laser driven reaction nanoscopy on aerosolized silica nanoparticles
    ([London] : Nature Publishing Group UK, 2019) Rupp, Philipp; Burger, Christian; Kling, Nora G; Kübel, Matthias; Mitra, Sambit; Rosenberger, Philipp; Weatherby, Thomas; Saito, Nariyuki; Itatani, Jiro; Alnaser, Ali S.; Raschke, Markus B.; Rühl, Eckart; Schlander, Annika; Gallei, Markus; Seiffert, Lennart; Fennel, Thomas; Bergues, Boris; Kling, Matthias F.
    Nanoparticles offer unique properties as photocatalysts with large surface areas. Under irradiation with light, the associated near-fields can induce, enhance, and control molecular adsorbate reactions on the nanoscale. So far, however, there is no simple method available to spatially resolve the near-field induced reaction yield on the surface of nanoparticles. Here we close this gap by introducing reaction nanoscopy based on three-dimensional momentum-resolved photoionization. The technique is demonstrated for the spatially selective proton generation in few-cycle laser-induced dissociative ionization of ethanol and water on SiO2 nanoparticles, resolving a pronounced variation across the particle surface. The results are modeled and reproduced qualitatively by electrostatic and quasi-classical mean-field Mie Monte-Carlo (M3C) calculations. Reaction nanoscopy is suited for a wide range of isolated nanosystems and can provide spatially resolved ultrafast reaction dynamics on nanoparticles, clusters, and droplets.
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    Onset of charge interaction in strong-field photoemission from nanometric needle tips
    (Berlin : de Gruyter, 2021) Schötz, Johannes; Seiffert, Lennart; Maliakkal, Ancyline; Blöchl, Johannes; Zimin, Dmitry; Rosenberger, Philipp; Bergues, Boris; Hommelhoff, Peter; Krausz, Ferenc; Fennel, Thomas; Kling, Matthias F.
    Strong-field photoemission from nanostructures and the associated temporally modulated currents play a key role in the development of ultrafast vacuum optoelectronics. Optical light fields could push their operation bandwidth into the petahertz domain. A critical aspect of their functionality in the context of applications is the impact of charge interaction effects. Here, we investigated the photoemission and photocurrents from nanometric tungsten needle tips exposed to carrier-envelope phase (CEP)-controlled few-cycle laser fields. We report a characteristic rapid increase in the intensity-rescaled cutoff energies of emitted electrons beyond a certain intensity value. By comparison with simulations, we identify this feature as the onset of charge-interaction dominated photoemission dynamics. Our results are anticipated to be relevant also for the strong-field photoemission from other nanostructures, including photoemission from plasmonic nanobowtie antennas used in CEP-detection and for PHz-scale devices.