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DDC: 500 × Type: Text × search.filters.applied.f.series: Nature Communications 10 (2019) × WGL Institute: MBI ×

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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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    Molecular movie of ultrafast coherent rotational dynamics of OCS
    ([London] : Nature Publishing Group UK, 2019) Karamatskos, Evangelos T.; Raabe, Sebastian; Mullins, Terry; Trabattoni, Andrea; Stammer, Philipp; Goldsztejn, Gildas; Johansen, Rasmus R.; Długołecki, Karol; Stapelfeldt, Henrik; Vrakking, Marc J. J.; Trippel, Sebastian; Rouzée, Arnaud; Küpper, Jochen
    Recording molecular movies on ultrafast timescales has been a longstanding goal for unravelling detailed information about molecular dynamics. Here we present the direct experimental recording of very-high-resolution and -fidelity molecular movies over more than one-and-a-half periods of the laser-induced rotational dynamics of carbonylsulfide (OCS) molecules. Utilising the combination of single quantum-state selection and an optimised two-pulse sequence to create a tailored rotational wavepacket, an unprecedented degree of field-free alignment, 〈cos2θ2D〉 = 0.96 (〈cos2θ〉 = 0.94) is achieved, exceeding the theoretical limit for single-pulse alignment. The very rich experimentally observed quantum dynamics is fully recovered by the angular probability distribution obtained from solutions of the time-dependent Schrödinger equation with parameters refined against the experiment. The populations and phases of rotational states in the retrieved time-dependent three-dimensional wavepacket rationalises the observed very high degree of alignment.
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    Enhancing laser beam performance by interfering intense laser beamlets
    ([London] : Nature Publishing Group UK, 2019) Morace, A.; Iwata, N.; Sentoku, Y.; Mima, K.; Arikawa, Y.; Yogo, A.; Andreev, A.; Tosaki, S.; Vaisseau, X.; Abe, Y.; Kojima, S.; Sakata, S.; Hata, M.; Lee, S.; Matsuo, K.; Kamitsukasa, N.; Norimatsu, T.; Kawanaka, J.; Tokita, S.; Miyanaga, N.; Shiraga, H.; Sakawa, Y.; Nakai, M.; Nishimura, H.; Azechi, H.; Fujioka, S.; Kodama, R.
    Increasing the laser energy absorption into energetic particle beams represents a longstanding quest in intense laser-plasma physics. During the interaction with matter, part of the laser energy is converted into relativistic electron beams, which are the origin of secondary sources of energetic ions, γ-rays and neutrons. Here we experimentally demonstrate that using multiple coherent laser beamlets spatially and temporally overlapped, thus producing an interference pattern in the laser focus, significantly improves the laser energy conversion efficiency into hot electrons, compared to one beam with the same energy and nominal intensity as the four beamlets combined. Two-dimensional particle-in-cell simulations support the experimental results, suggesting that beamlet interference pattern induces a periodical shaping of the critical density, ultimately playing a key-role in enhancing the laser-to-electron energy conversion efficiency. This method is rather insensitive to laser pulse contrast and duration, making this approach robust and suitable to many existing facilities.