Browsing by Author "Weninger, Clemens"

Now showing 1 - 3 of 3
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    Drop-on-demand sample delivery for studying biocatalysts in action at X-ray free-electron lasers
    (Nature Publishing Group, 2017) Fuller, Franklin D.; Gul, Sheraz; Chatterjee, Ruchira; Burgie, E.Sethe; Young, Iris D.; Lebrette, Hugo; Srinivas, Vivek; Brewster, Aaron S.; Michels-Clark, Tara; Clinger, Jonathan A.; Andi, Babak; Ibrahim, Mohamed; Pastor, Ernest; de Lichtenberg, Casper; Hussein, Rana; Pollock, Christopher J.; Zhang, Miao; Stan, Claudiu A.; Kroll, Thomas; Fransson, Thomas; Weninger, Clemens; Kubin, Markus; Aller, Pierre; Lassalle, Louise; Bräuer, Philipp; Miller, Mitchell D.; Amin, Muhamed; Koroidov, Sergey; Roessler, Christian G.; Allaire, Marc; Sierra, Raymond G.; Docker, Peter T.; Glownia, James M.; Nelson, Silke; Koglin, Jason E.; Zhu, Diling; Chollet, Matthieu; Song, Sanghoon; Lemke, Henrik; Liang, Mengning; Sokaras, Dimosthenis; Alonso-Mori, Roberto; Zouni, Athina; Messinger, Johannes; Bergmann, Uwe; Boal, Amie K.; Bollinger, J.Martin Jr.; Krebs, Carsten; Högbom, Martin; Phillips, George N.Jr.; Vierstra,, Richard D.; Sauter, Nicholas K.; Orville, Allen M.; Kern, Jan; Yachandra, Vittal K.; Yano, Junko
    X-ray crystallography at X-ray free-electron laser sources is a powerful method for studying macromolecules at biologically relevant temperatures. Moreover, when combined with complementary techniques like X-ray emission spectroscopy, both global structures and chemical properties of metalloenzymes can be obtained concurrently, providing insights into the interplay between the protein structure and dynamics and the chemistry at an active site. The implementation of such a multimodal approach can be compromised by conflicting requirements to optimize each individual method. In particular, the method used for sample delivery greatly affects the data quality. We present here a robust way of delivering controlled sample amounts on demand using acoustic droplet ejection coupled with a conveyor belt drive that is optimized for crystallography and spectroscopy measurements of photochemical and chemical reactions over a wide range of time scales. Studies with photosystem II, the phytochrome photoreceptor, and ribonucleotide reductase R2 illustrate the power and versatility of this method.
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    Generation of intense phase-stable femtosecond hard X-ray pulse pairs
    (National Academy of Sciences, 2022) Zhang, Yu; Kroll, Thomas; Weninger, Clemens; Michine, Yurina; Fuller, Franklin D.; Zhu, Diling; Alonso-Mori, Roberto; Sokaras, Dimosthenis; Lutman, Alberto A.; Halavanau, Aliaksei; Pellegrini, Claudio; Benediktovitch, Andrei; Yabashi, Makina; Inoue, Ichiro; Inubushi, Yuichi; Osaka, Taito; Yamada, Jumpei; Babu, Ganguli; Salpekar, Devashish; Sayed, Farheen N.; Ajayan, Pulickel M.; Kern, Jan; Yano, Junko; Yachandra, Vittal K.; Yoneda, Hitoki; Rohringer, Nina; Bergmann, Uwe
    Coherent nonlinear spectroscopies and imaging in the X-ray domain provide direct insight into the coupled motions of electrons and nuclei with resolution on the electronic length scale and timescale. The experimental realization of such techniques will strongly benefit from access to intense, coherent pairs of femtosecond X-ray pulses. We have observed phase-stable X-ray pulse pairs containing more than 3 × 107 photons at 5.9 keV (2.1 Å) with ∼1 fs duration and 2 to 5 fs separation. The highly directional pulse pairs are manifested by interference fringes in the superfluorescent and seeded stimulated manganese Kα emission induced by an X-ray free-electron laser. The fringes constitute the time-frequency X-ray analog of Young’s double-slit interference, allowing for frequency domain X-ray measurements with attosecond time resolution.
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    Ultrafast non-radiative dynamics of atomically thin MoSe2
    (Springer Nature, 2017) Lin, Ming-Fu; Kochat, Vidya; Krishnamoorthy, Aravind; Bassman, Lindsay; Weninger, Clemens; Zheng, Qiang; Zhang, Xiang; Apte, Amey; Tiwary, Chandra Sekhar; Shen, Xiaozhe; Li, Renkai; Kalia, Rajiv; Ajayan, Pulickel; Nakano, Aiichiro; Vashishta, Priya; Shimojo, Fuyuki; Wang, Xijie; Fritz, David M.; Bergmann, Uwe
    Photo-induced non-radiative energy dissipation is a potential pathway to induce structural-phase transitions in two-dimensional materials. For advancing this field, a quantitative understanding of real-time atomic motion and lattice temperature is required. However, this understanding has been incomplete due to a lack of suitable experimental techniques. Here, we use ultrafast electron diffraction to directly probe the subpicosecond conversion of photoenergy to lattice vibrations in a model bilayered semiconductor, molybdenum diselenide. We find that when creating a high charge carrier density, the energy is efficiently transferred to the lattice within one picosecond. First-principles nonadiabatic quantum molecular dynamics simulations reproduce the observed ultrafast increase in lattice temperature and the corresponding conversion of photoenergy to lattice vibrations. Nonadiabatic quantum simulations further suggest that a softening of vibrational modes in the excited state is involved in efficient and rapid energy transfer between the electronic system and the lattice.