27. March 2019

Jochen Küpper

Controlled molecules and nanoparticles

Center for Free-Electron Laser Science (CFEL) / Hamburg, Germany

High-resolution imaging of molecular structure and dynamics has evolved as a key paradigm to unravel the spatiotemporal evolution of (bio)molecular systems during (bio)chemical reactions. Single-particle diffractive imaging (SPI) is emerging as a new technique for 3D imaging of aerosolized nanoparticles at x-ray free-electron lasers (XFELs). However, one of the primary bottlenecks in realizing SPI is the efficient delivery of isolated, reproducible target particles into the x-ray focus. Generally, all these novel imaging approaches could strongly benefit from, or simply are enabled by, strongly controlled samples that allow to experimentally average over many molecules while still observing the single molecule’s “movie”.

In this keynote, I will discuss our approaches for controlled delivery of nanoscale objects, i.e., large biological molecules and nanoparticles, into (near) atomic-resolution imaging experiments. The control schemes include the shockfreezing of particles, the preparation of focused beams of cold molecules and nanoparticles, and the laser-control of nanoparticle motion. The experiments are complemented by a detailed simulation pipeline, which provides quantitative insight into the control and further improvements as well as estimates of cooling rates and temperatures. Time permitting, I will show some early results from single-particle imaging experiments at the European XFEL.


Short bio

Jochen Küpper has pioneered methods to strongly control complex molecules in the gas phase, including the spatial separation of neutral molecular species, such as conformers, cluster sizes, and individual quantum states, and advanced methods of fixing these molecules in space. These samples are exploited in experiments ranging from chemical reactivity studies to the atomic resolution imaging of ultrafast chemical dynamics. Recently, he has initiated the development of comparable methods for biological and artificial nanoparticles for the controlled and reproducible delivery of very large molecules and nanoparticles into single-particle imaging experiments. We have developed theoretical and computational tools related to the molecular control that provide spectroscopic-accuracy descriptions of molecules and their nuclear dynamics even in strong electric fields. Exploiting these, we have proposed novel approaches toward the creation, investigation, and control of molecular chirality.

Jochen Küpper studied chemistry at Heinrich-Heine Universität Düsseldorf, where he received his doctorate for precision spectroscopy of complex molecules. He was a postdoc at the University of North Carolina at Chapel Hill, NC, USA and the FOM Instituut voor Plasma Fysica, Nieuwegein, The Netherlands. He was a group leader at the Fritz-Haber-Institut der MPG, Berlin, Germany, and received his Habilitation in Experimental Physics from Freie Universität Berlin. He holds a joined call as a group leader at Deutsches Elektronen-Synchrotron DESY and a professor of physics at Universität Hamburg; he is also adjunct professor of chemistry and a principal investigator of the cluster of excellence ‘Advanced Imaging of Matter’ at Universität Hamburg.

Recognitions
  • Nernst-Haber-Bodenstein Prize of the German Bunsen Society for Physical Chemistry
  • Fellow of the Royal Society of Chemistry
  • ERC Consolidator Grant COMOTION
  • Feodor-Lynen Fellowship of the Alexander von Humboldt Foundation
  • Rao Prize
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