Hannover 2016 – wissenschaftliches Programm
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MO: Fachverband Molekülphysik
MO 14: Posters 3: Novelties in Molecular Physics: Theory of Molecular Dynamics, Collisions and Energy Transfer, and Experimental Techniques
MO 14.22: Poster
Mittwoch, 2. März 2016, 16:30–19:00, Empore Lichthof
Optical focusing of isolated particles for diffractive imaging experiments — •Salah Awel1, 2, Rick Kirian4, Jochen Küpper1,2,3 und Henry Chapman1,2,3 — 1Center for Free-Electron Laser Science, DESY — 2The Hamburg Center for Ultrafast Imaging, University of Hamburg, — 3Department of Physics, University of Hamburg — 4Arizona State University, Tempe
The short, intense, and coherent x-ray pulses produced by x-ray free-electron lasers (XFELs) have lead to major advances in macromolecular structure determination. Single-particle imaging is among the new paradigm to emerge consists of directing a stream of randomly oriented bioparticles across the focus of the XFEL beam so that high-resolution 3D structure can be constructed from diffraction patterns of multiple identical particles. Presently, the difficulty of efficiently delivering bioparticles to a sub-micrometer x-ray focus is a limiting factor. For a 100 nm x-ray focus, current sample delivery efficiencies (fraction of particles intercepted by an x-ray pulse) are on the order of 10−7 on average, and hit fractions (fraction of x-ray pulses intercepting a particle) are below 0.1%. In order to mitigate this problem, we are developing techniques for guiding aerosolized nanoparticles to the X-ray focus with specially shaped laser illumination [1]. Our current experiments aim at transversely confining streams of aerosolized particles as they exit an aerosol injector with a counter-propagating "hollow" quasi-Bessel beam, using radiation pressure and thermal (photophoretic) forces [2].
[1] Eckerskorn et al., Opt. Exp. 21, 30492-30499 (2013).
[2] Eckerskorn et al., Phys. Rev. Applied (accepted 29 Oct. 2015).