- https://www.cells.es/ca/actualitat/agenda/esdeveniments-publics-dalba/ultra-bright-electron-beams-for-ultra-fast-science-new-tools-for-structural-dynamics-in-material-science-chemistry-and-biology
- Ultra-bright Electron Beams for Ultra-fast Science: New Tools for Structural Dynamics in Material Science, Chemistry and Biology
- 2017-03-03T14:30:00+01:00
- 2017-03-03T15:30:00+01:00
- Daniele Filippetto, Lawrence Berkeley National Laboratory
- Què
- events
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Mar 03, 2017
de 14:30 a 15:30 (Europe/Madrid / UTC100) - On
- ALBA Synchrotron, Maxwell Auditorium
- Nom de contacte
- Raquel Muñoz
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Ultrafast electron diffraction and microscopy techniques have been extensively applied to material and chemical science problems, demonstrating an enormous potential as techniques for structural dynamics characterization. Relativistic probe energies have been generated with radiofrequency-based (RF) accelerating cavities, providing high density pulses, and successfully applied to scientific problems, approaching and even beating 100fs temporal resolution.
The main challenge for UED instrumentation is related to the transverse beam quality. The achievable transverse coherence length at the sample is of the order of few nanometers for beam sizes of tens-to-hundreds of micrometers. Such probes are orders of magnitude larger than what is achievable with static electron microscopes, limiting the type of samples that can be studied and the scientific questions that can be addressed. Filling the gap in spatial resolution between static and dynamics experiments would provide a leap in electron instrumentation, enabling the study of dynamics around local defects and boundaries, and producing pulses of the right spatial scale to probe single molecules, non-periodic samples and nanostructures.
Large coherence lengths and small spot size could be produced at expenses of number of electrons within the pulse. At Lawrence Berkeley National Laboratory we have developed a new electron source (APEX) that, in addition to providing relativistic ultrashort pulses, is able to run at very high repetition rate (MHz), with an average electron flux of more than 3 orders of magnitude above state-of-art electron sources. Such enormous flux can then be used to probe rare events, or traded for enhanced transverse/longitudinal beam properties, providing probe sizes below 100nm and relative energy spreads in the 10-5 range, with enough electron flux for carrying out the experiment. An electron diffraction beamline (HiRES) based on the APEX source has been designed, built and successfully tested at LBNL.
