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PULSE visitor Jan-Michael Rost to give Photon Science Seminar, May 27

Jan-Michael Rost, Director of the Max Planck Institute for the Physics of Complex Systems, and PULSE sabbatical visitor, will be giving a talk entitled, "Slow electrons and fast protons from activation of matter with intense light pulses" as part of today's Photon Science Seminar. The seminar will begin at 3 pm in the Redtail Hawk Conference Room (SLAC Building 901, Room 108A). Please find a preview of the talk below.

Intense short laser pulses are usually associated with “high” energy phenomena such Above Threshold Ionization (ATI) in atoms and molecules. Experimental photo electron spectra from illuminating different targets with few cycle mid infrared pulses exibit a universal peak at a few eV, the so called “Low Energy Structure” (LES). We will show that soft recollisons of electrons are responsible for the LES in surprisingly far reaching complementarity to ATI which can be viewed as the consequence of hard recollisions. Both types of recollisions give rise to dynamically distinct and very different but universal characteristica, independent of target details. This fact allows us to analytically predict the pulse length dependent and focus averaged spectral position of the LES in good agreement with recent experiments.

In the second part of the talk we will use hydride clusters (from water, ammonia and methane molecules) to elucidate the role of proton dynamics in the explosion of such clusters when illuminated by intense X-ray pulses. We find that the maximal kinetic energy of the ejected protons reaches a maximum in a small but experimentally relevant intensity window of the light pulse accompanied by a significant reduction of the electron temperature in the target. Consequences, in particular for radiation damage, will be discussed analyzing the Coulomb explosion of Lyzozyme molecules.

PULSE Special Seminar: Dynamical Phase Control in Atomic and Nuclear Physics

PULSE will host a special seminar on Friday, May 15 at 2 pm in the Sycamore Conference Room (Building 40, Room 192). At this seminar, Andreas Kaldun from the Max Planck Institute, will present a talk entitled, "Dynamical Phase Control in Atomic and Nuclear Physics". 

Han Dao, PULSE research assistant, publishes first paper as a lead author

PULSE would like to congratulate Han Dao who had his first paper as a lead author published last month in the journal, Structural Dynamics. This research was carried out by the PULSE NPI group and is also one of the first occasions where Dr. Hasan DeMirci, PULSE Research Associate, was listed as the senior author. The paper, entitled "Goniometer based femtosecond X-ray diffraction of mutant 30S ribosomal subunit crystals", was made possible by combining the expertise of the PULSE NPI group in sample preparation, the development of sample handling hardware at the Stanford Synchrotron Radiation Light Source, and the exceptional user support at the Linac Coherent Light Source (LCLS) prior to and during the team's data collection. Through their research, the NPI group was primarily interested in "elucidating the contribution of this ribosomal protein to the overall subunit structure" and was able to demonstrate the feasibility of pursuing high resolution data collection at an x-ray free electron laser. In light of the proposed future of the MFX hutch at LCLS, the method used by the scientists in this paper could serve as a preview of what the user community might use there once it goes online.

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