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AMO PHYSICS SEMINAR


"Controlled electron acceleration from nanoparticles and clusters"


Matthias F. Kling
J.R. Macdonald Laboratory
Physics Department, Kansas-State University


ABSTRACT 

The talk will highlight two recent studies on electron acceleration from nanometer-sized materials. In the first study we explored the emission and directional control of highly energetic electrons from isolated dielectric nanoparticles in few-cycle waveform-controlled laser fields [1]. The momentum distributions of the emitted electrons were obtained by velocity-map imaging. The angular resolved observation of these electrons provides insight into their dynamics and the surface charging of the particle [2]. Liberated electrons are accelerated / decelerated in the local field at the surface (see figure), which exceeds the external laser field, and are affected in their dynamics by the build-up of a surface trapping potential and electron-electron interactions. By using a beam of isolated nanoparticles, the target is replaced after every laser shot and we can explore the regime near, at and beyond the material damage threshold. The extremely short pulse duration of only a few cycles in our studies ensures that the electron dynamics responsible for the observed phenomena occurs before any nuclear dynamics. In the second study, carried out in collaboration with the University of Rostock, Germany, we have explored the controlled acceleration of electrons in Ag clusters using waveform controlled laser fields. Here, we tuned the plasmonic properties of the clusters by preheating them with a second laser pulse.

References
  1. S. Zherebtsov et al., Nature Phys. 7, 656 (2011).
  2. S. Zherebtsov et al., New J. Phys. 14, 074010 (2012).



Friday, November 30, 2012
IQSE 578, 2:00 p.m.
Mitchell Physics Building


Department of Physics and Astronomy
Texas A&M University

(Coffee and Cookies to be served at 1:45 p.m.)