11-04 :: April/May 2011

nanotimes News in Brief

63

Figure 1: Mechanism of the acceleration of electrons near silica nanos- pheres. Electrons (depicted as green particles) are released by the laser field (red wave). These electrons are first accelerated away from the particle surface and then driven back to it by the laser field. After an elastic collision with the surface, they are accelerated away again and reach very high kinetic energies. The figure shows three snapshots of the acceleration (from left to right): 1) the electrons are stopped and forced to return to the surface , 2) when reaching the surface, they elastically bounce right back 3) the electrons are accelerated away from the surface of the particle reaching high kinetic energies. © Christian Hackenberger/LMU

Figure 2: Amplified near-fields at the poles of a silica nanosphere. The local field on the polar axis is plotted as function of time, where time within the few-cycle wave runs from the lower right to the upper left. The fields show a pronounced asymmetry along the polarization axis of the laser (i.e. along the rims and valleys of the wave). This asym- metry leads to higher energies gained by electrons on one side of the nanoparticle as compared to the other side. For the given example the most energetic electrons are emitted from the backside, where the highest peak field is reached. The energies of the electrons and their emission directions are determined from the experiment. © Christian Hackenberger/LMU