Dresden 2020 – wissenschaftliches Programm
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O 18.8: Vortrag
Montag, 16. März 2020, 17:00–17:15, WIL A317
Strong-Field Angle-Resolved Plasmoemission Spectroscopy — •Pascal Dreher, David Janoschka, Jan-Henrik Herrig, Michael Horn-von Hoegen, and Frank-J. Meyer zu Heringdorf — Faculty of Physics, University of Duisburg-Essen, Germany
Photoemission in strong fields has received a lot of attention in the past and the coherent interaction of electrons with the field after the emission process has been revealed, i.e. using plasmonic near-field enhancement at nanotips. The behavior of electrons within the solid, however, can as well become dominated by the influence of strong fields, and the respective electron dynamics is expected to be fundamentally different from the electronic equilibrium. Clarifying the dominant interaction processes in this case ultimately requires electronic state resolution as well as precise control over the exact field.
We combine nanofocusing of femtosecond surface plasmon polariton (SPP) pulses on flat surfaces with photoemission electron microscopy to achieve angle-resolved plasmoemission spectroscopy (ARPLES) in the strong-field regime. The emission of electrons from the Au(111) Shockely surface state into SPP-dressed electron final states by the absorption of up to seven SPP quanta is observed. The ponderomotive energy that the emitted electrons acquire within the strong plasmonic nanofocus is determined and provides us with a direct measure for the transient SPP field strength in the focus point.