Regensburg 2022 – wissenschaftliches Programm

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O: Fachverband Oberflächenphysik

O 2: Ultrafast Electron Dynamics at Surfaces and Interfaces 1

O 2.10: Vortrag

Montag, 5. September 2022, 12:45–13:00, H3

Coherent Time-Resolved Above-Threshold Plasmoemission from the Au(111) Shockley Surface State — •Pascal Dreher, David Janoschka, Alexander Neuhaus, Michael Horn-von Hoegen, and Frank Meyer zu Heringdorf — Faculty of Physics, University of Duisburg-Essen, 47048 Duisburg, Germany

Strong nonperturbative interactions of an intense driving light field with the electronic band structure in a solid can result in exotic material properties that do not exist under equilibrium conditions. For suitable driving conditions, Floquet theory predicts that the originally unperturbed electronic structure is modified by the formation of light-dressed electron states in strong fields. Observing such dressing requires electronic state resolution as well as precise control over the intense periodic driving field to overcome intrinsic dissipation and decoherence in the solid.

Here, we explore nano-focusing of femtosecond surface plasmon polariton (SPP) pulses on flat surfaces as a possible route towards strong-field control over electronic states within a solid using time- and angle-resolved photoemission spectromicroscopy. We observe above-threshold electron emission from the Au(111) Shockely surface state by the absorption of up to seven SPP quanta. Two-dimensional time-resolved photoelectron spectroscopy using a birefringent delay line provides us with direct access to the coherent and incoherent dynamics of the electron emission process with attosecond precision. The presented results clearly indicate the coherent nature of the interaction of the intense SPP nano-focus with the band structure of the material.