Regensburg 2019 – wissenschaftliches Programm

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O: Fachverband Oberflächenphysik

O 63: Poster Wednesday: Ultrafast Processes

O 63.2: Poster

Mittwoch, 3. April 2019, 17:45–20:00, Poster B1

Quenching of charge density wave states in ultrafast transmission electron microscopy — •Till Domröse, Thomas Danz, and Claus Ropers — 4th Physical Institute - Solids and Nanostructures, University of Göttingen, Germany

Ultrafast transmission electron microscopy (UTEM) allows for investigation of nanoscale dynamics in a laser-pump/electron probe scheme [1]. Employing photoemission from a Schottky emitter, the Göttingen UTEM provides spatial resolution down to the subnanometer regime with down to 200fs temporal resolution [2].

Here, we present a time-resolved investigation of charge density wave (CDW) state quenching in UTEM. The diffraction pattern of 1T-TaS₂ in its nearly-commensurate (NC) phase gives insights into structural dynamics triggered upon optical excitation by analyzing diffraction intensities associated with the periodic lattice distortion (PLD) coupled to the CDW. The temporal evolution of the CDW amplitude and the transient lattice fluctuations are followed with femtosecond resolution over a range of excitation fluences. Following an initial quench of the CDW/PLD amplitude in the NC phase, we observe a partial recovery within few picoseconds and the excitation of a broad phonon population.

[1] A. H. Zewail, Science 328, 187 (2010)

[2] A. Feist et al., Ultramicroscopy 176, 63 (2017)