Berlin 2015 – wissenschaftliches Programm

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O: Fachverband Oberflächenphysik

O 81: Gerhard Ertl Young Investigator Award

O 81.3: Vortrag

Donnerstag, 19. März 2015, 11:30–12:00, MA 042

Atto-to-Nanosecond Electron Dynamics at Surfaces probed by Time-Resolved Core-Level Photoelectron Spectroscopy — •Stefan Neppl — Lawrence Berkeley National Laboratory, Berkeley, CA, USA

In the first part of my talk, I will discuss recent experiments that address the ultrafast dynamics inherent to all photoemission processes in condensed phase matter. In these measurements, an XUV attosecond light pulse launches photoelectron wave packets inside a solid. The emission dynamics of the photoelectrons are probed with a few-cycle VIS/NIR laser pulse [1,2]. We demonstrate that this streaking approach is capable of resolving subtle emission delays between electron wave packets that are released from different energy levels of the solid with a precision of only a few attoseconds (1 as = 10-18 s). For the simple metal magnesium we show that these time shifts can be interpreted as the real-time observation of photoelectrons propagating through the crystal lattice prior to their escape into vacuum [3]. In the second part, I will describe the implementation of femto- and picosecond time-resolved photoelectron spectroscopy at the Linac Coherent Light Source and at the Advanced Light Source with the goal to follow light-driven electron dynamics at dye-semiconductor interfaces on femto- to nanosecond timescales [4,5].

[1] Cavalieri et al. Nature 449, 1029 (2007); [2] Neppl et al. Phys. Rev. Lett. 109, 087401 (2012); [3] Neppl et al. Nature (2014) accepted; [4] Siefermann et al. J. Phys. Chem. Lett 5, 2753 (2014); [5] Neppl et al. Faraday Discuss. 171, 219 (2014).