13–20 Sept 2013
Magnus-Haus of the German Physical Society
Europe/Berlin timezone

Ultrafast surface dynamics probed with time resolved photoemission at FLASH

Not scheduled
20m
Magnus-Haus of the German Physical Society

Magnus-Haus of the German Physical Society

Am Kupfergraben 7 10117 Berlin

Speaker

Mr Florian Hieke (Institue for Experimental Physics and Center for Free Electron Laser Science)

Description

Time resolved photoemission from core levels (trPES) at FELs is a tool for studying surface dynamics in real-time. Basis for this is the sensitivity of core-levels to their chemical environment. By probing their spectral evolution after an ultra-short excitation one can get insight on both, electronically caused excitations (fs- up to several-ps time-scales) as well as responses of the crystal lattice sub-ps to hundreds of ps).

In the present study we monitored the evolution of the 4f core levels of clean Ir(111) after an ultra-short (<120fs) optical excitation (800nm) by means of trPES at a photon energy of 198eV. The experiments were performed at the Free Electron Laser FLASH at the plane-grating monochromator beamline PG2. The setup allowed us to resolve temporal changes with a precision down to 1,1ps.

By analyzing the recorded data on a shot-to-shot basis we are able to fully characterize and control spectral shifts and broadening induced by X-ray and 800nm induced space-charge effects.

We observe a pump induced broadening in the surface component of the 4f lines which fully relaxes after 2ps. The early-component (<1,1ps) of this spectral broadening corresponds to the appearance of sidebands whereas a remaining excitation in the post-sideband time-scales (>1,1ps) can be explained by an increased electronic temperature.

Primary authors

Mr Florian Hieke (Institue for Experimental Physics and Center for Free Electron Laser Science) Dr Harald Redlin (DESY Hamburg) Martin Beye (Helmholtz Zentrum Berlin für Materialien und Energie) Dr Martina Dell'Angela (Institute for Experimetal Physics and Center for Free Electron Laser Science) Dr Natalia Gerasimova (European XFEL GmbH, ) Mr Nils Gerken (Institute for Experimetal Physics and Center for Free Electron Laser Science) Nomi Sorgenfrei (Universität Hamburg, Department of Physics and Centerfor Free-Electron Laser Science) Wilfried Wurth (INiversität Hamburg, Department of Physics and center for Free electron Laser Science)

Presentation materials