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DS: Fachverband Dünne Schichten
DS 21: Optical Analysis of Thin Films
DS 21.3: Vortrag
Freitag, 22. März 2024, 10:15–10:30, A 053
Probing ultrafast dynamics employing a laser-driven broadband soft X-ray reflectometer — •Jasmin Jarecki1, Martin Hennecke1, Lutz Ehrentraut1, Matthias Schnürer1, Stefan Eisebitt1, 2, and Daniel Schick1 — 1Max-Born-Institut für Nichtlineare Optik & Kurzzeitspektroskopie, Berlin, Germany — 2Institut für Optik & Atomare Physik, TU Berlin, Germany
Soft X-ray reflectometry (XRR) combines elemental and chemical sensitivity when hitting core-to-valence resonances, few-nanometer spatial resolution due to short X-ray wavelengths, and femtosecond temporal resolution when employing ultrashort sources. This allows probing of ultrafast dynamics of buried layers and across interfaces of stratified nanostructures. Here, we present a laboratory-based setup for time-resolved XRR, employing broadband soft X-ray pulses with energies ranging from 200 to 600 eV and pulse durations of 26 fs provided by a high harmonics generation (HHG) source. In contrast to synchrotron radiation or FEL sources, the quasi-continuous spectrum of the HHG offers efficient probing of broad spectra, e.g. across L-edges of transition metals, and of a large volume in reciprocal space in only a single acquisition. We benchmark our setup by probing laser-induced structural dynamics of a Mo/Si superlattice (SL). In very good agreement with simulations, we observe a shift of the 1st SL Bragg peak in reciprocal space probed at photon energies around 500 eV. Our results are an important step towards accessing also ultrafast electronic and magnetic dynamics in similar scattering experiments at such high photon energies outside of large-scale facilities.
Keywords: Soft X-ray reflectometry; HHG light source; ultrafast dynamics; white light probing