Regensburg 2025 – wissenschaftliches Programm
Bereiche | Tage | Auswahl | Suche | Aktualisierungen | Downloads | Hilfe
O: Fachverband Oberflächenphysik
O 99: Ultrafast Electron Dynamics IV
O 99.6: Vortrag
Freitag, 21. März 2025, 11:45–12:00, H11
Ultrafast energy flow among electrons and phonons in a Pb/Si nanoscale heterosystem — •Christian Brand1, Mohammad Tajik1, Tobias Witte1, Laurenz Rettig2, Birk Finke1, Björn Sothmann1,3, Uwe Bovensiepen1,3, and Michael Horn-von Hoegen1,3 — 1Department of Physics, University of Duisburg-Essen, Germany — 2Department of Physical Chemistry, Fritz Haber Institute, Germany — 3Center for Nanointegration Duisburg-Essen, Germany
In condensed matter, microscopic excitations interact on ultrafast time scales. The combination of suitable time domain experiments allows the analysis of processes such as the energy transfer from electrons to the nuclei subsequent to femtosecond laser pulse excitation. In this study, we used time-resolved photoelectron spectroscopy and ultrafast electron diffraction to probe the spatially confined dynamics of electrons and phonons in ultrathin epitaxial Pb films on Si(111). While the electrons lose their excess energy within 400 fs, the lattice vibrational displacements gradually increase over 3-8 ps. Within the time gap, the energy is transiently stored in high-frequency phonon modes as simulated in a three-temperature model. Their temperature is experimentally accessible by the transient electron temperature after equilibration with such hot phonons. The excitation of low-frequency phonons and the subsequent thermalization and equilibration of the lattice are facilitated by anharmonic phonon-phonon coupling within the Pb film.
Keywords: ultrafast dynamics; electron dynamics; lattice dynamics; ultrathin films; energy flow