Dresden 2011 – wissenschaftliches Programm
Bereiche | Tage | Auswahl | Suche | Aktualisierungen | Downloads | Hilfe
HL: Fachverband Halbleiterphysik
HL 82: Ultrafast Phenomena
HL 82.4: Vortrag
Donnerstag, 17. März 2011, 15:15–15:30, POT 251
Coherent Lattice Vibrations in TiO2 — •Elisabeth Bothschafter1,2, Alexander Paarmann3, Nicholas Karpowicz2, Reinhard Kienberger1,2, Ralph Ernstorfer1,2,3, and Ferenc Krausz2,4 — 1Fakultät für Physik, TUM, Garching — 2Max-Planck-Institut für Quantenoptik, Garching — 3Fritz-Haber-Institut der MPG , Berlin — 4Department für Physik, LMU, Garching
Ultrafast time-resolved reflectivity measurements with femtosecond pulses allow investigations of the fast interplay between electronic and structural dynamics triggered by nonequilibrium electron distributions (e.g. [1]).
Here we study the ultrafast optical reflectivity changes of the rutile TiO2(110) surface with sub-5-fs ultraviolet pump and probe pulses centered at 5 eV. At the overlap of pump and probe the reflected intensity drops by 3.5% and is subsequently modulated at the frequency of the A1g phonon at 18.1 THz [2]. The above bandgap excitation represents an effective charge transfer within the unit cell as the valence band density of states (DOS) is dominated by O2p states whereas the conduction band has mainly Ti3d character [3]. We assume that the abrupt change in the potential energy surface upon excitation induces the observed coherent lattice oscillation.
[1] M. Hase, M. Kitajima, A. M. Constantinescu, H. Petek, Nature 426(6), 51 (2003). [2] C. Lee et al., Phys. Rev. B 50, 13379 (1994). [3] H. Wang, J.P. Lewis, J. Phys., Condens. Matter 18, 421-434 (2006).