Erlangen 2018 – wissenschaftliches Programm
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A: Fachverband Atomphysik
A 20: Attosecond Science III
A 20.4: Vortrag
Dienstag, 6. März 2018, 15:15–15:30, K 1.011
Finite system effects on high harmonic generation: from atoms to solids — •Kenneth Hansen1, Dieter Bauer2, and Lars Bojer Madsen1 — 1Department of Physics and Astronomy, Aarhus University, DK-8000, Denmark — 2Institute of Physics, University of Rostock, 18051 Rostock, Germany
Using time-dependent density field theory (TDDFT)[1] high harmonic generation (HHG) has been studied in one-dimensional structures of intermediate sizes from a single nucleus upto hundreds of nuclei.
The well known HHG cutoff for atomic systems is observed to extent linearly with system size and is found to converge into previously observed cutoffs for bulk solids only for large systems. The change from atomic HHG to solid state HHG is observed from system sizes of 6-8 nuclei and is first fully converged at system sizes of 60 nuclei.
The systems size dependence of the observed HHG cutoffs is found to follow the limitations of movement of classical electron-hole pairs in the band structure. Because of the correlation between recombination energy and electron-hole propagation length high energy recombination events are not possible in small systems, but become available for larger systems resulting in the change of the cutoff energies with system size.
When varying the field intensity we observe that the cutoffs move linearly with the intensity even for small systems that are far from a true bulk solid.
[1] Kenneth K. Hansen, Tobias Deffge, Dieter Bauer, High-order harmonic generation in solid slabs beyond the single-active-electron approximation, Phys. Rev. A 96, 053418 (2017).