Hannover 2020 – scientific programme
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MO: Fachverband Molekülphysik
MO 2: Atomic Clusters (joint session A/MO)
MO 2.5: Talk
Monday, March 9, 2020, 15:30–15:45, a320
Coherent diffractive imaging of excited state population dynamics in a helium droplet — •Björn Kruse1, Benjamin Liewehr1, Christian Peltz1, and Thomas Fennel1,2 — 1Institut für Physik, Universität Rostock, Albert-Einstein-Str. 23, D-18059 Rostock — 2Max-Born-Institut für Nichtlineare Optik und Kurzzeitspektroskopie, Max-Born-Str. 2A, D-12489 Berlin
Coherent diffractive imaging (CDI) of isolated helium nanodroplets has been successfully demonstrated with a lab-based HHG source [1] operating in the vicinity of the 1s - 2p transition of helium. To reconstruct the shape and orientation of nanoparticles, CDI experiments have so far been analyzed in terms of a classical linear response description [2]. However, for high intensities and especially for resonant excitation, population dynamics of bound electrons and stimulated emissions may become important, violating the assumptions underlying a linear description. To what extend and how nonlinear processes influence CDI scattering images is currently largely unknown. In our theoretical analysis, we describe the quantum-mechanical few-level bound state dynamics using a density matrix formalism and incorporate this into a 3D Maxwell solver based on the finite-difference time-domain method (FDTD). We discuss the spatio-temporal population dynamics and its impact on scattering images.
[1] D. Rupp et al., Nat. Commun. 8, 493 (2017)
[2] I. Barke et al., Nat. Commun. 6, 6187 (2015)