Hannover 2016 – wissenschaftliches Programm
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MO: Fachverband Molekülphysik
MO 11: Posters 2: Novelties in Molecular Physics: Femtosecond Spectroscopy, Quantum Control, Electronic Spectroscopy, Biomolecules and Photochemistry
MO 11.7: Poster
Dienstag, 1. März 2016, 16:30–19:00, Empore Lichthof
Optimisation of strong laser field-free alignment using tailored light fields — •Evangelos Thomas Karamatskos1,2, Terry Mullins1, Sebastian Trippel1, Rosario González-Férez3, Arnaud Rouzée4, and Jochen Küpper1,2,5 — 1Center for Free-Electron Laser Science, DESY — 2Department of Physics, University of Hamburg — 3Instituto Carlos I, Universidad de Granada — 4Max Born Institute, Berlin — 5The Hamburg Center for Ultrafast Imaging, University of Hamburg
Laser induced electron diffraction and molecular frame photoelectron angular distribution measurements have emerged as potential new techniques for imaging molecular structure and dynamics. Control over the rotational motion of molecules represents the first step towards this goal. Here, we present a combined theoretical and experimental effort to optimise the degree of laser field-free alignment of molecules in the gas phase. We start by solving the time-dependent Schrödinger equation for a rigid rotor in interaction with a non-resonant laser field and a static electric field [2] and use an iterative learning-loop algorithm to determine the ideal pulse shape that optimises the degree of alignment. These calculations serve as a guide to complement the experiments where the temporal profile of the alignment laser pulse is optimally tailored using a spatial light modulator in a feedback loop, using the same evolutionary strategies as in the simulations. We discuss the simulation results and the experimental realization on the example of the linear molecule OCS. [1] Stapelfeldt et al., Rev. Mod. Phys. 75, 543 (2003) [2] Omiste et al., J. Chem. Phys. 135, 064310 (2011)