Freiburg 2024 – scientific programme

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MO: Fachverband Molekülphysik

MO 22: Poster: Molecules in Strong Fields

MO 22.3: Poster

Thursday, March 14, 2024, 17:00–19:00, Tent C

Time-resolved Imaging of CH4 Fragmentation in Strong Laser Fields — •Weiyu Zhang, David Vacas Chicharro, Nikolas Rapp, Thomas Pfeifer, and Robert Moshammer — Max-Planck-Institut für Kernphysik, Saupfercheckweg 1, 69117 Heidelberg, Deutschland

With a Reaction Microscope (ReMi) [1] the ionization and dissociation dynamics of methane in strong laser fields were studied in a series of pump-probe experiments. For the creation of temporally separated laser pulses and pulse shaping a spatial light modulator (SLM) was used. It allows control of laser pulses in terms of amplitude, polarization, and phase [2, 3]. By employing the SLM technique we successfully compressed the laser pulses to below 10 fs and achieved a precise control over the time-delay between the two pulses. Upon strong-field ionization the molecule undergoes fragmentation and Coulomb explosion (CE) [4] and the corresponding ionic fragments are collected with the ReMi. For example, in the case of CE the initial inter-nuclear distances can be determined via the measurement of final kinetic energies, and in pump-probe measurements the evolution of the molecular geometry is visualized as function of time. Selected results will be presented and discussed.

References:

[1] J. Ullrich et al.,2003, Rep. Prog. Phys. 66, 1463-1545

[2] Stefanie Kerbstadt, 2016, MA thesis. Universität Oldenburg

[3] T Brixner and G Gerber, 2001, Opt. Lett. 26,557-559

[4] Larsen, J et al., 1998, J. Chem. Phys. 109, 8857-8863

Keywords: femtosecond laser pulses; molecular fragmentation; coincident measurement; Coulomb explosion; pulse shaping