Bonn 2025 – wissenschaftliches Programm
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MO: Fachverband Molekülphysik
MO 21: Poster – Interaction with Strong or Short Laser Pulses (joint session A/MO)
MO 21.8: Poster
Mittwoch, 12. März 2025, 17:00–19:00, Tent
Pulsed standing waves at 100 MHz repetition rate for multiphoton ionization experiments — •Jan-Hendrik Oelmann, Tobias Heldt, Lennart Guth, Lukas Matt, Thomas Pfeifer, and José R. Crespo López-Urrutia — Max-Planck-Institut für Kernphysik, Heidelberg, Germany
We investigate multiphoton ionization (MPI) at high laser intensity (1013 W/cm2) and high repetition rate (100 MHz) using a novel polarization-insensitive enhancement cavity for amplified near infrared frequency comb laser pulses. A velocity-map imaging (VMI) spectrometer is integrated into the cavity and allows measuring photoelectron angular distributions (PADs) [1]. By turning the laser polarization axis, we were able to tomographically reconstruct 3D PADs from xenon MPI, revealing resonant Rydberg states during ionization [2].
Additionally, the bow-tie cavity supports counter-propagating pulses forming an intense standing wave at the cavity focus. We use the intrinsic nanometric structure of this standing light field to study and control photoemission from a sharp tungsten tip at the nanometer scale [3]. For gas-phase ionization studies, colliding pulses offer the advantage of reducing the interaction volume at the focus and doubling the intensity [4].
[1] J. Nauta et al., Opt. Lett. 45, 2156 (2020). [2] J.-H. Oelmann et al., Rev. Sci. Instrum., 93(12), 123303 (2022). [3] T. Heldt et al., Nanophotonics, 2024. [4] T. Heldt et al., Opt. Lett. 49, 6825-6828 (2024)
Keywords: Multiphoton Ionization; Velocity-Map Imaging; Enhancement Cavity; Tomography; Standing Wave