Freiburg 2024 – scientific programme

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A: Fachverband Atomphysik

A 30: Precision Spectroscopy of Atoms and Ions IV (joint session A/Q)

A 30.5: Talk

Thursday, March 14, 2024, 15:30–15:45, HS 1098

Using Non-linear Dissociation Processes of BeH+ for the Alignment of the Laser Pulse Overlap in XUV Frequency Comb Spectroscopy of He+ — •Florian Egli, Jorge Moreno, Theodor Wolfgang Hänsch, Thomas Udem, and Akira Ozawa — Max-Planck-Institut für Quantenoptik, Garching, Deutschland

The energy levels of hydrogen-like atoms and ions are accurately described by bound-state quantum electrodynamics (QED). With spectroscopic measurements of hydrogen and hydrogen-like atoms, the Rydberg constant and the proton charge radius can be determined. The comparison of the physical constants obtained from different combinations of measurements serves as a consistency check for the theory. The hydrogen-like He⁺ ion is an interesting spectroscopic target for QED tests. Due to their charge, He⁺ ions can be held nearly motionless in the field-free environment of a Paul trap, providing ideal conditions for high-precision measurements. The 1S-2S two-photon transition in He⁺ can be directly excited by an extreme-ultraviolet frequency comb at 60.8 nm generated by a high-power infrared frequency comb using high-order harmonic generation (HHG). In order to perform Doppler-free spectroscopy on the 1S-2S transition, the frequency comb is split into double pulses which are overlapped at the ions. As a signal for the pulse overlap alignment, we investigate non-linear dissociation processes of BeH⁺. The processes discussed here are using 204 nm and 255 nm light, which can be generated from our infrared frequency comb.

Keywords: Paul Trap; High-Harmonic Generation; QED Test; Frequency Comb; Molecular Dissociation