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O: Fachverband Oberflächenphysik

O 48: Poster Session - Electronic Structure of Surfaces: Spectroscopy, Surface States

O 48.12: Poster

Dienstag, 17. März 2020, 18:15–20:00, P2/EG

Designing High Energy Resolution Laser-Based Tunable Pump and Probe ARTOF Workstations — Alexander Forsman, •Viktor Jonsson, Luca Piazza, Magnus H. Berntsen, Jonas Weissenrieder, and Oscar Tjernberg — Materials Physics, KTH Royal Institute of Technology, Electrum 229, SE-16440 Kista, Stockholm, Sweden

We present recent upgrades of a laser-based angle-resolved time-of-flight spectrometer including our plans to move our system to modern facilities, add time-resolving capabilities and radically improve the optical design. The current system is driven by a 45W fiber laser 300 fs pulses at 1030 nm. The 9^th,15^th and 21^st harmonic is generated in an argon-gas jet, separated by a horizontal groove grating and focused by 2 toroidal mirrors to around 0.1mm at the sample position. We demonstrate an energy resolution of 20 meV at space charge limited flux. In the new lab a Tangor Amplitude laser will generate 500 fs to 2 ps pulses for the probe while feeding the fiber laser which will after an optical parametric amplification act as a tunable pump at wavelengths from 200 to 1000 nm. The new optical design relies on movable narrow bandwidth spherical mirrors inside a monochromator. Instead of using filters to separate the 5· 10⁻¹¹ vacuum from the much lower 10⁻⁶ vacuum in the monochromator we use sets of turbo pumps and a XIA differential pump to enable a free path for the XUV to the sample position. Our new system will increase the flux making it feasible to probe using the additional 27^th harmonic.