Surface Physics
Osterwalder Group
Greber Group

Ultrafast electron dynamics and scattering

Figure 1: Surface state and bulk sp-band of Ag(111) taken with a 2D-CCD detector at 6 eV photon energy.

This project is aimed at understanding the dynamics of electronic and structural changes in solid surfaces. Typical timescales of such ultrafast phenomena are in the range of attosecond to picoseconds.

We employ pump-probe spectroscopy with various light sources to investigate these processes. Typically the pump laser pulse is used to trigger the ultrafast process by promoting electrons from the ground state into excited states of the system under scrutiny. The probe pulse arrives at a well-defined delay after the pump pulse and provides information of the out-of-equilibrium electronic structure at a given instant in time.

Our lab is equipped with a commercial femtosecond laser system consisting of a mode-locked Ti:sapphire oscillator, regenerative amplifier and optical parametric amplifier that covers photon energies between 1.5 and 6.0 eV at typical pulse energies of 5 nJ, 40 μJ and 70 nJ at repetition rates of 76 Mhz, 250 kHz and 100 kHz, respectively.

Current projects

We built a new highly versatile and mobile surface science apparatus that can be connected to various specific photon sources available within NCCR MUST and at large scale research facilities. Here we probe the fastest possible electronic processes in solids including photoemission itself with attosecond resolution.
We advance established x-ray photoelectron diffraction (XPD) towards lower energies in the UV to probe the structure of solid surfaces and molecular adlayers.

In collaboration with the Ultrafast Laser Physics Group at ETH and the group of Prof. Markus Meuwly (Universität Basel) and several members of the National Center of Competence in Research Molecular Ultrafast Science and Technology NCCR MUST.


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Funding