Imaging of ultrafast processes in atoms and molecules
Nonlinear interactions of matter with attosecond XUV pulses
Theory of strong field processes
Strong field processes in solids
Msc. Johannes Blöchl
Msc. Ritika Dagar
Msc. Weiwei Li
Dr. Zilong Wang
What happens when matter is exposed to intense laser pulses with electric fields comparable to those holding the electrons bound to the nuclei? How can we use such strong electric fields to control and steer the electron motion with a precision reaching down into the attosecond time scale? These are questions addressed in the strong field physics team. We are working with different experimental setups to investigate these questions in various materials, ranging from atoms and molecules to solids. The work horse of our experimental research are ultrashort laser pulses generated with state-of-the-art laser systems, and with durations barely longer than a single light wave oscillation.
In the COLTRIMS (COLd Target Recoil Ion Momentum Spectroscopy) project, the interaction of near single cycle laser pulses with atoms and molecules is studied by measuring the momentum of the fragments (electrons and ions) in coincidence. The combination of COLTRIMS with single-shot carrier-envelope phase measurements enables the control of ionization and dissociation processes with sub-cycle temporal resolution.
Image: C. Hackenberger
When ultrashort and intense laser pulses are focused onto an atomic gas, different ionic charge states are generated upon multiple photoionization. The spatial distribution of the different charge states depends on the intensity distribution in the laser focus. By spatially resolving the charge state distribution, our ion microscopy technique provides access tointensity resolved ion yields. The technique is particularly well suited to studying ultrafast light-matter interactions in the XUV spectral range. It has recently allowed the first demonstration ofnonlinear interactions between attosecond XUV pulses and core electrons in xenon.
Image: C. Hackenberger
Reaction nanoscopy is a novel technique designed to study the interaction of few-cycle laser pulses with nanoparticles and molecules adsorbed on their surface. Nanoparticles are of great interest in nanochemistry since they offer unique properties as photo-catalysts due to their large surface area. Enhanced near-fields, induced on the nanoparticle’s surface under irradiation with ultrashort light pulses can be used to control molecular photoionization and dissociation reactions on the nanoscale.
All-optical nanoscopic spatial control of molecular reaction yields on nanoparticles
W. Zhang et al.
Optica 9, 551 (2022) | DOI: 10.1364/OPTICA.453915
Near-Field Induced Reaction Yields from Nanoparticle Clusters
P. Rosenberger et al.
ACS Photonics 7, 1885 (2020) | DOI: 10.1021/acsphotonics.0c00823
Few-cycle laser driven reaction nanoscopy on aerosolized silica nanoparticles
P. Rupp et al.
Nature Communications 10, 4655 (2019) | DOI: 10.1038/s41467-019-12580-0
In the ultrafast current project, we explore alternative routes to sample the field of few-cycle laser pulses. The principle relies on the generation of strongly driven currents in solids and gases. Beyond the application to CEP measurements and field sampling, we use the information contained in the ultrafast currents to gain a deeper understanding of the strong-field electron dynamics in various materials.