Recent research highlights:


Electron spin polarization in strong-field ionization of Xenon atoms
Nature Photonics 10, 526-528 (2016)


Imaging the He2 quantum halo state using a free electron laser
PNAS 113, 51 (2016)

Electron localization in dissociating H2+ by retroaction of a photoelectron onto its source
PRL 116, 043001 (2016)
Observation of the Efimov state of the helium trimer
Science 348, 551 (2015)

Streaking Temporal Double-Slit Interference by an Orthogonal Two-Color Laser Field
PRL 114, 143001 (2015)

Imaging the structure of the trimer systems 4He3 and 3He4He2
Nat. Comm. 5, 5765 (2014)

Vortices associated with the wavefunction of a single electron emitted in slow ion-atom collisions
PRL 112, 083201 (2014)

Resonant Auger decay driving intermolecular Coulombic decay in molecular dimers
Nature 505, 664 (2014)

A Single Atom Antenna
PRL 111, 233004 (2013)

A molecular movie of interatomic Coulombic decay
PRL 111, 093401 (2013)

Attosecond movies without attosecond pulses:
Electron motion in dissociating H2+

Nature Communications, 4, 2177 (2013)

Momentum Transfer to a Free Floating Double Slit:
A Realization of Einstein's Thought Experiment

PRL 111, 103201 (2013)

Direct Determination of Absolute Molecular Stereochemistry in Gas Phase by Coulomb Explosion Imaging
Science 341, 1096 (2013)

Single photon double ionization: observatioin of a new mechanism
PRL 111, 013003(2013)

Probing the tunneling site of electrons in strong field enhanced ionization of molecules
Nature Communications (2012)

Spatial Imaging of the H2+ Vibrational Wave Function at the Quantum Limit
Physical Review Letters (2012)

Enhanced production of low energy electrons by alpha particle impact
We study the electron emission of Ne monomers and dimers after He+ ion impact ionization at a projectile energy of 162.5 keV/u.
PNAS (2011) vol. 108, no. 29, 11821-11824

Electron diffraction self imaging of molecular fragmentation in two step double ionization of water
Physical Review Letters (2011)

The "Over-Barrier-Model"
If a slow, highly charged projectile is moving into the target zone the Coulombic barrier between the projectile and the target decreases and the target electrons are "molecularized" and may, by a certain probability, be captured by the projectile.
PRL 104, 103201 (2010)

The breakup of helium dimers investigated in fast ion collisions
With alpha-particles at an energy of 150keV/u as projectile, we investigated the different break-up mechanisms of a helium dimer, finding different pathways for a double ionization of the dimer.

Hydrogen molecular ions in strong laserfields
Using the offset velocity of an accelerated H2+ beam we are able to perform the world-wide first and only experiment measuring protons as well as electrons in reactions of H2+ with short laserpulses.

Search for Differences in the Ionization Dynamics of H2 and D2
With a He+ projectile (energy 650 keV) we investigated the simultaneous ionization of projectile and target (loss mechanism) using H2 and D2 looking for differences in total ionization yield, predicted by C. A. Chatzidimitriou-Dreismann et al.

Intermolecular Coulombic Decay in water dimers - observation of an ultrafast decay mechanism
We observed a novel decay mechanism called "Intermolecular Coulombic Decay" (ICD) in water dimers.
Nature Physics (2010), doi:10.1038/NPHYS1498

Angular distribution of photoelectrons of H2 and its dependence on the internuclear distance
At 150eV we investigated the kinetic energy release (KER) and the angular distribution of the emmitted photoelectrons with linear and circular polarized photons at the ALS in Berkeley. Results show a difference in the mean value of the KER at different polarizations.

Photoionization of the helium dimer - how to ionize two atoms with a single photon
The mechanism of how a double ionization of a helium dimer by absorption of just one photon can take place have been investigated at the BESSY in Berlin.
Phys. Rev. Lett. 104, 153401 (2010)
Phys. Rev. Lett. 104, 133401 (2010)

Double Photoemission from Superconductors
The mechanism of how cooper-pairs are created in High-Temperature Superconductors (HTSC) is under heavy debate. With the approach of the COLTRIMS-System we try to get new insights into this topic.

Ultrafast Probing of Core Hole Localization in N2
Chemists and physicists have long debated the question of whether the core vacancy created in a homonuclear diatomic molecule by absorption of a single x-ray photon is localized on one atom or delocalized over both. We have been able to clarify this question.
Science 320, 920 (2008)

Decoherence in the smallest double slit
Interference and decoherence in H2 double ionization In double ionization of H2 by high energy photons one of the ejected electrons shows a double slit interference pattern, the second one forms a minimal environent causing the first step of the quantum-to-classical transtion.
Science 318, 949 (2007)
PRL 100, 133005 (2008)

Proofing virtual photons in interatomic coulombic decay
ICD for dipole allowed transition is found to be fast, dipole forbidden transition decay only after.the dimer has contracted so the electronic wave functions overlap.
PRL. 99, 153401 (2007)

Breaking the symmetry of H2
Even though the simplest molecule in the universe, H2, is perfectly symmetric, one can break its symmetry by absorption of one single photon. We examined a process where different ionization pathways involving doubly excited states mix and lead to asymmetric photo electron angular distributions.
Science 315, 629 (2007)
Complete Fragmentation of the Hydrogen molecule
In the measurements presented here quadruple coincidences (2 electrons and 2 recoil ions) could be realized. Thus it was possible to derive electron momentum distributions relative to the orientation of the molecular axis and to the polarization vector of the ionizing photon. Double photo ionization at 80eV shows an unexpected strong dependene on the internuclear distance

Experimental Observation of Interatomic Coulombic Decay (ICD) in Neon Dimers
Coincidence detection of electrons and ionic fragments after 2s ionization of Neon dimers give unique fingerprint of interatomic coulombic decay.

Auger electron emission from fixed-in-space CO
The Auger decay of core ionized CO has been investigated by an Auger-electron fragment ion coincidence. We confirm the validity of the two step model and find a narrow search light cone of Auger electrons emitted in the direction of the Oxygen, modulated by a diffraction pattern.
Ground state electron correlation in fast Transfer Ionization
We use a fast projectile to remove a fast electron from the Helium ground state at large distances from the nucleus. The shake off of the second electron gives a direct access to the correlated motion in the non S2 contribution to the gound state.

Circular Dichroism in K-Shell Ionization of small molecules
We have measured the angular distributions of 1s-photoelectrons excited by circularly and linearly polarized light from fixed-in-space CO and N2 molecules. A strong circular dichroism is found for both molecules.

Mechanisms of Photo Double Ionization of Helium by 529 eV Photons
The angular distributions show that the very slow electrons get into the continuum via shake-off while slightly faster electrons are mostly emitted at 90 degree to the fast electron indicating an (e,2e) like collision between the two electrons (TS1).
Electron repulsion in nonsequential strong field double ionization
We have measured the coincident momenta of both electrons emitted in argon double ionization at 780 nm and 4.7*1014W/cm.

Double photoelectron ejection from surfaces
First results on double photo emission from a Ag(100) surface induced by 55eV photons.