T3: Ultrafast electronic decay and fragmentation dynamics at XUV and X-ray wavelength

T3: Ultrafast electronic decay and fragmentation dynamics at XUV and X-ray wavelengths

We investigate the femtosecond relaxation dynamics following the interaction of molecules and nanoparticles with ultrashort XUV and X-ray pulses. Our goal is to understand photoionization and fragmentation mechanisms of isolated systems at these wavelengths. We are currently following two pathways:

Ultrafast relaxation dynamics of molecular cations

Sketch of the time-compensated monochromator beamline used to select individual harmonics

Evgenii Ikonnikov, Lorenz Drescher, Jochen Mikosch, Oleg Kornilov

One of the main mechanisms following the interaction of a molecule with a high energy photon is the removal of one electron resulting in the formation of a molecular cation that, depending on the photon energy, can further fragment. We use either broadband XUV pulses or individual harmonics obtained from a novel time-compensating monochromator to prepare excited cations and resolve in time the photoionization and fragmentation dynamics using single photon XUV ionization and photoion and photoelectron detection.

XUV refractive optics

Refraction in a dense He jet that serves as an XUV prism. XUV radiation close to the atomic resonances is either deflected upwards or downwards.

Oleg Kornilov, Bernd Schütte

Refraction of visible light is well known and is the underlying working principle of glasses, camera objectives and microscopes. We study and exploit refraction in the XUV range using dense atomic and molecular jets that form prisms or lenses. These deformable optical elements have a much higher transmission than typical reflective XUV mirrors or gratings. We further apply pump-probe schemes to control and exploit the transient refractive properties of atoms and molecules at XUV frequencies.