LDM
Low Density Matter at FERMI
The Low Density Matter (LDM) beamline has been built as part of the FERMI free-electron laser (FEL) facility to serve the atomic, molecular and cluster physics community. |
Research highlights | Publications![]() Generation and measurement of intense few-femtosecond superradiant extreme-ultraviolet free-electron laser pulses
Three-stage superradiant cascade (SRC) starting from an ultraviolet (UV) seed pulse and reaching the EUV spectral range have been realized at FERMI in order to shorten the pulse duration with femtosecond accuracy. N. S. Mirian et al.Nature Photonics 15, 523 (2021)
![]() Enhancement of Above Threshold Ionization in Resonantly Excited Helium Nanodroplets
Clusters and nanodroplets hold the promise of enhancing high-order nonlinear optical effects due to their high local density. Here we explore the nonlinear optical response of He nanodroplets prepared in multiply excited states by irradiation with relatively intense XUV pulses.R.Michiels et al.Physical Review Letters 127 093201 (2021) ![]() Ultrafast Resonant Interatomic Coulombic Decay Induced by Quantum Fluid DynamicsHere, we directly measure the timescale of interatomic Coulombic decay (ICD) in resonantly excited helium nanodroplets using a high-resolution, tunable, extreme ultraviolet free-electron laser. A.C.LaForge et al. Physical Review X 11, 021011 (2021) Read More![]() Photoelectric effect with a twist
Photons have fixed spin and unbounded orbital angular momentum (OAM). Here we have found, that the OAM of an optical field can be imprinted coherently onto a propagating electron wave. Our results reveal new aspects of light–matter interaction and point to a new kind of single-photon electron spectroscopy. G. De Ninno et al. Nature Photonics, 14, 554 (2020)
![]() Tracking attosecond electronic coherences using phase-manipulated extreme ultraviolet pulses
The direct control and manipulation of the phase of individual pulses within an XUV pulse sequence opens exciting possibilities for coherent control and multidimensional spectroscopy, but has not been accomplished. Here, we overcome these constraints in a highly time-stabilized and phase-modulated XUV-pump, XUV-probe experiment, which directly probes the evolution and dephasing of an inner subshell electronic coherence. A. Wituschek et al. Nature Communications 11, 883 (2020)
![]() New Method for Measuring Angle-Resolved Phases in Photoemission
Here we present a new attosecond-precision interferometric method of angle-resolved measurement for the phase of the photoionization amplitudes, using two phase-locked extreme ultraviolet pulses of frequency ω and 2ω, from a free-electron laser. D.You et al. Physical Review X, 10, 031070 (2020) ![]() Ultrafast relaxation of photoexcited superfluid He nanodropletsSuperfluid He nanodroplets are ideal model systems for studying the photodynamics in weakly-bound nanostructures, both experimentally and theoretically. The present work shows that it is now possible to follow the relaxation dynamics of free nanodroplets in great detail using ultrashort tunable XUV pulses. ![]() Attosecond pulse shaping using a seeded free-electron laserWe demonstrate amplitude and phase manipulation of the harmonic components of an attosecond pulse train in combination with an approach for its temporal reconstruction. The results presented here open the way to performing attosecond time-resolved experiments with free-electron lasers. ![]() Tracking the ultraviolet-induced photochemistry of thiophenone during and after ultrafast ring openingHere we apply time-resolved photoelectron spectroscopy with a seeded extreme ultraviolet free-electron laser to trace the ultrafast ring opening of gas-phase thiophenone molecules following ultraviolet photoexcitation. S. Pathak et al. Nature Chemistry 12, 795 (2020) Read More![]() Deep neural networks for classifying complex features in diffraction images
This work provides a general introduction on the capabilities of neural networks and provide results on the first domain adaption of neural networks for the use case of diffraction images as input data. J. Zimmermann et al. Physical Review E 99, 063309 (2019)
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