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.

The LDM beamline features a modular end-station accommodating a broad range of detectors and systems for producing targets. The combined capabilities of the photon source (high brilliance, short pulse length, variable polarization, coherence), photon transport (variable-focusing optics) and end-station allow the investigation of many targets, such as very dilute systems, matter under extreme irradiation conditions (multiple electronic excitation, multiple ionization, Coulomb explosion, non-linear optics) and dichroism. The split-and-delay line as well as, a synchronized optical laser allows time-resolved experiments with different combinations of femtosecond pulses.

The beamline was commissioned in 2012 and is undergoing rapid development. The LDM beamline is now open to external users .

Research highlights | Publications

Novel Collective Autoionization Process Observed in Electron Spectra of He Clusters

  Intense femtosecond extreme ultraviolet pulses that are well defined in energy and wavelength can efficiently trigger novel collective autoionization mechanisms in nanoscale objects. The process occurs when the photon energy is resonant with excited states of the constituent atoms. This process, here investigated in helium nanodroplets, is expected to be very efficient, and has a general character. Y. Ovcharenko et al., Phys. Rev. Lett (2014).  

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A modular end-station for atomic, molecular, and cluster science at the Low Density Matter beamline of FERMI

The Low Density Matter end-station at FERMI is used for experiments on atoms, molecules and their aggregates. The charged particles produced by the ionization and fragmentation of the samples by the intense light of FERMI are detected simultaneously and analyzed to yield mass spectra, as well as photoelectron energy and angular distributions.  V. Lyamayev et al, J. Phys. B: At. Mol. Opt. Phys (2014). 

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Determining the polarization state of an EUV FEL beam using atomic circular dichroism

Continuously-variable polarization of FERMI is used here to study dichroic phenomena in photon-matter interactions.  The experimental scheme adopted is also an elegant , non-invasive and straightforward method to characterize the polarization properties of XUV FEL beams.  T. Mazza et al., Nat. Comm. (2014).

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A velocity map imaging apparatus for gas phase studies at FERMI@Elettra

The design and evaluation of a velocity map imaging spectrometer specifically optimised for experiments
at the FERMI free electron laser source has been perfomed.  P. O'Keeffe et al. NIM B. (2011).

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The FERMI@Elettra free-electron-laser source for coherent x-ray physics: photon properties, beam transport system and applications

FERMI@Elettra comprises two free electron lasers (FELs) that will generate short pulses ( ~ 25–200 fs) of highly coherent radiation in the XUV and soft x-ray region.  E. Allaria et al. New J. Phys. 12 (2011) 075002

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 Scattering detector commissioning at LDM


  The LDM scattering detector has been recently commissioned. The image shows the single-cluster scattering pattern from a He droplet of diameter 950 nm, taken with FERMI pulses at a wavelength of 64 nm.

Magnetic bottle commissioning at LDM

A magnetic bottle spectrometer, designed and built by Raimund Feifel and co-workers, has been installed, commissioned, and used for beamtime at LDM. The image shows a test spectrum, with O2 as target gas, taken at 21.2 eV photon energy
[contact: http://www.physics.gu.se/english/about-the-department/staff?languageId=100001&userId=xfeira ]

 VMI station at LDM

  An experimental station, devoted to experiments on gaseous samples at the Elettra GasPhase beamline and at LDM, was built and commissioned. The station is based on a Velocity Map Imaging detector for angular resolved photoelectron spectroscopy. A thorough description of this photoelectron analyser has been recently published in Nucl. Instr. Meth. B (2011),  doi:10.1016/j.nimb.2011.07.020. 




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Last Updated on Sunday, 20 September 2015 14:41