DiProI_2011

DiProI beamline at FERMI@Elettra DiProI is the Diffraction and Projection Imaging beamline dedicated to static and time-resolved experiments, enabled by the nearly full coherence and variable polarization of the short seeded pulses provided by the FERMI@Elettra Free Electron Laser (FEL). The versatile end station was designed in partnership with Lawrence Livermore National Laboratory (LLNL), the DESY Centre for Free-Electron Laser Science (CFEL) and the University of Uppsala; it was constructed and commissioned at Elettra. Its adaptable modular set-ups, including exchange of sample stages, aerosol particle delivery and detection systems, allow static and time-resolved studies on both fixed and free-standing nano-objects of different origin. In the first operating stage at FERMI@Elettra, the DiProI end station will perform Coherent Diffraction Imaging (CDI), in-line and Fourier transform holography. Projection imaging illuminated by non-conventional focusing diffractive optics and stereo imaging are under development and planned to be implemented as well.

First FEL coherent diffraction pattern taken at the DiProI beamline.

Exploit all features of the FERMI seeded FEL The nearly full coherence and extreme brightness of FEL pulses have opened extraordinary opportunities for lensless CDI imaging in achievable spatial and temporal resolution, limited only by the pulse wavelength and duration and the detector numerical aperture. The intense femtosecond FEL pulse is shorter than the timescales for detectable radiation-induced damage of the object, which ensures to obtain single shot images before the sample's Coulomb explosion. Stroboscopic imaging with femtosecond time resolution to explore ultrafast dynamics at nanometer length scales is possible in a pump-probe mode by using a triggered Ti:Sapphire laser, a split-delay correlation system and other novel approaches under consideration. The seeded FEL also provides wavelength tunability, with a narrow spectral width close to the transform limit, allowing to perform resonant CDI by tuning the photon energy to the atomic absorption edges of specimen constituents. Along with imaging of elemental spatial distribution in anisotropic specimens, the linear and circular polarizations provided by the FERMI pulses add dichroic scattering contrast when the samples are illuminated by beams of different chirality, which enables resonant CDI to monitor temporal changes in various forms of magnetic or electronic segregations.

News

The DiProI end station has performed the first Coherent Diffraction Imaging and Resonant Magnetic Scattering experiments. Improvements foreseen for 2012 include the commissioning of better focusing optics and the installation of new instruments, such as a Time of Flight mass spectrometer, a particle delivery system, a new imaging detector.