The pump-probe spectroscopy infrastructure @ FORTH provides in-situ probes of the excited state of the matter, i.e. in the time/frequency domain at the fs-ps scales.
Tabletop workstations, based on fs laser sources combining wavelengths from the UV to visible to NIR and THz, can follow in time the electronic and lattice evolution, gaining thus insight in the material dynamics. Carrier transport and recombination dynamics, as well as phase transition dynamics in nanosystems, can be monitored, via their optical and near-optical signature through absorption and photoluminescence changes that are induced by ultrafast laser excitation.
The NFFA-SPRINT facility @ CNR-IOM is designed to provide pump-probe photoelectron spectroscopy (ARPES and Spin Polarimetry) experiments. The High Harmonics Generation (HHG) beamline is based on a PHAROS laser, providing 20 W, 400 mJ pulses @ 50 kHz, with a tunable repetition rate from single shot to 1 MHz and a pulse duration around 290 fs. 90% of this radiation is used to generate high harmonics in gases (Ar and Ne), covering the energy range between 17 to 76 eV, with high photons flux, up to 1012 photons/seconds @ 27 eV, 50 kHz, and allowing very good generation also @ 200 kHz. The remaining 10% can be used to pump two Optical Parametric Amplifiers (OPA), in the range 630 nm -16000 nm, used for pump-probe measurements.
The facility is connected with two end station for Time resolved-ARPES (T-ReX group) and Spin polarimetry (SPRINT). The SPRINT end station is a stand-alone spectrometer for UV and soft X-ray time-resolved photoelectron spectroscopy, readily moveable to FEL sources, but routinely available for users at NFFA-SPRINT. A Scienta SES-2002 electron spectrometer devoted to PES and ARPES is presently equipped with a phosphor detector and CCD camera and will be soon upgraded with a crossed delay-line detector (developed by Elettra Detector group) to allow pump-probe experiments. A reference statistical VUV source, a resonant HeI-II lamp, provides 21.2 eV and 40.8 eV light for reference photoemission spectra and resolution tests. Cryogenic temperature control (down to 40 K) is implemented. The samples are prepared in an annex sample preparation module that can also receive samples via a UHV shuttle.