Science

Innovative light sources such as Free Electron Laser (FERMI, at LeadPartner) and sources based on Laser High-order Harmonic Generation (CITIUS at Partner PP2) are among the most powerful tools for exploring the inner properties of matter with unprecedented temporal and spatial resolutions. The most important features of these light sources that are expected to pave the way to new science are high brightness, wavelength tunability, and the ability to generate ultra-short pulses. Further development of innovative light sources will have a strong impact on many different disciplines ranging from fundamental science to biology and medicine, and from nano-electronics to material science. The knowledge gained through experiments by utilizing innovative light sources could be used in a variety of scientific and technological applications.

 

Free-Electron Lasers (FELs)

The main ingredients of a FEL are a bunch of electrons, which are accelerated close to the speed of light by a linear accelerator, and an array of magnets (an undulator) that forces the electrons to slightly wiggle in the transverse direction. The wiggling electrons emit pulses of ultraviolet radiation or X-rays, i.e. radiation with wavelengths between a few hundred and 0.1 nanometers (1 nm = one billionth of a meter) along the direction of motion. The nature of the FEL interaction between the electrons and the emitted radiation “squeezes” the electrons in the initial uniform bunch into thin slices separated by the emission wavelength. The waves radiated by electrons from different slices are coherently combined resulting in output powers of several Gigawatts (1 GW = 1 billion watts). The duration of such light pulses is determined by the length of the electron bunch divided by the speed of light and approaches a few tens of femtoseconds (1 fs = 10-15 s, i.e. one millionth of one billionth of a second). Pulses from a FEL can be used to perform highly interdisciplinary experiments spanning fields such as chemistry, material science, and biology.

Sources based on High-order Harmonic Generation (HHG) in gases

As opposed to FELs, where light is produced by “free” electrons, in sources based on the HHG principle, the electrons responsible for emission of short-wavelength radiation are bound to atoms. A noble gas jet is intercepted by femtosecond pulses from an infrared driving laser. The electrons bound to atoms in the gas gain energy from the driving laser, are ionized, and in the next step recombine with the original atoms. In this process an electron absorbs multiple low-energy (long wavelength) photons and emits a single high-energy (short wavelength) photon during recombination with the atom. Sources based on HHG can deliver coherent femtosecond pulses with tunable wavelengths extending into the soft X-ray regime (<10 nm). As in the case of FELs, pulses from a HHG source are expected to open the path towards novel experiments in many fields of research.

Bio-mimetic organic molecules time resolved studies

Characterisation of small organic molecules (Porphyrins or Phtalocyanines) with applications in several fields: photovoltaics, photodynamic therapy…

CIGS based solar cells investigations

Investigation of novel thin films for photovoltaics applications.

Characterisation of HHG pulses

Temporal characterisation of HHG pulses. Demonstration of basic working principles of ILS.

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