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Dipartimento di Fisica - Politecnico di Milano

Attosecond dynamics in solids: from bulk to advanced 2D materials

Fundamental electron dynamics driven by attosecond and intense extreme ultraviolet pulses
The first steps of the interaction between the matter and an external electromagnetic field are dominated by the electronic response of the system. Electronic correlation (i.e. the interaction between the different electrons composing the system) and the coupling between the electronic and nuclear motion can lead to a large variety of fundamental processes (such as auto ionization) that characterize the attosecond and femtosecond dynamics occurring in small system.

Attosecond electron dynamics in atoms and small molecules
The main goal of the current experimental project is the time resolved investigation of electronic and nuclear dynamics occurring in atoms (for example, helium) and small molecules (for example, nitrogen, hydrogen, and oxygen).
The experiments will be based on the combination of state-of-the-art experimental equipment featuring a 10 kHz repetition rate extreme ultraviolet source delivering isolated and trains of attosecond pulses and an electron/ion spectrometer for coincidence measurement. This spectrometer (usually referred to as Reaction Microscope) offers the possibility to measure in coincidence the momenta all charged fragments emitted during the reaction initiated by the attosecond pulses. As such it represents the most powerful detection system for the complete characterization of reaction leading to photoionization and photo-dissociation of small molecules. For a short description of our laboratory and of the main experimental techniques applied, you can refer to the following link:

The thesis work will be based on performing pump-probe experiment on diatomic molecules (nitrogen and hydrogen) and on the analysis of the photoelectron and photo ion angular distributions acquired with the Reaction Microscope spectrometer.



                                                                      Photoelectron momenta distribution measured in Krypton using the ReMi


Nonlinear extreme ultraviolet excitation of electronic correlation in atoms and clusters
The main goal of the current project is the characterization of the electronic response of atoms and clusters under irradiation with an intense, tunable, femtosecond, extreme ultraviolet source.
The experiments have been performed at the Free Electron Laser FERMI operating in Trieste. FERMI presents unique characteristics compared to other FELs operating worldwide in the XUV spectral region as it combines intense pulses tunable in the extreme ultraviolet spectral range with femtosecond pulse duration. For a description of the working principle of FERMI, you can refer to:

The work will be mainly focused on the analysis of data acquired during a previous experimental campaign (December 2013) on auto ionization of neon ion. Participation to further experimental campaigns will be possible within the thesis work.

                                                                               XUV FEL "FERMI", Trieste (Nature Photonics 7, 852–854 (2013))

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