Seminars Archive

Ultrafast absorption spectroscopy on nonequilibrium condensed matter at FERMI@Elettra

Abstract
Condensed matter exposed to high energy density sub-ps laser pulses undergoes ultrafast drastic transformations initially involving the electron subsystem (t<1 ps) and finally the ion lattice (t>1 ps). The transient states originated by those processes, such as the so called "warm dense matter" (WDM), are normally present in stars as well as in the core of large planets. Therefore, fs laser technology provides the valuable opportunity to investigate in the laboratory matter under regimes not accessible with standard techniques. The beamline EIS-TIMEX, operating at the FERMI@Elettra free electron laser (FEL), is a new experimental facility specialized in the study of matter under extreme thermodynamic conditions driven by ultrafast FEL/laser heating. Absorption spectroscopy is one of the experimental techniques available at EIS-TIMEX that exploit the unique wavelength tunability and spectral purity of FERMI@Elettra. Preliminary experiments carried out on FEL-heated solid samples at EIS-TIMEX indicate the occurrence of an ultrafast (~ 100 fs) rearrangement of the electron population around the Fermi level and demonstrate that absorption spectroscopy is a valid tool for investigating condensed matter under nonequilibrium conditions.