Speaker: Caterina Vozzi, CNR
Program Description:
High-order harmonics are generated from the interaction of intense femtosecond laser pulses with noble gases. Recently, high-order Harmonic Generation (HHG) led to the realization of table-top sources of coherent Soft-X Ray radiation. With these sources, ultrafast spectroscopy can be performed with extreme temporal resolutions, down to the attosecond regime, and with the site and chemical selectivity. These features grant access to purely electronic dynamics in molecules and solids and fundamental processes of light-matter interaction.
Furthermore, HHG has been successfully used as a spectroscopic tool in the gas phase and condensed matter, allowing the study of electron dynamics in a cation following sudden ionization, all-optical band structure reconstruction, and berry phase retrieval. These findings demonstrate the flexibility and potentiality of this technique.
Here I will report on the recent developments in ultrafast spectroscopy based on HHG at CNR-IFN. I will describe our recent developments in efficient XUV generation in microfluidic devices fabricated by femtosecond laser irradiation followed by chemical etching. With this approach, we were able to control the harmonic generation process in the gas on the micro-meter scale with high flexibility, enabling a high photon flux and phase matching on broadband harmonics up to 200 eV. This source is part of a new beamline for transient absorption/reflectivity measurements in molecules and solids recently developed at CNR-IFN and equipped with a flexible XUV spectrometer for high-resolution and high dynamic range measurement, with a polarimeter for the characterization of the HHG polarization. I will also describe the beamline developed for HHG spectroscopy in solids available at CNR-IFN and report on preliminary results in dielectrics and semiconductors.
