We propose a time-resolved Terahertz (THz) investigation of ultra-fast dynamics in semimetals and carbon nanotubes. The THz spectroscopy is a direct and powerful tool to explore the optical properties in the far- and mid-infrared. When combined with a visible pump beam, it can measure the transient dielectric response of an excited system with time resolution better than 100fs.
This unique capability has been already exploited to observe the building up of electron-hole plasma in semiconductors and the exci tonic transitions in heterostructures. On the track of these promising results, we aim to characterize hot electrons dynamics in graphite. Our goal is to extend the investigation to the carbon nanotubes and observe the influences of the reduced dimensionality on the fast conductivity transients.
The project chaises also the optimisation of innovative gas sensors that would detect toxic and polluting species. It is well established that the conductivity of metal-phtalocyanine films changes dramatically under NOx exposure. Together with the electronic transport, also the thickness and the optical properties of the film modify considerably. We propose a THz investigation of these solid-gas systems in order to characterize the plasma frequency, the quasiparticle scattering rate and the molecular vibration during the absorption of the sensing gas.
Fields of science
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