In this project we have developed a versatile experimental setup capable of performing time-resolved spontaneous, and stimulated Raman spectroscopy measurements. In addition, we have developed another complementary technique, called transient reflectivity which is able to access information related to both electron and phonon dynamics in our materials. With these techniques we were able to characterize thermal and electron dynamics of a range of materials: from bulk semiconductors, to supported graphite, to suspended graphite of different thicknesses.
Firstly, we performed spontaneous time-resolved Raman measurements on bulk materials. Since spontaneous Raman scattering efficiency is extremely weak, we also implemented time-resolved stimulated Raman spectroscopy measurements that allow us to critially increase the Raman signal from these materials. These techniques enable us to extract the phonon lifetime of materials after excitation, which is key to better understand thermal transport at the nanoscale, as well as to extract the temperature evolution of the phonons, key to observe also exotic thermal behaviors.
Finally, we implemented and used our transient reflectivity setup to study the ultrafast dynamics of graphite of different layer thicknesses at room temperature. Graphene is a material extremely relevant to push the limits of heat transfer as it has shown clear deviation from the conventional diffusive thermal transport. This technique helped us to understand the influence of a silicon substrate on the dynamics of heat carriers at different time-scales, such as electrons at short times (~fs, few ps), and phonons at longer times (~100ps). It also provided information about the electron-phonon coupling which is key to understand the energy relaxation mechanisms.
The following actions were taken during the duration of the fellowship for its dissemination:
- Link to the MSCA website for the project, linked to the existing Zardo group homepage.
- Publication of articles in peer-reviewed journals in which the MSCA:
o B. Abad et al. “The 2022 Applied Physics by Pioneering Women: a Roadmap” Journal of Physics D: Applied Physics. (Accepted) 2022. We were invited to write section 15: “Nanophotonics and Nanophononics”.
o Articles in preparation.
- Oral presentations at international conferences:
o Swiss NanoConvention 2022, invited by Prof. Barbara Rothen-Rutishauser, Fribourg (Switzerland), July 2022 (Invited talk)
o “Phonon engineering in semiconductor superlattice nanowires: phonons and thermal transport”. Nanowire Week 2022, Chamonix, France, 2022.
o “Extreme ultraviolet beams probe mechanical and structural properties of nanostructured metalattices”. E-MRS Spring 2021, Online, France, 2021.
o “Mechanical and structural properties of nanostructured metalattices probed by coherent EUV beams”. MRS Spring 2021, Online, USA, 2021.
- Other outreach activities:
o NCCR video campaign celebrated the 50th anniversary of women obtaining the right to vote in Switzerland, showing the implemented setup -
https://www.youtube.com/watch?v=Wv9e85QpLik(odnośnik otworzy się w nowym oknie)
