AMADEUS Seminar - Prof. Michele Giocondo, - Monday 4 november 2019, 10:30 am - CRPP (Salle de l'oeuf)04/11 : 10h30
Prof. Michele Giocondo
CNR-Nanotec UOS di Cosenza
Dipartimento di Fisica, Università della Calabria,
87036 Arcavacata di Rende, Cosenza, Italia
Some physics behind the two-photon photo-reduction of gold precursors
Multi-photon direct laser writing (MP-DLW) in polymeric matrices doped with a tetrachloroauric acid solution allows creating clusters of gold nanoparticles (GNPs) inside the focus figure of a tightly focused ultrafast laser beam. In this work, some key physical phenomena involved in the process are highlighted analyzed.
Multi Photon Absorption (MPA) triggers the photo-reduction of AuCl4–ions and the creation of GNPs, but this process leads to the local heating of the spotted volume as well, which in turn generates a thermal shock-wave influencing the morphology of the created structures. Due to the concentration gradients of the gold precursor and water arising upon the MPA, two distinguished diffusive processes take place on different timescales.
A simple yet effective technique to get an estimation of the micron-scale temperature distribution reached during MP-DLW is proposed.
Finally, some experiments reveal the role of the surface affinities between the GNPs, the substrate and water.