The fact that pulsed excitation of the surface plasmon resonance in metallic nanoparticles causes coherent excitation of breathing vibrational modes is a well know experimental fact. The textbook explanation of this phenomenon is based on the ultrafast heating of electrons following the optical excitation and further heat transfer to the ionic lattice. The sudden temperature rise of the metal ions causing expansion modes to be preferentially excited. In this talk I will present some results obtained from real time quantum dynamical simulations of coupled electron-ion dynamics. The ultrafast dynamic response of nanoparticles to laser excitation shown by the simulations points to a new mechanism other than equilibrium electron–phonon scattering previously assumed, which takes a much longer timescale. A sharp weakening of all bonds during laser excitation is observed, thanks to plasmon damping into excited electrons in anti-bonding states. This sudden weakening of bonds leads to a uniform expansion of the nanoparticles and launches coherent breathing oscillations.

Prof. Sánchez is Deputy Director of the Department of Theoretical and Computational Chemistry, National University of Córdoba and PI of National Council for Scientific and Technological Research. He serves as principal investigator of a consolidated research group dedicated to the development, implementation and application of new methods for the simulation of quantum dynamics of nano and bio-systems out of equilibrium. His research projects deal with problems like the description of the primary process in photosynthesis, the optical response of nanoscopic systems and the dynamics of photo induced charge transfer. He is also a founder and CTO in the Quantum Dynamics startup at his University’s Incubator.