­Strong Field Catalysis in SiO₂ Nano Particle Surfaces

Strong field laser excitation of nanoparticles has recently been explored as a unique avenue for enhancement of catalytic reactions resulting from near-field enhancements and large particle surface area. While a large body of experimental and theoretical work has been done to understand the dynamics of laser induced electronic ionization and subsequent field/charge generation on the particle surface, undestanding the resulting charge induced molecular dynamics at nano-scale that lead to processes such as molecular fragmentation and ion emission from the nano particle surface as yet to be well undertsood. To better understand these dynamics, we developed a multiscale approach utilizing non-adiabatic quantum molecular dynamics simulations on a wetted silica surface with field boundary conditions to match that of an ionized nanoparticle. We find fragmenation of molecular species is strongly driven by localization of holes and displays a threshold behavior in terms of charge generated on the surface. In this strongly ionzied enviorment, sillica behaves analgous to metal allowing charge transfer to surface molecules inducing catalytic reacations such as water splitting. Further understanding such dynamics in highly charged nanoparticles will be critcal for not only strong-field catalysis but other fields such as atmospheric chemistry and solar geoengineering.