Specifics of substrate-mediated photo-induced chemical processes on supported nm-sized metal particles

Abstract

Substrate-mediated mechanism of photochemical reactions on metals includes direct and/or plasmon-related excitation of electron-hole pairs in the bulk by photons and subsequent chemical transformation due to interaction of excited (hot) electrons (or holes) with the adsorbate. In nm-sized metal particles, the excited electrons are confined. We show in detail that this factor is beneficial for photochemistry under low-intensity steady-state conditions (linear regime) and also during intensive sub-ps laser pulses (non-linear regime). In both cases, the confinement may increase the contribution of secondary hot electrons to the photochemical conversion. In addition, in the non-linear regime the decrease of electron temperature after heating may be much slower than that on the surfaces of bulk samples and accordingly photochemical reactions may be more probable.