Lifetime of Photogenerated Positive Charges in Hybrid Cerium Oxide-Based Materials from Space and Mirror Charge Effects in Time-Resolved Photoemission Spectroscopy

Space and mirror charge effects in time-resolved photoemission spectroscopy can be modeled to obtain relevant information on the recombination dynamics of carriers. We successfully extracted from these phenomena reneutralization characteristic time positive charges generated by photoexcitation CeO2-based films. For above-band-gap excitation, a large fraction carriers with lifetime that exceeds 100 ps are generated. Otherwise, sub-band-gap excitation induces formation significantly smaller lifetimes tens picoseconds, ascribed defect sites or multiphoton absorption. When oxide is combined Ag nanoparticles, localized surface plasmon resonances leads times longer than 300 ps. This was interpreted considering electronic unbalance at nanoparticles injection electrons, via resonance (LSPR) decay, into CeO2. study represents an example how exploit space effect gaining access carrier CeO2 within picosecond range time, which fundamental describe photocatalytic processes.