Competing nonradiative channels for hot electron induced surface photochemistry Original Research Article

We report experiments in which we investigated the ultrafast dynamics of competing nonradiative channels for hot electron mechanisms in various polycrystalline metal samples. Time resolved two-photon photoemission, based on the equal pulse correlation technique, is used to measure the energy relaxation and the transport of the photoexcited carriers. In these studies the role of coherent effects in auto- and crosscorrelation experiments has been considered. While the inelastic lifetime of Ag is in qualitative and quantitative agreement with the Fermi liquid theory, the result obtained for Au is very different. The measured inelastic relaxation time for transition metals with unoccupied d orbitals is shorter as compared to the noble metals. The results demonstrate the feasibility of studying electron relaxation in noble and transition metals directly in the time domain and provide a framework for understanding the dynamics of hot electron transfer from a metal surface to the adsorbate.