Berlin 2024 – wissenschaftliches Programm

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CPP: Fachverband Chemische Physik und Polymerphysik

CPP 32: Focus Session: Novel Approaches to Surface Plasmon Generated Charges and Heat for Photocatalysis I (joint session O/CPP)

CPP 32.6: Topical Talk

Mittwoch, 20. März 2024, 16:30–17:00, MA 141

Disentangling plasmonic catalysis contributions by time-resolved spectroscopy — •Holger Lange — The Hamburg Centre for Ultrafast Imaging — Institute of Physics and Astronomy, University of Potsdam

According to current understanding, the nanoparticle plasmon decay is a series of sequential scattering events, separated by their timescales of vastly increasing duration. At first, Landau damping polarizes the electron density. Electron-electron scattering equilibrates the excess energy and subsequent electron-phonon coupling leads to rapid electron cooling and a simultaneous increase in lattice temperature. Several of these processes might contribute to the reaction rate enhancement on plasmonic nanoparticles. I will discuss a range of experiments to specifically address the individual steps of the plasmon decay. The temperature of the thermalized hot electron gas can be observed as a contrast in optical pump-probe experiments, the excited lattice is accessible by time-resolved x-ray scattering. I will present the first reconstruction of the decaying gold nanoparticle plasmon field in the time domain by the detection of transient currents. This data combined with reaction dynamics studies under monochromatic excitation reveals both, non-equilibrium carriers and field-induced excitation as most relevant contributions for two different reactions, highlighting the selectivity of the processes.

Keywords: plasmon dynamics; pump-probe spectroscopy; metal nanoparticles