Size dependent surface plasmons, revisited

Palestrante: Prof. Dr. Matthias Hillenkamp

Abstract: The question of how physical properties like the localized surface plasmon resonance in metal nanoparticles depend on the particle size has been discussed for several decades. It has recently regained increased interest with the rise of experimental techniques that allow us to study plasmons (of both surface and volume) on the single particle level in Transmission Electron Microscopes [1]. Here it is now possible to directly link structural and electronic properties for clusters down to 2 nm diameter, deep in the range of where quantum confinement dominates the particle properties and responses. The interpretation and theoretical description of the recent data remains, however, highly controversial.
In this presentation I will show and discuss new experimental results contrasting single particle STEM-EELS with ensemble measurements through optical spectroscopy of the same benchmark system, i.e. mass-selected silver nanoparticles embedded in silica. The at first glance contradictory results are discussed and explained and a comprehensive overview of the necessary theoretical description is given. Notably the dominating role of the particle-matrix interface is discussed and all recent data are put into context.

[1] Scholl, J. A., Koh, A. L., and Dionne, J. A. Nature 483, 421 (2012).