Abstract text (incl. figure legends and references)

Based on their plasmonic properties, noble metal nanoparticles find many technical applications including solar cells, catalysis, cancer treatment, sensors amongst others. Since the characterization of small individual free clusters remains extremely challenging due to the low interaction cross-section with light, most analysis is done by averaging over many clusters. Alternatively, plasmon resonances have been studied for deposited nanoparticles where the dielectric environment influences the plasmon resonance leading to diverse observations in literature [1,2]. In this contribution, we want to reassess the intrinsic plasmonic properties of size selected gas-phase deposited silver nanoparticles in the size range of 10 nm and well below. By means of STEM-EELS we investigate the locally excited plasmonic response of individual nanoparticles. Figure 1 exemplarily shows a HAADF STEM image of a 4 nm silver nanoparticle at the edge of a carbon substrate. Clearly visible is its plasmon resonance in the electron energy loss spectrum. The results are discussed with respect to the inhomogeneous dielectric surrounding, i.e. the substrate and possible surface adsorbates.

[1] A. Campos et al., Nature Physics 15 (2019), 275

[2] J. A. Scholl et al., Nature 483 (2012), 421

Figure 1: HAADF STEM image of a 4 nm silver nanoparticle at the edge of a carbon substrate together with the unprocessed electron energy loss spectrum taken at the marked position.