Examining Substrate-Induced Plasmon Mode Splitting and Localization in Truncated Silver Nanospheres with Electron Energy Loss Spectroscopy

Abstract

Motivated by the need to study the size dependence of nanoparticle-substrate systems, we present a combined experimental and theoretical electron energy loss spectroscopy (EELS) study of the plasmonic spectrum of substrate-supported truncated silver nanospheres. This work spans the entire classical range of plasmonic behavior probing particles of 20-1000 nm in diameter, allowing us to map the evolution of localized surface plasmons into surface plasmon polaritons and study the size dependence of substrate-induced mode splitting. This work constitutes the first nanoscopic characterization and imaging of these effects in truncated nanospheres, setting the stage for the systematic study of plasmon-mediated energy transfer in nanoparticle-substrate systems.

Mode Mixing and Substrate Induced Effect on the Plasmonic Properties of an Isolated Decahedral Gold Nanoparticle

“…So from above analysis we can conclude that the mode mixing starts to begin for a Au decahedron with an edge length of 130 nm for a single 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 curve) but shows a weak peak in presence of substrate with enhanced broadening as the edge length increases. Very recently, it is shown by Li et al 45 that for truncated Ag sphere in free space, electron beam preferentially interacts low order modes i.e dipolar mode for small size particles but it almost vanishes for a particle with a size of about 200 nm which is quite consistent with the present analysis in absence of substrate (spec...…”

The Substrate Effect in Electron Energy-Loss Spectroscopy of Localized Surface Plasmons in Gold and Silver Nanoparticles

“…In many cases, modest attention has been given to the influence of the substrate, where it is either not taken into account 6,8,29 or assumed to act as a homogeneous background medium, whose effective permittivity is fitted by comparing simulations to experimental results 27,30,31 . More recently, a number of studies have focused on specific substrate induced effects in EELS, such as mode splitting and energy transfer between LSPs and the substrate in the optical response of truncated nanospheres and nanocubes [32][33][34][35] . In this work, we investigate the substrate effect in EELS through a systematic study of the LSP resonances appearing in the EELS spectra of Ag and Au nanoparticles supported on a variety of substrates, allowing a full examination of the role of substrate material composition and thickness.…”

Characterizing Localized Surface Plasmons Using Electron Energy-Loss Spectroscopy

“…Though the basic science needed to create mode maps has been around for decades, it was not until 2007 that Nelayah et al were able to image the LSP modes of Ag nanoprisms [92]. This technique was quickly improved upon and applied to a variety of particles such as nanorods [93][94][95], nanodecahedra [96], nanodisks [97,98], nanocubes [99,100], truncated nanospheres [101] and multi-nanoparticle systems [102][103][104][105]. Mode maps allow researchers to experimentally visualize the near-field character of LSPs and correlate the near-field profile of LSPs to nanoparticle geometry, something that previously required the use of theory.…”

“…Note the radial symmetry of the mode map in contrast to the nodal structure seen in the electric field plot. Reproduced with permission from Reference [101]. Copyright 2015 American Chemical Society.…”