Effect of surface roughness on self-assembled monolayer plasmonic ruler in nonlocal regime
Date
2014-04-15
Authors
Hajisalem, Ghazal
Min, Qiao
Gelfand, Ryan
Gordon, Reuven
Journal Title
Journal ISSN
Volume Title
Publisher
Optics Express
Abstract
Recently, self-assembled monolayers (SAMs) have been used for plasmonic rulers to measure the nonlocal influence on the Au nanoparticle - metal film resonance wavelength shift and probe the ultimate field enhancement. Here we examine the influence of surface roughness on this plasmonic ruler in the nonlocal regime by comparing plasmonic resonance shifts for as-deposited and for ultra-flat Au films. It is shown that the resonance shift is larger for ultra-flat films, suggesting that there is not the saturation from nonlocal effects previously reported for the spacer range from 0.7 nm to 1.6 nm. We attribute the previously reported saturation to the planarization of the as-deposited films by thinner SAMs, as measured here by atomic-force microscopy. This work is of interest both in probing the ultimate limits of plasmonic enhancement with SAMs for applications in Raman and nonlinear optics, but also in the study of SAM planarization as a function surface roughness.
Description
Keywords
Surface plasmons, Plasmonics
Citation
Hajisalem, G., Min, Q., Gelfand, R. & Gordon, R. (2014). Effect of surface roughness on self-assembled monolayer plasmonic ruler in nonlocal regime. Optics Express, 22(8), 9604-9610.