Abstract
Surface enhanced Raman scattering (SERS) was measured on periodic and randomly arranged patterns of Au nano-bricks (rectangular parallelepipeds). Resonant SERS conditions were investigated of a near-IR dye deposited on nanoparticles. Random mixtures of Au nano-bricks with different aspect ratio R showed stronger SERS enhancement as compared to periodic patterns with constant aspect ratio (R varies from 1 to 4). SERS mapping revealed up to ~ 4 times signal increase at the hot-spots. Experimental observation is verified by numerical modeling and is qualitatively consistent with generic scaling arguments of interaction between plasmonic nanoparticles. The effect of randomization on the polarization selectivity for the transverse and longitudinal modes of nano-bricks is shown.
Highlights
The applications of localized surface plasmons originated in metal nano-particles, are set to be fundamental in several fields of science and engineering research, such as plasmonics and optoelectronics [1,2,3,4], and surface enhanced Raman scattering (SERS) spectroscopy [5,6,7,8,9,10], enabling detection of tiny amounts of substance down to single molecules
The longitudinal resonance always has lower resonant frequency decreasing with increase in aspect ratio R, as the longitudinal electric field gets progressively less contained inside the metal nano-bricks, and the restoring force driving the oscillation decreases
We experimentally observed resonance SERS enhancement induced by randomization of nano-brick patterns
Summary
The applications of localized surface plasmons originated in metal nano-particles (gold, silver, etc.), are set to be fundamental in several fields of science and engineering research, such as plasmonics and optoelectronics [1,2,3,4], and surface enhanced Raman scattering (SERS) spectroscopy [5,6,7,8,9,10], enabling detection of tiny amounts of substance down to single molecules In this context, strong importance is given to short-range plasmonic interactions in nanometricsize gaps between close particles [11], which locally produce strong light intensity enhancement [12, 13]. Use of randomness in relationship with the particle shape is promising as a way to enhance performance of plasmonic structures, with a view to metal nanoparticle-based spasers [22, 23] and random lasers [24], and to influence chiral effects [25]
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
