title: Additional enhancement of electric field in surface-enhanced Raman Scattering due to Fresnel mechanism.
abstract: Surface-enhanced Raman scattering (SERS) is attracting increasing interest for chemical sensing, surface science research and as an intriguing challenge in nanoscale plasmonic engineering. Several studies have shown that SERS intensities are increased when metal island film substrates are excited through a transparent base material, rather than directly through air. However, to our knowledge, the origin of this additional enhancement has never been satisfactorily explained. In this paper, finite difference time domain modeling is presented to show that the electric field intensity at the dielectric interface between metal particles is higher for "far-side" excitation than "near-side". This is reasonably consistent with the observed enhancement for silver islands on SiO2. The modeling results are supported by a simple analytical model based on Fresnel reflection at the interface, which suggests that the additional SERS signal is caused by near-field enhancement of the electric field due to the phase shift at the dielectric interface.
authors.affiliation: Faculty of Engineering & Industrial Science, Swinburne University of Technology, John Street, Hawthorn, Victoria 3122, Australia.
authors.forename: Sasani
authors.initials: S
authors.lastname: Jayawardhana
authors.forename: Lorenzo
authors.initials: L
authors.lastname: Rosa
authors.forename: Saulius
authors.initials: S
authors.lastname: Juodkazis
authors.forename: Paul R
authors.initials: PR
authors.lastname: Stoddart
mesh_terms: D003198:Computer Simulation; D008567:Membranes, Artificial; D053768:Metal Nanoparticles / Q000737:chemistry* / Q000528:radiation effects / Q000648:ultrastructure*; D008956:Models, Chemical; D012031:Refractometry / Q000379:methods*; D013059:Spectrum Analysis, Raman / Q000379:methods*; D013499:Surface Properties / Q000528:radiation effects
chemical_list: D008567:Membranes, Artificial
references.citation: Appl Opt. 1980 Dec 15;19(24):4159-74
references.pmid: 20309031
references.citation: Science. 1997 Feb 21;275(5303):1102-6
references.pmid: 9027306
references.citation: Opt Lett. 2012 Jun 1;37(11):2142-4
references.pmid: 22660148
references.citation: Anal Bioanal Chem. 2009 Aug;394(7):1761-74
references.pmid: 19407993
references.citation: Opt Express. 2007 Oct 1;15(20):13310-7
references.pmid: 19550601
references.citation: Annu Rev Anal Chem (Palo Alto Calif). 2008;1:601-26
references.pmid: 20636091
references.citation: Analyst. 2012 Jan 7;137(1):35-48
references.pmid: 22003492
references.citation: Appl Spectrosc. 2009 Feb;63(2):133-40
references.pmid: 19215642
references.citation: Talanta. 1989 Jan-Feb;36(1-2):227-34
references.pmid: 18964694
references.citation: Acc Chem Res. 2009 Jun 16;42(6):734-42
references.pmid: 19361212
references.citation: Opt Express. 2007 Dec 10;15(25):17433-42
references.pmid: 19551037
references.citation: Appl Opt. 2011 Jan 10;50(2):155-62
references.pmid: 21221139
references.citation: Anal Bioanal Chem. 2009 Aug;394(7):1819-25
references.pmid: 19305981
references.citation: Science. 2008 Jul 18;321(5887):388-92
references.pmid: 18583578
references.citation: Anal Bioanal Chem. 2005 Aug;382(8):1751-70
references.pmid: 16049671