Influence of silver-nanoparticle layer in a chiral sculptured thin film for surface-multiplasmonic sensing

Abstract

Multiple surface-plasmon-polariton (SPP) waves can be guided by the interface of a metal and a chiral sculptured thin film (STF). It is possible to embed within the chiral STF a layer of silver nanoparticles as sites to bind recognition molecules for sensing analytes of a certain kind. Chiral STFs were deposited on aluminum thin films. 5-nm-thick layers of silver nanoparticles were deposited in the chiral STF at different depths in different samples. The samples were then deployed in the Turbadar-Kretschmann-Raether configuration to observe the effects the silver-nanoparticle layer had on the multiple SPP-wave modes in relation to the depth. We concluded that the silver-nanoparticle layer tends to shift the angular locations of the SPP-wave modes but does not necessarily affect the location of the SPP-wave modes to an extent that would render the data uninterpretable.

Influence of silver-nanoparticle layer in a chiral sculptured thin film for surface-multiplasmonic sensing of analytes in aqueous solution

“…Moving towards eventually a practical implementation of SMPRI for multi-analyte sensing, we decided to fabricate chiral STFs containing thin layers of silver nanoparticles [27]. But as the effects of silver-nanoparticle layers on surface multiplasmonics and optical sensing of analytes were not known within an experimental setting, we undertook the research reported here.…”

“…Since the angular locations of an SPP-wave mode do not greatly depend whether the silvernanoparticle layer is after either the first or second period in the SMRPI chip, we chose to limit further investigation to the silver-nanoparticle layer inserted after the first period of the chiral STF. Instead of water, we used droplets of 100, 200, or 300-mM aqueous solutions of sucrose [27]. The refractive indexes of those sucrose solutions are n 100 , n 200 , and n 300 ∼ 1.338, 1.343, and 1.348, respectively [33].…”