Effect of Surface Coverage of Gold Nanoparticles on the Refractive Index Sensitivity in Fiber-Optic Nanoplasmonic Sensing

Abstract

A simple theoretical model was developed to analyze the extinction spectrum of gold nanoparticles (AuNPs) on the fiber core and glass surfaces in order to aid the determination of the surface coverage and surface distribution of the AuNPs on the fiber core surface for sensitivity optimization of the fiber optic particle plasmon resonance (FOPPR) sensor. The extinction spectrum of AuNPs comprises of the interband absorption of AuNPs, non-interacting plasmon resonance (PR) band due to isolated AuNPs, and coupled PR band of interacting AuNPs. When the surface coverage is smaller than 12.2%, the plasmon coupling effect can almost be ignored. This method is also applied to understand the refractive index sensitivity of the FOPPR sensor with respect to the non-interacting PR band and the coupled PR band. In terms of wavelength sensitivity at a surface coverage of 18.6%, the refractive index sensitivity of the coupled PR band (205.5 nm/RIU) is greater than that of the non-interacting PR band (349.1 nm/RIU). In terms of extinction sensitivity, refractive index sensitivity of the coupled PR band (−3.86/RIU) is similar to that of the non-interacting PR band (−3.93/RIU). Both maximum wavelength and extinction sensitivities were found at a surface coverage of 15.2%.

Helium nanodroplet assisted synthesis of bimetallic Ag@Au nanoparticles with tunable localized surface plasmon resonance

“…The sum of both contributions leads to the relatively broad single plasmon resonance feature that is observed in the absorption spectrum. Furthermore, at a surface coverage of about 15% the coupling of LSPR modes between individual particles becomes important [39], the corresponding features may contribute to the spectrum in the red part of the spectra in Figure 4 at longer wavelength [40].…”

Enhancing photoelectrochemical water splitting with plasmonic Au nanoparticles

“…5d. 67 Lee and co-workers distinguished between hot electrons generated from interband and intraband transitions in Cu NPs/TiO2 and Au NPs/TiO2 diodes. 68 To achieve this, they measured the incident photon-to-current conversion efficiency (IPCE) using a monochromator system.…”

Preparation and Application of Metal Nanoparticals Elaborated Fiber Sensors

“…The coverage ratio of metal NPs on the surface of optical fiber is not directly proportional to the performance of the sensor. Wu et al concluded through experiments and simulation analysis that when the surface coverage ratio of Au NPs is 15.2%, the refractive index probe based on coated muti-mode fiber (MMF) has the highest (saturated) sensitivity [ 60 ]. The specific value of the surface coverage ratio will vary for different fiber structures and metal NPs.…”