Facile Tuning and Refractive Index Sensitivity of Localized Surface Plasmon Resonance Inflection Points in Hollow Silver
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Facile Tuning and Refractive Index Sensitivity of Localized Surface Plasmon Resonance Inflection Points in Hollow Silver Nanoshells Jagmeet Singh Sekhon 1 Received: 17 June 2020 / Accepted: 31 August 2020 # Springer Science+Business Media, LLC, part of Springer Nature 2020
Abstract Hollow metal nanostructures are fascinating because of their unique and surrounding environment-sensitive localized surface plasmon resonances (LSPRs). Herein, we have investigated the hollow silver nanoshell (HSN) sensitivity of different inner core radii and shell thicknesses with respect to change in surrounding medium refractive index. Also, we have shown that the extinction peak of HSNs can be fine-tuned in the visible region as well as biological windows by manipulating the size parameters. Moreover, an enhancement in refractive index sensitivity of 133 to 283 nm/RIU can be achieved in the biological windows by thick hollow silver nanoshells in comparison to thin ones. To achieve a comprehensive study, the sensitivity of homogeneous LSPR extinction inflection points with change in refractive index is also investigated. A consistent improvement in bulk refractive index sensitivity of 36% and 15% is predicted with thick and thin shell layers, respectively. Finally, thick HSNs showed higher refractive index sensitivity when compared with thin ones. Moreover, we envision the idea of more than one molecule detection by tracking the curvature changes. Therefore, we provide a deeper insight into the refractive index sensitivity of homogeneous LSPR inflection points for their use in LSPR-based sensors. Keywords Plasmonics . Nanoparticles . Biochemical sensors . Core-shell . Mie theory . Hybridization theory
Introduction In the past decade, noble metal nanoparticles have attracted tremendous interest in bio- and chemical sensing because of their tunable localized surface plasmon resonance (LSPR) from the visible to near-infrared (NIR) regime. The LSPR wavelength depends on the nanoparticle size, shape, composition, interparticle distance, underlying substrate, and surrounding medium [1–5]. Silver nanoparticles in this regard are of particular interest and have been investigated theoretically as well as experimentally [5–12]. Although gold nanoparticles are more stable and biocompatible as compared to silver, LSPR peak tunability of silver is better than gold over the visible to near-infrared region by controlling the size and shape of nanoparticle for specific purpose and application [9, 13]. More importantly, for a given shape and size, silver nanoparticles provide enormous extinction efficiency and superior refractive index sensitivity (RIS) when compared with other * Jagmeet Singh Sekhon [email protected] 1
Department of Physics, Govind National College Narangwal, Govind Nagar, Narangwal, Ludhiana, Punjab 141203, India
coinage metals (Au, Al, and Cu) [13]. In addition to this, variety of shapes including nanospheres [13], nanorods [9, 13], nanostars [14], nanocages [15], nanoboxes [16], and nanoshells [6, 7, 17, 18] were studie
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