Effect of the Dielectric Constant of the Surrounding Medium and the Substrate on the Surface Plasmon Resonance Spectrum and Sensitivity Factors of Highly Symmetric Systems: Silver Nanocubes

Abstract

Silver nanocubes (AgNCs), 60 nm, have four extinction surface plasmon resonance (SPR) peaks. The finite difference time domain (FDTD) simulation method is used to assign the absorption and scattering peaks and also to calculate the plasmon field intensity for AgNCs. Because AgNCs have a highly symmetric cubic shape, there is a uniform distribution of the plasmon field around them, and they are thus sensitive to asymmetric dielectric perturbations. When the dielectric medium around a nanoparticle is changed anisotropically, either by placing the particle on a substrate or by coating it asymmetrically with a solvent, the plasmon field is distorted, and the plasmonic absorption and scattering spectra could shift differently. For the 60 nm AgNC, we found that the scattering resonance peak shifted more than the absorption peak. This changes the extinction bandwidth of these overlapping absorption and scattering bands, and consequently the figure of merit of the nanoparticle, as a localized SPR sensor, no longer has a constant value.

Preparation of silver and copper nanoparticles in presence of ascorbic acid and investigation of their antibacterial activity

“…They have found applications in many different areas such as catalysis (Yacamán et al, 2001;Zhang et al, 2013), electronics (Li et al, 2005), optical sensing (Wang et al, 2012;Li et al, 2015) and biosensing (Walcarius et al, 2013). Numerous publications for synthesis of silver (Maria et al, 2013;Dong et al, 2009;Hu et al, 2004;Zhang et al, 2011;Mahmoud et al, 2012;Qin et al, 2010;Chekin & Ghasemi, 2014) and copper (Salavati-Niasari & Davar, 2009;Youngil et al, 2008;Zhu et al, 2005;Ramyadevi et al, 2012;Zain et al, 2014;Valodkar et al, 2011) colloids have been reported, and the most frequently used method is a chemical reduction of their ions, whereas various reducing and stabilizing agents were used. So far it has been reported the use of ascorbic acid as a reducing agent for metal NPs synthesis by using microwave irradiation (Qin et al, 2010;Chekin and Ghasemi, 2014).…”

Assessment of total silver and silver nanoparticle extraction from medical devices

“…Saline may be a poor extract medium because chloride ions in saline might react with Ag + ions from the devices (Rigo et al, 2012), leading to precipitate of AgCl, although no precipitates were observed in this study. AgNPs exhibit characteristic light absorbance at around 400 nm, which is due to the surface plasmon resonance effect (Mahmoud et al, 2012). Others have demonstrated the usefulness of UV-VIS in differentiating silver ions and AgNPs (Zook et al, 2011).…”

Silver Nanocube Aggregates in Cylindrical Pores for Higher Refractive Index Plasmonic Sensing

“…[ 42 ] AgNC 60 nm on glass from El-Sayed et al includes PVP coating [ 43 ] and AgNC 60 nm on silicon from Ianoul and co-workers. [ 42 ] The gold nanostars value is from Hafner et al [ 44 ] and the gold nanoframe value is from El-Sayed et al [ 45 ] …”