On the Use of Plasmonic Nanoparticle Pairs As a Plasmon Ruler: The Dependence of the Near-Field Dipole Plasmon Coupling on Nanoparticle Size and Shape

Abstract

The localized surface plasmon resonance (LSPR) spectral band of a gold or silver nanoparticle is observed to shift as a result of the near-field plasmonic field of another nanoparticle. The dependence of the observed shift on the interparticle distance is used as a ruler in biological systems and gave rise to a plasmonic ruler equation in which the fractional shift in the dipole resonance is found to decrease near exponentially with the interparticle separation in units of the particle size. The exponential decay length constant was observed to be consistent among a small range of nanoparticle sizes, shapes, and types of metal. The equation was derived from the observed results on disks and spherical nanoparticles and confirmed using results on a DNA conjugated nanosphere system. The aim of the present paper is to use electron beam lithography and DDA calculations to examine the constancy of the exponential decay length value in the plasmonic ruler equation on particle size and shape of a number of particles including nanoparticles of different symmetry and orientations. The results suggest that the exponent is almost independent of the size of the nanoparticle but very sensitive to the shape. A discussion of the nanoparticles most suitable for different applications in biological systems and a comparison of the plasmonic ruler with Forster resonance energy transfer (FRET) is mentioned.

Numerical Study of Plasmon Resonance Silver Nanoparticles Coated Polyvinyl Alcohol (PVA) using Bohren-Huffman-Mie Approximation

“…Similar observations were also reported by Ananth [6] and Mbhele [17]. The red-shift phenomenon of the LSPR Ag-NPs was simply can examined by scattering [18]. Increasing the particle size will increase the scattering process and the external driving field becomes non uniform across each particle.…”

Universal scaling of local plasmons in chains of metal spheres

“…If a universal scaling law exists then interparticle distances can be measured to nanometer resolution by simply measuring the mode shift. In some papers [2,5] it has been suggested that mode shifting due to two arbitrary particles is universally exponential, however other experimental and numerical results for coupled gold rods [6] implied a different relationship, as have other studies. We shall now summarize some relevant investigations of linear chain of n spheres, including the special bisphere or dimer case where n = 2.…”

“…In particular, it has been suggested that the mode shifting could be employed as a nanometric ruler [2,5], by relating the position of the mode to the gap between particles. If a universal scaling law exists then interparticle distances can be measured to nanometer resolution by simply measuring the mode shift.…”

Controllable Cobalt Oxide/Au Hierarchically Nanostructured Electrode for Nonenzymatic Glucose Sensing

“…Electron-phonon coupling efficiency can be described in part by the coupling constant g and is known to increase linearly with increasing S/V ratio [148,149,[178][179][180][181][182].…”