A plasmon ruler based on nanoscale photothermal effect

Abstract

The determination of nanoscale distances or distance changes necessitates a nanoscale ruler. In the present paper, distance dependence of particle temperature in an optically heated gold nanoparticle pair is quantitatively investigated to explore the possibility of creating a plasmon ruler based on this effect. The two origins of the distance-dependence, i.e., electromagnetic coupling and thermal accumulative effect, are studied. For the particle temperature, a scaling behavior is found, and it suggests that the decay of particle temperature with the interparticle gap for different particle sizes follows a common exponential decay equation. This scaling behavior is qualitatively explained with a simple dipolar-coupling model combined with a point heat source interaction model. On the basis of this scaling behavior of absorption power, we further establish a plasmon ruler equation relating the particle temperature and the interparticle distance. Our findings can serve as an excellent guideline for designing and optimizing temperature-based plasmon rulers.

Dimerization of Colloidal Particles through Controlled Aggregation for Enhanced Properties and Applications

“…This concept was demonstrated theoretically by Qiu and coworkers, who showed that the LSPR peak positionc ould be tuned to 620 nm by decreasing the gap distance from 100 nm all the way down to 2nm ( Figure 10 A). [31] It is importantt o note that this effect is only prominentw hen the light polarization direction is parallel to the long axis of the dimer,w here ac lear red-shift in the LSPR is observed. If thep olarization direction is perpendicular to the long axis of the dimer,t he redshifted hybrid peak will not be observed.…”

Molding of Plasmonic Resonances in Metallic Nanostructures: Dependence of the Non-Linear Electric Permittivity on System Size and Temperature

“…In 2012, Chen et al [82] studied photothermal effects in gold nanospheres finding structures entering a pre-melting regime at 519 K and changing sensitively shape around 795 K, much lower than bulk gold melting point (1337 K). Photothermal interaction between nanospheres has also been proposed as a plasmon ruler by Zhang et al in [83]; the effect is based on the sensitivity of the absorption power on the distance between two NPs placed on a substrate. Being able to measure the absorption differences, can lead to nanometric gaps characterizations.…”

Aggregation effect on absorbance spectrum of laser ablated gold nanoparticles

“…Changing diameter of gold nanoparticles is a simple way to vary plasmon frequency. However, this way only changes plasmon frequency up to certain frequency [6]. Fabricating multishell of metallic nanoparticles is one effective way to produce two plasmon frequencies [7].…”