Microscale Heat Transfer Transduced by Surface Plasmon Resonant Gold Nanoparticles

TLDR

Visible radiation at resonant frequencies is converted into thermal energy by surface plasmons on gold nanoparticles. The authors determined a microscale heat‑transfer time constant by balancing the heat input from resonant irradiation of gold nanoparticles with outward conduction and radiation, thereby quantifying transduction efficiency. In ≤10‑µL aqueous suspensions of 20‑nm gold particles, the equilibrium temperature increased with laser power and nanoparticle concentration, and transduction efficiency rose from 3.4 % to 9.9 % when the continuous‑wave irradiation was modulated.

Abstract

Visible radiation at resonant frequencies is transduced to thermal energy by surface plasmons on gold nanoparticles. Temperature in ≤10-μL aqueous suspensions of 20-nm gold particles irradiated by a continuous wave Ar+ ion laser at 514 nm increased to a maximum equilibrium value. This value increased in proportion to incident laser power and in proportion to nanoparticle content at low concentration. Heat input to the system by nanoparticle transduction of resonant irradiation equaled heat flux outward by conduction and radiation at thermal equilibrium. The efficiency of transducing incident resonant light to heat by microvolume suspensions of gold nanoparticles was determined by applying an energy balance to obtain a microscale heat-transfer time constant from the transient temperature profile. Measured values of transduction efficiency were increased from 3.4% to 9.9% by modulating the incident continuous wave irradiation.