Optical measurements of three-dimensional microscopic temperature distributions around gold nanorods excited by surface plasmonics

TL;DR

This paper demonstrates a novel method for three-dimensional microscopic temperature measurement around gold nanorods using refractive index changes, enabling detailed thermodynamic analysis at sub-micrometer resolution.

Contribution

It introduces an experimental technique to measure 3D temperature distributions in microscopic systems via refractive index mapping, a capability not previously demonstrated.

Findings

Achieved 3D temperature mapping with sub-micrometer resolution.

Quantified temperature sensitivity of 2.88°C.

Enabled analysis of heat flux and thermal conductivity.

Abstract

The measurement and control of the temperature in microscopic systems, which are increasingly required in diverse applications, are fundamentally important. Yet, the measurement of the three-dimensional (3D) temperature distribution in microscopic systems has not been demonstrated. Here, we propose and experimentally demonstrate the measurement of the 3D temperature distribution by exploiting the temperature dependency of the refractive index (RI). Measurement of the RI distribution of water makes it possible to quantitatively obtain its 3D temperature distribution above a glass substrate coated with gold nanorods with sub-micrometer resolution, in a temperature range of 100C and with a sensitivity of 2.88C. The 3D temperature distributions that are obtained enable various thermodynamic properties including the maximum temperature, heat flux, and thermal conductivity to be extracted and analyzed quantitatively.