Probing Millikelvin Temperature Sensitivity in Chiral Nanoparticles via Optical Forces

TL;DR

This paper demonstrates a tip-based optical force technique capable of detecting temperature changes as small as 0.1 K at the nanoscale, enabling in situ thermal mapping of chiral nanoparticles without extra temperature-sensitive layers.

Contribution

It introduces a novel nanoscale thermometry method using optical force nanoscopy with phase-informed decomposition, achieving high temperature sensitivity under ambient conditions.

Findings

Achieved approximately 0.1 K temperature sensitivity.

Enabled nanoscale thermal mapping without additional layers.

Provided insights into photothermal force origins.

Abstract

With increasing interest in utilizing nanostructures as nanoscale heat sources, the ability to precisely measure photothermal effects at the nanoscale has become increasingly significant. Techniques based on fluorescence or Raman signals often suffer from challenges in accurate calibration, far-field imaging methods are limited by diffraction-limited spatial resolution, and electron microscopy requires vacuum conditions, restricting in situ applicability. In contrast, tip-based measurement techniques offer sub-diffraction spatial resolution under ambient conditions, making them well-suited for nanoscale photothermal mapping. In this study, we employ tip-based optical force nanoscopy combined with phase-informed decomposition to investigate the origin of the photothermal force, enable nanoscale mapping, and evaluate temperature sensitivity. Our system achieves a temperature sensitivity of approximately 0.1 K without necessitating an additional temperature-sensitive layer. We anticipate that our approach has the potential to serve as a versatile platform for investigating localized thermal effects in fields such as semiconductors, nanophotonics, and photocatalysis.