Time-domain Brillouin Scattering as a Local Temperature Probe in Liquids

TL;DR

This paper demonstrates the use of time-domain Brillouin scattering (TDBS) as a technique to measure local temperatures in liquids by analyzing frequency shifts caused by coherent acoustic waves, with potential applications in ultrathin liquid layers.

Contribution

The study introduces TDBS as a novel method for local temperature measurement in liquids, leveraging ultrafast pump-probe techniques and frequency shift analysis.

Findings

TDBS can accurately determine local liquid temperature.

Frequency shifts correlate with temperature and laser power.

First step towards ultrathin liquid temperature probing.

Abstract

We present results of time-domain Brillouin scattering (TDBS) to determine the local temperature of liquids in contact to an optical transducer. TDBS is based on an ultrafast pump-probe technique to determine the light scattering frequency shift caused by the propagation of coherent acoustic waves in a sample. Since the temperature influences the Brillouin scattering frequency shift, the TDBS signal probes the local temperature of the liquid. Results for the extracted Brillouin scattering frequencies recorded at different liquid temperatures and at different laser powers - i.e. different steady state background temperatures- are shown to demonstrate the usefulness of TDBS as a temperature probe. This TDBS experimental scheme is a first step towards the investigation of ultrathin liquids measured by GHz ultrasonic probing.