Accurate measurement of gas temperature is fundamental to many applications, including industrial processes, climate observation and emission surveillance.

However, traditional contact methods come with a number of issues, such as poor thermal contact with the gas or lack of resilience when used under harsh conditions. Spectroscopic methods are often employed instead, relating the temperature of the gas to the spectrum of radiation it absorbs or emits. Spectroscopy allows for remote sensing, which is useful for ground-based climate observations and other long-distance surveying.

However, these methods still need to be validated. Additionally, there is a need to extend the range of gas pressures and gas species which can be monitored.

The project will expand monitoring capabilities to include a number of new ‘sensor’ molecules, such as CO, CO₂ and O₂, determining the optimal transitions to measure for each at temperatures of 200–400 K. It will develop a methodology for these measurements using Rotational-Vibrational Spectroscopic Gas Thermometry (RVSGT), developing the infrastructure needed to make primary gas temperature measurements using existing spectroscopy capabilities, with a target uncertainty of 25 mK. The developed RVSGT technique will be cross validated against other non-contact methods such as Doppler broadening thermometry and two-line laser thermometry.

The work of the project will increase the number of gas species RVSGT can be used to analyse, expanding the utility of spectroscopic thermometry.

This will lead to more accurate measurements of gas temperature, allowing for more accurate climate observation and emission surveillance at longer distances and with more resilience to harsh conditions.