Postgraduate Spotlight

10 Jan 2025

The School of Physics would like to highlight the work of Postgraduate Student Paul Wills, a PhD student in the Laser Spectroscopy Group led by Professor Andy Ruth. Paul is pictured on the left above while attening the RADICAL symposium which was held in January 2025. At this event, Paul obtained the Best Student Talk prize on his talk “A new cavity ring-down instrument for airborne monitoring of N₂O₅, NO₃, NO₂ and O₃ in the upper troposphere lower stratosphere”.

As part of Paul's research, he is building a spectroscopic instrument called CARDINO (CAvity Ring-Down Instrument for Nitrogen Oxides) which is designed to measure four important trace gases in the atmosphere (N₂O₅, NO₃, NO₂, O₃).  These gases naturally occur in low concentrations which make them difficult to detect, especially in the upper atmosphere, where NO₃ and N₂O₅ have never been detected before. Although they exist in small concentrations, they can have far-reaching effects on the atmosphere. To measure these gases, Paul uses a highly sensitive technique called Cavity Ring-Down Spectroscopy. Using a laser and highly reflective mirrors, it is possible to determine the light absorbed by these trace gases. From the absorption, their concentrations can be determined with high sensitivity.

For his PhD, Paul is working with working with many international researchers as part of the CARIBIC consortium (Civil Aircraft for the Regular Investigation of the atmosphere Based on an Instrument Container), where an aircraft cargo container is used as a flying laboratory. The container houses 19 highly sensitive instruments, including CARDINO, and is installed onboard a Munich based Lufthansa Airbus 350-900, which flies commercially across the globe. The passenger jet has an air inlet nozzle through which air is guided into the aircraft and into the container during flights, where it can be immediately analysed. All instruments including CARDINO are completely automated. They take measurements throughout the flight all by themselves. The aim of the project is to develop a long-term, global set of atmospheric data with high sensitivity to develop a better understanding of the chemistry of pollutants and their transport in the upper atmosphere. Over 100 atmospheric trace species can be measured with the CARIBIC container, which is the only one of its kind in the world. 

Paul's work is funded by AtmoTrace, a Research Ireland Frontiers for Future Award (contract: 21/FFP-A/8973) and quotes:

“It’s fantastic to contribute to such an ambitious and unique project that advances our understanding of the upper atmosphere on a global scale.”