A researcher from the University of Leeds in northern England has designed a system that detects trace gases such as methane and other hydrocarbons in the Earth's atmosphere. The system, dubbed FAGE (fluorescence assay by gas expansion), incorporates a powerful UV laser, a pump, and assorted optical and electronic components. To test the new system, Dwayne Heard and his crew traveled to the western shores of Ireland, where air samples were sucked into a detection chamber. The sample then expanded, forming a supersonic molecular beam expansion. A UV laser targeted the sample, causing free radicals to fluoresce measurably. The laser, tuned to 282 nm, excites only the fluorescence from the hydroxyl radical.