3·, gave rise to the first aromatic ring, benzene. The current study is the first demonstration of the so-called “radical propargyl self-reaction” under astrochemical and combustion conditions. Using a high-temperature, coin-sized chemical reactor called the “hot nozzle,” the researchers simulated the high-pressure, high-temperature environment inside a combustion engine as well as the hydrocarbon-rich atmosphere of Saturn’s moon Titan, and observed the formation of isomers – molecules with the same chemical formula but different atomic structures – from two propargyl radicals leading up to the benzene ring. The hot-nozzle technique, which co-senior author Musahid Ahmed, senior staff scientist in Berkeley Lab’s Chemical Sciences Division, adapted 10 years ago at Berkeley Lab’s Advanced Light Source (ALS) for synchrotron experiments, relies on vacuum ultraviolet (VUV) spectroscopy to detect individual isomers. The ALS is a type of particle accelerator known as a synchrotron that generates extremely bright beams of light ranging from infrared through X-rays.