Probing Aromaticity with Supersonic Jet Spectroscopy: A Case Study on Furan, Thiophene, and Selenophene.

Aromaticity is a century-old concept that is even introduced in high school textbooks. However, the determination of the order of aromaticity of molecules as simple as furan, thiophene, and selenophene is still challenging. This work describes how different theoretical and experimental methods posit different aromaticity orders.