Rotational spectroscopy could provide definitive proof of aromatic molecules in space. 

Polycyclic aromatic hydrocarbons, known as PAHs, contain fused aromatic rings. They are thought to be candidate molecules for the basis for the earliest forms of life. 

Recently, there have been reports that polycyclic aromatic nitrogen heterocycles (PANHs) have been detected in interstellar space, however, discrepancies in observed and laboratory data mean that this has not been conclusively proven. 

Don McNaughton at Monash University, Victoria, Australia, and colleagues have, for the first time, measured the millimetre wave spectrum of a small PANH using rotational spectroscopy. The data in this region of the spectrum can be compared with observations made using large radio telescopes, explained McNaughton. Identifying PANHs in space through their rotational spectra would provide another route into understanding their role in astrochemistry, he said. 

Measuring the distinct fingerprint of PANHs in the millimetre region could 'provide a route into proving without doubt the presence and abundance of such molecules in the interstellar medium,' he added.

Sarah Dixon