Bottom-up formation of cyclic aromatic ions relevant to interstellar medium chemistry

Recent work on cold and controlled ion-molecule reactions have revealed bottom-up reactions of unsaturated hydrocarbons may play an important role in the formation of small aromatic molecules in the interstellar medium(ISM). However, very few systems have been studied under low-temperature and low-pressure conditions, similar to the ISM. To facilitate new astrochemical models and identify candidates for astronomical observation, we have carried out sequential cold and controlled ion-molecule reactions of protonated propyne with propyne. We find that many products are produced, but a unique feature of all final products is that they are aromatic structures. This has implications on the formation of small aromatic species and our understanding of the ion-molecule chemistry that occurs in the ISM.