Chain Formation during Hydrogen Loss and Reconstruction in Carbon Nanobelts

Using laser-induced vaporisation to evaporate and ionise a source of curved polyaromatic hydrocarbons (carbon nanobelts), we show collision impacts between species cause mass loss and the resultant ions are catalogued via mass-spectrometry. These data are interpreted via a series of in-silico-simulated systematic hydrogen-loss studies using density functional theory modelling, sequentially removing hydrogen atoms using thermodynamic stability as a selection for subsequent dehydrogenation. Initial hydrogen loss results in the formation of carbyne chains and pentagon-chains while the nanobelt rings are maintained, giving rise to new circular strained dehydrobenzoannulene species. The chains subsequently break, releasing CH and C-2. Alternative routes towards the formation of closed-cages (fullerenes) are identified but shown to be less stable than chain formation, and are not observed experimentally. The results provide important information on collision degradation routes of curved molecular carbon species, and notably serve as a useful guide to high-energy impact conditions observed in some astrochemical environments.

Automated summary

In this study, we used laser-induced vaporisation to evaporate and ionise carbon nanobelts and analysed the resultant ions through mass-spectrometry. We simulated systematic hydrogen-loss studies and found that the initial hydrogen loss led to the formation of carbyne chains and pentagon-chains while maintaining the nanobelt rings. However, the alternative routes towards the formation of closed-cages were shown to be less stable than chain formation and were not observed experimentally. These results provide important insights into the collision degradation routes of curved molecular carbon species and their implications in astrochemical environments.