Stability and morphology of cyanonaphthalene icy mantles on ISM cold dust analogues

The recent identification of the polycyclic aromatic hydrocarbon molecules, 1-cyanonaphthalene, and 2-cyanonaphthalene in the interstellar medium (ISM) requires laboratory support to understand the physicochemical nature of these molecules when they are present as icy mantles on cold dust grains. Therefore, we have carried out the infrared spectroscopic characterization of these molecules under astrochemical conditions. When deposited at 7 K, the spectra of the cyanonaphthalene ices were amorphous in nature. Upon warming to higher temperatures, cyanonaphthalene ices appear to remain amorphous until sublimation. Both sublimate at very high temperatures, 250-265 K, suggesting their presence on the ISM dust over a large temperature range such that they may influence the chemical complexity across the ISM. Graphical abstract: SYNOPSIS Infrared spectroscopic characterization of cyanonaphthalene molecules under astrochemical conditions were carried. Cyanonaphthalene ices show no phase change upon warming. Cyanonaphthalene sublimation at very high temperatures, 250-265 K, suggests their presence on the ISM dust over a large temperature range and may further influence the chemical complexity.[Figure not available: see fulltext.]