Al₂O Photochemistry

Abstract The chemistry within the interstellar medium (ISM) is notably influenced by the interplay between kinetics and photochemical processes, which play significant roles in both the formation and destruction of molecular species. This study focuses on theoretical investigations of Al 2 O photochemistry, aiming to elucidate the mechanisms underlying the production of AlO and Al in the VY-CMa star. Utilizing advanced theoretical methodologies, we explore the lowest electronic states with singlet and triplet spin multiplicities in linear Al 2 O. We investigated the photostability of Al 2 O in the near UV‒Vis region, revealing the low likelihood of photodissociation and photoconversion while suggesting the plausibility of fluorescence and phosphorescence phenomena. Calculations also identify three prominent peaks in the UV range at 261.5, 206.2, and 199 nm. Finally, Al 2 O is predicted to be photostable and cannot be the parent molecule of the diatomic AlO or even the astrochemical reservoir of atomic aluminum. These results contribute to improving the astronomical models in simulating aluminum chemistry in the ISM.