Structural rearrangement of the acrylonitrile (AN) cluster in the gas phase under VUV one-photon radiation explored by mass-selected infrared spectroscopy

Abstract Acrylonitrile (AN), one of the most abundant nitriles in space, is considered to closely relate to the formation of interstellar prebiotic nitrogen-containing aromatics. Herein, we measured the vibrational spectra of acrylonitrile cluster cations ( AN ) 2,3 + in a supersonic jet using infrared (IR) dissociation with vacuum-ultraviolet (VUV) photoionization and time-of-flight mass spectroscopy. Interestingly, the observed IR spectra demonstrate that a new molecular ion [ CH 2 = CHC = N − C ( H ) 2 C ( H ) C ≡ N ] + , is generated from the dimer and trimer of AN upon VUV single-photo ionization. Calculation results reveal that the new molecular cations can be generated through a relative low energy barrier after ionization of the neutral (AN)2. However, the reaction pathways are barrierless for the trimer, in which the third solvent AN acts as a catalyst. The mechanisms of those reactions also have been discussed in detail. This study contributes to a deeper understanding of ion-molecule reaction in gas-phase and the quest for the formation of prebiotic N -containing molecules in the outer space.