Molecular Growth Inside of Polycyclic Aromatic Hydrocarbon Clusters Induced by Ion Collisions

R Delaunay and M Gatchell and P Rousseau and A Domaracka and S Maclot and Y Wang and MH Stockett and T Chen and L Adoui and M Alcami and F Martin and H Zettergren and H Cederquist and BA Huber, JOURNAL OF PHYSICAL CHEMISTRY LETTERS, 6, 1536-1542 (2015).

DOI: 10.1021/acs.jpclett.5b00405

The present work combines experimental and theoretical studies of the collision between keV ion projectiles and clusters of pyrene, one of the simplest polycyclic aromatic hydrocarbons (PAHs). Intracluster growth processes induced by ion collisions lead to the formation of a wide range of new molecules with masses larger than that of the pyrene molecule. The efficiency of these processes is found to strongly depend on the mass and velocity of the incoming projectile. Classical molecular dynamics simulations of the entire collision process from the ion impact (nuclear scattering) to the formation of new molecular species reproduce the essential features of the measured molecular growth process and also yield estimates of the related absolute cross sections. More elaborate density functional tight binding calculations yield the same growth products as the classical simulations. The present results could be relevant to understand the physical chemistry of the PAR-rich upper atmosphere of Saturn's moon Titan.

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