Abstract
AbstractRecent laboratory studies have shown that PAH cations dehydrogenate to give charged molecules consisting of only carbon atoms. Our experiments using ion-trap time-of-flight mass spectrometry show that a key group of photodissociation fragments from the coronene cation $({{\rm{C}}_{24}}{\rm{H}}_{12}^ + )$ are carbon clusters of ${\rm{C}}_n^ +$ composition. Density functional theory calculations shed light onto potential dissociation pathways leading up to the main ${\rm{C}}_{11}^ +$ and ${\rm{C}}_{12}^ +$ clusters, and highlight the importance of pentagon formations in the carbon backbone of the precursor molecule in generating certain fragments.
Highlights
Recent experiments using time-of-flight photo-ionisation mass spectrometry have revealed that extensive photo-processing of PAH cations causes them to dehydrogenate and form charged species that are comprised of only carbon atoms likely organised in a ring or cage structure (West et al (2014); Zhen et al (2014a,b))
We use time-of-flight mass spectrometry alongside density functional theory to study the photo-stability of the coronene cation (C24H+12) and investigate the importance of dehydrogenation and pentagon incorporation in the pathways to form smaller carbonaceous species
Experiments were performed on our custom-made mobile Instrument for the Photodynamics of PAHs (i-PoP), consisting of a quadrupole ion-trap (QIT) and a reflectron time-of-flight mass spectrometer (Zhen et al (2014a))
Summary
Polycyclic aromatic hydrocarbons (PAHs) lock up 15% of all interstellar elemental carbon and are known to influence the local physical and chemical conditions of the interstellar medium (ISM) (Tielens (2008)). Sanjana Panchagnula1,2 , Jordy Bouwman1 , Jerry Kamer1, Harold Linnartz1 and Alexander Tielens2 Recent laboratory studies have shown that PAH cations dehydrogenate to give charged molecules consisting of only carbon atoms.
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