Formation of the acenaphthylene cation as a common C₂H₂-loss fragment in dissociative ionization of the PAH isomers anthracene and phenanthrene

Abstract

Polycyclic aromatic hydrocarbons (PAHs) are thought to be a major constituent of astrophysical environments, being the carriers of the ubiquitous aromatic infrared bands (AIBs) observed in the spectra of galactic...

Fingerprinting fragments of fragile interstellar molecules: dissociation chemistry of pyridine and benzonitrile revealed by infrared spectroscopy and theory

“…A variety of studies has been investigating the fragmentation processes of astronomical relevant molecules in detail ranging from theoretical [29][30][31] to experimental studies using dissociative ionization and infrared spectroscopy [32][33][34][35][36][37] or imaging Photoelectron-Photoion-Coincidence (iPEPICO) spectroscopy [38][39][40] . By using a combination of techniques, some of these studies have provided structural information of the fragment ions.…”

“…Finally, we have performed molecular dynamics (MD) simulations with the electronic structure determined at the self-consistent-charge density functional based tight binding (SCC-DFTB) 54 level of theory to predict the observed fragmentation channels including the molecular structures. Such a combined approach has been successfully used to disentangle the dissociation mechanism of cationic PAHs such as anthracene and phenanthrene 37 . This work can guide experimental and astronomical studies in finding new astrochemical relevant species, and, furthermore, provides vibrational fingerprint spectra of dominant fragment ions as reference data for sensitive infrared astronomical searches, such as with the James Webb Space Telescope (JWST) 55 .…”

“…Such a combined approach has been successfully used to disentangle the dissociation mechanism of cationic PAHs such as anthracene and phenanthrene. 37 This work can guide experimental and astronomical studies in nding new astrochemical relevant species, and, furthermore, provides vibrational ngerprint spectra of dominant fragment ions as reference data for sensitive infrared astronomical searches, e.g., with the James Webb Space Telescope (JWST). 55…”

Ionic fragmentation products of benzonitrile as important intermediates in the growth of polycyclic aromatic hydrocarbons

“…Other studies have been looking into the destruction processes of astronomical relevant species to understand their stability and fragmentation processes. [17][18][19][20][21][22][23][24][25][26][27][28] Fragmentation processes are shown to play a role for the astronomically detected Buckminsterfullerenes C 60 , C 70 and C 60 + that are thought to be formed via top-down chemistry from large PAHs. 3,29,30 In a chemical environment like the interstellar medium the fragmentation and formation reactions are strongly intertwined.…”

Photoprocessing of cationic triazacoronene: dissociation characteristics of polycyclic aromatic nitrogen heterocycles in interstellar environments

“…1,6,13 Smaller PA(N)Hs get photoprocessed on astronomical time scales and fragment into thermodynamically more stable species. The dissociation of several model PAHs, such as dicoronylene, dibenzopyrenes, 14,15 naphthalene, 16 and anthracene 17 have been studied experimentally in detail. In catacondensed PAHs like dibenzopyrenes the inital dehydrogenation is always accompanied by the loss of acetylene (C 2 H 2 ) fragments, whereas H-loss dominates for more symmetrical PAHs like coronene and dicoronylene.…”