Laboratory Photo-chemistry of PAHs: Ionization versus Fragmentation
arXiv:1505.00576 · doi:10.1088/2041-8205/804/1/L7
Abstract
Interstellar polycyclic aromatic hydrocarbons (PAHs) are expected to be strongly processed by vacuum ultraviolet photons. Here, we report experimental studies on the ionization and fragmentation of coronene (C24H12), ovalene (C32H14) and hexa-peri-hexabenzocoronene (HBC; C42H18) cations by exposure to synchrotron radiation in the range of 8--40 eV. The results show that for small PAH cations such as coronene, fragmentation (H-loss) is more important than ionization. However, as the size increases, ionization becomes more and more important and for the HBC cation, ionization dominates. These results are discussed and it is concluded that, for large PAHs, fragmentation only becomes important when the photon energy has reached the highest ionization potential accessible. This implies that PAHs are even more photo-stable than previously thought. The implications of this experimental study for the photo-chemical evolution of PAHs in the interstellar medium are briefly discussed.
References in corpus (6)
- Laboratory formation of fullerenes from PAHs: Top-down interstellar chemistry
- Theoretical evaluation of PAH dications properties
- PAH emission and star formation in the host of the z~2.56 Cloverleaf QSO
- Dehydrogenated polycyclic aromatic hydrocarbons and UV bump
- Carriers of the mid-IR emission bands in PNe reanalysed. Evidence of a link between circumstellar and interstellar aromatic dust
- Characterizing the infrared spectra of small, neutral, fully dehydrogenated PAHs
Cited by in corpus (17)
- Polycyclic Aromatic Hydrocarbon in Protoplanetary Disks around Herbig Ae/Be and T Tauri Stars
- Astrochemical relevance of VUV ionization of large PAH cations
- Polyacenes and diffuse interstellar bands
- Shiva: the dust destruction model
- Multiply charged naphthalene and its C10H8 isomers: bonding, spectroscopy and implications in AGN environments
- Impact of PAH photodissociation on the formation of small hydrocarbons in the Orion Bar and the Horsehead PDRs
- PDRs4All. XII. FUV-driven formation of hydrocarbon radicals and their relation with PAHs
- Infrared action spectroscopy of doubly charged PAHs and their contribution to the aromatic infrared bands
- Orion Bar as a window to the evolution of PAHs
- Restructuring and destruction of hydrocarbon dust in the interstellar medium
- Top-down formation of ethylene from fragmentation of superhydrogenated polycyclic aromatic hydrocarbons
- Laser-induced fragmentation of coronene cations
- Impact of HAC evolution on the formation of small hydrocarbons in the Orion Bar and the Horsehead PDRs
- Ethynyl around the HII regions S255 and S257
- Carbon accretion and desorption by interstellar polycyclic aromatic hydrocarbons
- PDRs4All: XVIII. The evolution of the PAH ionisation and PAH size distribution across the Orion Bar
- JWST Observations of Starbursts: Dust Processing in the M82 Superwind