Visible photodissociation spectroscopy of PAH cations and derivatives in the PIRENEA experiment

• Published in: arXiv.org 2010-05
• Main Authors: Useli-Bacchitta, F, Bonnamy, A, Mulas, G, Malloci, G, Toublanc, D, Joblin, C
• Format: Article
• Language: English
• Subjects: Absorption cross sections; Cations; Cyclotron resonance; Dehydrogenation; Density functional theory; Electron transitions; Electronic spectra; Fourier transforms; Optical Parametric Oscillators; Parametric amplifiers; Phase transitions; Photodissociation; Polycyclic aromatic hydrocarbons; Spectrum analysis; Time dependence
• ISSN: 2331-8422
• DOI: 10.48550/arxiv.1003.4006

The electronic spectra of gas-phase cationic polycyclic aromatic hydrocarbons (PAHs), trapped in the Fourier Transform Ion Cyclotron Resonance cell of the PIRENEA experiment, have been measured by multiphoton dissociation spectroscopy in the 430-480 nm spectral range using the radiation of a mid-band optical parametric oscillator laser. We present here the spectra recorded for different species of increasing size, namely the pyrene cation (C16H10+), the 1-methylpyrene cation (CH3-C16H9+), the coronene cation (C24H12+), and its dehydrogenated derivative C24H10+. The experimental results are interpreted with the help of time-dependent density functional theory calculations and analysed using spectral information on the same species obtained from matrix isolation spectroscopy data. A kinetic Monte Carlo code has also been used, in the case of pyrene and coronene cations, to estimate the absorption cross-sections of the measured electronic transitions. Gas-phase spectra of highly reactive species such as dehydrogenated PAH cations are reported for the first time.