Dehydrogenated coronene cations and interstellar extinction

Dehydrogenated coronene molecules have been proposed as the carrier of the interstellar UV extinction bump and of some diffuse interstellar bands. To test this hypothesis, we have undertaken a combined a) theoretical and b) experimental work on the subject. a) We use the (time-dependent) density functional theory to study the effect of hydrogenation on the UV absorption cross-section of neutral and ionised coronene molecules. b) For the visible and near-UV, these calculations provide useful guidelines to analyse and interpret the electronic spectra obtained with the PIRENEA experimental set-up dedicated to astrochemistry.