Dissociative double photoionization of singly deuterated benzene molecules in the 26–33 eV energy range

摘要

This work provides new experimental and theoretical results about the formation and dissociationof benzene dication. The experiment has been carried out by using a vacuum ultraviolet radiationfrom a synchrotron source together with a time-of-flight spectrometer and a position sensitive iondetector. Isotopically labeled benzene molecules with a single deuterium atom have been used inorder to study the symmetric dissociation of the benzene dication, not well evident in previous experiments.A threshold of 30.1 ± 0.1 eV has been observed for this dissociation reaction. Moreover,the lifetime of the dissociation of the benzene metastable dication producing CH3+ and C5H3+ hasbeen obtained as a function of the photon energy, by the use of a Monte Carlo trajectory analysis ofthe coincidence distributions. The determined lifetime is independent of the photon energy and hasan average value of 0.75 ± 0.22 μs. Theoretical calculations of the energy and structure of dissociationproduct ions have been also performed to provide crucial information about the dynamics ofthe charge separation reactions following the photoionization event.