High resolution energy-time of flight spectrometer: Dehydrogenation of fluorene cation as case study

Abstract

Testing and performance validation of a new multipurpose time-of-flight mass spectrometer followed by an energy analyzer is presented. The instrument with high mass and energy resolution is primarily designed to study cations of polycyclic aromatic hydrocarbons (PAHs) and their dehydrogenation process. The energy correlated time-of-flight measurement is supplemented by Monte Carlo simulation to probe the dehydrogenation process in a relatively small PAH cation. The experiment is carried out on fluorene+ on a timescale of several microseconds. Fluorene cations with high internal energies were produced using UV multiphoton ionization. Specific n-photon processes leading to ionization as well as H-loss reaction were identified. The average value of dehydrogenation rate is estimated by fitting the measured data to the outcome of simulations. The quantification of H loss decay rate is in agreement with previously reported decay rate measurement. This corresponds to the internal energy available by inner valence electron emission caused by three photon process. The effectiveness of the instrument to access a range of decay rates (103–107 s−1) in a single measurement is demonstrated.