Coulomb Explosion Dynamics of Multiply Charged para-Nitrotoluene Cations.

ABSTRACT

This work explores Coulomb explosion (CE) dissociation pathways in multiply charged cations of para-nitrotoluene (PNT), a model compound for nitroaromatic energetic molecules. Experiments using strong-field ionization and mass spectrometry indicate that metastable cations PNT2+ and PNT3+ undergo CE to produce NO2+ and NO+. The experimentally measured kinetic energy release from CE upon formation of NO2+ and NO+ agrees qualitatively with the kinetic energy release predicted by computations of the reaction pathways in PNT2+ and PNT3+ using density functional theory (DFT). Both DFT computations and mass spectrometry identified additional products from CE of highly charged PNTq+ cations with q > 3. The dynamical timescales required for direct CE of PNT2+ and PNT3+ to produce NO2+ were estimated to be 200 and 90 fs, respectively, using ultrafast disruptive probing measurements.