A Combined Experimental and Theoretical Treatment of Ionic Liquid Thermal Dissociation

摘要

Unimolecular dissociation rate constants are calculated using Rice-Ramsperger-Kassel-Marcus (RRKM) theory, derived from quantum mechanical (QM) simulations, and from molecular dynamics (MD) trajectories for the cationic clusters of the ionic liquid EMIM-Tf_2N and EMIM-DCA. The measurement of the binding energy of an ionic liquid cluster under single-collision conditions is also reported, which shows excellent agreement with the binding energies calculated from the QM and MD methods. The effects of temperature and size on the unimolecular dissociation rate constant are examined for typical small ionic clusters encountered in a needle-type emitter electrospray beam. The MD determined rate constants are applied to a realistic experimental system using realistic electric fields to ascertain the impacts of unimolecular decay.