Mechanism of Collisional Heating in Electrospray Mass Spectrometry: Ion Trajectory Calculations

Abstract

To simulate the multicollisional heating process taking place in the intermediate pressure region of an electrospray source, ion trajectory calculations have been performed by introducing in the SIMION program a subroutine for handling the collision dynamics. The simulated internal energy distributions are compared with already available experimental distributions obtained by the “survival ion yield” method (Collette, C.; Drahos, L.; De Pauw, E.; Vékey, K. Rapid Commun. Mass Spectrom. 1998, 12, 1673). The latter have been satisfactorily reproduced by using a statistical model for the energy redistribution between the ion and the target gas. This model takes into account both activation and deactivation processes occurring upon collision in the acceleration/fragmentation region. It accounts for the important role of the number of degrees of freedom of the target on the shape of the internal energy distribution.