Internal energy content of ions in a travelling wave ion guide

Travelling wave ion guides (TWIGs) separate of ions according to their mobility and, at constant charge, according to their shape. The ion mobility separation itself should not modify the shape of the systems investigated. It was recently suggested by Shvartsburg et al. that the higher fields used in TWIGs than in traditional drift tubes would cause significant heating of the ions. We present a quantitative analysis of the amount of internal energy imparted to ions as they are separated in TWIGs. Benzylpyridinium ions were chosen as “thermometer” ions. Based on arrival time distributions, the fragment ion population is separated as a function of the place of formation: before, in, or after the TWIG. Fragmentation all along the TWIG was observed. The roles of the travelling wave’s voltage, speed, and of the gas nature and pressure will be discussed in detail as well of the consequences on instruments performances.