Collision Cross Section Measurement within a Time-of-Flight Mass Analyzer

A proportion of ions travelling through a time-of-flight analyzer inevitably suffer collisions with background gas, resulting in unwanted transmission losses. As collision probability depends upon the ions’ collision cross section, it has been considered that measurement of ion transmission with variation of pressure, or flight path in the case of some multi-reflection analyzers, allows cross section to be determined. A theoretical model is presented, and practical evaluations performed upon a Thermo Scientific Orbitrap Astral mass spectrometer.