ABSTRACT
The ion mobility spectrum has many forms that share one common feature: The ion current intensity is measured as a function of an ion’s mobility in a gas. As with other types of spectrometry, the ion mobility spectrum is obtained by correlating a change in a spectrometer’s parameter with a physical property of the ions. In light spectrometry, the number of photons is recorded as a function of photon energy; in mass spectrometry, the number of ions is recorded as a function of mass, and in ion mobility spectrometry (IMS), the number of ions is recorded as a function of an ion’s collision cross section, which is related to its mobility. The type of IMS depends on the instrumental parameter that is scanned to produce the intensity versus mobility spectrum. To understand the many types of mobility spectra, we must rst consider the relation among mobility, electric eld, and pressure.
