The origin of non-integer overtone peaks in overtone mobility spectrometry (OMS) spectra is investigated by ion trajectory simulations. Simulations indicate that these OMS features arise from higher-order overtone series. An empirically-derived formula is presented as a means of describing the positions of peaks. The new equation makes it possible to determine collision cross sections from any OMS peak. Additionally, it is extended as a means of predicting the resolving power for any peak in an OMS distribution.
© American Society for Mass Spectrometry, 2011