mass analyzed ion kinetic energy spectrometry true This child of the former purgatory term mass spectrometer was made obsolete. OBSOLETE Spectra that are obtained from a sector mass spectrometer that incorporates at least one magnetic sector plus one electric sector in reverse geometry. The accelerating voltage, V, and the magnetic sector field, B, are set at fixed values to select the precursor ions, which are then allowed to dissociate or to react in a field free region between the two sectors. The kinetic energy product ions of m/z selected precursor ions is analyzed by scanning the electric sector field, E. The width of the product ion spectrum peaks is related to the kinetic energy release distribution (KERD) for the dissociation process. MIKES MS MS:1000267