Patent ID: 9437412
Filing Date: 2016-09-06
CPC Classification: H01J

Claim Text:
1. A method of analyzing ions trapped in a trapping volume of a mass spectrometer, comprising: providing the trapping volume defined between an inner electrode and an outer electrode surrounding the inner electrode, at least one of the inner electrode or the outer electrode comprise an array of electrodes extending in a spaced arrangement along a longitudinal axis of the trapping volume, the array of electrodes including elements of the outer electrode but not elements of the inner electrode or the array of electrodes including elements of the inner electrode but not the outer electrode; applying voltages to the inner and outer electrodes, at least three electrodes of the array of electrodes receive a different voltage, the voltages are applied to the array of electrodes thereby producing a trapping field to trap the ions in a trapping volume such that the ions adopt oscillatory motion along the longitudinal axis and remain constrained in the direction between the inner and outer electrodes; and detecting mass spectra from the ions using image current detection, a frequency of the oscillatory motion along the longitudinal axis varies according to the mass-to-charge ratios of the ions.