Patent ID: 7102129
Filing Date: 2006-09-05
Classification: H01J

Abstract:
1. A mass spectrometer, comprising: an ion source for generating ions from a sample; ion optics for transporting the ions from the ion source to an ion trap having a plurality of electrodes, the ion trap having an interior region into which ions are admitted; an RF trapping voltage source for applying an RF trapping voltage having a first amplitude to one or more of the plurality of electrodes to generate a field for trapping at least a portion of the ions admitted into the ion trap; a resonance excitation voltage source for applying a resonance excitation voltage pulse for a pulse duration to cause at least a portion of a selected set of ions to undergo collisions and break into ion fragments, the ion fragments including low-mass ion fragments; and the RF trapping voltage source being configured to reduce the RF trapping voltage after a predetermined delay period following termination of the resonance excitation voltage pulse to a second amplitude such that a substantial portion of the low-mass ion fragments are retained in the ion trap for later analysis.