Sweeping method for superimposed-field mass spectrometer

Claim 1

A sweeping method for detecting daughter ions originating from parent ions by the use of a mass spectrometer having a rear stage having superimposed fields that consist of a magnetic field B and an electric field E perpendicular to the magnetic field, the mass spectrometer also having at least another electric field in a front stage in front of said rear stage having said superimposed fields, said sweeping method comprising the steps of: (a) detecting reference ions having known mass and known energy; (b) finding the voltage Vdx 2 necessary to produce the electric field in said front stage and the voltage Vdx 1 necessary to produce the electric field of the superimposed fields in said rear stage when the reference ions are detected; (c) varying the voltages necessary to produce the electric field in said front stage and the electric field of the superimposed fields in said rear stage while maintaining the intensity of the magnetic field of the superimposed fields constant to detect unknown ions; (d) finding the voltage Vdx 2 ' necessary to produce the electric field in said front stage and the voltage Vdx 1 ' necessary to produce the electric field of the superimposed fields in said rear stage when the unknown ions are detected; and (e) determining the mass and energy of the unknown ions from the voltages Vdx 1 , Vdx 2 , Vdx 1 ', Vdx 2 '.