Constraining arcuate divergence in an ion mirror mass analyser

摘要

A method of selecting ions of interest from a beam of ions using an analyzer, the method comprising: (i) providing an analyzer comprising two opposing ion mirrors each mirror comprising inner and outer field-defining electrode systems elongated along an analyzer axis z, each system comprising one or more electrodes, the outer system surrounding the inner; (ii) causing the beam of ions to fly through the analyzer along a main flight path in the presence of an analyzer field so as to undergo within the analyzer at least one full oscillation in the direction of the analyzer axis while orbiting about or oscillating between one or more electrodes of the inner field defining electrode system; (iii) providing one or more sets of electrodes adjacent the main flight path; (iv) constraining the arcuate divergence from the main flight path of ions of interest by applying one set of voltages to one or more of the sets of electrodes adjacent the main flight path when the ions of interest are in the vicinity of at least one of said one or more sets of electrodes adjacent the main flight path and applying one or more different sets of voltages to the said one or more sets of electrodes adjacent the main flight path when the ions of interest are not in the vicinity of at least one of said one or more sets of electrodes adjacent the main flight path; and: (v) ejecting the ions of interest from the analyzer. Also provided is a charged particle analyzer comprising the two opposing ion mirrors comprising inner and outer field-defining electrode systems elongated along an analyzer axis z; and at least one arcuate focusing lens for constraining the arcuate divergence of a beam of charged particles within the analyzer while the beam orbits around the axis z, the analyzer further comprising a disc having two faces at least partly spanning the space between the inner and outer field defining electrode systems and lying in a plane perpendicular to the axis z, the disc having resistive coating upon both faces.

主权项

1. A method of selecting ions of interest from a beam of ions using an analyser, the method comprising:
(i) providing an analyser comprising two opposing ion mirrors each mirror comprising inner and outer field-defining electrode systems elongated along an analyser axis z, each system comprising at least one electrode, the outer system surrounding the inner system; (ii) causing the beam of ions to fly through the analyser along a main flight path in the presence of an analyser field so as to undergo within the analyser at least one full oscillation in the direction of the analyser axis whilst orbiting about at least one electrode of the inner field defining electrode system or oscillating between at least two electrodes of the inner field defining electrode system; (iii) providing at least one set of electrodes adjacent to the main flight path; (iv) constraining the arcuate divergence from the main flight path of ions of interest by applying one set of voltages to at least one of the sets of electrodes adjacent to the main flight path when the ions of interest are in the vicinity of at least one of the at least one set of electrodes adjacent to the main flight path and applying at least one different set of voltages to the at least one set of electrodes adjacent to the main flight path when the ions of interest are not in the vicinity of at least one of the at least one set of electrodes adjacent to the main flight path; and, (v) ejecting the ions of interest from the analyser.