| 摘要 |
<p num="1"><br/><br/><br/>A mass spectrometer system has an elongated rod set having an entrance end, an <br/>exit end, a plurality of rods and a central longitudinal axis. The mass <br/>spectrometer system is operable to perform the following steps: a) admitting a <br/>first plurality of groups of ions into the entrance end of the rod set; b) <br/>producing a field between the plurality of rods to confine the first plurality <br/>of groups of ions in the rod set; c) selecting a first mass/charge range for a <br/>first group of ions in the first plurality of groups of ions; d) providing a <br/>first radial excitement field to radially displace the first group of ions <br/>within the first mass/charge range from the central longitudinal axis, and <br/>concurrently retaining a second group of ions closer to the central <br/>longitudinal axis than the first group of ions, the second group of ions being <br/>within a second mass/charge range disjoint from the first mass/charge range; <br/>and then e) providing a first axial force acting on the first group of ions by <br/>providing an axial acceleration field. The first axial force is not provided <br/>during step d).<br/>
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