Patent ID: 8975578
Filing Date: 2015-03-10
Classification: G01N,H01J

Abstract:
1. A linear ion trap comprising: a plurality of longitudinally extending, stacked electrodes; a device arranged and adapted to apply an asymmetric voltage waveform to one or more of said electrodes so that, in use, ions become radially separated in a first radial direction according to their differential ion mobility; and a device arranged and adapted to form, in use, a DC axial potential barrier at a position along the axial length of said linear ion trap so that ions having a first differential ion mobility and a first radial displacement are retained axially within said linear ion trap by said axial potential barrier whereas ions having a second different differential ion mobility and a second different radial displacement emerge axially or are ejected axially from said linear ion trap when a force acting on the ions having the second different differential ion mobility in the axial direction is sufficient to overcome the DC axial potential barrier applied to exit electrodes; wherein said linear ion trap is operated or maintained, in use, at a pressure <100 mbar.