METHOD OF TRAPPING IONS IN AN ION TRAPPING DEVICE

摘要

A quadrupole ion trapping device has a ring electrode (11) and two end-cap electrodes (12, 13). Ions are introduced into a trapping region (15) of the ion trapping device via a hole (14) in a first of the end-cap electrodes (12) and are retarded by application of a DC retarding voltage to the second of the end-cap electrodes (13). The retarding voltage is removed when the retarted ions are about to change their direction of motion towards the first end-cap electrode (12), and an ion trapping field is established by applying a radio frequency voltage to the ring electrode (11) when the ions are inside the ion trapping device.