Characterization of a serial array of miniature cylindrical ion trap mass analyzers

Two small (5 mm internal radius) cylindrical ion traps (CITs) are arranged in series and operated using a single ion source, detector and radio freque ncy (rf) trapping signal. Ions are trapped in the first CIT and later trans ferred to the second by applying a direct current (dc) pulse to the endcap electrode of the first trap. This process is facilitated if a second, appro priately timed, retarding de pulse is applied to the exit endcap electrode of the the second trap. Mesh endcaps are used for the CITs to increase the number of ionizing electrons entering the trap and to maximize the transfer efficiency and detected signal. The transfer efficiency is dependent on th e amplitude of the de potential applied to eject the ions from the first tr ap, the amplitude of the de potential applied to retain the ions in the sec ond trap, and the period during which the retarding potential is applied. T he amplitude and phase of the rf also affect the transfer process. Ions tha t readily dissociate upon collision have low transfer efficiencies; more st able ions can be transferred with up to 50% efficiency. Copyright (C) 1999 John Wiley & Sons, Ltd.