Travelling wave ion guide

Ion-mobility may be implemented in IMS-MS systems in the form of (a) drift tubes, as already discussed [138, 139, 144], (b) differential ion-mobility or high-field asymmetric waveform ion mobility spectrometiy (FAIMS) devices [145-147], and (c) traveling-wave ion guide devices [44,148]. Tandem IMS-IMS-MS systems... 

Fig. 4.71. Effect of a traveling wave DC pulse along a stacked ring ion guide. Ions in front of the DC pulse are moving along from stack to stack and are thus propulsed through the device (T-wave ion guide). A buffer gas is required to narrow down the thermal energy distribution. Reproduced from Ref. [242] with permission. Elsevier Science Publishers, 2007.

Giles, K. Pringle, S.D. Worthington, K.R. Little, D. Wildgoose, J.L. Bateman, R.H., Applications of a travelling wave-based radio-frequency-only stacked ring ion guide. Rapid Commun. Mass Spectrom. 2004, 18, 2401-2414. 

The initial setup was developed into a hybrid quadrapole-ion-mobility-TOF instrument [148], The collision cell region of this instrument features three traveling-wave stacked ring ion guides, of which the middle one is used as ion-mobility drift tube and the other two may be used as collision cell, when applicable. The 185 imn long IMS part is operated at pressures up to 1 mbar with up to 200 ml/min Ar whereas the collision cells are 100 mm long and operated at 10 mbar with up to 10 ml/min gas [148]. The system can be used for a wide variety of applications. 

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