IMS APPARATUS

摘要

An ion mobility spectrometer has a drift chamber (4) along which an electric field is applied to cause ions to move from an ionization chamber (2) via a gate (3) to a collector (6). In normal operation the field applied along the drift chamber is at a conventional value of between about 20OV/cm and 30OV/cm where the speed of the ions is related linearly to the field. If there is ambiguity in identifying the ions, the applied field is switched to a much higher value, typically around 1OkV/cm where the speed of the ions is related to the field in a non-linear manner and the ions separate in an alternative fashion.