| 摘要 |
In an apparatus for an air sample analysis, employing a dual polarity Ion Mobility Spectrometer (IMS), a method for stabilizing equilibrium conditions associated with the switching of the electric fields in the IMS cell comprises the steps of modulating a duty cycle of the electric field at the shutter grid located between the reactor region and the drift region of the IMS cell. During the switching of the electric fields at the cell, the open time of the duty cycle of the electric field at the shutter grid is extended. After the background polarity has been switched to the opposite polarity, the open time is returned to its normal value.
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