Technology

DMS - Differential Mobility spectrometry

DMS is an atmospheric ion separation techique

Differential Mobility Spectrometer (DMS) is an ion filter, which operates in atmospheric pressure and separates ions based on their characteristic electric field behavior.  The ions are created with ion reactions initiated with an ionisation source. In the IonVision DMS, ions are produced with  4.9 keV photoionisation.

Example of positive dispersion plot
DMS is CONTINOUS AND REAL TIME TECHNIQUE

 The IonVision maximises the ion separation with a special waveform generator which creates ideal square shaped pulses for the DMS filter.  Both positive and negative ions are measured simultaneously which maximises the measurement speed.

DMS filter
Ideal DMS waveform
DMS is an ION FILTER

In the filter, the ionized gas is exposed to an asymmetric waveform. Ideal waveform has two components:  high field and  low field. When the ions are under the low field, their mobility is a linear function of the field strength. When the ions are exposed to the high field, mobility has a field dependent component and thus it is a nonlinear function of the electric field. When the ions are in the filter,  the field forces  them to move. Oscillating ions drift towards the walls of the filter if the mobility difference is not compensated.  When a small DC-field is superimposed to the oscillating field, the drifting can be cancelled and the ions can pass the filter.

Principle structure of DMS filter
DMS is CONTINOUS AND REAL TIME TECHNIQUE

 The IonVision maximises the ions separation with a special waveform generator which creates ideal square shaped pulses for the DMS filter.  Both positive and negative ions are measured simultaneously which maximises the measurement speed.