A study of focusing effect in the variable DC electric fields Ion mobility spectrometry

Drift tube Ion Mobility Spectrometry (IMS) is an atmospheric analysis technology which was developed in the 1970s. It has been widely used in the detection of drugs, explosives and environmental monitoring. IMS has characteristics of high sensitivity, portability and quick detection. In addition, it has a focusing effect for the ions passed by. In the work reported in this paper, a variable DC electric fields Ion Mobility Spectrometry was constructed, and the characteristic of focusing was studied by simulation and experiments. The results showed that the focusing effect had a strong correlation with the field distribution. With the increasing of the additional voltage δv, the focusing effect enhanced. The peak intensity of the IMS increases, and the drift time increases firstly and then decreases. The good agreements between simulation and experiment show that the simulation has predictive power for ion motion in IMS. This study can serve as visual aids for intuitively understanding the factors that determine ion transport.