Patent ID: 7244931
Filing Date: 2007-07-17
Classification: G01N

Abstract:
1. An ion mobility spectrometer comprising: an ionization chamber, which can be passed through by an analyte-containing gas; a radiation source directing ionizing radiation, which is suitable for at least partially ionizing the analyte-containing gas, to enter said ionization chamber; a transition area, into which the at least partially ionized gas as ion carrier gas and an almost ion-free gas as said drift gas are charged such that at least at the end of said transition area a flow is established including a cross-sectional area mainly passed through by said ion carrier gas and other cross-sectional areas mainly passed through by said drift gas; a separation area lying in the direction of flow downstream of said transition area, said separation area having a cross-sectional area mainly passed through by said ion carrier gas and other cross-sectional areas mainly passed through by said drift gas, whereby said drift gas and said ion carrier gas flow unidirectionally, wherein said cross-sectional area mainly passed through by said ion carrier gas is smaller at least in one dimension than said cross-sectional areas that are mainly passed through by said drift gas; and electrodes including a detector electrode, an auxiliary electrode and a counterelectrode, said electrodes being arranged in said separation area whereby an electric field can be formed between them, said electric field having at least one field component that does not run parallel to the direction of flow in said separation area, whereby at least one said other cross-sectional areas that are mainly passed through by said drift gas is located between said cross-sectional area that is mainly passed through by said ion carrier gas and said detector electrode.