Patent ID: 8941054
Filing Date: 2015-01-27
Classification: G01N,H01J

Abstract:
1. A method for the collection of ions of a predetermined ion mobility range μ 1 >μ>μ 2 , comprising: (a) passing ions from an ion source to two consecutive ion mobility low pass filters, a first filter followed by a second filter downstream from the first filter, each filter formed by entraining ions in a gas flowing away from the ion source and driving the entrained ions against a DC electric field barrier of predetermined, the first filter comprising a first DC electric field barrier blocking the passage of ions with a mobility of μ≧μ 1 and the second filter comprising a second DC electric field barrier blocking the passage of ions with a mobility of μ≧μ 2 , where μ 2 <μ 1 , wherein the DC electric field barrier of the first filter and the DC electric field barrier of the second filter are each stationary along an axis parallel to the direction of the flow of the gas; and (b) collecting ions from the ion source in said predetermined ion mobility range in a space between the two filters.