Patent ID: 7189967
Filing Date: 2007-03-13
Classification: H01J

Abstract:
1. An apparatus for analyzing chemical species, comprising: (a) an ion source for producing ions from a sample substance; (b) at least two vacuum pumping stages; (c) a detector located in one of said at least two vacuum pumping stages; (d) at least one multipole ion guide each comprising at least two multipole ion guide segments for transporting said ions, each said multipole ion guide being located in a plurality of vacuum stages such that each said multipole ion guide begins in one vacuum pumping stage and extends into at least a second vacuum stage of said at least two vacuum stages; (e) a region comprising neutral gas molecules wherein at least a portion of at least one of said at least two multipole ion guide segments is positioned, and wherein the neutral gas pressure is high enough that collisions occur between said ions traversing said ion guide and said neutral gas molecules; and (f) RF and DC voltage sources that supply DC voltages and RF voltages with substantially the same RF frequency and phase to any one of said at least one multipole ion guide, and (g) means to control the amplitudes of said RF voltages and said DC voltages supplied to one of said at least two multipole ion guide segments independently of said RF voltages and said DC voltages supplied to others of said at least two multipole ion guide segments.