Method and apparatus to increase ionization efficiency in an ion source

摘要

A method and an apparatus for collecting ions in which ions are produced from a sample in an ion source. An electric field is provided that is more uniform in an area adjacent the sample than in an area adjacent an inlet to the ion transfer device or that is larger in field strength at the sample than at a point removed from the sample towards the inlet of the ion transfer device. Ions are received into the electric field and transferred through the ion transfer device to a sampling orifice of the mass spectrometer. The apparatus includes an ion transfer device coupled to a sampling orifice of a mass spectrometer. The ion transfer device has an inlet with a surface that extends in a direction from an axis of the ion transfer device. The ion transfer device can extend a distance of at least 10 times an inner diameter of a sampling orifice of the mass spectrometer.