Buffer gas and q{sub eject} effects on the performance of an ion trap

Conference · Sun Dec 31 04:00:00 EST 1995

OSTI ID:210696

Lammert, S A; Wells, J M ^[1]

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1. Oak Ridge National Lab., TN (United States)

The transformation of the ion trap from ion storage device to mass spectrometer was assisted in no small part by the discovery that the addition of a helium buffer gas greatly improved the mass resolution and sensitivity. Ions formed in the ion trap are kinetically cooled to the center of the ion trap by collisions with the helium buffer gas. In the earliest form of the experiment, these ions were then ejected from the trap via a mass instability scan. It was later discovered that the application of a resonant ac voltage could further improve the performance of the ion trap by resonantly ejecting ions as they approached the stability boundary in a process that was named {open_quotes}axial modulation{close_quotes}. Until recently, it has been widely held that the ion trap must operate using a helium buffer gas. The development by Bruker-Franzen of the Chemical and Biological Mass Spectrometer (CBMS) and later the Generic Detector (GD) for the US Army has demonstrated that ion traps can be operated without helium, using only air as the buffer gas. Attempts, however, to operate ion traps from Finnigan-MAT using an air buffer gas have not been successful. This research examines the role of the helium buffer gas in an ion trap mass spectrometer and explores the possibility of substituting ambient air as the buffer gas.

• OSTI ID: 210696
• Report Number(s): CONF-9505261--
• Country of Publication: United States
• Language: English

Related Subjects

44 INSTRUMENTATION
INCLUDING NUCLEAR AND PARTICLE DETECTORS
DESIGN
DYNAMIC MASS SPECTROMETERS
MASS SPECTROSCOPY
PERFORMANCE