INTERNAL GLOW-DISCHARGE FOURIER-TRANSFORM ION-CYCLOTRON RESONANCE MASS-SPECTROMETRY

A glow discharge (GD) ion source has been developed to work within the high magnetic field of a Fourier transform ion cyclotron resonance (F TICR) mass spectrometer. Characterization of this source revealed that the optimum operating voltage, pressure, and current are significantl y lower than those for normal glow discharges. The sputter rate was lo wered to 1/30th of that found with a normal glow discharge source oper ated external to the high magnetic field region. Operation of the GD s ource closer to the FTICR analyzer cell than with previous experimenta l designs resulted in improved ion transport efficiency. Preliminary r esults from this internal GD source have established detection limits in the low parts per million range for selected elemental species.