AN IMPROVED ION GUIDE FOR EXTERNAL ION INJECTION IN GLOW-DISCHARGE FOURIER-TRANSFORM ION-CYCLOTRON RESONANCE MASS-SPECTROMETRY

To improve the existing ion transport optics of our glow discharge (GD)-Fourier transform-ion cyclotron resonance (FT-ICR) mass spectrometer, we simulated several ion trajectories between the GD source region and the ICR analyzer cell. These calculations suggested that a number of simple improvements, including the use of an ion flight tube and an electrically isolated conductance limit, would increase the efficiency of ion transfer through the fringing fields of the FT-ICR superconducting magnet and into the ICR analyzer cell. Ion beam intensity was monitored as a function of the distance between the GD source and the analyzer cell before and after implementing these improvements. A twentyfold improvement in the transport efficiency, as well as a fifteenfold enhancement in detected FT-ICR signals, was observed.