EXTERNAL SOURCE FOURIER-TRANSFORM ION-CYCLOTRON RESONANCE MASS-SPECTROMETRY BY USING A SPLIT-PAIR MAGNET

A new instrument has been designed, built, and tested for high perform ance Fourier transform ion cyclotron resonance mass spectrometry (FTIC RMS) that allows operation at gas pressures of up to similar to 20 Ton in the ion source and up to similar to 0.01 Ton in the ion trap. FTIC RMS performance is not compromised at these pressures due to an extern al, high throughput ion source and pulsed gas introduction/rapid gas e vacuation of the vacuum chamber at the trapped ion cell. This system i s the first to retain ions at 0.01-Torr gas pressure in the ion trap w ith high sensitivity. This performance is achieved while obtaining hig h mass resolution and ppm mass accuracies. (Int J Mass Spectrom 177 (1 998) 63-81). (C) 1998 Elsevier Science B.V.