Simplified electron ejection in Fourier transform ion cyclotron resonance mass spectrometry by suspended trapping

✍ Scribed by Brian T. Cooper; Steven W. Buckner

• Publisher: John Wiley and Sons
• Year: 1993
• Tongue: English
• Weight: 567 KB
• Volume: 28
• Category: Article
• ISSN: 1076-5174
• DOI: 10.1002/oms.1210280815

✦ Synopsis

Suspended trapping is used to eject electrons in negative-ion Fourier transform ion cyclotron resonance (FT-ICR) mass spectrometric experiments. In contrast to electron ejection by resonant excitation of the trapping motion, suspended trapping involves allowing the electrons to escape along the z-axis (perpendicular to the trap plates) while the trapping potential is briefly removed. The duration of this event is sufficiently short (-10 ps) so that ion losses are negligible; the overall effect is that of a 'high-pass mass filter'. Suspended trapping is simpler to implement and more generally applicable to various cell geometries than resonant electron ejection. The effectiveness of the suspended trapping technique is not compromised by the anharmonicity of the potential well in 'elongated' ICR traps, but depends simply on the time it takes the electrons to escape the cell. Finally, a small, positive offset potential (-+0.25 V) applied to the trap plates during the suspended trapping event increases the efficiency of the ejection.