Efficient Ion Remeasurement Using Broadband Quadrupolar Excitation FTICR Mass Spectrometry

Quadrupolar excitation is achieved over a wide mass range by using repetitive chirp excitation, filtered noise excitation, and high-amplitude, single-frequency excitation for matrix-assisted laser desorption FTICR mass spectrometry. These methods efficiently axialize ions over a wide range of masses in a 4.7 T FTICR spectrometer. Remeasurement efficiencies are >99.5% for broadband repetitive chirp excitation, 99% with filtered white noise, and 99.4% with high-amplitude, single-frequency broad-band quadrupolar excitation. Results indicate that z-axis ejection of ions during detection is the primary mechanism for ion loss during remeasurement experiments. Capacitive coupling of the excitation signal to the trapping plates of the open-ended cylindrical analyzer cell is required for high remeasurement efficiency.