The form of FTMS signals is analyzed for the general case of multiple electrode ICR cells with detailed results for two, eight and sixteen electrodes. The analysis is based on an elongated cylindrical cell to reduce the problem of treating the electric field distribution to two dimensions. The relative contributions of cyclotron and magnetron motion to the detected signal are analyzed for multiple electrode detection to establish the conditions for maximizing high order harmonic detection as a strategy for simultaneously enhancing mass resolution and sensitivity for characterizing high mass ions in FTMS. For pure cyclotron motion (no magnetron motion) only the basic frequency and its odd harmonics are detected by two electrodes; for multiple electrodes the transformed frequencies (originating from the commutation effect) and their odd harmonics are detected. The relative intensities of harmonic signals are greatly enhanced in large orbits, which also maximize the signal strength. Good agreement between the modeled FTMS signal and experimental results for a sixteen electrode ICR cell is demonstrated. The general conclusion is that minimization of magnetron motion is required for simplification and optimization of the FTMS signal with multiple electrode detection. This is entirely feasible with current technology and is a useful strategy for significantly enhancing mass resolution and S/N ratio in FTMS.
|Number of pages||18|
|Journal||International Journal of Mass Spectrometry and Ion Processes|
|Publication status||Published - 1996|
- Ion cyclotron resonance