Application of simultaneous excitation/detection to generate real-time excitation profiles in fourier transform ion cyclotron resonance mass spectrometry
Simultaneous excitation/detection (SED), which permits observation of ion motion during an excitation event, is used to generate real-time Fourier transform ion cyclotron resonance (FTICR) excitation profiles that track the radial extent of ion motion in a trapped-ion cell. The conventional FTICR excitation profile is collected in a series of individual experiments in which peak magnitude is monitored as excitation voltage is increased. In contrast, SED permits the single-scan detection of ion cyclotron motion within the trapped-ion cell and consequently yields the data that produces a real-time excitation profile. Data analysis techniques are presented that facilitate conversion of a time domain SED profile into an excitation profile. An order of magnitude decrease in the amount of time is required to acquire an excitation profile, while the precision of the measurement is improved. To demonstrate the utility of the technique, it is applied to the study of axial and radial ion loss mechanisms for argon, benzene, and acetophenone ions under different conditions. SED excitation profiles are also used to illustrate the facility of quadrupolar excitation for minimizing radial ion loss.