Fig. 6: Detecting radial ion motion in an Orbitrap analyser.
a,b, The detected peaks for two individual instances of HBV T = 3 single ions. On the left, the peak at the standard axial frequency (ωz) is displayed (shown in the m/z domain). On the right, signals originating from the radial frequency modulations, ω+ and ω– (at higher and lower frequency with respect to ωz, respectively) are displayed in the lower and higher m/z region (top and bottom). The raw data is shown in grey, the smoothed signal in black. The ion in a illustrates a highly stable radial frequency, whereas the single ion in b represents a non-stable radial frequency, for example caused by non-circular orbits. Note that in b the signals originating from the modulation by ω+ and ω– are, as expected, mirror images of each other in the frequency domain.
