A study of octupolar excitation for mass-selective centering in Penning traps

Octupolar excitation has been investigated with respect to mass-selective ion centering in buffer-gas filled Penning traps for the isolation of an ion species of interest. To this end, off-line test measurements have been performed with the preparation Penning trap of the mass spectrometer ISOLTRAP located at ISOLDE/CERN including a comparison with the conventional quadrupolar excitation. The experimental results are compared to numerical simulations of ions under influence of quadrupolar and octupolar excitation.

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► We investigate the applicability of octupolar excitation in buffer-gas filled Penning traps.
► The experiment yields a drop of resolving power for octupolar excitation as compared to the expectations.
► A simulation including ion-atom collisions has been written in order to explain the measurements.
► The simulation shows a crucial influence of the buffer-gas on the ion trajectory during octupolar excitation.