A novel broadband ion axialization method has been developed for Fouri
er transform ion cyclotron resonance mass spectrometry based on Pennin
g trapping of ions. Ions of arbitrary mass-to-charge ratio range(s) ma
y be driven to the center of the trap (axialization) by azimuthal quad
rupolar irradiation with repeated low-amplitude stored-wave-form inver
se Fourier transform excitations in the presence of a buffer gas. We d
emonstrate highly mass-selective axialization and subsequent high-reso
lution Fourier transform ion cyclotron resonance detection of ions spa
nning a mass-to-charge ratio range of 500.