A high-frequency @M03732@ in which the @C01509@ motion of ions, having different mass/charge ratios, in a constant magnetic field is excited essentially simultaneously and coherently by a pulse or a radio-frequency electric field applied perpendicular to the magnetic field. The excited @C01509@ motion of the ions is subsequently detected on so-called receiver plates as a time domain signal that contains all the @C01509@ frequencies that have been excited. Fourier @T06446@ of the time domain signal results in the frequency domain FT-ICR signal which, on the basis of the inverse proportionality between frequency and the mass/charge ratio, can be converted into a @M03749@. The term is sometimes contracted to Fourier transform @M03732@ (FT-MS).