Fourier series resolving power

Figure 9.2 Spectra of ESTgenerated cytochrome c ions obtained with (a) an ion trap (IT) and (b) a Fourier transform ion cyclotron resonance (FT-ICR) mass spectrometer. The mass resolving power of the IT is low, so the charge state distribution has to be derived from a series of peaks at different charge states. The mass resolving power of the FT-ICR is high enough to resolve the isotopic pattern of one charge state. The insets display the isotopic patterns of the charge state +/3...

For quasi-periodic trajectories, like those for the normal-mode Hamiltonian in Eq. (69), I to) consists of a series of lines at the frequencies for the normal modes of vibration. In contrast, a Fourier analysis of a chaotic trajectory results in a multitude of peaks, without identifiable frequencies for particular modes. An inconvenience in this approach is that for a large molecule with many modes, a trajectory may have to be integrated for a long time T to resolve the individual lines in a power spectrum for a quasi-periodic trajectory. Moreover, in the presence of a resonance between different modes, the interpretation of the power spectrum may become misleading. 

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