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Eur. J. Mass Spectrom. DOI: 10.1255/ejms.627 |
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Excitations of ions by high-harmonic frequency components in Paul and Penning traps and ion guides. 1. Selective simultaneous dipolar excitation of high charge states with clipped sinusoidal and non-harmonic waveforms in linear quadrupole ion guide | ||
V. Sergey Rakov and Craig D. Whitehouse |
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ABSTRACT: | ||
Simultaneous excitation of multiple high charge states of a molecular ion by its first charge state's resonant frequency waveforms, other than pure sinusoid, is demonstrated in a harmonic ion trap, namely a quardupolar mass filter operated in an RF-only mode. The method employs a variety of time-domain excitation waveforms, all rich in harmonic (multiples of the main) frequency components allowing simultaneous translational excitation of ensembles of high charges. Amplitude restriction (clipping) of sinusoidal signal is demonstrated to be simple and effective way of activating harmonic frequencies. Special attention is paid to clipped superposition of two sinusoids different in frequency by factor of two, which facilitates selective harmonic suppression when relative amplitudes of the sinusoids and clipping are varied. Multiple protonation states of melittin produced by electrospray ionization were used to investigate high charge states' excitation by harmonic frequencies. | ||
Keywords: quadrupole, resonance, auxiliary excitation, high-order harmonic frequencies, amplitude clipping |
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