Production and properties of CO2 cluster anions |
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Authors: | M Lezius T Rauth V Grill M Foltin T D Märk |
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Institution: | 1. Institut für Ionenphysik, Leopold Franzens Universit?t, Technikerstrasse 25, A-6020, Innsbruck, Austria
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Abstract: | Stoichiometric and non-stoichiometric negatively charged CO2 cluster ions have been produced in a crossed neutral cluster/electron beam ion source. The abundance and stability of these ions have been studied with a double focussing sector field mass spectrometer. The observed abundance anomalies (“magic numbers”) in the mass spectra of (CO2) n ? and (CO2) n O? ions correlate with corresponding small and large metastable fractions of these ions (for loss of one CO2 unit). Variation of the measured metastable fractions as a function ofn are related to corresponding changes in the monomer binding energies. In addition, we have observed for the first time (CO2) n O 2 ? ions (i.e. at electron energies above 8 eV with an energy resonance at about 14 eV) and we discuss possible production mechanisms for these ions. Relative electron attachment cross sections have been determined in the energy regime O<E≦20 eV for (CO2) n ? , (CO2) n O? and (CO2) n O 2 ? withn=1 to 20. The shape of the cross section function for (CO2) n O? is strongly dependent on the cluster sizen. |
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