Geometrical Structures of Gas-Phase Cerium Oxide Cluster Cations Studied by Ion Mobility Mass Spectrometry
journal contributionposted on 17.06.2019 by Toshiaki Nagata, Jenna W. J. Wu, Motoyoshi Nakano, Keijiro Ohshimo, Fuminori Misaizu
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Geometrical structures of cerium oxide cluster cations, CenOm+ (n = 2–6, m ≤ 2n), were studied by ion mobility mass spectrometry (IMMS). The most plausible structure for each composition was determined by comparison of a collision cross section (CCS) measured by IMMS with simulated CCSs of several candidate structures obtained from density functional theory (DFT) calculations. For Ce2O2,3+, Ce3O4,5+, and Ce5O9+, the IMMS results were mostly consistent with those of the vibrational spectroscopic study, whereas a more compact structure was suggested for Ce4O7+. The geometrical structures of some species, Ce4O5,6+, Ce5O6–8+, and Ce6O8–12+, were studied for the first time. For CenO2n+ clusters, the IMMS measurements suggested more compact structures than the reported DFT calculations. Structures with a peroxide ion (O22–) were found to be the most reasonable for CenO2n+ compositions because they are consistent with the experimental results and have the lowest energies among the examined candidate structures, whereas other structures without O22– are also possible. These findings offer important insights into the reaction mechanisms involving those clusters.