Compact Non-Rock-Salt Structures in Sodium Fluoride Cluster Ions at Specific Sizes Revealed by Ion Mobility Mass Spectrometry

Abstract

Structures of small sodium fluoride cluster cations, Na(n)F(n-1)(+), have been determined for n = 5-23 by ion mobility mass spectrometry. In the mass spectrum of Na(n)F(n-1)(+) cluster ions measured after collisions in the ion-drift cell, cuboid ions with near-regular hexahedron such as n = 14 (3 × 3 × 3), 23 (3 × 3 × 5), 38 (3 × 5 × 5), 63 (5 × 5 × 5), and 88 (5 × 5 × 7) were predominantly observed as magic numbers. By comparison of the collision cross sections obtained from the ion mobility measurements with theoretical ones, we have experimentally shown that the ions of n = 7 and 10 have stable non-rock-salt type structures in which one sodium atom is encapsulated into the sodium fluoride cuboid lattice. The collision cross sections of n = 12 and 13 are almost equal to that of the n = 14 cuboid. A similar feature was also observed in collision cross sections of n = 21 and 22, which are equal to that of the n = 23 cuboid. These features indicate that the cluster ions of n = 12, 13, 21, and 22 have near-cuboid structures with some surface defects.

Compositions and Structures of Vanadium Oxide Cluster Ions VmOn± (m = 2–20) Investigated by Ion Mobility Mass Spectrometry

“…Finally, product ions from these reactions passed through the cell. In our previous study for sodium fluoride cluster cations, stable magic number cluster cations were clearly observed as collision-induced dissociation products under high E inj conditions …”

Collision cross sections of negative cluster ions of phosphoric acid in N2 determined by drift tube ion mobility and their use in travelling wave ion mobility

“…13,14,15 Cluster ions are readily produced using direct infusion of salt solutions with an electrospray ion source and are routinely used for calibration of mass analyzers. 16,17,18,19,20 A number of ionic clusters derived from alkali halides salts, 21,22,23 ionic liquids 24,25,26,27 and transition metal oxides 28,29,30,31,32,33 have been studied by drift tube ion mobility mainly and differential mobility analysis-time-of-flight mass spectrometry. Since a first study in 2014, 34 we have started studying negative phosphoric acid cluster ions in view of investigating their potential as reference for the calibration of the TWIMS.…”

Application of Ion Mobility-Mass Spectrometry to the Study of Ionic Clusters

“…1. [18][19][20]25) Either of the positive or negative ions were examined by this apparatus, by changing the polarity of voltages applied in the electrodes. Cluster ions were produced by combination of a laser vaporization method with subsequent chemical reactions.…”

“…From these analyses, geometrical structure was determined for each cluster ion. 20) In particular, the cross sections of above magic number clusters were explained by the cuboid structures. Figure 4 shows total ion mass spectrum of sodium uo- ride cluster cations Na n F + n−1 obtained by summing up each mass spectrum at a given arrival time constituting the 2D plot of Fig.…”

“…Firstly from the results of sodium uoride cluster ions, we have con rmed that the stable clusters (magic number clusters) were predominantly formed by CID reactions in the cell. 20) Next we show the results of investigation of stable chemical compositions for rst-row transition metal oxide cluster ions. As for the stable composition of the transition metal oxides, there have been several investigations using CID, 21,22) photodissociation 23) and thermal heating.…”