Structures and energetics of small lead cluster ions

Abstract

By a combination of gas phase ion mobility measurements and relativistic density functional theory calculations with inclusion of spin-orbit coupling, we assign structures of lead cluster cations and anions in the range between 4 and 15 atoms. We find a planar rhombus for the tetramer, a trigonal bipyramid for the pentamer, and a pentagonal bipyramid for the heptamer, independent of charge state. For the hexamer, the cation and anion structures differ: we find an octahedron for the anion while the cation consists of fused tetrahedra. For the octamer, we find in both cases structures based on the pentagonal bipyramid motif plus adatom. For the larger clusters investigated we always find different structures for cations and anions. For example, Pb(12)(-) is confirmed to be a hollow icosahedron while Pb(12)(+) is a truncated filled icosahedron. Pb(13)(+) is a filled icosahedron but Pb(13)(-) is a hollow icosahedron with the additional atom capping a face. In order to get experimental information on the relative stabilities, we investigated the collision induced dissociation mass spectra for the different cluster sizes and charge states, and observe a strong correlation with the calculated fragmentation energies. Up to n = 13 the main fragmentation channel is atom loss; for the larger cluster sizes we observe fission into two large fragments. This channel is dominant for larger anions, less pronounced but clearly present for the cations.

Structures of small bismuth cluster cations

“…We note in advance that -unlike for example Pb clusters 35 -SOC has significant impact on the results and that results accounting for SOC generally are better in line with the experimental data. We further note that for some cases two-component calculations starting from two different minima of the one-component treatment end up with the same minimum structure.…”

“…This threshold was chosen to be slightly higher than in previous analogous treatments of other elements 35 to be on the safe side -given the unexpectedly large effects observed upon accounting for SOC. The cross sections calculated by the SEDI model were determined as described previously and are listed in Table I.…”

Global optimization of clusters using electronic structure methods

“…We emphasize again that all these studies include scalar-relativistic effects (at most) at the GA stage. Only recently, the first studies that include SO effects or perform relativistic two-component calculations at the refinement stage were published for Pb [141] and Bi [143] cations.…”

“…[146,147] FP-GA studies for multielement systems are quite new and, consequently, it is not surprising that only a few examples exist so far (Table 1). Apart from the nanoalloys, to date mostly metal oxide species have been investigated by GA-DFT in combination with infrared (IR) spectroscopy, because they serve as model systems for oxide surfaces or , [130] and c) Au 8 /F/MgO [141] . a) The GM (I) and low energy isomers (II;III) exhibit planar, bowl-like, or double-wheel like structures which cannot be reproduced by EPs.…”

Photoelectron velocity-map imaging signature of structural evolution of silver-doped lead Zintl anions

“…[1][2][3][4] A large number of "ligand-free" Group 14 Zintl clusters have been prepared via the synthesis in the liquid phase or the laser vaporization in the gas phase, of which geometric and electronic structures have been explored experimentally and theoretically. [5][6][7][8][9][10][11][12][13][14][15][16][17][18] In particular, the identifications of highly symmetric cage structures of the fascinating Pb 10 2− , Sn 12 2− , and Pb 12 2− clusters [10][11][12][13] intrigue and invite investigation of the metal-doped Zintl clusters [10][11][12] in the knowledge of whether a doped atom is endohedral or exohedral. Most of this work has involved the heavy Group 14 element species with the magic cluster size number of 10 and 12.…”