Structural assignment of small cationic silver clusters by far-infrared spectroscopy and DFT calculations

Abstract

The structures of small cationic silver clusters Ag (n = 3-13) are investigated by comparing measured far-infrared multiple photon dissociation spectra of cluster-argon complexes with the calculated harmonic vibrational spectra of different low-energy structural isomers. A global structure search was carried out using the CALYPSO structure prediction method, after which isomers were locally optimized with the meta GGA functional TPSS. The obtained structures of the cationic silver clusters are mostly consistent with earlier ion mobility measurements and photodissociation spectroscopy studies for Ag (n = 3-11) and allowed excluding several structural isomers that were considered in those earlier studies, which illustrates the strength of combining multiple experimental techniques for conclusive structural identification. The growth pattern of the cationic silver clusters is discussed and differences with other cationic coinage metal clusters are highlighted.

The structures of cationic gold clusters probed by far-infrared spectroscopy

“…For instance, it is now known that neutral Au20 adopts a tetrahedral (pyramidal) structure [10,11,12], and that anionic gold clusters form hollow cages [13]. The relativistic character of gold [14] is manifested when comparing the predicted and experimentally observed structures of Au clusters with those of Cun and Agn [15,16]. While Cu and Ag clusters adopt 3D structures from n = 5, Au clusters retain planar geometries up to significantly larger n.…”

Assessment of interaction-strength interpolation formulas for gold and silver clusters

“…49,50 On the other hand, for cationic silver clusters it has been suggested that the dimensional transition occurs already for Ag + 5 , which has a 2D structure with a slightly lower energy than the 3D one, while Ag + 6 and Ag + 7 display lowest energy 3D structures. 39,107 Anyway, this is a quite difficult problem because experimentally it is not trivial to distinguish clusters of the same size but different dimensionality. A computational support is thus required.…”

Structures and magnetic properties of small ${{\rm Co}_{n}^{+}}$ and Co n−1Cr+ (n = 3–5) clusters

“…The authors stated that these effects are attributed to symmetry breaking, which enhances electron density polarization of the cobalt clusters induced by Ar tagging. This strong effect of Ar addition is markedly different from other, larger, metal clusters, such as cationic niobium, tantalum, and silver clusters, in which the influence of the rare-gas atoms on the IRMPD spectra was found to be small and limited to frequency shifts of a few wavenumbers only [52][53][54]. Co4 + and Co5 + were previously studied by Fielicke and co-workers [16], who reported IRMPD spectra for Co4Ar1,2,4,5 + and Co5Ar1,5 + .…”