The Structures of Ag55+and Ag55-:  Trapped Ion Electron Diffraction and Density Functional Theory

Ligand-free metal clusters can be prepared over a wide size range, but only in comparatively small amounts. Determining their size-dependent properties has therefore required the development of experimental methods that allow characterization of sample sizes comprising only a few thousand mass-selected particles under well-defined collisionfree conditions. In this review, we describe the application of these methods to the geometric structural determination of Au + n and Au − n with n = 3-20. Geometries were assigned by comparing experimental data, primarily from ion-mobility spectrometry and trapped ion electron diffraction, to structural models from quantum chemical calculations.

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“…Ag + 55 and Ag − 55 ), where fitting parameters were found to be identical within experimental error (Schooss et al 2005).…”

Section: (I) Collision Cross Sections From Ion-mobility Spectrometrymentioning

confidence: 65%

Determining the size-dependent structure of ligand-free gold-cluster ions

Schooss

Weis

Hampe

et al. 2010

Phil. Trans. R. Soc. A.

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112

108

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“…Three experimental procedures were employed to determine anion cluster properties: ion mobility spectroscopy (IMS), collision-induced dissociation (CID; Weis et al 2002) and trapped ion electron diffraction (TIED; Schooss et al 2005). IMS measurements were done for up to 15 atoms; TIED was not possible for n ≤ 12 since intensities were too low.…”

Section: Tin Cluster Anions: From Spherical To Prolate To Clusters Ofmentioning

confidence: 99%

Quantum chemical treatments of metal clusters

Weigend

Ahlrichs

2010

Phil. Trans. R. Soc. A.

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This work focuses on finding and rationalizing the building principles of clusters with approximately 300 atoms of different types of metals: main group elements (Al, Sn), alkaline earth metals (Mg), transition metals (Pd) and clusters consisting of two different elements (Ir and Pt). Two tools are inevitable for this purpose: (i) quantum chemical methods that are able to treat a given cluster with both sufficient accuracy and efficiency and (ii) algorithms that are able to systematically scan the (3n−6)-dimensional potential surface of an n-atomic cluster for promising isomers. Currently, the only quantum chemical method that can be applied to metal clusters is density functional theory (DFT). Other methods either do not account for the multi-reference character of metal clusters or are too expensive and thus can be applied only to clusters of very few atoms, which usually is not sufficient for studying the building principles. The accuracy of DFT is not known a priori, but extrapolations to bulk values from calculated series of data show satisfying agreement with experimental data. For scans of the potential surface, simulated annealing techniques or genetic algorithms were used for the smaller clusters (approx. 20-30 atoms), and for the larger clusters considerations were restricted to selected packings and shapes. For the mixed-metallic clusters, perturbation theory turned out to be efficient and successful for finding the most promising distributions of the two atom types at the different sites.

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“…2 Information on the shape of cluster ions can be obtained from ion mobility measurements [3][4][5] and, recently, electron diffraction of trapped charged clusters has shown to be promising for revealing their structure. [6][7][8] Information on the binding geometry of a given cluster is also contained in its vibrational spectrum, since the force constants are directly dependent on the structural arrangement of the atoms. In some cases, vibrational structure has been found in electronic excitation spectra.…”

Section: Introductionmentioning

confidence: 99%

Experimental vibrational spectra of gas-phase tantalum cluster cations

Gruene

Fielicke

Meijer

2007

The Journal of Chemical Physics

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We present gas-phase infrared spectra of tantalum cluster cations containing 6-20 atoms. Infrared multiple photon dissociation (IR-MPD) of their complexes with argon atoms is used to obtain vibrational spectra in the region between 90 cm −1 and 305 cm −1 . Many spectra have features in common with the vibrational spectra of the lighter homologues, vanadium and niobium, pointing to a common cluster growth mechanism.

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The Structures of Ag₅₅⁺and Ag₅₅^-: Trapped Ion Electron Diffraction and Density Functional Theory

Cited by 124 publications

References 48 publications

Determining the size-dependent structure of ligand-free gold-cluster ions

Determining the size-dependent structure of ligand-free gold-cluster ions

Quantum chemical treatments of metal clusters

Experimental vibrational spectra of gas-phase tantalum cluster cations

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