Silver clusters geometry

The optical behaviour of silver island films embedded in optical thin film materials has been studied by spectrophotometry. The silver cluster surface plasmon absorption line position and width strongly depend on deposition temperature and ambient material. Electron micrographs of the samples allow to establish the correlation between silver cluster geometry and optical behaviour. The first results of Rigorous Coupled Wave Approximation (RCWA) calculations reproduce the spectrophotometric experimental results. 

A comparison of the bonding energy per atom (BE/n) for silver clusters of one- and three-dimensional structure is made in Fig. 3. The stability increases in the order 3d < 2d < Id in this size range. The geometries treated were straight-chain linear, square planar, and symmetric three-dimensional structures. 

C-2b c In the cationic Ag(I) arylacetylide complexes [Ag3(dppm)3L]2+ (111) and [Ag3(dppm)3L2] + (112) the trinuclear silver cluster has triangular pyramidal or bipyramidal geometry, with acetylenic C atoms in apical positions. Interatomic distances, 111 Ag—Ag... 

Figure 2. Left The optical loss L of the samples, where the silver clusters are embedded in AI2O3. Solid Line measured Dash RCWA-calculation. Right TEM image of the sample (top) and assumed island geometry in the RCWA-calculation (bottom). Area 300 nm x 300 nm. The silver islands appear as dark...

In spite of great interest in preparation and studying of silver clusters Ag , their structures are not clearly determined yet. Thus, only structures of clusters with n=3,4,5 are fairly well established. The most effective method of investigations of clusters structures is a comparison of quantum chemical predictions for different stable geometries with experimental data. The central problem in reliable identification of clusters structures by this method is an increase of the amount of structures characterized by closely allied values of energetic characteristics as the size of the cluster grows. As a consequence, structural assigmnent even for relatively simple clusters is a very difficult problem [1]. 

Figure 2. Optimized geometries and relative energies of silver clusters.

Silver dithiocarboxylato complexes also tend to form dimers, polymers and clusters with various geometries around the silver atoms [109-111]. For example, in the tetranuclear silver clusters 55 and 56 bearing dithiocarboxylato ligands, four silver atoms are in a roughly square-planar array and a highly distorted tetrahedral array, respectively (Fig. 13) [32]. In these complexes, each sulfur atom is attached to one or two silver atoms, respectively. 

The results of NeNePo with clusters of live, seven, and nine silver atoms are graphically presented, together with the relevant geometries that resulted from ab initio calculations [25], in Fig. 27. The temporal progressions have... 

In terms of its coordination chemistry, the silver(I) ion is typically characterized as soft . Although originally believed to only bind ligands in a linear arrangement, it was soon shown that it can adopt a variety of coordination environments, the most common one being a four-coordinate tetrahedral geometry. Square-planar complexes are not rare, and various silver(I) cluster complexes also contain three-and five-coordinate sUver(I) ions. 

An adsorption of silver dimer on a rutile (110) surface has been studied using a DFT model within both cluster and periodic approaches. The calculations show that the interaction of silver dimers can occur both with bridging chain of oxygen atoms or with atoms located in the hollows between chains. The bonding of Ag2 in the hollow is characterized by the positive adsorption energy according to the periodic model. On the other hand, the geometry optimization of similar structures within the cluster model leads to desorption or dissociation of silver dimer. The periodic model is shown more appropriate for this system. 

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