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We present a theoretical study of the structural and optical properties of isolated silver cluster-tripeptide hybrid systems. We show that small silver clusters induce enhancement of the optical absorption of peptides. Moreover, silver clusters bound to peptides can reduce the conformational flexibility and invoke changes of the secondary structure. Thus, they might serve as local optical probes in biolabelling applications. [ABSTRACT FROM AUTHOR]

Here, we present the dynamical aspects and the role of internal energy redistribution (IVR) in the reactivity of noble metal clusters towards O2. We show on the example of Ag3O2 - / Ag3O2 / Ag3O2 + that NeNePo spectroscopy carried out under zero electron kinetic energy (ZEKE) conditions can be a powerful tool to investigate the geometry relaxation and IVR induced by photodetachment in real time. Furthermore, we demonstrate that difference in the reactivity of Ag6 - and Au6 - towards O2 can be attributed to different nature of the IVR process. Dissipative IVR in Ag6 - favors fast complex stabilization, whereas resonant IVR found for Au6 - might be an important factor determining the catalytic activity of Au6 - cluster in the CO oxidation. [ABSTRACT FROM AUTHOR]

In this paper, we present results from our joint experimental and theoretical study of the reactivity of anionic gold oxide clusters Au2,3O1-4 - towards CO. We provide clear evidence that, although O–O bond weakening/dissociation is important to enable CO oxidation, the presence of atomic oxygen can be favorable but is not always sufficient. Furthermore, we show that with the addition of a single gold atom the reactivity channels can be changed. As a consequence, in contrast to CO oxidation in the case of anionic gold dimer oxides, association of CO or replacement of O2 by CO become the dominant reaction channels for Au3On -. This demonstrates the nonscalable properties of gold clusters in the size regime in which each atom counts. [ABSTRACT FROM AUTHOR]

Bimetallic silver-gold clusters are well suited to study changes in metallic versus “ionic” properties involving charge transfer as a function of the size and the composition. We present structures, ionization potentials (IP) and vertical detachment energies (VDE) for neutral and charged bimetallic AunAgm ( 2≤(n + m)≤5) clusters obtained from density functional level of theory. In the stable structures of these clusters Au atoms assume positions which favor charge transfer from Ag atoms. In clusters with equal numbers of hetero atoms (n = m = 1- 4) heteronuclear bonding is preferred to homonuclear bonding, giving rise to large values of ionization potentials. For larger clusters (n=m=5, 10) stable structures do not favor neither hetero bonding nor segregation into the single components, although they exhibit more metallic than ionic features. This remains valid also for Au8Ag12 cluster characterized by strong charge transfer to gold subunit. The influence of doping of pure gold clusters with silver atoms on VDE and IP values is discussed in context of their reactivity towards O2 and CO molecules. As a starting point we consider reactivity towards CO and O2 molecules on the example of AgAu- dimer. The results show that the catalytic cycle can be fullfilled. [ABSTRACT FROM AUTHOR]