Reduced Metallic Properties of Ligand-Stabilized Small Metal Clusters

Abstract

Low-temperature ultrahigh-vacuum scanning tunneling microscopy was employed to analyze the electronic behavior of Au 55 clusters stabilized by [P(C 6 H 5 ) 3 ] 12 Cl 6 ligands. At 7 K, the actual arrangement of the C 6 H 5 rings of the ligand molecules could be imaged. Spectroscopic data reveal discrete energy levels with an average spacing of 170 meV that can be attributed to the Au 55 core. Additionally, characteristic charge-quantization phenomena were observed. Energy and charge quantization both support the view that the clusters consist of a metallic core extending slightly beyond the first close-packed shell of Au atoms.

A study of charge quantization on ligand-stabilized Au55cluster monolayers

“…This can be explained by the fact that the transmission probability of the tunnelling electrons increases with increasing bias, whereas it is assumed to be constant in the calculation. The small step at about 0.4-0.6 V in the measured curve occurs due to the energy quantization of the cluster [19].…”

“…This asymmetry could have been caused by both the charge quantization (Coulomb staircase) [17] of the metal core and the electronic structure of the ligand molecules. Discrete energy levels of the cluster due to the quantum size effect [18] can be excluded here because the level spacings are expected to be much smaller than the step width [19].…”

Surface chemistry of catalysis by gold

“…One of the first examples of a magic cluster is Au55 which was discovered by Schmid et al (414) and has since seen extensive study (415)(416)(417). Boyen et al recently confirmed that Au55 clusters display unusual chemical behaviour (418).…”

Metallnanopartikel als Einelektronenschalter: Nanotechnologie: Schlüsseltechnologie des neuen Jahrhunderts?

“…Ein wichtiges zusätzliches Ergebnis wurde durch eine Tieftemperaturmessung der gleichen Nanopartikel erhalten: die Coulomb-Blockade ist durch eine Feinstruktur gekennzeichnet, aus der diskrete elektronische Energieniveaus hervorgehen, die ein Elektron auf dem Weg zur Gegenelektrode stufenweise zu überwinden hat (Abbildung 11) [8]. Um diese Feinstruktur zu erkennen, trägt man vorzugsweise anstelle des Stroms I die erste Ableitung dI/dV auf, wodurch die CB als Minimum wiedergegeben wird.…”