A study of the electronic properties of Au nanowires and Au nanoislands on Au(111) surfaces

Abstract

By means of ion bombardment of clean Au(111) films, atomically flat nanoparticles of various shapes and sizes were created, ranging from several tens of nm(2) down to only a few nm(2). Both two-dimensional Au islands as well as one-dimensional Au nanowire-like structures have been investigated by means of low-temperature scanning tunneling microscopy and spectroscopy. We were able to probe their local electronic structure in a broad energy range, which was found to be dominated by pronounced size-dependent confinement effects. Mapping of the local density of states revealed complex standing wave patterns that arise due to interference of scattered Au surface state electrons at the edges of the Au nanoparticles. The observed phenomena could be modeled with high accuracy by theoretical particle-in-a-box calculations based on a variational method that can be applied to '2D boxes' of arbitrary polygonal shape and that we have previously successfully applied to explain the electronic wave patterns on Co islands on Au(111). Our findings support the general validity of this particle-in-a-box model.

End and Edge States: Entrapment and Polarization

“…13.3 Size-resolved valence LDOS of Au-MD and Au-CO clusters shows that as the number of atoms is reduced, the LDOS moves up toward E F (positioned at 0) (reprinted with permission from [15]). The polarization trend agrees with STM/S observations of gold islands of different sizes [14] and gold monatomic chain [4]. The polarization is most significant of the lowest coordinated atoms peak area normalized.…”

“…13.2, show the same trend to the chain ends. The narrow cross section enhances the polarization [14].…”

Electronically decoupled stacking fault tetrahedra embedded in Au(111) films

“…Moreover, in the case of subsurface Ar bubbles, one expects to still probe the Au(111) bulk conduction band in d I /d V spectra recorded above the bubble. The Au SFTs have an appearance that is similar to that of Au vacancy islands that can be controllably created by mild ion bombardment and annealing23. However, while vacancy islands have a depth of one atomic layer that is independent of the applied tunnelling voltage, Au SFTs have a sub-monolayer depth/height that depends strongly on the applied tunnelling voltage as discussed above.…”

“…However, while vacancy islands have a depth of one atomic layer that is independent of the applied tunnelling voltage, Au SFTs have a sub-monolayer depth/height that depends strongly on the applied tunnelling voltage as discussed above. Moreover, the electronic behaviour of Au SFTs differs strongly from that of Au vacancy islands2324. Au vacancy islands confine the surface state of the Au(111) surface within their step boundaries.…”

Catalytic enhancement of gold nanocages induced by undercoordination-charge-polarization

“…Results indicate that electrons of the undercoordinated surface atoms engage mainly in the catalytic reactions, in accordance with experimental observations. 45 The Au valance bands of the Au monomer and dimer, 45 monatomic chain end, 46 smaller NPs, 21 narrower nanowire, 47 and thinner layers of adatoms 48 have been revealed to be polarized to upper energy compared with that of bulk gold as observed using scanning tunneling spectroscopy.…”