Chromium Nano-Islands on Au(111)

Abstract

Ordered chromium islands of nanometer sizes formed by sub-monolayer Cr deposition on Au(111) have been studied in this work by scanning tunneling microscopy under ultra high vacuum. Bimodal size distribution of the islands are observed in 0.25-0.45 monolayer (ML) coverage: the bigger islands are formed at the elbows of the herringbone reconstruction, while relatively smaller sized Cr islands appear due to the distortion of the herringbone pattern by the islands formed at the bulged elbows. Further deposition results in increase of the island size with characteristic shapes. Eventually, the islands coalesce resulting in pseudomorphic growth of Cr layers showing (1×1) hexagonal low energy electron diffraction pattern similar to the substrate indicating that Cr grows pseudomorphically on Au(111).

Structure and Reactivity of Cu-doped Au(111) Surfaces

“…Nucleation of guest metals on Au(111) generally occurs via the place-exchange mechanism [5], which was initially ruled out for the adsorption of copper; however, it was later reported that the onset of copper adsorption does occur via a place-exchange mechanism, at specific sites identified as the narrowed regions within the highly reactive elbows of the Au(111)-(22× √ 3), irrespective of hcp or fcc stacking [1]. Other than for copper [6][7][8], this is also the case for other transition metals such as nickel [9][10][11][12], iron [13,14], and chromium [15,16], to name a few. Added clusters are regarded as a source of reactive metal atoms, over a surface commonly considered as a 2D inert support, opening up the possibility of modifying the reactivity of the Au(111) surface itself, via the formation of surface alloys, whereby both the added metal and gold are present in the top layer.…”

Stability of Pd Islands on Ag(111) and Au(111)

“…A variety of metals deposited on Au(111) have been studied, including Co, Cr, Fe, Mn, Mo, Ni, − Pd, ,− Pt, Rh, , Sn, Ti, and Zn. , Of most relevance to the present study are the STM results on the nucleation and growth of Pd islands on Au(111) by Stephenson et al and Casari et al Although these studies focused on the nucleation of Pd islands at room temperature (RT), they did not report on the stability of Pd islands as a function of annealing temperature as we do here. Baber et al also studied Pd on Au(111) using STM, and they discovered that the herringbone structure of Au(111) provided the entry sites for the incorporation of Pd atoms into the Au lattice and that the extent of mixing of Pd atoms with the Au surface depended on temperature .…”

“…A variety of metals deposited on Au(111) have been studied, including Co, 23 Cr, 24 Fe, 25 Mn, 26 Mo, 27 Ni, 28−31 Pd, 4,32−35 Pt, 36 Rh, 37,38 Sn, 39 Ti, 40 and Zn. 41,42 Of most relevance to the present study are the STM results on the nucleation and growth of Pd islands on Au(111) by Stephenson et al 33 and Casari et al 34 Although these studies focused on the nucleation of Pd islands at room temperature (RT), they did not report on the stability of Pd islands as a function of annealing temperature as we do here.…”

Metallosupramolecular Assembly of Cr and p-Terphenyldinitrile by Dissociation of Metal Carbonyls on Au(111)

“…Figure 1e shows the 1D MOCN chain model overlaid on the STM image. Dosing Cr(CO) 6 on a clean Au(111) surface led to no visible features that could be attributed to Cr in STM scans, even at doses greater than 9400 L. Rai et al 32 reported that the preferred adsorption location for chromium on Au(111) is at the elbows of the herringbone reconstruction. RAIRS experiments were attempted to determine the presence of metal carbonyls on the surface (Figure S2); however, no carbonyl vibrations were detected.…”