| 1. |
- Chaika, Alexander N., et al.
(författare)
-
Rotated domain network in graphene on cubic-SiC(001)
- 2014
-
Ingår i: Nanotechnology. - : IOP Publishing. - 0957-4484 .- 1361-6528. ; 25:13
-
Tidskriftsartikel (refereegranskat)abstract
- The atomic structure of the cubic-SiC(001) surface during ultra-high vacuum graphene synthesis has been studied using scanning tunneling microscopy (STM) and low-energy electron diffraction. Atomically resolved STM studies prove the synthesis of a uniform, millimeter-scale graphene overlayer consisting of nanodomains rotated by +/- 13.5 degrees relative to the < 110 >-directed boundaries. The preferential directions of the domain boundaries coincide with the directions of carbon atomic chains on the SiC(001)-c(2 x 2) reconstruction, fabricated prior to graphene synthesis. The presented data show the correlation between the atomic structures of the SiC(001)-c(2 x 2) surface and the graphene/SiC(001) rotated domain network and pave the way for optimizing large-area graphene synthesis on low-cost cubic-SiC(001)/Si(001) wafers.
|
|
| 2. |
- Luebben, Olaf, et al.
(författare)
-
Fe Nanoclusters on the Ge(001) Surface Studied by Scanning Tunneling Microscopy, Density Functional Theory Calculations and X-Ray Magnetic Circular Dichroism
- 2011
-
Ingår i: Nano Reseach. - : Springer Science and Business Media LLC. - 1998-0124 .- 1998-0000. ; 4:10, s. 971-978
-
Tidskriftsartikel (refereegranskat)abstract
- The growth of Fe nanoclusters on the Ge(001) surface has been studied using low-temperature scanning tunneling microscopy (STM) and density functional theory (DFT) calculations. STM results indicate that Fe nucleates on the Ge(001) surface, forming well-ordered nanoclusters of uniform size. Depending on the preparation conditions, two types of nanoclusters were observed having either four or sixteen Fe atoms within a nanocluster. The results were confirmed by DFT calculations. Annealing the nanoclusters at 420 K leads to the formation of nanorow structures, due to cluster mobility at such temperature. The Fe nanoclusters and nanorow structures formed on the Ge(001) surface show a superparamagnetic behaviour as measured by X-ray magnetic circular dichroism.
|
|
| 3. |
- Murphy, Barry E., et al.
(författare)
-
Homolytic Cleavage of Molecular Oxygen by Manganese Porphyrins Supported on Ag(111)
- 2014
-
Ingår i: ACS Nano. - : American Chemical Society (ACS). - 1936-086X .- 1936-0851. ; 8:5, s. 5190-5198
-
Tidskriftsartikel (refereegranskat)abstract
- Oxygen binding and cleavage are important for both molecular recognition and catalysis. Mn-based porphyrins in particular are used as catalysts for the epoxidation of alkenes, and in this study the homolytic cleavage of O-2 by a surface-supported monolayer of Mn porphyrins on Ag(111) is demonstrated by scanning tunneling microscopy, X-ray absorption, and X-ray photoemission. As deposited, {5,10,15,20-tetraphenylporphyrinato}Mn(III)CI(MnCITPP) adopts a saddle conformation with the average plane of its macrocyde parallel to the substrate and the axial CI ligand pointing upward, away from the substrate. The adsorption of MnCITPP on Ag(111) Is accompanied by a reduction of the Mn oxidation state from Mn(III) to Mn(II) due to charge transfer between the substrate and the molecule. Annealing the Mn(II)CITPP monolayer up to 510 K causes the chlorine ligands to desorb from the porphyrins while leaving the monolayer intact. The Mn(II)TPP is stabilized by the surface acting as an axial ligand for the metal center. Exposure of the Mn(11)TPP/Ag(111) system to molecular oxygen results in the dissociation of O-2 and forms pairs of Mn(111)OTPP molecules on the surface. Annealing at 445 K reduces the Mn(111)OTPP complex back to Mn(II)TPP/Ag(111). The activation energies for Cl and 0 removal were found to be 0.35 +/- 0.02 eV and 0.26 +/- 0.03 eV, respectively.
|
|
