title: Surface structure. Subatomic resolution force microscopy reveals internal structure and adsorption sites of small iron clusters.
abstract: Clusters built from individual iron atoms adsorbed on surfaces (adatoms) were investigated by atomic force microscopy (AFM) with subatomic resolution. Single copper and iron adatoms appeared as toroidal structures and multiatom clusters as connected structures, showing each individual atom as a torus. For single adatoms, the toroidal shape of the AFM image depends on the bonding symmetry of the adatom to the underlying structure [twofold for copper on copper(110) and threefold for iron on copper(111)]. Density functional theory calculations support the experimental data. The findings correct our previous work, in which multiple minima in the AFM signal were interpreted as a reflection of the orientation of a single front atom, and suggest that dual and triple minima in the force signal are caused by dimer and trimer tips, respectively.
authors: Institute of Experimental and Applied Physics, Department of Physics, University of Regensburg, 93053 Regensburg, Germany.
authors: Matthias
authors: M
authors: Emmrich
authors: Institute of Experimental and Applied Physics, Department of Physics, University of Regensburg, 93053 Regensburg, Germany.
authors: Ferdinand
authors: F
authors: Huber
authors: Institute of Experimental and Applied Physics, Department of Physics, University of Regensburg, 93053 Regensburg, Germany.
authors: Florian
authors: F
authors: Pielmeier
authors: Institute of Experimental and Applied Physics, Department of Physics, University of Regensburg, 93053 Regensburg, Germany.
authors: Joachim
authors: J
authors: Welker
authors: Institute of Experimental and Applied Physics, Department of Physics, University of Regensburg, 93053 Regensburg, Germany.
authors: Thomas
authors: T
authors: Hofmann
authors: Institute of Experimental and Applied Physics, Department of Physics, University of Regensburg, 93053 Regensburg, Germany.
authors: Maximilian
authors: M
authors: Schneiderbauer
authors: Institute of Experimental and Applied Physics, Department of Physics, University of Regensburg, 93053 Regensburg, Germany.
authors: Daniel
authors: D
authors: Meuer
authors: Department Chemie, Ludwig-Maximilians-Universität München, Butenandtstrasse 11, 81377 München, Germany.
authors: Svitlana
authors: S
authors: Polesya
authors: Department Chemie, Ludwig-Maximilians-Universität München, Butenandtstrasse 11, 81377 München, Germany.
authors: Sergiy
authors: S
authors: Mankovsky
authors: Department Chemie, Ludwig-Maximilians-Universität München, Butenandtstrasse 11, 81377 München, Germany.
authors: Diemo
authors: D
authors: Ködderitzsch
authors: Department Chemie, Ludwig-Maximilians-Universität München, Butenandtstrasse 11, 81377 München, Germany.
authors: Hubert
authors: H
authors: Ebert
authors: Institute of Experimental and Applied Physics, Department of Physics, University of Regensburg, 93053 Regensburg, Germany. franz.giessibl@ur.de.
authors: Franz J
authors: FJ
authors: Giessibl