Individual surface atoms identified by atomic force microscopy

Copyright Macmillan Publishers Ltd 2007

The image illustrating the cover of the 2007, 1st of March issue of Nature is an atomically resolved topographic image of a surface alloy made up of silicon (red), tin (blue) and lead atoms (green) blended in equal proportion on a Si(111) substrate. This image was acquired using a dynamic dorce microscope operated under the Frequency Modulation detection method, technique also known as non-contact AFM (NC-AFM), and it demonstrates a robust approach to identifying atoms using AFM (Nature 446 64-67; 2007).

Altough in the topography some of these atoms appear completely indistinguishable, it is possible to identify them by measuring, very precisely, the chemical short-range forces between the last atom of the AFM tip and each of the atoms at the surface. In this landmark paper in the SPM field, the microscope operation and data acquisition was performed using a Nanotec's Dulcinea controller Unit, powered by the WSxM software.

Y.Sugimoto et al. Nature 446 64-67 (2007) .