[Color-Images with the Scanning Tunneling Microscope
] A Scanning Tunneling Micoscope (STM) in principle shows the topography of the sample being scanned, down to atomic dimensions. But this description is only a good appoximation, in reality the electronic structure of the sample plays an important role in the imaging process. This fact can be used to obtain STM- images in color, with these images not only being very aesthetical, but with the color variations representing varying electronic structures of the sample surface.
Sample: Crystallites or "islands" of GdFe2, prepared by simultanously evaporating Gd and Fe onto the W(110) substrate and annealing at 430°C. The left island is 2.8 nm thick. Among the islands, the substrate is covered with a monolayer of GdFe2. The GdFe2 monolayer exhibits a slightly different color than the GdFe2 of the islands, what means, that the electronic structures are different. The reason is the monolayer being stressed by the underlying W(110) substrate, with a continous stress release to the thicker islands.
75 nm x 75 nm
10% topography+ 90% deviated topography at 0.1 V
three constant current topographical images at:
red = 0.1 V
green = 1 V
blue = 2.1 V