STM+Gallery

STM Main Page
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Here are some examples of what STM can help us obtain and edited as well as added coloration. I hope you like them. If you want to see some images obtained by AR check it oout this are raw images media type="custom" key="408557"

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__Terbium island__
grown on a Tungsten (W) single crystal in (110) orientation. The rare earth metals are extremely sensitive to contamination, for instance from a vacuum that is not good enough or from an insufficient cleaning process of the [|evaporant.] As this sample was prepared the cleaning process that is carried out by melting and degassing the Tb under high vacuum, was not finished. This results in the formation of diverse adsorbate induced [|reconstructions]. Here they are visible mainly at the rim in blue. || Tunneling bias: red: 0.3 V, green: 1 V, blue: 1.8 V ||
 * [[image:http://www.physnet.uni-hamburg.de/home/vms/pascal/tb_isl0.jpg width="250" height="250" align="right" caption="Image size: 450 nm x 450 nm." link="http://www.physnet.uni-hamburg.de/home/vms/pascal/tb_isl.htm"]] || Crystallite or [|"island"] of the rare earth metal [|Terbium] (Tb)
 * Image size: 450 nm x 450 nm

__Reconstruction on terbium__
visible in this image resembles the radioactivity warning sign! The origin of this reconstruction are adsorbates ( possibly CO ) from an insufficient degassing process of the [|evaporant.] (see also the describtion for the image [|"Terbium island"]) ||
 * [[image:http://www.physnet.uni-hamburg.de/home/vms/pascal/tb_dnw.jpg width="250" height="240" align="middle" caption="Image size: 120 nm x 120 nm." link="http://www.physnet.uni-hamburg.de/home/vms/pascal/tb_vnw.htm"]] || No, Terbium is not radioactive, although the [|reconstruction]

__Terbium on W(110)__
W([|110]) [|single crystal]as a thin film. The thickness of the film was less than one single atomic layer. At this low coverage the Tb atoms arrange in parallel lines, so- called "[|superstructures]", visible as stripes. Areas with different distances of the monoatomic stripes are visible. Since the electronic structure of the superstructures depend on this stripe distance, each superstructure exhibits a characteristic color in this three color composite. This is the main //scientific// message of these images: __different colors mean different electronic structure!__ || Tunneling bias: red: 0.3 V green: 0.8 V blue: 1.2 V ||  ||
 * [[image:http://www.physnet.uni-hamburg.de/home/vms/pascal/tb_sup.jpg width="250" height="250" align="middle" caption="=Image size: 125 nm x 125 nm" link="http://www.physnet.uni-hamburg.de/home/vms/pascal/tb_w110.htm"]] || The rare earth metal [|terbium] ( Tb ) was evaporated onto a
 * Image size: 125 nm x 125 nm

__Gadolinium and terbium on W(110)__

kind of chainlike structures on top of the W(110) substrate. What happens if the two metals are alloyed in the coverage range below one monolayer? Is it possible to distiguish between them with the STM? The alloy consisting of Gd and Tb by a ratio of 1:1 looks exactly the same as the pure metals. We found no hint to distinguish between them.
 * [[image:http://www.physnet.uni-hamburg.de/home/vms/pascal/gdtb_sml.jpg width="250" height="254" align="middle" caption="Image size: 125 nm x 125 nm" link="http://www.physnet.uni-hamburg.de/home/vms/pascal/tb_w110.htm"]] || Both rare earth metals gadolinium and terbium arrange in the same

In the rectangular area marked with a box we achieved atomic resolution. Click on this area to see [|atomic resolution] as well as a structure model. || Tunneling bias: red: 0.3 V green: 0.8 V blue: 1.2 V ||
 * Image size: 125 nm x 125 nm

__GdFe2 on W(110)__
the W(110) substrate. They form an alloy, GdFe2, visible as the olive-green areas. A surplus of Gd results in the Gd superstructures, (identical to the [|Tb superstructures]) visible as the blue striped areas. || Tunneling bias: red: 0.3 V green: 0.8 V blue: 1.2 V ||
 * [[image:http://www.physnet.uni-hamburg.de/home/vms/pascal/gdfe_sml.jpg width="250" height="251" align="middle" caption="Image size: 140 nm x 140 nm" link="http://www.physnet.uni-hamburg.de/home/vms/pascal/gdfe_sml.htm"]] || Gadolinium and iron were deposited on
 * Image size: 140 nm x 140 nm

__GdFe2 islands__
is covered with a monolayer GdFe2. Notice the different colors of the monolayer and the top of the islands! Do you remember what it means? Different electronic structures! (It was explained with the image "[|Terbium on tungsten]") This is the case because the alloy is stressed in the first monolayer. This alone may result in a changed electronic structure, but perhaps a different crystal structure may also play a role. We are still at it. || Tunneling bias: red: 0.1 V green: 1 V blue: 2.1 V ||
 * [[image:http://www.physnet.uni-hamburg.de/home/vms/pascal/gdfe_isl.jpg width="250" height="256" align="middle" caption="Image size: 75 nm x 75 nm" link="http://www.physnet.uni-hamburg.de/home/vms/pascal/gdfe_isl.htm"]] || [|Islands] of GdFe2, grown on W(110). Among the islands, the [|substrate]
 * Image size: 75 nm x 75 nm

__Hydrogen adsorption on Gadolinium__
islands of Gadolinium grown on tungsten. Where the surface appears blue, hydrogen has been adsorbed on it changing the surface electronic structure drastically.
 * [[image:http://www.physnet.uni-hamburg.de/home/vms/pascal/h_gd.jpg width="250" height="250" link="http://www.physnet.uni-hamburg.de/home/vms/pascal/h2_gd.htm"]] || The brown, small and large objects that look like stones are

The three color composite process was slightly different for this image than for the other ones: The topographic image was colorized via three current imaging [|spectroscopical] images at different bias voltages. ||