Topographic artifacts

On the other hand, the sensitivity of STM to electronic structure can lead to undesired artifacts when the surface is composed of regions of varying conductivity. For example, an area of lower conductivity will be represented as a dip in the image. If the surface is not well known, separating topographic effects from electronic effects can be difficult. 

Other artifacts that have been mentioned arise from the sensitivity of STM to local electronic structure, and the sensitivity of SFM to the rigidity of the sample s surface. Regions of variable conductivity will be convolved with topographic features in STM, and soft surfaces can deform under the pressure of the SFM tip. The latter can be addressed by operating SFM in the attractive mode, at some sacrifice in the lateral resolution. A limitation of both techniques is their inability to distinguish among atomic species, except in a limited number of circumstances with STM microscopy. 

A similar concern due to lateral motion also applies to purely qualitative imaging. Sugisaki et al. [38] observed an artifact in their simultaneously topographic and adhesion... 

In this part the electronic properties of chemisorbed hydrogen on Gd(OOOl) will be discussed. For the photoemission investigation, smooth Gd(OOOl) films were prepared and subsequently exposed to hydrogen. It was already shown in Sect. 3.1 (Chap. 3) that the Gd smface state exists both on smooth films and multilayer Gd islands. Therefore, multilayer island films were chosen for the STM investigations to provide topographical contrast in order to distinguish between sample states and tip induced artifacts as well as to determine the influence of different island heights. The detailed preparation procedure was already described in Sect. 3.1 (Chap. 3). 

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