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Miscellaneous - Image Gallery


Analytical Theory for the Adhesive Sphere-Plane Contact

Hertzian contact     Comparison between Maugis-Dugdale theory and new theory     U. D. Schwarz.
Journal of Colloid and Interface Science 261, 99 (2003).
A new method to calculate the elastic deformation of a sphere on a flat surface (left image) has been proposed. In contrast to earlier models, this theory describes the nature of these deformations in the intermediate regime between the so-called JKR and DMT limits by simple analytic expressions. Equations for the calculation of the contact radius, the deformation, and the pressure distribution are given. The right image featuring a comparison between the new model (dashed line) and the well-established, but more complex Magis-Dugdale model (solid line) for different values of the transition parameter λ shows good agreement.


Electrostatic Domains on a Ferroelectric Material Visualized by Force Microscopy

Topography of the GASH(0001) Surface     Electrostatic Domain Structure on the GASH(0001) Surface     H. Bluhm, U. D. Schwarz, and R. Wiesendanger.
Physical Review B 57, 161 (1998).
Guanidinium aluminum sulfate hexahydrate (GASH) is a ferroelectric material that exhibits differently charged domains at its (0001) surface. If the tip is made sensitive to detect charges, the domain structure including the absolute polarization of the domains can be locally resolved (right) even if the topography of the material is absolute flat and featureless (left). This imaging mode is called electrostatic force microscopy. Image size: 40 µm x 40 µm.


CVD Diamond Layer

CVD Diamond Layer         U. D. Schwarz, O. Zwörner, P. Köster, and R. Wiesendanger.
Physical Review B 56, 6987 (1997).
Force micrograph of a (001)-oriented diamond film grown by chemical vapor deposition (image size: 13 µm x 13 µm). The largest individual grains exhibit terraces of about 1 µm². The tilt of such a terrace against the horizontal image plane is typically 2-5°.


Dendritic Growth of C60 Monolayers on Germanium Sulfide

C60 Monolayers on Germanium Sulfide         U. D. Schwarz, W. Allers, G. Gensterblum, J.-J. Pireaux, and R. Wiesendanger.
Physical Review B 52, 5967 (1995).
Force micrograph of C60 monolayers deposited on germanium sulfide in ultrahigh vacuum. The image was recorded in air and at room temperature. The dendritic growth structure of the individual islands can easily be studied. The separation between individual terraces is about 1 nm.