Nanoscopic surface structures

F. Burmeister, C. Schlafle, B. Keilhofer, C. Bechinger, J. Boneberg, P. Leiderer. From mesoscopic to nanoscopic surface structures lithography with colloid monolayers. Adv Mater 70 495—497, 1998. 

The concept of using block copolymers for preparation of nanoscopically structured material and surfaces was advanced further by introducing a third block in the chain structure [29]. One of the consequences of the multiphilicity and versatility of the ABC triblock copolymers is their tremendous richness and diversity in morphology. One of the most peculiar structures is shown in Fig. 28 where the helices of a polybutadiene microphase are wound around columns of polystyrene which are embedded in a matrix of polymethylmethacrylate. Complementary to the TEM studies of the bulk morphology (Fig. 28a,b), SFM has been used to image the surface structure of the triblock copolymer films. Figure 28c shows the wrapped PS cylinders oriented parallel to the surface, where one... 

AFM experiments are carried out by AFM using a Dimension 3000 microscope coupled to a Nanoscope Ilia electronic controller (Digital Instruments, Veeco-FFI Co., USA). All experiments were performed in tapping mode. The AFM was equipped with the phase extender electronic modulus, making it possible to record the phase shift variations between the instantaneous oscillation of the tip and the oscillation applied to the cantilever in tapping mode. In our case, this phase shift depended strongly on the local moduli between the different components of the material and reflected the surface structure of the thin films [27-34]. 

These nanotubes were embedded in larger fibers (see Figure 17) inside the shelled deposit of the arc which was nominally 50 pm in diameter and 1 mm. Several individual nanotubes typically were found to protrude from this fiber, and the longest of these, having a diameter of 14 nm and a length of 2.2 pm, was used to establish contact with the liquid metal surface. It is therefore possible that nanoscopic graphitic structures will eventually be used as electronic elements. 

Additionally, the surface structure of silica samples was examined with atomic force microscope (AFM) NanoScope 111 (Digital Instruments, USA). 

The role of electrolyte is critical in these nanoscopic interfaces, but is difficult to predict and quantify. For sufficiently large rigid interfacial structures, one can apply the model of electrolyte interaction with a single charged surface in Figure 1(a). The double-layer theories or the recent integral-equation theories have been applied. Reviews of this subject are available in the literature [4,5]. For electrolytes in a nanostructure, the double layers from two surfaces overlap and behave differently from the case of a single surface. Ad-... 

To fully exploit the nanoscopic properties of materials, for example, in catalysis, this structure size is much too large since it corresponds to a regime where the bulk properties of materials still dominate. An alternative approach can be the patterning of a surface by direct manipulation of atoms or molecules with the scanning tunneling microscopy (STM) [8], which has been successfully employed in the past... 

When dendrimers are exposed to forced intermolecular contact by increasing their concentration in solution, or by placing them on a surface, do they freely pass through one another or do they avoid interpenetration and align themselves Dendrimers have sizes in the range 1-20 nm and would be excellent candidates for nanoscopic structures if such ordering does occur. 

In many catalytic systems, nanoscopic metallic particles are dispersed on ceramic supports and exhibit different stmctures and properties from bulk due to size effect and metal support interaction etc. For very small metal particles, particle size may influence both geometric and electronic structures. For example, gold particles may undergo a metal-semiconductor transition at the size of about 3.5 nm and become active in CO oxidation [10]. Lattice contractions have been observed in metals such as Pt and Pd, when the particle size is smaller than 2-3 nm [11, 12]. Metal support interaction may have drastic effects on the chemisorptive properties of the metal phase [13-15]. Therefore the stmctural features such as particles size and shape, surface stmcture and configuration of metal-substrate interface are of great importance since these features influence the electronic stmctures and hence the catalytic activities. Particle shapes and size distributions of supported metal catalysts were extensively studied by TEM [16-19]. Surface stmctures such as facets and steps were observed by high-resolution surface profile imaging [20-23]. Metal support interaction and other behaviours under various environments were discussed at atomic scale based on the relevant stmctural information accessible by means of TEM [24-29]. 

Using the Hamiltonian, we can obtain attractive or repulsive forces that play a role of external forces in Equation (22). A spin analogy/ lattice gas model will be developed that can describe the oversimplified molecular structure, while still capturing the essence of the molecule/ surface interaction. The relaxation time in SRS-LBM will contain shear rate and other nanoscopic information. 

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