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I link ai risultati e alle pubblicazioni dei progetti del 7° PQ, così come i link ad alcuni tipi di risultati specifici come dataset e software, sono recuperati dinamicamente da .OpenAIRE .
Risultati sfruttabili
The main results of the project and their scientific significance are as follows:
(a) Using dedicated ultraclean, passivated, extremely stable STM nanotips it has been proved by elementary resolved scanning tunnelling microscopy that during the initial stages of growth of transition metals like Fe and Co on single crystalline noble metal substrates of low index orientation a significant amount of atomic exchange takes place, leading to mutual segregation of both layer components within an interfacial region of 3 ... 4 monolayers. The typical lateral scale on which this mutual segregation process takes place is determined by the parameters of the deposition process i.e. deposition rate and substrate temperature, but the driving force for the process itself being given by the difference in the surface free energies of the constituents
The result is significant in a sense that it provides a safe base for the understanding of the peculiarities of the further growth process, because a substantial deal of thin layer properties are determined by the characteristics of the interface region
(b) Investigations of nucleic acids (chicken-DNA, dpA, pAxpU+Lys5 e.g.) on a graphite (HOGP) surface proved that the adlayer/substrate interaction is weak enough to allow self-organization processes in the deposited highly concentrated biomolecular solution, the result of which could be imaged by contact force mode AFM. In the area of imaging self-organization of biopolymers our AFM measurements were among the first successful ones world-wide
Moreover, in another experimental series it has been found that the stronger the interaction if DNA with mica substrates in combination with the rolling drop method proved to be a good presupposition for imaging of single nucleic acid molecules and nucleic acid-association domains as well.
(c) Applying appropriate microelectronics technology processes buried co-planar metal-insulator-metal nanojunctions with gap widths down to 8 nm have been successfully produced and characterized using AFM. Structures of this kind are unique in their capabilities to serve as support, contact and clamp for selected biomolecules
(d) Stoichiometry and solubility of interpolyelectrolyte complexes were characterized. The methods for preparing TEM samples have been optimzsed with respect to concentration, pH value, and salt conditions of sample and support. First images of IPE complexes were obtained, yielding information of their overall shape. These results should serve as a base for further high resolution STM/AFM imaging.
(e) Three different procedures for the fabrication of self-supporting and substrate backed nanoshaped electrodes have been developed, successfully tested and applied to the preparation of first samples nanobridge of Bi between deposited Bi-electrodes on a carbon strip bridging the edges of a nanoslit in a Si3N4 supporting membrane; similar Bi nanobridge on an intermediate Si3N4 bridge; similar bridge, but using a carbon deposition mask procedure
Having at hand this kind of versatility one will be able to produce nanocontacts of many different desired shapes, the overall nano-measurement system being of adaptable insulating/conducting properties.
Ultrasharp, clean and passivated tungsten tips as well as Re nanotips on top of commercial AFM cantilever tips have been produced and successfully tested. Carbon nanotips for AFM systems have been made available commercially by other parties in the meantime, but the ones fabricated here are of controlled electrical conductivity and are capable of serving in combined SYM+AFM systems, thus providing the unique possibility of tunnelling under controlled force interaction between tip and sample and simultaneously collect AFM data.
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