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| Author(s): |
Alberto Luís Dario Moreau
Total Authors: 1
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| Document type: | Master's Dissertation |
| Press: | Campinas, SP. |
| Institution: | Universidade Estadual de Campinas (UNICAMP). Instituto de Física Gleb Wataghin |
| Defense date: | 2005-11-17 |
| Examining board members: |
Mônica Alonso Cotta;
Maurício Urban Kleinke;
Carlos Frederico Oliveira Graeff
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| Advisor: | Mônica Alonso Cotta |
| Abstract | |
In this work we have implemented the force spectroscopy technique using the Atomic Force Microscopy (AFM) equipment at the LPD/IFGW/UNICAMP; this technique was applied to the study of functionalized tips and samples with thiol (mercaptoundecanoic acid). In particular, a detailed characterization of AFM tips with Electron Microscopy was carried out. We have studied the tip metalization with Au (necessary for functionalization), the tip radius and the several modes of tip-sample approximation. We have also studied models for the cantilever spring constant in order to evaluate the absolute force values. The force measurements were carried out in N2 atmosphere to prevent capillary forces, though we also carried out some measurements in laboratory atmosphere. Tip metalization techniques (sputtering and thermal deposition), the thiol/ethanol solution concentration and the functionalization times of tip and samples were varied in this work. The sample roughness can interfere in the contact area between tip and sample, and, thus on the thiol adhesion force measurements ¿ particularly on force values dispersion. In spite of that, our measurements provided values for the thiol adhesion forces and free energies in the same order of magnitude of the literature in the area. Parallel to this work, we have carried out resistance and durability tests with carbon nanotubes tips, in collaboration with Prof. Daniel Ugarte, as well as AFM images of plasmid DNA samples, a likely candidate for future work using funcionalized tips (AU) | |