Construção de nanoestruturas de tetrafenil porfirinas e ftalocianinas em superfícies metálicas

Author(s)

Shadi Passam Fatayer

• Document type: Master's Dissertation
• Press: Campinas, SP.
• Institution: Universidade Estadual de Campinas (UNICAMP). Instituto de Física Gleb Wataghin
• Defense date: 2014-08-18

Examining board members

Abner de Siervo; Andre Avelino Pasa; Alexandre Fontes da Fonseca

• Advisor: Abner de Siervo

Abstract

The study of molecular systems on top of metal substrates has gathered increased atten-tion of the scientific community. Better understanding over different self-assembly haracteristics and the ability to control them in molecules has led to the development of quicker and cheaper routes of the use of the bottom-up approach in nanoscience. Among the diverse studies, we can cite the development of gas sensors that use the mag-netic signal of a self-assembled layer of molecules and the eventual binding of small molecules such as CO or NO leading to the emergence of magnetism on the sample. Another interesting aspect of the study of molecular systems is the similarity of molecules commonly used with molecules found in nature processes, e.g. chlorophylls and hemeglobins. This means that by studying simple molecules one can try to mimic the natural processes of those natural molecules. In this sense, in our work we have studied two classes of molecules ¿ Porphyrins and Phthalocyanines ¿ and their structural properties when deposited on different metal substrates. The porphyrins were analyzed on a low-index miller surface, Cu(111) and compared to their be-havior when deposited on vicinal substrates, Au(332) and Au(788). The porphyrins were ob-served to form 1D structures when deposited in small quantities depending on the nature of the substrate and its terrace width. At higher coverages, porphyrins formed different close-packed 2D structures, with square and parallelogram symmetry. Electronically was observed the modifica-tion of the chemical environment of nickel when NiTPP is adsorbed on Cu(111). The phthalo-cyanines were deposited on different substrates as well, towards the goal of producing co-assembling of two types of molecules as chessboard arrays. After the chessboard array was obtained, we gathered knowledge about the mechanisms that formed such structures. Towards the goal of studying molecular self-assembly, we have employed proper surface sensitive techniques such as Scanning Tunneling Microscopy, Scanning Tunneling Spectroscopy and X-Ray Photoelectron Spectroscopy. Such techniques allowed us to obtain the structural and electronic properties of the nanostructures formed (AU)

• FAPESP's process: 12/16860-6 - Study of the electronic and atomic structure of tetraphenyl porfirin nanoribbons self-assembled on vicinal surfaces
• Grantee: Shadi Passam Fatayer
• Support Opportunities: Scholarships in Brazil - Master