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| Author(s): |
Klester dos Santos Souza
Total Authors: 1
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| Document type: | Doctoral Thesis |
| Press: | São Paulo. |
| Institution: | Universidade de São Paulo (USP). Conjunto das Químicas (IQ e FCF) (CQ/DBDCQ) |
| Defense date: | 2016-02-26 |
| Examining board members: |
Marcia Laudelina Arruda Temperini;
Pedro Henrique Cury Camargo;
Italo Odone Mazali;
Joel Camargo Rubim;
Henrique Eisi Toma
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| Advisor: | Marcia Laudelina Arruda Temperini; Erico Teixeira Neto |
| Abstract | |
Surface enhanced Raman Spectroscopy (SERS) is a Raman enhancing effect of molecules adsorbed on nanostructured metal surfaces. This characteristic allows the use of SERS in the vibrational study of Molecular Junction systems (MJ) (MJ is a system formed by Molecular Wires (pi-conjugated molecules) synthesized in metal junctions like metal|molecular-wire|metal). In addition, we can also use SERS to understand the influence of morphological characteristic of gold nanostructures. This thesis aims: (a) synthesis and characterization of gold nanospheres (AuNS), nanorods (AuNR) and gold electrode (electrochemically activated); (b) synthesis and vibrational studies of molecular wires in JM; (c) plasmon coupling studies between flat surface and gold nanorods; (d) correlation SERS - AuNR morphology of individual aggregates. For the best of our knowledge, this was the first time that oligophenilenelimine (OPI) as molecular wire was characterized by Raman and SERS. The MJ showed an unusual behavior such that the v(CS) vibrational mode remained constant in intensity with the increasing of the gap spacing (within 5 nm) while the β(CH) increased with the increase of the gap. This behaviour was related to the different nature of the interaction between plasmons resonances in JM (surface plasmon resonance (LSPR) - dipole image) for the first case and due to chemical contributions by the molecular wires for the second vibrational mode. The results for SERS - morphology AuNR aggregates correlation showed (for small aggregates) that when in the aggregate predominated end-by-end interaction SERS spectra showed a higher intensity when compared to those in which interactions side-by-side predominated. Although, this behavior was not observed for aggregates containing more than five nanoparticles indicating that there is not a preferential interaction between the nanorods for such aggregates and that a mixture of both will be preferable for large SERS intensities. (AU) | |
| FAPESP's process: | 11/17923-9 - SERS study of the behavior of Oligophenyleneimine and Dithiolated in Au surfaces |
| Grantee: | Klester dos Santos Souza |
| Support Opportunities: | Scholarships in Brazil - Doctorate |