Electrochemical-SERS analysis of R6G using a microcontroller based Portable Potentiostat

• Autor(a) principal: Crespo, João Rios
• Data de Publicação: 2017
• Tipo de documento: Dissertação
• Idioma: eng
• Título da fonte: Repositório Científico de Acesso Aberto de Portugal (Repositórios Cientìficos)
• Texto Completo: http://hdl.handle.net/10362/53149
• topic: Rhodamine 6G; Electrochemical-Surface enhanced Raman spectroscopy (EC-SERS); potentiostat; Domínio/Área Científica::Engenharia e Tecnologia::Engenharia dos Materiais

The first Surface-Enhanced Raman Spectroscopy (SERS) spectra were obtained from an electrochemical cell, which led to the discovery of the SERS effect in mid-1970s. Up to date, a lot of papers have been published on various aspects of SERS from electrochemical systems. SERS consists in a very sensitive technique for detection of analytes at very low concentrations. Furthermore, SERS can give information of how the analytes interacts with the metal surface, becoming a very useful technique for surface engineering and research. To fully explore this metal-analyte interaction SERS has been perform in an electrochemical environment. Thus, in this Electrochemical-SERS (EC-SERS) technique there are two distinctively different properties of electric fields, an electromagnetic field and a static electrochemical field, co-existing in electrochemical systems in the interface of the electrolyte, containing the target analyte, and the nanostructured metal electrode. To apply the desired potential at the nanostructured working electrode, a microcontroller based portable potentiostat device was design and fabricated to fit in the Raman microscope along with an electrochemical cell that can hold the electrolyte and the respective electrodes to perform simultaneously SERS measurements. Great efforts have been done to comprehensively understand SERS and EC-SERS spectra based on the chemical and physical enhancement mechanisms to provide meaningful information for revealing the mechanisms of electrochemical adsorption and reaction. Finally, Rhodamine-6G was used as target analyte for EC-SERS measurements with the objective of providing a new insight of the charge transfer mechanisms reported in theoretical calculations which are hard to detect experimentally using higher excitation energies due to the strong fluorescence yield.