Intercalated 4-aminobenzenethiol Between Au And Ag Nanoparticles: Effects Of Concentration And Nanoparticles Neighborhood On Its Sers Response

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)In this work is reported the investigation of the 4-aminobenzenethiol (4-ABT) surface-enhanced Raman scattering (SERS) response for different 4-ABT concentrations as well as when this molecule is intercalated between Ag and Au nanoparticles (AgNP and AuNP). SERS substrates consisting of the individual AgNP or AuNP and bi-layer AgNP/4-ABT/AuNP or AuNP/4-ABT/AgNP were prepared on glass slides. It was observed a decreasing trend of the bands intensity ratios b(2)/a(1) as a function of the 4-ABT solutions concentration. Since the b(2) modes are enhanced through the charge transfer (CT) mechanism, this result indicates that this mechanism is less effective for low concentration of 4-ABT. Also, a dependence between a(1) and b(2)-type bands intensities could be identified for the samples where 4-ABT molecules were intercalated between AgNP and AuNP. A significantly increase in the SERS intensities of the a(1) mode around 1074 cm(-1) and b(2) mode around 1142 cm(-1) is observed when AgNP are present in the samples. This result indicates that AgNP promote amplifications of the Raman signal thorough the CT and electromagnetic (EM) mechanisms, whereas for the AuNP the SERS effect is related manly to EM mechanism. These results show that the 4-ABT SERS response can provide more information than the SERS substrate activity. Its SERS signal pattern is rich in information, allowing investigations about the local where the molecule is, details about the substrate surface, and also on the mechanisms present in the system under study.265970977Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq