Intercalated 4-Aminobenzenethiol between Au and Ag Nanoparticles: Effects of Concentration and Nanoparticles Neighborhood on its SERS Response
AUTOR(ES)
Santos, Elias de Barros, Sigoli, Fernando Aparecido, Mazali, Italo Odone
FONTE
J. Braz. Chem. Soc.
DATA DE PUBLICAÇÃO
2015-05
RESUMO
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 b2/a1 as a function of the 4-ABT solutions concentration. Since the b2 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 a1 and b2-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 a1 mode around 1074 cm-1 and b2 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.
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