| Texto completo | |
| Autor(es): |
dos Santos, Diego P.
[1]
;
Andrade, Gustavo F. S.
[1, 2]
;
Temperini, Marcia L. A.
[1]
;
Brolo, Alexandre G.
[1, 2]
Número total de Autores: 4
|
| Afiliação do(s) autor(es): | [1] Univ Sao Paulo, Inst Quim, BR-05513970 Sao Paulo - Brazil
[2] Univ Victoria, Dept Chem, Victoria, BC V8W 3V6 - Canada
Número total de Afiliações: 2
|
| Tipo de documento: | Artigo Científico |
| Fonte: | Journal of Physical Chemistry C; v. 113, n. 41, p. 17737-17744, OCT 15 2009. |
| Citações Web of Science: | 35 |
| Resumo | |
Time-dependent fluctuations in surface-enhanced Raman scattering (SERS) intensities were recorded from a roughened silver electrode immersed in diluted solutions of rhodamine 6G (R6G) and congo red (CR). These fluctuations were attributed to a small number of SERS-active molecules probing regions of extremely high electromagnetic field (hot spots) at the nanostructured surface. The time-dependent distribution of SERS intensities followed a tailed statistics at certain applied potentials, which has been linked to single-molecule dynamics. The shape of the distribution was reversibly tuned by the applied voltage. Mixtures of both dyes, R6G and CR, at low concentrations were also investigated. Since R6G is a cationic dye and CR is an anionic dye, the statistics of the SERS intensity distribution of either dye in a mixture were independently controlled by adjusting the applied potential. The potential-controlled distribution of SERS intensities was interpreted by considering the modulation of the surface coverage of the adsorbed dye by the interfacial electric field. This interpretation was supported by a two-dimensional Monte Carlo simulation that took into account the time evolution of the surface configuration of the adsorbed species and their probability to populate a hypothetical hot spot. The potential-controlled SERS dynamics reported here is a first step toward the spectroelectrochemical investigation of redox processes at the single-molecule level by SERS. (AU) | |
| Processo FAPESP: | 01/09497-8 - Espectroscopia, caracterização e modelagem de microambientes |
| Beneficiário: | Marcia Laudelina Arruda Temperini |
| Modalidade de apoio: | Auxílio à Pesquisa - Temático |