| Grant number: | 14/07841-3 |
| Support Opportunities: | Scholarships in Brazil - Post-Doctoral |
| Start date: | June 01, 2014 |
| End date: | January 31, 2017 |
| Field of knowledge: | Physical Sciences and Mathematics - Chemistry - Physical-Chemistry |
| Principal Investigator: | Marcia Laudelina Arruda Temperini |
| Grantee: | Monica Benicia Mamian Lopez |
| Host Institution: | Instituto de Química (IQ). Universidade de São Paulo (USP). São Paulo , SP, Brazil |
| Associated research grant: | 12/13119-3 - Vibrational spectroscopy in condensed phases, AP.TEM |
Abstract The observation of SERS spectra of a few molecules in condensed phase is today a reality in the field and opens great interest in its applications in analytical chemistry. The single molecule SERS detection presents a high signal fluctuation in time (and in space) giving spectral changes such as frequency shifts and the appearance and disappearance of bands that are observed when a set of hundreds and thousands of spectra are acquired.The aim of this project is to understand this fluctuation from the point of view of the interaction between the scattering molecule and the hot spot, an important region near the metallic surfaces of nanoparticles. These hot spots are important because they are the entities responsible for the enhancement of the Raman signal making possible the single molecule detection. These structures are also responsible for the experimentally observed changes in the relative intensities of the SERS bands.In this study, to support the experimental results two kinds of calculation will be done. One is based in DDA (Discrete Dipole Approximation), and gives the local electric field in the hot-spot, and the other in MC (Monte Carlo) simulation, that gives the adsorption behavior in the hot spots. The analysis of the experimental and theoretical data will permit to obtain the hot spot properties, for example the plasmon frequencies. These kinds of results have been done in our lab. In addition, the changes in the molecular dynamics due to the geometry and number of hot spot investigated under laser radiation and how these parameters will affect the fluctuation of intensities will be evaluated. It is well known that the magnitude on the interaction between the molecule and the surface is another important parameter that affects the SERS intensity fluctuations as well as the charge transfer between metal-molecule. In this context it is proposed to determine the role of equilibrium constant in the dynamics of the intensity fluctuations. | |
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