Abstract
Time Resolved Raman spectroelectrochemistry (TR-Raman-SEC) has been used for the first time to obtain two different Raman spectra of one single analyte in the same experiment. This double detection has been accomplished thanks to the use of electrochemical surface enhanced Raman scattering (EC-SERS) and electrochemical surface oxidation enhanced Raman scattering (EC-SOERS) in the same experiment. These two Raman enhancement phenomena can provide a broad insight into the interaction between analyte and substrate surface when they are combined. To prove the possibilities of this methodology, a Raman spectroelectrochemistry study of uracil (U) and 5-fluorouracil (5-FU), two analytes with relevance in medicine and biochemistry, have been performed. Density functional theory (DFT) calculations has been carried out to shed more light on the interaction of these molecules with silver substrates in acidic media.
Highlights
Raman spectroscopy is a vibrational spectroscopy used for many years in the characterization of a wide range of molecules both in solid and in solution, mainly due to the capability of this technique to provide spectroscopic fingerprints of substances [1]
We present a new experimental methodology based on TR-Raman-SEC that allows the acquisition of two different Raman spectroscopic signals of one analyte in a single experiment, thanks to the presence of two different Raman enhancement phenomena: electrochemical surface enhanced Raman scattering (EC-surface enhanced Raman scattering (SERS)) and EC-SOERS
TR-Raman-SEC allowed us to obtain the evolution of the Raman spectra on a Ag-screen-printed electrodes (SPEs) surface during a cyclic voltammetry experiment of a 10−3 M U solution in 0.1 M HClO4 and 10−2 M KCl
Summary
Raman spectroscopy is a vibrational spectroscopy used for many years in the characterization of a wide range of molecules both in solid and in solution, mainly due to the capability of this technique to provide spectroscopic fingerprints of substances [1]. Electrochemical surface enhanced Raman scattering (EC-SERS) has been studied for the last 40 years [2]. The first one is related to the intensification of the electric field on the surrounding of a plasmonic nanostructure during localized surface plasmon resonance, and can be responsible of an enhancement factor of Raman scattering up to 109 [3,4]. The CE is related with the change of the polarizability of molecules due to charge transferences between the analyte and the substrate. The latter mechanism is related with lower enhancement factors than the EM, between 102 and 103 [4,5]
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