Elaboración de depósitos nanoestructurados de Ag por ablación láser y deconvolución de los espectros obtenidos mediante la técnica SERS

Abstract

The laser ablation technique is a process that is achieved through radiation-matter interaction (by striking a laser beam on the material, under specific experimental conditions), it generates a plasma that allows material to be extracted from a solid or liquid, to later be deposited on a substrate. In this way, nanostructured deposits can be generated that represent a key part of this paper, since they can be used as substrates for the use of the experimental technique, Raman spectroscopy with improved surface, SERS (for its acronym in English). Generally, these substrates are nanostructured deposits of noble metals, in particular Au, Ag or Cu, deposited on glass or silicon surfaces. Gold and silver are used more commonly, as they are more stable metals in air compared to copper, which is more reactive. However, all three metals undergo localized surface plasmon resonance, LSPR, which is responsible for the enhancement caused by amplification of the Raman signal. Also, this SERS effect covers most of the visible and infrared wavelength field, which is the spectral range where most Raman measurements occur. The purpose of this work is to identify the presence of amplification in the Raman signal on the surface (SERS) of monolayers of Methylene Blue, deposited on nanostructured substrates previously elaborated by the laser ablation technique. For which, the synthesis and subsequent characterization of nanostructured silver (Ag) substrates made by means of the aforementioned technique will be presented. Subsequently, its vibrational characterization is carried out by means of Raman spectroscopy for the identification of the SERS signal using Methylene Blue (AM) as a test molecule. With the generated spectrum, the active Raman peaks are identified by means of a process of deconvolution of the spectra, using Gaussian functions. The results obtained allow us to observe an amplification of the Raman signal in the samples made.