Silver Nanoparticles for SERS Identification of Dyes
- PDF / 502,724 Bytes
- 12 Pages / 432 x 648 pts Page_size
- 62 Downloads / 212 Views
Silver Nanoparticles for SERS Identification of Dyes Edgar Casanova-González1, Angélica García-Bucio1, José Luis Ruvalcaba-Sil1, Víctor SantosVasquez2, Baldomero Esquivel3, María Lorena Roldán4, Concepción Domingo4 1 Departamento de Física Experimental, Instituto de Física, Universidad Nacional Autónoma de México, Circuito de la Investigación Científica s/n, Ciudad Universitaria, Mexico DF 04510, Mexico. e-mail: [email protected] 2 Coordinación Nacional de Conservación del Patrimonio Cultural, INAH, Mexico. 3 Instituto de Química, Universidad Nacional Autónoma de México, Mexico. 4 Instituto de Estructura de la Materia, CSIC, Serrano 121, 28006-Madrid, Spain. ABSTRACT Coinage metals nanoparticles have been widely used in last decade for enhancing the Raman signal of a variety of compounds. Several preparation methods have been proposed, including chemical reduction of gold or silver salts with sodium citrate, hydroxylamine or sodium borohydride, microwave-assisted reduction with glucose, Tollens mirror, electrodeposition, vacuum evaporation and pulsed-laser deposition. In this work, gold and silver nanoparticles were prepared by chemical reduction with sodium citrate and hydroxilmanine, characterized by UV-Vis spectroscopy and High Resolution Transmission Electronic Microscopy and tested as SERS substrate. Carminic acid, cochineal, axiote, muitle and zacatlaxcalli SERS spectra were recorded at different pH. Natural dyes samples were prepared by extraction from its natural sources, following traditional recipes. Although differs for each dye, best results were achieved by performing SERS experiments at pH neutral to basic. INTRODUCTION Since its discovery in 1974 [1], Surface Enhanced Raman Spectroscopy (SERS) had been applied in several fields and the number of papers published each year on the subject had grown steadily to add more than a thousand in 2008 [2]. In the field of art, history and archaeology, SERS has become an alternative to classical techniques for the identification of organic materials, mainly dyes, in objects of artistic or historical interest [3-6]. Non-destructive or micro-destructive techniques are needed for the study of such objects and several techniques have proven to be useful in the identification of inorganic pigments, among them X-ray Diffraction (XRD), X-ray Fluorescence (XRF), Particle Induced X-ray Emission (PIXE) and Transmission Electron Microscopy (TEM). For organic materials, on the other hand, their non-invasive characterization is difficult, since high-performance liquid chromatography (HPLC) and gas chromatography (GC) [7-9], the most common analytical techniques in organic chemistry, generally require a relatively large sample. Raman spectroscopy has been successfully applied to the study of artistic objects [10-12], but for organic dyes the technique shows some limitations regarding signal intensity and interference from the fluorescence [13]. Some alternatives have been proposed to overcome these limitations, mainly Subtracted Shifted Raman Spectroscopy [14, 15], and Surfac
Data Loading...
