Preparation and characterization of surface enhanced raman scattering substrate through electro deposition of silver-PEDOT film on ITO glass surface


Thesis Type: Postgraduate

Institution Of The Thesis: Orta Doğu Teknik Üniversitesi, Faculty of Arts and Sciences, Department of Chemistry, Turkey

Approval Date: 2011

Student: ÜZEYİR DOĞAN

Supervisor: MÜRVET VOLKAN

Abstract:

Detection of chemicals is a vital part of chemistry. For this reason, many detection systems are developed by scientists and every detection system has its own advantages. Raman spectroscopy is one of these detection systems having many advantages. However, this technique suffers from low signal intensity disadvantage. By developing a well prepared substrate, this problem can be easily solved; moreover, even single molecule detection can be possible. In this study, a novel surface enhanced Raman scattering (SERS) substrate was prepared in two steps: In the first step, ethylenedioxythiophene (EDOT) monomer was polymerized electrochemically onto indium tin oxide (ITO) coated glass. In the next step, silver ions were reduced electrochemically onto surface prepared in the previous step.In the substrate preparation part, the reduction potential of silver ion, the concentration of silver ions in solution, the polymer film thickness and reduced silver amount on substrates were optimized to get the best SERS performances from substrates. The prepared substrates were characterized by cyclic voltammetry (CV), ultraviolet-visible (UV-Vis) spectroscopy, scanning electron microscopy (SEM), and energy dispersive X-ray spectroscopy (EDX) attached to SEM. In the SERS performance investigation part, homogeneity and the shelf life of the prepared silver-PEDOT substrates were tested. Homogeneity is very important in terms for the applications of Raman technique in quantitative analysis since most of the reported substrates are lack homogeneity consideration, our study will be an important contribution to the literature. The stability of the substrate was investigated for a period of one month. The very small change in the signal at the end of one month indicated that the substrate can be used even longer time with high efficiency. In all the studies, brilliant cresyl blue (BCB) is used as a model compound. Some important Raman active chemicals, namely, rhodamine 6G (R6G) and 4-mercapto benzoic acid (4-MBA) were detected by using the prepared substrates.