Bahareh Morovvati , Rasoul Malekfar,
Volume 13, Issue 2 (12-2019)
Abstract
The active substrates in surface enhanced Raman scattering (SERS) spectroscopy were prepared through self-assembly of nanoparticles on functionalized glasses. Colloidal silver nanoparticles (Ag NPs) were prepared chemically in two different sizes by reduction of AgNO3 using trisodium citrate and sodium borohydride. Gold–silver core–shell nanoparticles were also prepared to compare between the optical behaviors of their silver shell and Ag NPs. Absorption spectra of nanoparticles were measured by ultraviolet–visible (UV–Vis.) spectroscopy, and their approximate sizes were determined by dynamic light scattering (DLS). The core–shell nanoparticles were approximately the same size as the largest Ag NPs (35 nm) and had the same maximum absorption wavelength. The potential of these substrates for detection applications was investigated with 1 M and 0.1 mM solutions of Raman-active molecule of crystal violet (CV) dye. The Raman enhancement signal was recorded for 0.1 mM solution with 532 nm laser wavelength, and the obtained spectra enhancement factor (EF) was calculated. EF values indicated that although the silver and gold–silver core–shell nanoparticles had the same surface plasmon resonance, the substrate with smaller Ag NPs had the highest enhancement factor compared to other substrates, which was 9.5´103, and the core–shell substrate even had a slightly lower enhancement factor in compare with the large Ag NPs.
Maryam Bahreini, Zahra Sabzevari,
Volume 18, Issue 1 (10-2024)
Abstract
Due to the unique properties of graphene, since its discovery, many applications in different fields from chemical sensors to transistors have been proposed for it. One of the most important applications of graphene is in the enhancement of Raman spectroscopy, which has recently attracted the attention of scientists. This article investigates its potential as a substrate for Raman enhancement called graphene-enhanced Raman spectroscopy (GERS). We use rhodamine 6G (R6G) and crystal violet (CV) to illustrate the effect of graphene oxide on Raman enhancement. It was shown that Raman peaks of rhodamine 6G and crystal violet solutions deposited by solution soaking on the graphene-based substrate have significantly increased compared to those deposited on the bare glass substrate. Using a Raman spectrometer, The Raman spectra of these materials were taken and their graphs were compared. It is shown that this method can enhance the Raman signals of molecules of rhodamine 6G and crystal violet.
