Surface-Enhanced Raman Scattering: Introduction and Applications

Abstract

Scattering of light by molecules can be elastic, Rayleigh scattering, or inelastic, Raman scattering. In the elastic scattering, the photon’s energy and the state of the molecule after the scattering events are unchanged. Hence, Rayleigh scattered light does not contain much information on the structure of molecular states. In inelastic scattering, the frequency of monochromatic light changes upon interaction with the vibrational states, or modes, of a molecule. With the advancement in the laser sources, better and compact spectrometers, detectors, and optics Raman spectroscopy have developed as a highly sensitive technique to probe structural details of a complex molecular structure. However, the low scattering cross section (10−31) of Raman scattering has limited the applications of the conventional Raman spectroscopy. With the discovery of surface-enhanced Raman scattering (SERS) in 1973 by Martin Fleischmann, the interest of the research community in Raman spectroscopy as an analytical method has been revived. This chapter aims to familiarize the readers with the basics of Raman scattering phenomenon and SERS. This chapter will also discuss the latest developments in the SERS and its applications in various fields.

Tip-Enhanced Raman Spectroscopy of 2D Semiconductors

“…by using surface-enhanced Raman scattering (SERS) is required. SERS has seen tremendous increase in applications in recent years [32]. Compared to conventional Raman cross sections SERS cross section can be up to ten orders of magnitude larger allowing e.g.…”

Plasmonic Spherical Nanoparticles Coupled with Titania Nanotube Arrays Prepared by Anodization as Substrates for Surface-Enhanced Raman Spectroscopy Applications: A Review

“…In the late 1970s, it was discovered that Raman signals could be highly amplified by using a roughened silver substrate [36]. This new technique was named surface-enhanced Raman spectroscopy (SERS) and has attracted the attention of researchers because it is able to detect a wide variety of analytes like dyes, food additives, pesticides, explosives, DNA, and other biomolecules in very low concentrations [1]. Furthermore, SERS analysis possesses a broad range of properties: it is non-destructive, portable, easy to perform, highly sensitive, fast, cost-effective, and can be used when samples are present in water since the background signal is negligible [2,3].…”

“…Thus, for achieving stronger Raman signals, one of both parameters can be increased, which is possible by two mechanisms: (i) electromagnetic and (ii) chemical [1,6,9]. The electromagnetic mechanism is believed to be the most important and arises due to the localized surface plasmon resonance (LSPR) of a nanostructured metallic substrate, an optical phenomenon in which light interacting with noble metallic nanoparticles, smaller than the incident wavelength, provokes the surface electrons to become polarized and oscillate collectively, which is known as a surface plasmon.…”

“…When these two are close enough, their wave functions will overlap and electrons can be transferred, changing the polarizability of the molecule and intensifying the Raman signals. For this reason, the enhancement will decrease rapidly as the distance between the analyte and the substrate increases, but they do not have to be in direct contact [1,43,44]. However, this mechanism alone does not result in SERS, because its maximum contribution to the EF is of 2-3 orders of magnitude.…”

“…Surface-enhanced Raman spectroscopy (SERS) has become one of the most attractive analytical techniques due to its versatility and high sensitivity for a variety of analytes like dyes, food additives, pesticides, explosives, DNA, and other biomolecules at very low concentrations [1]. Furthermore, SERS analysis presents a broad range of advantages: it is non-destructive, portable, easy to perform, highly sensitive, fast, cost-effective, and can be used with aqueous samples since the water background signal is negligible [2,3].…”