Noble Metal Ion Embedded Nanocomposite Glass Materials for Optical Functionality of UV–Visible Surface Plasmon Resonance (SPR) Surface-Enhanced Raman Scattering (SERS) X-ray and Electron Microscopic Studies: An Overview

Raman spectroscopy (RS) is a modern scientific analytic fingerprint technique that detects, examines, and analyzes the constituent chemical composition of various substances (solid–liquid–gas and plasmons) through interaction of laser light with matter. It is intelligent to present qualitative and quantitative information about the sample’s chemical composition, polymorphism, phase, crystallinity, stress/strain, and contamination and impurity/defects. The key mechanism is profoundly based on the Raman principle that was originally named after and discovered by the Indian primer scientist C.V Raman, who won the Nobel prize after the exposure of the Raman effect [Raman 1916; Krishnan 1928]. This review briefly presents the physical origin of Raman scattering explaining the key classical and quantum mechanical concepts. Molecular variations of the Raman effect will also be considered, including resonance, coherent, and enhanced Raman scattering. Further, we discuss the molecular origins of prominent bands often found in the Raman spectra of SPR (surface plasmon resonance) samples. Finally, we examine the several active variations of Raman spectroscopy techniques in practice, looking at their applications, strengths, and challenges. This review is intended to be a starting resource for scientists new to Raman spectroscopy, providing theoretical background and practical examples as the foundation for further study and exploration of SPR and surface-enhanced Raman spectroscopy (SERS) techniques. While RS is now used in biology and medicine for novel pandemic diseases, Raman spectroscopy found its first applications in physics and chemistry and was mainly used to study vibrations and structure of molecules. One early factor limiting the implementation of RS was the weak scattering signal. Large intensities of monochromatic light are required to excite a detectable signal. This requirement became much easier to realize following the invention of the laser in 1960. Over the past decades, Raman spectroscopy has been prominently exploited better in biological applications, where it is able to detect and analyze DNA and RNA molecules. Generally, there are four main types of Raman spectroscopy, but the most feasible in biological field is the SERS. The noble metal nanoclusters play an important role for nanobiomedical and modern optical devices. The present review explored the single and bi-metallic (silver (Ag), copper (Cu), silver–copper (Ag–Cu), and copper–silver (C