What Is Vibrational Raman Spectroscopy: A Vibrational or an Electronic Spectroscopic Technique or Both?

Abstract

Modern Raman spectroscopy covers several noninvasive reflection techniques for identification of molecules and investigation of molecular properties. All are based on the Raman effect, occurring when polarized laser light is inelastically scattered by a molecular sample. Vibrational Raman spectroscopy is the Raman technique most widely used in chemical analysis, and it is relevant for the characterization of molecules in solution, biomolecules, and solids (crystals and powders). In this chapter vibrational Raman spectroscopy is discussed under the headline: "What is vibrational Raman spectroscopy: a vibrational or an electronic spectroscopic technique, or both?" The answer to this question is gained through a discussion of different scattering situations, and it is demonstrated that the Raman technique is more than an alternative technique to infrared and near-infrared absorption spectroscopy. Starting with the Kramers-Heisenberg equation, the answer is obtained through a discussion of: State tensors and Raman tensors, nonresonance and resonance Raman scattering (RRS) excited with a single laser wavelength, and unpolarized and polarization-resolved RRS excited with variable laser wavelengths (RADIS), dispersive Raman vibrations as a tool for noninvasive detection of molecular color changes and that RADIS data are automatically born as three-dimensional multivariate data with high information contents.

Nanoporous chromium thin film for active detection of toxic heavy metals traces using surface-enhanced Raman spectroscopy

“…The highest peak (peak II) is located at 1054, 1052, and 1050 cm −1 for Cd 2+ , Hg 2+ , and Pb 2+ , respectively. This may be due to the peak position depends upon the vibrational energy states which related to the chemical structure of the molecules responsible for the scattering [27,28]. Raman spectrum of Cr/Al uploaded with 0.5 μl after mixing the three heavy metal ions (Hg 2+ , Pb 2+ , and Cd 2+ solutions) at concentration 4 ppm is shown in figure 5(B).…”

Identification and Authentication of Honey Using Chemometric Analysis Based on Atr-Ftir and Raman Spectroscopy

“…Identification and classification of honey authenticity methods will be designed using Discriminant Analysis (DA) methods based on ATR-FTIR and Raman spectroscopy. Raman spectroscopy is a spectroscopic analysis technique in which light scattering is used to produce vibrational spectra of a compound [7]. The advantages of Raman spectroscopy are usable for samples in the form of solids or liquids, no sample preparation, the chemical fingerprint obtained is specific for material, and spectra can be generated quickly in just seconds [8].…”

Machine Learning Approach to Raman Spectrum Analysis of MIA PaCa-2 Pancreatic Cancer Tumor Repopulating Cells for Classification and Feature Analysis

“…This is because Raman spectroscopy is a nondestructive technique requiring little or no sample preparation that can be applied in vivo or in vitro. Moreover, it provides qualitative and quantitative information about the chemical structure and composition of the sample via an analysis of the inelastic scattering from discrete vibrational and rotational transitions in molecules [ 10 , 11 ].…”