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Typically, resonance Raman spectroscopy is performed in the same manner as ordinary Raman spectroscopy, using a single laser light source to excite the sample. The difference is the choice of the laser wavelength, which must be selected to match the energy of an electronic transition in the sample.
A Fermi resonance is the shifting of the energies and intensities of absorption bands in an infrared or Raman spectrum. It is a consequence of quantum-mechanical wavefunction mixing. [ 1 ] The phenomenon was first explained by the Italian physicist Enrico Fermi .
It states that no normal modes can be both Infrared and Raman active in a molecule that possesses a center of symmetry. This is a powerful application of group theory to vibrational spectroscopy, and allows one to easily detect the presence of this symmetry element by comparison of the IR and Raman spectra generated by the same molecule. [1]
The name "Raman spectroscopy" typically refers to vibrational Raman using laser wavelengths which are not absorbed by the sample. There are many other variations of Raman spectroscopy including surface-enhanced Raman, resonance Raman, tip-enhanced Raman, polarized Raman, stimulated Raman, transmission Raman, spatially-offset Raman, and hyper Raman.
RRS effect (Resonance Raman Scaterring) The Raman resonance effect produces an increase in Raman intensity up to 10 6 times. In this phenomenon, the monochromatic light interaction with the sample produces the transition of the molecules from the fundamental state to an excited electronic state, instead of a virtual state as in normal Raman spectroscopy.
Raman spectroscopy is used to analyze a wide range of materials, including gases, liquids, and solids. Highly complex materials such as biological organisms and human tissue [26] can also be analyzed by Raman spectroscopy. For solid materials, Raman scattering is used as a tool to detect high-frequency phonon and magnon excitations.
The term surface enhanced Raman spectroscopy implies that it provides the same information that traditional Raman spectroscopy does, simply with a greatly enhanced signal. While the spectra of most SERS experiments are similar to the non-surface enhanced spectra, there are often differences in the number of modes present.
Coherent anti-Stokes Raman spectroscopy, also called Coherent anti-Stokes Raman scattering spectroscopy (CARS), is a form of spectroscopy used primarily in chemistry, physics and related fields. It is sensitive to the same vibrational signatures of molecules as seen in Raman spectroscopy , typically the nuclear vibrations of chemical bonds.