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The name "Raman spectroscopy" typically refers to vibrational Raman spectroscopy 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 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.
Wavelengths of commercially available lasers. Laser types with distinct laser lines are shown above the wavelength bar, while below are shown lasers that can emit in a wavelength range. The height of the lines and bars gives an indication of the maximal power/pulse energy commercially available, while the color codifies the type of laser ...
Raman microscopy of inorganic specimens, such as rocks, ceramics and polymers, [13] can use a broader range of excitation wavelengths. A related technique, tip-enhanced Raman spectroscopy, can produce high-resolution hyperspectral images of single molecules [14] and DNA. [15]
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.
The Raman shift chemical imaging spectral range spans from approximately 50 to 4,000 cm −1; the actual spectral range over which a particular Raman measurement is made is a function of the laser excitation frequency.
A Raman laser is a specific type of laser in which the fundamental light-amplification mechanism is stimulated Raman scattering. In contrast, most "conventional" lasers (such as the ruby laser ) rely on stimulated electronic transitions to amplify light.
Rotational–vibrational spectroscopy is a branch of molecular spectroscopy that is concerned with infrared and Raman spectra of molecules in the gas phase. Transitions involving changes in both vibrational and rotational states can be abbreviated as rovibrational (or ro-vibrational ) transitions.