Raman spectroscopy

Raman spectroscopy identifies molecular vibrations by measuring the small frequency shifts that occur when monochromatic light scatters inelastically from matter.

Raman effect: The inelastic scattering of light that changes the scattered photons’ frequencies through interactions with matter. It is the physical scattering event that produces Raman spectra.
Raman microscopy: A technique that combines Raman spectroscopy with optical microscopy to map chemical composition at microscopic scales. It localizes molecular signatures across small regions of a sample.
Infrared spectroscopy: A spectroscopic method that measures infrared absorption associated with molecular vibrational transitions. Its vibrational selection rules complement Raman spectroscopy’s polarizability-based signals.
C. V. Raman: Indian physicist who discovered the inelastic scattering of light later named the Raman effect. His experiments established the phenomenon underlying the technique.
Molecular vibration: Periodic motion of atoms in a molecule around their equilibrium positions. Raman spectra are interpreted as signatures of these molecular motions.
Stokes scattering: Inelastic scattering in which a photon loses energy to a molecular excitation. Its lower-frequency scattered light forms the most commonly measured Raman bands.
Raman imaging: Spatial mapping of Raman spectra to show the distribution of chemical components in a sample. It turns molecular fingerprints into chemical maps.
Fluorescence spectroscopy: A method that measures light emitted after a substance absorbs photons and enters an excited state. Fluorescence can overwhelm the much weaker Raman signal in some samples.
K. S. Krishnan: Indian physicist who collaborated with C. V. Raman on experiments studying light scattering in liquids. His experimental work contributed to the discovery of the Raman effect.
Vibrational spectroscopy: Spectroscopic methods that probe quantized vibrational motions in molecules. Raman spectroscopy is one route to measuring molecular vibrations.

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