Raman effect rä´mən [key], appearance of additional lines in the spectrum of monochromatic light that has been scattered by a transparent material medium. The effect was discovered by C. V. Raman in 1928. The energy and thus the frequency and wavelength of the scattered light is changed as the light either imparts rotational or vibrational energy to the scattering molecules or takes energy away. The line spectrum of the scattered light will have one prominent line corresponding to the original wavelength of the incident radiation, plus additional lines to each side of it corresponding to the shorter or longer wavelengths of the altered portion of the light. This Raman spectrum is characteristic of the transmitting substance. Raman spectrometry is a useful technique in physical and chemical research, particularly for the characterization of materials.
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