[rah-muh
n] 
| the change in wavelength of light scattered while passing through a transparent medium, the collection of new wavelengths (Raman spectrum) being characteristic of the scattering medium and differing from the fluorescent spectrum in being much less intense and in being unrelated to an absorption band of the medium. |
| Raman effect n. Physics The alteration in frequency and random alteration in phase of light passing through a transparent medium. [After Sir Chandrasekhara Venkata Raman.] |
| Raman effect
The alteration of the frequency and the phase of light as it passes through a transparent medium. The Raman effect is caused by small differences between the energy of photons absorbed by the molecules that make up the medium and the energy of photons re-emitted. |
Raman effect
change in the wavelength of light that occurs when a light beam is deflected by molecules. The phenomenon is named for Sir Chandrasekhara Venkata Raman, who discovered it in 1928. When a beam of light traverses a dust-free, transparent sample of a chemical compound, a small fraction of the light emerges in directions other than that of the incident (incoming) beam. Most of this scattered light is of unchanged wavelength. A small part, however, has wavelengths different from that of the incident light; its presence is a result of the Raman effect.
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