Raman scattering spectroscopy abbr., RSS (rus. спектроскопия комбинационного рассеяния otherwise рамановская спектроскопия abbr., КР) — a spectroscopic technique used to study matter based on the phenomenon of combinational (Raman) scattering of monochromatic light.

Description

This method consists of the registration of radiation spectral lines scattered by the sample (in solid, liquid or gaseous phase). These spectral lines, which are not present in the primary (exciting) radiation spectrum, correspond to specific vibrations of atom groups. This makes it possible to determine the presence of certain functional groups by the characteristic vibration frequencies of their fragments (see also the "Vibrational Spectroscopy" article).

In resonance Raman scattering spectroscopy (RSS), a laser frequency is chosen in accordance with electronic transitions (which correspond to excited electronic states) in a molecule or crystal. This approach ensures high scattering intensity in the absence of unwanted fluorescence interference whose frequency is lower than the frequency of the exciting radiation.

The resonant Raman scattering effect also serves as a basis for the coherent anti-Stokes Raman spectroscopy (CARS) method. This method uses two lasers one of which has fixed and the other variable oscillation frequency. When the difference between the lasers' frequency coincides with the molecules' vibrations frequency resonant radiation is stimulated.

By varying the tunable laser's frequency the resonance Raman spectrum can be obtained. In addition to the resonance, surface-enhanced Raman scattering (SERS) spectroscopy is widely used, in particular, to study biomolecules grafted to nanoparticles of precious metals. Laser irradiation of the surface of metal nanoparticles (10-100 nm) causes the formation of plasmons which increase the electric field around the metal. Given that the signal intensity in Raman spectroscopy is proportional to the electric field the signal increases substantially (up to 1014 times) which facilitates the recording of the Raman scattering spectra of a single molecule. Such molecules may be antibodies, nucleic acids, etc. A special kind of surface-enhanced Raman spectroscopy, where the signal is amplified by the tip of a scanning probe microscope, is called tip enhanced Raman scattering (TERS) spectroscopy.

Finally, Raman spectroscopy with optical tweezers (OTRS - Optical Tweezers Raman Spectroscopy) is used to study individual particles as well as biochemical processes in cells by means of optical tweezers, a device that allows manipulating microscopic objects with the use of laser light.

Authors

  • Veresov Alexander G.
  • Streletskiy Alexey V.

Sources

  1. Raman scattering spectroscopy // Chemical encyclopedia (in Russian). V. 2. — Мoscow: Sovetskaja ehnciklopedija, 1990. 436–438 pp.
  2. Larionov A.I. Nanometrology: Raman scattering spectroscopy (in Russian). // Nanometr. — www.nanometer.ru/2009/06/09/internet_olimpiada_155836.html (reference date: 31.07.2010).
  3. Is there a color in the nanoworld? (in Russian) // Nanometr. — www.nanometer.ru/2007/09/14/skaniruushaa_zondovaa_mikroskopia_4264.html (reference date: 31.07.2010).

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