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Raman received the Nobel Prize in 1930 for his work on the scattering of light. [6] In 1998 the Raman effect was designated a National Historic Chemical Landmark by the American Chemical Society in recognition of its significance as a tool for analyzing the composition of liquids, gases, and solids. [7]
Although the inelastic scattering of light was predicted by Adolf Smekal in 1923, [3] it was not observed in practice until 1928. The Raman effect was named after one of its discoverers, the Indian scientist C. V. Raman, who observed the effect in organic liquids in 1928 together with K. S. Krishnan, and independently by Grigory Landsberg and Leonid Mandelstam in inorganic crystals. [1]
Like ordinary Raman spectroscopy, resonance Raman is compatible with samples in water, which has a very weak scattering intensity and little contribution to spectra. However, the need for an excitation laser with a wavelength matching that of an electronic transition in the analyte of interest somewhat limits the applicability of the method.
RRS effect (Resonance Raman Scaterring) The Raman resonance effect produces an increase in Raman intensity up to 10 6 times. In this phenomenon, the monochromatic light interaction with the sample produces the transition of the molecules from the fundamental state to an excited electronic state, instead of a virtual state as in normal Raman spectroscopy.
An example is when a red laser pointer illuminates the end of a finger - the light scatters throughout all of the tissue in the finger. Wherever the light goes there will be some inelastic scattering due to the Raman effect, so, at some point, most parts of an object will generate a detectable Raman signal, even if it is not at the surface.
The SERS effect is so pronounced because the field enhancement occurs twice. First, the field enhancement magnifies the intensity of incident light, which will excite the Raman modes of the molecule being studied, therefore increasing the signal of the Raman scattering. The Raman signal is then further magnified by the surface due to the same ...
Raman amplification / ˈ r ɑː m ən / [1] is based on the stimulated Raman scattering (SRS) phenomenon, when a lower frequency 'signal' photon induces the inelastic scattering of a higher-frequency 'pump' photon in an optical medium in the nonlinear regime. As a result of this, another 'signal' photon is produced, with the surplus energy ...
The Raman scattered light is emitted by the stimulation of the electric field of the incident light. Therefore, the direction of the vibration of the electric field, or polarization direction, of the scattered light might be expected to be the same as that of the incident light. In reality, however, some fraction of the Raman scattered light ...