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When the exciting laser energy corresponds to an actual electronic excitation of the molecule then the resonance Raman effect occurs. A classical physics based model is able to account for Raman scattering and predicts an increase in the intensity which scales with the fourth-power of the light frequency.
Therefore, the Raman spectrum (scattering intensity as a function of the frequency shifts) depends on the rovibronic states of the molecule. [7] The Raman effect is based on the interaction between the electron cloud of a sample and the external electric field of the monochromatic light, which can create an induced dipole moment within the ...
Stimulated Raman spectroscopy, also referred to as stimulated Raman scattering (SRS), is a form of spectroscopy employed in physics, chemistry, biology, and other fields. . The basic mechanism resembles that of spontaneous Raman spectroscopy: a pump photon, of the angular frequency , which is scattered by a molecule has some small probability of inducing some vibrational (or rotational ...
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 ...
The Raman cross section for the vibration of the aromatic ring in toluene around 1000 cm −1 is on the order of 10 −29 cm 2 /molecule·steradian. Therefore, the Raman signal is around 26×10 −23 W/molecule·steradian or 3.3×10 −21 W/molecule (over 4π steradians). That is 0.014 photon/sec·molecule.
Energy level diagram showing relationship between Rayleigh, Raman, and resonance Raman scattering and fluorescence. Resonance Raman spectroscopy (RR spectroscopy or RRS) is a variant of Raman spectroscopy in which the incident photon energy is close in energy to an electronic transition of a compound or material under examination. [1]
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.
Raman microscopy, and in particular confocal microscopy, can reach down to sub-micrometer lateral spatial resolution. [7] Because a Raman microscope is a diffraction-limited system, its spatial resolution depends on the wavelength of light and the numerical aperture of the focusing element. In confocal Raman microscopy, the diameter of the ...