Anti-Stokes scattering

The upper sign is for anti-Stokes scattering, the lower for Stokes scattering. The factor in the parentheses is... 

Raman scattering and (b) anti-Stokes Raman scattering. In Stokes scattering, tlie cluomophore is initially in the ground vibrational state, g, and oi > CO2. hr spontaneous anti-Stokes scattering, the cluomophore must be initially m an excited vibrational state,/ Also note that in (b), M2 is (arbitrarily) defined as being greater than... 

Fiq. 2. The quantum mechanical view of Raman scattering, (a) Stokes scattering process (b) anti-Stokes scattering process (8). 

Grochala, Kudelski, and Bukowska [228] have described the anion-induced charge-transfer enhancement in S E RS and S E RRS spectra of rhodamine 6G on Ag electrode as a function of the electrode potential, upon addition of chloride and citrate anions. In a very recent paper, Brolo et al. [229] have discussed the ratio of the surface-enhanced anti-Stokes scattering to the surface-enhanced Stokes-Raman... 

Figure 7.15 Fringe structure of the anti-Stokes scattering observed by the interference of two Raman excitations. Open circles are observed data and solid lines are sine functions fitted to the observed data, (a) The delay is scanned around 10 ps. (b) The delay Tjj g is scanned around 500 ps. In both cases, the probe pulse is irradiated at 1 ns after the first excitation. The intensity is normalized by the signal intensity when only the single IRE pulse is irradiated. Reproduced with permission from Ref. [43]. Copyright 2013 by the American Physical Society.

For any vibrational mode, the relative intensities of Stokes and anti-Stokes scattering depend only on the temperature. Measurement of this ratio can be used for temperature measurement, although this application is not commonly encountered in pharmaceutical or biomedical applications. Raman scattering based on rotational transitions in the gas phase and low energy (near-infrared) electronic transitions in condensed phases can also be observed. These forms of Raman scattering are sometimes used by physical chemists. However, as a practical matter, to most scientists, Raman spectroscopy means and will continue to mean vibrational Raman spectroscopy. 

Rayleigh scattering V / Stokes scattering anti-Stokes scattering... 

The coherent anti-Stokes scattering of a probing pulse generating radiation with frequency a> = m > + mq and wave vector kA is depicted in... 

Figure 1 Schematic representation of a time-resolved coherent Raman experiment, (a) The excitation of the vibrational level is accomplished by a two-photon process the laser (L) and Stokes (S) photons are represented by vertical arrows. The wave vectors of the two pump fields determine the wave vector of the coherent excitation, kv. (b) At a later time the coherent probing process involving again two photons takes place the probe pulse and the anti-Stokes scattering are denoted by subscripts P and A, respectively. The scattering signal emitted under phase-matching conditions is a measure of the coherent excitation at the probing time, (c) Four-photon interaction scheme for the generation of coherent anti-Stokes Raman scattering of the vibrational transition.

Inverse Raman spectroscopy The Inverse Raman effect is a form of Raman scattering, first noted by W.J. Jones and B.P. Stoicheff, wherein stokes scattering can exceed anti-Stokes scattering resulting in an absorption line (a dip in intensity) at the sum of irradiated monochromatic light and Raman frequency of the material. This phenomenon is referred to as the inverse Raman Effect, application of the phenomenon is referred to as inverse Raman spectroscopy, and a record of the continuum is referred to as an inverse Raman spectrum. 

---