Raman+Spectroscopy

=Introduction= C.V Raman discovered the following:
 * 1) A fraction of visible radiation scattered by certain molecules differs from the incident beam
 * 2) Wavelength shifts correspond to the chemical structure of the scattering molecules.

Raman and infrared spectra are closely resembled. Near-infrared leaser have improved the ease of data collection from impure samples that fluoresce. Unlike IR, Raman can analyze aqueous solutions and glass samples without interference.

=Raman Theory= Samples are irradiated visible or near-infrared monochromatic light powered by a laser source. Raman lines are a fraction of the laser intensity (0.001%). There are three types of scattering listed in the table below: Stokes shifts are more sensitive to florescence than anti-stokes shifts. The Raman shifts are independent of excitation sources. The Stokes shift nomenclature is arbitrarily assigned to longer wavelengths due to the similar patterns observed in florescence spectra. Caveat: the wavenumber shift (delta v) has a "reversed scale. Therefore, "greater than" mean right on the number line, but values that are negative.
 * Scattering Type || Characteristic ||
 * Stokes || shifted //less than// the Rayleigh peak, less intense peaks ||
 * Rayleigh || Wavelength = excitation source, most intense peaks ||
 * anti-Stokes || shifted //greater than// the Rayleigh peak, less intense peaks ||

=References=