Raman spectroscopy

Raman spectroscopy (named after C. V. Raman) is a spectroscopic technique used to study vibrational, rotational, and other low-frequency modes in a system. It relies on inelastic scattering, or Raman scattering, of monochromatic light, usually from a laser in the visible, near infrared, or near ultraviolet range. The laser light interacts with phonons or other excitations in the system, resulting in the energy of the laser photons being shifted up or down. The shift in energy gives information about the phonon modes in the system.

Typically, a sample is illuminated with a laser beam. Light from the illuminated spot is collected with a lens and sent through a monochromator. Wavelengths close to the laser line, due to elastic Rayleigh scattering, are filtered out while the rest of the collected light is dispersed onto a CCD detector.
Raman spectroscopy is the method of choice to analyse the structure of all kind of carbon materials like graphite, graphene, carbon nano tubes and fullerenes. Information about crystaline or amourphous structure, the underlying carbon network and crystalite size are available from shift and shape of vibration modes.
The state and quality of nanostructured materials for battery research as well as lithium content can be concluded by their characteristic vibration-modes.

 see also in situ Raman spectrocopy