Inelastic information about vibrational modes

Raman spectroscopy is based on the inelastic scattering of light. Similar to IR spectroscopy the Raman technique yields information about vibrational modes of molecular bonds. A Raman spectrum can yield complementary information about the vibration modes observed in IR spectroscopy. However, Raman spectroscopy is not directly equivalent to IR spectroscopy. The condition for a molecular bond to be Raman active is a change in the polarization of the electron cloud during the interaction with a photon. 

The final chapters of this book review the progress of three recently developed techniques that provide information about the vibrational states of adsorbed molecules. Perhaps the most important of these techniques is electron energy loss spectroscopy that, despite its inherent low resolution, gives valuable information on vibrational modes that are either inactive in the IR, or inaccessible because of experimental difficulties. The applications of this technique are discussed in two chapters by Somorjai and Weinberg. The review of new experimental techniques concludes with presentations on inelastic electron tunneling spectroscopy and neutron scattering by Kirtley and Taub. 

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