Raman Spectroscopy

(Raman Effect, and Normal Raman Scattering) When light is scattered from a molecule most photons are elastically scattered. The scattered photons have the same energy (frequency) and, therefore, wavelength, as the incident photons. However, a small fraction of light (approximately 1 in 107 photons) is scattered at optical frequencies different from, and usually lower than, the frequency of the incident photons. The process leading to this inelastic scatter is the termed the Raman effect. Raman scattering can occur with a change in vibrational, rotational, or electronic energy of a molecule. Chemists are concerned primarily with the vibrational Raman effect. We will use the term Raman effect to mean vibrational Raman effect only. The difference in energy between the incident photon and the Raman scattered photon is equal to the energy of a vibration of the scattering molecule (Smith E, Dent G (2004) Modern Raman spectroscopy. Wiley, New York). Raman spectroscopy determines the maximum...