Resonance Raman spectroscopy

Resonance Raman spectroscopy (RR spectroscopy or RRS) is a variant of Raman spectroscopy in which the incident photon energy is close in energy to an electronic transition of a compound or material under examination. This similarity in energy (resonance) leads to greatly increased intensity of the Raman scattering of certain vibrational modes, compared to ordinary Raman spectroscopy.

Resonance Raman spectroscopy has much greater sensitivity than non-resonance Raman spectroscopy, allowing for the analysis of compounds with inherently weak Raman scattering intensities, or at very low concentrations. It also selectively enhances only certain molecular vibrations (those of the chemical group undergoing the electronic transition), which simplifies spectra. For large molecules such as proteins, this selectivity helps to identify vibrational modes of specific parts of the molecule or protein, such as the heme unit within myoglobin. Resonance Raman spectroscopy has been used in the characterization of inorganic compounds and complexes, proteins, nucleic acids, pigments, and in archaeology and art history.