Coherent Raman spectroscopy

Abstract

In 1928 Chandrasekhara Raman reported a process in which a material would simultaneously absorb one photon and emit another. The energies of the two photons differed by an amount corresponding to the energy difference between two quantum‐mechanical levels of the medium. Raman scattering, as the phenomenon came to be known, provided a tool for the spectroscopic investigation of energy levels not accessible by the usual absorption and emission techniques. For the first thirty‐five years Raman scattering was a laborious and exotic technique, important more for the quantum‐mechanical principles it illustrated than for its practical applications.