Electronic Circular Dichroism-Circularly Polarized Raman (eCP-Raman): A New Form of Chiral Raman Spectroscopy

This Concept article summarizes recent work on the development of a new form of chiral Raman spectroscopy, e CP-Raman, which combines two spectroscopies: electronic circular dichroism (ECD) and circularly polarized Raman (CP-Raman). First, some puzzling observations while carrying out Raman optical activity (ROA) measurements of several transition metal complexes under resonance are described, as well as the search for the mechanisms responsible. Then an equation for quantifying the e CP-Raman contribution is presented, followed by several examples of how e CP-Raman influences the I_R−I_L spectra of achiral and chiral solvent molecules and of a number of chiral solutes under resonance. The conditions to extract resonance ROA, when the e CP-Raman contribution is minimized, are also discussed. Finally, we comment on the potential applications of e CP-Raman.