 Since that time there have been numerous studies of MCD spectra for a very large variety of samples, including stable molecules in solutions, in isotropic solids, and in the gas phase, as well as unstable molecules entrapped in noble gas matrices.More recently, MCD has found useful application in the study of biologically important systems including metalloenzymes and proteins containing metal centers.In natural optical activity, the difference between the LCP light and the RCP light is caused by the asymmetry of the molecules.