Practice question

Biological macromolecules possess intrinsic chirality from L-amino acids and ordered folds, causing different interaction with left and right circularly polarized light components that constitute plane polarized light. CD spectrometer alternately shines left-handed and right-handed circularly polarized light and measures absorbance for each. Difference delta A equals A left minus A right, converted to ellipticity. Emission difference describes fluorescence anisotropy, refraction index concerns light bending, spin transitions relate to electron paramagnetic resonance. Absorption difference between left and right circularly polarized light therefore underlies CD phenomenon.