A technique for determination of the asymmetry of a molecule. Unlike in a conventional polarimeter, where light is restricted to oscillation in a plane, in CD the direction of oscillation turns clockwise around the direction of the beam (right-circularly polarized) or counter-clockwise (left-circularly polarized). CD is expressed as (A_L-A_R)/lm, where for any wavelength A_L and A_R are the absorbances of left- and right-circularly polarised light respectively, l is the pathlength through a solution, and m is the molarity of a chiral solute. A CD spectrum of a protein in the far-ultraviolet, where the peptide bond absorbs, is characteristic of its conformation, whether α-helix, β-sheet or random coil.