Knowledge Bank

The instrument described, manufactured under the trade name ''Dichrograph'', comprises a source of monochromatic radiation in the spectral region 220 to 600 millimicrons, a polarizing prism, a birefringent modulator to provide circular polarization, a sample holder, detector, and the required power supplies and amplifiers. Any circular dichroism exhibited by the sample produces a 60-cycle signal that is amplified, rectified, and recorded against wavelength. The deflection is linear with optical density, and is upscale (positive) or downscale (negative), according to whether the extinction is greater for right or left handed circularly polarized radiation.