Spin one-half optical activity

Spin one-half optical activity, i.e., the various polarization effects caused by the scattering of spin one-half particles from chiral molecules, is discussed. We show how spin one-half circular dichroism and optical rotation may be easily understood as arising from a spin-dependent index of refraction and present an order of magnitude estimate for these effects for the specific case of sodium atom scattering. We find that sodium atom optical rotation is on the order of 10−3 n deg/cm where n is molar density of scatterers. With present technology the measurability of this effect is poor.