Optical Rotation of Oriented Helices. IV. A Free Electron on a Helix

Abstract

The absorption and rotation of light is derived for a free electron constrained to move on a helix. This model is probably the simplest optically active system for which exact wavefunctions can be obtained. It is found that a randomly oriented right-handed helix has a positive rotational strength for the longest wavelength absorption band. As expected, this free electron model gives results very similar to an exciton model in which only nearest-neighbor interactions are considered.