  Optical beams with a new and distinctive type of helicity have become the
subject of much recent interest. While circularly polarised light comprises
photons with spin angular momentum, these optically engineered 'twisted beams'
(optical vortices) are endowed with orbital angular momentum. Here, the wave-
front surface of the electromagnetic fields assumes helical form. To date,
optical vortices have generally been studied only in their interactions with
achiral matter. This study assesses what new features, if any, can be expected
when such beams are used to interrogate a chiral system.
