Theory of Rayleigh-Brillouin optical activity light scattering applicable to chiral liquids.

It has long been understood that dilute samples of chiral molecules such as rarefied gases should exhibit Rayleigh optical activity. We extend the existing theory by accounting for molecular dynamics and correlations, thus obtaining a more general theory of Rayleigh-Brillouin optical activity applicable to dense samples such as neat liquids.

Mechanical chiral resolution.

Mechanical interactions of chiral objects with their environment are well-established at the macroscale, like a propeller on a plane or a rudder on a boat. At the colloidal scale and smaller, however, such interactions are often not considered or deemed irrelevant due to Brownian motion. As we will show in this tutorial review, mechanical interactions do have significant effects on chiral objects at all scales, and can be induced using shearing surfaces, collisions with walls or repetitive microstructures, fluid flows, or by applying electrical or optical forces. Achieving chiral resolution by mechanical means is very promising in the field of soft matter and to industry, but has not received much attention so far.

Optical activity in the scattering of structured light.

We observe that optical activity in light scattering can be probed using types of illuminating light other than single plane (or quasi plane) waves and that this introduces new possibilities for the study of molecules and atoms. We demonstrate this explicitly for natural Rayleigh optical activity which, we suggest, could be exploited as a new form of spectroscopy for chiral molecules through the use of illuminating light comprised of two plane waves that are counter propagating.

Diffraction gratings for chiral molecules and their applications.

We suggest the use of certain readily producible types of light to exert a force that points in opposite directions for the enantiomers of a chiral molecule and propose multiple devices based upon this novel manifestation of optical activity: in particular, our discriminatory chiral diffraction grating; a device that could be employed, for example, to measure the enantiomeric excess of a sample of chiral molecules simply and to high precision. Our work is relevant for many types of molecules and our proposed devices may be realizable using currently existing technology.

Spatial distribution of mercury and other potentially toxic elements using epiphytic lichens in Nova Scotia.

The use of naturally occurring epiphytic lichens can be an effective tool for regional monitoring of mercury (Hg) and other potentially toxic elements (PTEs). Nova Scotia, Canada is a hotspot for mercury and other trace metal accumulation in ecosystems; partially attributed to long-range transport of air pollution. The relative contribution of local and international sources of Hg to local air in Nova Scotia is unknown. This study assessed the potential of epiphytic lichens (Usnea spp.) as passive samplers for PTE air pollution in Nova Scotia. Lichens (n = 190) collected across mainland Nova Scotia were analyzed for PTEs. Results indicate that there are 3 distinct clusters of PTEs which suggest patterns and sources for each elemental cluster. Hg was correlated with longitude and prevailing wind direction, and Hg was not significantly different in site-specific hotspot sampling nor year of sampling. Our data support the hypothesis that Hg in lichens is from historical and ongoing long-range transport and diffuse emission patterns rather than localized pollution sources. PTE concentrations were shown to have median values that are similar to other remote regions (such as the Antarctic) however the maximum values were observed to be substantially higher for some elements (e.g. lead, cadmium). This research supports the use of lichens as biomonitors and provides a baseline for future monitoring efforts to identify changes in PTE distribution in Nova Scotia with ongoing industrial activity and a changing climate.

Chirality and the angular momentum of light.

Chirality is exhibited by objects that cannot be rotated into their mirror images. It is far from obvious that this has anything to do with the angular momentum of light, which owes its existence to rotational symmetries. There is nevertheless a subtle connection between chirality and the angular momentum of light. We demonstrate this connection and, in particular, its significance in the context of chiral light-matter interactions.This article is part of the themed issue 'Optical orbital angular momentum'.