Spotlight shone on sped up photochemical reactions in droplets

‘Hot spots’ of light can greatly amplify photochemical reaction rates in aerosols, researchers in Switzerland have shown. The effect could explain deviations of atmospheric reaction rates from models and affect climate change predictions, for example. It might potentially also be relevant for photochemical synthesis.

 Many of the photochemical reactions that regulate the Earth’s climate and influence air quality, such as the nitrate photolysis that leads to ozone pollution in cities, involve chemicals that exist in the atmosphere in sub-micrometre water droplets called aerosols. Researchers had assumed that the photochemistry occurred in the gas around the droplets, but in 2015 atmospheric scientist Alma Hodzic at the National Center for Environmental Research in Boulder, Colorado and colleagues observed secondary organic aerosols…