Tiny particles in the air known as aerosols play an important role in cloud formation, which in turn has an impact on our planet’s climate. However to date the effect of aerosols on cloud formation remains full of uncertainties. Among these uncertainties is the reactivity of organic films that have been found to coat atmospheric aerosols. Now researchers have turned their attention to studying these using the Surface and Interface Diffraction beamline (I07) at Diamond Light Source.