Mixed films of palmitic acid (PA) and galactocerebrosides (GCB) –a proxy for marine aerosol– exhibit attractive interactions due to H-bonding of galactose and carbonyl head groups. We will expose these films to nitrate radicals (NO3) to investigate the impact of atmospheric ageing on surface interactions and ordering. We will harvest the recently developed capability of INTER to simultaneously study deuterated surfactants by NR and obtain information about hydrogenated co-surfactants (as well as the deuterated surfactant) by IRRAS. We will study the oxidation of PA/GCB mixtures (with and without added Ca2+) and then –in an exploratory study– replace PA by its unsaturated analogue palmitoleic acid (POA). We will thus be able to quantify the impact of H-bonding/Ca2+ on the oxidation kinetics and on the material left at the interface, key for the aerosol droplet's fate and cloud formation.