Glancing-angle Raman study of nitrate and nitric acid at the air-aqueous interface

► Glancing-angle Raman scattering probed the surface of nitrate-containing solutions. ► The extent of nitric acid dissociation in the surface region is similar to that in the bulk. ► We obtained an adsorption isotherm for nitrate to the aqueous surface. ► Nitrate exhibits near neutral surface activity.