Quantification of the absorption cross sections of surface-adsorbed nitric acid in the 335-365Â nm region by Brewster angle cavity ring-down spectroscopy

► We quantified absorption cross sections of surface-adsorbed HNO3 over 335-365 nm range. ► Surface cross sections were obtained by Brewster angle cavity ring-down spectroscopy. ► HNO3 surface cross sections are at least 100 times larger than those in the gas-phase.