Heterogeneous uptake of NO by sodium acetate droplets and secondary nitrite aerosol formation.

The high NO concentration in fine particulate matters (PM) during heavy haze events has attracted much attention, but the formation mechanism of nitrates remains largely uncertain, especially concerning heterogeneous uptake of NO by aqueous phase. In this work, the heterogeneous uptake of NO by sodium acetate (NaAc) droplets with different NO concentrations and relative humidity (RH) conditions is investigated by microscopic Fourier transform infrared spectrometer (micro-FTIR). The IR feature changes of aqueous droplets indicate the acetate depletion and nitrite formation in humid environment.