Under 308 nm UV light,photolysis of HNO3 in the gas phase and on the α-Fe2O3 films was studied by using ultravioletvisible spectrophotometer( UV-Vis),Fourier transform infrared spectrometer( FTIR) combined with ion chromatography( IC)technique. The effects of HNO3 initial concentration,relative humidity( RH) and illumination time were systematically investigated.Results showed photolysis of HNO3 could produce NO2 and NO in the gas phase and on the α-Fe2O3 films. With the increase of reaction time and HNO3 i...