Tunable deep-UV Raman spectroscopy reveals nitrate photolysis

Deep-UV Raman spectroscopy is a promising method for the analysis of nitrates and nitrites in water at ppm (mg/l) concentrations.In addition to the high sensitivity, the tunability of the laser source allows to deeper investigate the photoinduced reactions taking place under deep-UV illumination.Under these conditions, nitrate ions decompose into oxygen and nitrite through different reaction pathways.Analysis of the evolution of nitrate and nitrite Raman modes as a function of the excitation wavelength allows for estimating the photo-energy dependent quantum yield of the photolysis process.The results highlight the limits and capabilities of deep UV Raman as a on-line nitrate and nitrite monitoring method.