Characterization of Imidazole Compounds in Aqueous Secondary Organic Aerosol Generated from Evaporation of Droplets Containing Pyruvaldehyde and Inorganic Ammonium

Imidazole compounds are important constituents of atmospheric brown carbon. The imidazole components aqueous secondary organic aerosol (aqSOA) that generated from the evaporation droplets containing pyruvaldehyde and inorganic ammonium on-line characterized by an laser time-of-flight mass spectrometer (ALTOFMS) off-line detected optical spectrometry in this study. results demonstrated desorption/ionization spectra aqSOA particles were ALTOFMS contained characteristic peaks imidazoles at m/z = 28 (CH2N+), 41 (C2H3N+) 67 (C3H4N2+). Meanwhile, extraction solution measured techniques showed absorption 217 nm 282 appeared UV-Vis spectrum, stretching vibration C-N bond C=N emerged infrared spectrum. Based on these spectral information, 4-methyl-imidazole 4-methyl-imidazole-2-carboxaldehyde identified as main products reaction between ions. water accelerates formation inside droplets, possibly owing to highly concentrated environment. Anions, such F?, CO32?, NO3?, SO42? Cl? phase promote ions produce products, resulting averaged coefficient (<MAC>) range 200–600 increases, order promotion is: F? > CO32? ? NO3? Cl?. These will help analyze optics provide a useful basis for evaluating process radiative forcing particles.