Optical properties and chemical compositions of iodine-containing aerosols produced from the atmospheric photolysis of methylene iodide in the presence of Ozone

Optical properties of iodine-containing aerosols that were produced by ultraviolet photoirradiation of a mixture gas of CH ₂I ₂ and O ₃ with dry air diluent have been measured using a nephelometer, a particle soot absorption photometer and a cavity ring-down spectrometer. Single scattering albedo of iodine aerosols was determined to be 0.96 ± 0.01 at around 530 nm. Chemical compositions of the aerosols associated with particle size in the range of 0.21 μm was measured using a laser-ionization single-particle aerosol mass spectrometer. Positive and negative ion signals of iodine and iodine oxides, IO _n (n = 0-4), I ₃O _n (n = 0-6), and I ₃O _n (n = 0-1), carbon-containing compounds and HOI were detected.