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Rate coefficients for the reaction of NO3 radicals with 6 unsaturated volatile organic compounds (VOCs) in a 7300 L simulation chamber at ambient temperature and pressure have been determined by the relative rate method.The resulting rate coefficients were determined for isoprene,2-carene,3-carene,methyl vinyl ketone (MVK),methacrolein (MACR) and crotonaldehyde (CA),as (6.6 ± 0.8) × 10-13,(1.8 ± 0.6) × 10-11,(8.7 ± 0.5) × 10-12,(1.24 ± 1.04) × 10-16,(3.3 ± 0.9) × 10-15 and (5.7 ± 1.2) × 10-15 cm3/(molecule·sec),respectively.The experiments indicate that NO3 radical reactions with all the studied unsaturated VOCs proceed through addition to the olefinic bond,however,it indicates that the introduction of a carbonyl group into unsaturated VOCs can deactivate the neighboring olefinic bond towards reaction with the NO3 radical,which is to be expected since the presence of these electronwithdrawing substituents will reduce the electron density in the π orbitals of the alkenes,and will therefore reduce the rate coefficient of these electrophilic addition reactions.In addition,we investigated the product formation from the reactions of 2-carene and 3-carene with the NO3 radical.Qualitative identification of an epoxide (C10H16OH+),caronaldehyde (C10H1602H+) and nitrooxy-ketone (C10H1604NH+) was achieved using a proton transfer reaction time-of-flight mass spectrometer (PTR-TOF-MS) and a reaction mechanism is proposed.