Gas phase ion chemistry of HNO3

Abstract

The ion chemistry of HNO3 is studied at 298 °K. The attachment of thermal electrons to HNO3 to produce NO−2 is found to have a rate constant of (5±3) ×10−8 cm3/sec. HNO3 reacts rapidly (k∼10−9 cm3/sec) with a large variety of negative ions including Cl−, NO2−, O2−, and CO−3. HNO3 is also found to bond strongly to NO3−. The proton affinity of HNO3 is determined to be 176±7 kcal/mole. The present results indicate a strong similarity between protonated HNO3 and hydrated NO2+, suggesting that these ion species are identical. The implication of the present results for atomospheric ion chemistry is discussed.