Monday, 10 February 2003: 10:00 AM
Knudsen cell studies of the uptake and reaction of HNO3 and N2O5 on sub-layers of NaCl
Heterogeneous reactions involving sea salt aerosols rich in NaCl are important reactions occurring in the troposphere and therefore, understanding the kinetics and mechanisms governing these processes is essential to determining the tropospheric halogen budget. Two such reactions involve HNO3 and N2O5 reacting with NaCl to yield photochemically inert HCl and photochemically active ClNO2, respectively. The uptake of both HNO3 and N2O5 on NaCl and on synthetic sea salt has been studied using a Knudsen cell coupled to a quadrupole electron impact mass spectrometer. In order to probe the effects diffusion of the gas between particles plays in the uptake, multi- and sub-layers of NaCl particles were used ranging in particle size from 10 to 428 µm sizes. Reaction probabilities, found to differ by a factor of 2 between HNO3 and N2O5 for sub-layer experiments, will be presented and the atmospheric implications will be discussed.