Atmospheric nucleation is an important initial step in the chain reactions that lead to cloud formation, but the nucleation mechanisms are poorly understood.  Recent field studies and quantum chemical calculations show that amines can contribute to formation of nanometer size particles.  Amines and ammonia often have common atmospheric emission sources and have similar chemical and physical properties.  While the effects of ammonia on aerosol nucleation processes have been previously investigated, laboratory studies of homogeneous nucleation involving amines are critically lacking. We have conducted kinetics studies of multicomponent nucleation with sulfuric acid, water, ammonia and amines under conditions relevant to the atmosphere. Concentrations of aerosol precursors are measured with chemical ionization mass spectrometers, to provide constrained precursor conditions needed for nucleation. Particles sizes larger than 2 nm are measured with a nano-differential mobility analyzer and number concentrations of particles larger than 1 nm are measured with a particle size magnifier. These particle instruments allow us to investigate the nucleation and growth processes, independently. In this presentation, we will show how different amine compounds affect nucleation and growth of sulfuric acid particles, in comparison with ammonia. We will also show how ammonia and amines together affect formation of clusters and nanometer size particles.  Our results show that these organic and inorganic base compounds should be together taken into account in atmospheric aerosol formation processes.

Effects of amines on formation of atmospheric sub-3 nm particles and their subsequent growth

243rd National Meeting (2012)

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