The Role of Organic Species on Aerosol Nucleation and Growth

New particle formation in the atmosphere is known to affect climate and human health. The fundamental molecular mechanisms of new particle formation and growth are one of the least understood areas in atmospheric chemistry, which hinders regional pollution and global climate change predictions. In this presentation we report experimental results of the effects of organic acids on aerosol nucleation and growth processes. An aerosol nucleation chamber was employed to simulate aerosol nucleation and growth, and the number, size, and chemical composition of freshly nucleated particles as well as the gaseous aerosol precursors were simultaneously measured. Particle number concentrations were measured using a home built Particle Size Magnifier and an Ultrafine Condensation Particle Counter (TSI 3025A). Particle sizes were measured using a nano differential mobility analyzer (TSI 308500), gas concentrations were measured using Ion Drift- Chemical Ionization Mass spectrometry (Balzers QMG 420). Chemical composition of the critical nuclei was measured using Thermal Desorption-Ion Drift-Chemical Ionization Mass Spectrometry. Several different organic acids were employed in our measurements to examine the effects of organic functionality on aerosol nucleation and growth. The atmospheric implications of our experimental results will be discussed.