AAAR 32nd Annual Conference
September 30 - October 4, 2013
Oregon Convention Center
Portland, Oregon, USA
Abstract View
Studying Aerosol Processes, One Particle at a Time
JONATHAN P. REID, University of Bristol
Abstract Number: 17 Working Group: Invited by Conference Chair
Abstract Aerosol particles are dynamic, changing in size, composition and temperature as chemical and physical transformations occur. To fully characterise and understand the dynamical processes occurring, measurements must be able to access a wide range of lengthscales and timescales, spanning from the nanometre to the millimetre, and from nanoseconds to days. Although we must always remember that aerosols display collective ensemble behaviour, studying the mechanistic details of processes at the single particle level can provide important insights into the processes that influence the dynamics of the whole population. Over the decades, both electrodynamic and optical levitation techniques have demonstrated their value in isolating individual particles for study. When coupled with non-intrusive spectroscopic probes, temporal changes in size, composition and morphology can be followed. Indeed, in recent years we have shown that it is possible to manipulate multiple particles simultaneously using aerosol optical tweezers and to compare their properties directly in situ, bridging the gap between single particle and ensemble studies. In this talk, we will explore the advantages of studying aerosol processes, one particle at a time. More specifically, examples will be given of how processes, such as the evaporation and condensation of water from aerosol particles, can be resolved at the nanometre lengthscale, providing insights into the surface and bulk limited mechanisms and kinetics of hygroscopic growth. The timescales that must be accessed for such measurements span the range from millisecond to days, and are applicable to the inhalation of drugs to the respiratory tract through to the condensation kinetics of water on secondary organic aerosol. The dynamics occurring during the coalescence of aerosol particles will also be explored, with concomitant measurements of particle viscosity spanning almost 12 orders of magnitude. We will also see how the details of chemical aging of organic aerosol can be explored at the single particle level over timescales of days. Finally, the use of optical tools for manipulating aerosol particles to initiate controlled chemical transformations and to probe optical extinction will be introduced.