HR: 1340h
AN: A33B-0886    [Abstracts]
TI: Simultaneous Physical, Chemical and Optical Characterization of Ambient Aerosol Particles Using Single Particle Mass Spectrometry
AU: * Moffet, R
EM: rmoffet@ucsd.edu
AF: University of California, San Diego Department of Chemistry and Biochemistry, 9500 Gilman Dr, La Jolla, CA 92093 United States
AU: Furutani, H
EM: hfurutani@ucsd.edu
AF: University of California, San Diego Department of Chemistry and Biochemistry, 9500 Gilman Dr, La Jolla, CA 92093 United States
AU: Dall'osto, M
EM: mxd266@bham.ac.uk
AF: University of Birmingham, Division of Environmental Health and Risk Managment, Edgbaston, Birmingham, B15 2TT United Kingdom
AU: Prather, K
EM: kprather@ucsd.edu
AF: University of California, San Diego Department of Chemistry and Biochemistry, 9500 Gilman Dr, La Jolla, CA 92093 United States
AB: We have recently shown that optical information obtained with an optical particle tracking system in a single particle mass spectrometer may be used to determine the refractive index and effective density for laboratory particles as a function of chemical composition (R.C. Moffet, K. A. Prather Anal. Chem., accepted, 2005). This study focuses on the light scattering information obtained from ambient particles with Aerosol Time-of-Flight Mass Spectrometry (ATOFMS) during shipboard measurements off the coast of California. We have found that the majority of sea salt and processed sea salt particles appear to be spherical, with a refractive index and density in between that of a dilute solution and crystallized solute. A result similar to this was obtained in laboratory studies of salt (NaCl) particles. Most of the elemental carbon particles were found to be internally mixed with nitrate and sulfate. These elemental carbon particle classes are correlated with absorption measurements made with an aethalometer. Additionally, the optical information suggests that most of these elemental carbon particles have similar morphologies. The goal of this study is to determine the density and complex refractive index for single ambient particle classes for 1) optical closure studies and 2) input into optical models. As part of this presentation, we will discuss efforts aimed at evaluating whether the aethalometer data can be used to retrieve a complex refractive index for the elemental carbon particles. These measurements are unique because they are the first to couple single particle size and chemical composition with optical properties. This is an important step in linking particle mixing state with optical properties, and is therefore an essential step for an accurate understanding of the impacts that different aerosol sources have on the earth's climate system.
DE: 0305 Aerosols and particles (0345, 4801, 4906)
DE: 0365 Troposphere: composition and chemistry
DE: 1029 Composition of aerosols and dust particles
DE: 1694 Instruments and techniques
DE: 3305 Climate change and variability (1616, 1635, 3309, 4215, 4513)
SC: Atmospheric Sciences [A]
MN: Fall Meeting 2005