HR: 0800h
AN: A41C-05    [Abstracts]
TI: Can Aerosol Particles Develop Organic Surface Layers Under UT/LS Conditions?
AU: * Iraci, L T
EM: laura.t.iraci@nasa.gov
AF: NASA Ames Research Center, Mail Stop 245-5, Moffett Field, CA 94035, United States
AU: Deng, P H
EM: .
AF: NASA Ames Research Center, Mail Stop 245-5, Moffett Field, CA 94035, United States
AB: Tropospheric aerosol particles contain oligomers and macromolecular humic-like substances that may be created by reactions in or on the surface of particles. Marine aerosols have been observed to possess surface films of fatty acids which can survive the evaporation of water from the interior of the particle. This phenomenon of surface films is of current interest with regard to their potential influence on the rate of water uptake by atmospheric particles, particularly in the tropical tropopause region. Understanding the composition, morphology, and behavior of mixed aqueous/organic particles is important for evaluating effects on cloud growth and the resulting climate implications. We have observed very reproducible formation of self-assembled films on the surface of acidic solutions containing aldehydes such as propanal. These resilient films were highly colored, and their formation has definite temperature and acidity dependences. Thus, formation of such a surface film may depend critically on the temperature history of UT aerosols, and aerosols exposed to different temperature and relative humidity conditions may demonstrate differing behavior. We will present an exploration of the conditions necessary for film formation from acidic aqueous solutions of oxygenated compounds and describe several film stability and identification studies.
DE: 0305 Aerosols and particles (0345, 4801, 4906)
DE: 0320 Cloud physics and chemistry
DE: 0365 Troposphere: composition and chemistry
SC: Atmospheric Sciences [A]
MN: 2007 Joint Assembly