Elemental composition and morphology of individual particles separated by size and hygroscopicity with the TDMA

Peter H. McMurry, Mark Litchy, Po Fu Huang, Xiaoping Cai, Barbara J. Turpin, William D. Dick, Anne Hanson

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91 Scopus citations


Particles from the Minneapolis atmosphere were segregated according to hygroscopicity using a tandem differential mobility analyzer (TDMA) and collected with a specially designed aerodynamic focusing impactor for elemental analysis. Areal deposit densities obtained using the focusing impactor are up to a factor of 100 greater than those obtained using a conventional single-jet impactor, thereby reducing required sampling times by the same factor. A Philips CM30 scanning transmission electron microscope (STEM) equipped with an EDAX super ultra-thin-window detector was used to analyze for carbon and heavier elements. For the limited sample of 0.3-0.4 μm summertime aerosols examined in this study, less hygroscopic particles included chain agglomerates (~ 55%), irregular shapes (~ 33%), spheres and flakes (< 10% each) and contained mostly carbon, while more hygroscopic particles were liquid droplets that contained sulfur and sometimes carbon or ionic species such as sodium or potassium.

Original languageEnglish (US)
Pages (from-to)101-108
Number of pages8
JournalAtmospheric Environment
Issue number1
StatePublished - 1996

Bibliographical note

Funding Information:
Acknowledgments This research was supported by the Electric Power Research Institute (Grant No. EPRI RP2023-11) and by a U.S. DOE Graduate Fellowship for the Global Change Program (ML). Components of the aerodynamic focusing impactor were purchased with funds provided by a grant from Applied Materials.


  • Aerosol water content
  • CCN
  • Chemical composition
  • Electron microscopy impactor
  • Hygroscopic growth
  • Mixing characteristics
  • TDMA


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