Four different methods for measuring ultrafine particle size distributions in the 3–10-nm particle diameter range are compared and discussed. These methods all use an ultrafine condensation particle counter (TSI Inc. Model 3025 or its prototype) as the detector, but use different approaches to determine the size of the particles counted. Size classification was achieved using a Hauke Model VIE-06 differential mobility analyzer, a specially configured TSI Model 3040S diffusion battery, an ultrafine condensation particle counter with a variable condenser temperature, and an ultrafine condensation particle counter with a pulse height analyzer for signals produced by the optical detector. The response of these systems to ultrafine particles of known size and composition was studied during a workshop held in Lund, Sweden, during July 1991. After this workshop, measurements of ultrafine particles were made on the Swedish icebreaker Oden during the International Arctic Ocean Expedition 1991 (August 1, 1991 through October 7, 1991). In this article, the results of these laboratory and field measurements are discussed. The strengths and limitations of these measurement methods are emphasized.
Bibliographical noteFunding Information:
The Lund Workshop and the International Arctic Ocean Expedition 1991 were supported by a generous donation from the Knut and Alice Wallenberg Foundation and the Swedish National Science Foundation. The Nessling Foundation supported the work of P. Aalto at the Lund workshop, on the Arctic expedition, and during his stay at the University of Minnesota during the balance of 1991. P. McMurry's participation was supported by the United States Department of Energy Grant No. DE-FG-91ER61205. D. Covert was supported in part by NSF Grant ATM 9008443 and in part by the International Meteorological Institute in Stockholm.