Abstract
Abstract. Condensation particle counters (CPCs) are crucial instruments for detecting sub-10 nm aerosol particles. Understanding the detection performance of a CPC requires thorough characterization under well-controlled laboratory conditions. Besides the size of the seed particles, chemical interactions between the working fluid and the seed particles also influence the activation efficiencies. However, common seed particle materials used for CPC characterizations are not chosen with respect to chemical interactions with vapor molecules of the working fluid by default. Here, we present experiments on the influence of the seed particle material on the detection efficiencies and the 50 % cutoff diameters of commonly used CPCs for the detection of sub-10 nm particles. A remarkable set consisting of six different and commercially available particle detectors, including the newly developed TSI V-WCPC 3789 and a tuned TSI 3776, was tested. The corresponding working fluids of the instruments are n-butanol, diethylene glycol and water. Among other materials we were able to measure detection efficiencies with nanometer-sized organic seed particles reproducibly generated by the oxidation of β-caryophyllene vapor in a flow tube. Theoretical simulations of supersaturation profiles in the condensers were successfully related to measured detection efficiencies. Our results demonstrate the importance of chemical similarities between seed particles and the working fluids used when CPCs are characterized. We anticipate our study to contribute to a deeper understanding of chemical interactions during heterogeneous nucleation processes.
Highlights
Ultrafine aerosol particles ( < 100 nm) might cause severe effects on human health (Pedata et al, 2015) and impact the global climate through the aerosol indirect effect (Bauer and Menon, 2012; Albrecht, 1989)
Our results demonstrate the importance of chemical similarities between seed particles and the working fluids used when Condensation particle counters (CPCs) are characterized
The water-based CPC shows a much smaller 50 % cutoff diameter for NaCl and ammonium sulfate compared to the butanol-based counter (2.30 ± 0.12 nm vs. 4.08 ± 0.51 nm for NaCl)
Summary
Ultrafine aerosol particles ( < 100 nm) might cause severe effects on human health (Pedata et al, 2015) and impact the global climate through the aerosol indirect effect (Bauer and Menon, 2012; Albrecht, 1989). Aerosol particles have primary and secondary sources. Secondary particles form when gaseous precursors oxidize to lowvolatility compounds, which at high enough abundances can form molecular clusters. Clusters grow by condensation into the nucleation- and Aitken-mode size range and eventually reach sizes at which they can act as cloud condensation nuclei (CCN). A detailed understanding of the mechanisms leading to aerosol formation and growth, i.e., new particle formation (NPF; Nieminen et al, 2018), requires the careful measurement of particles in the cluster–particle transition and nucleation-mode size regime. Quantitative measurements of aerosol particles in the size range 1–10 nm remain a major challenge for the understanding of the mechanisms responsible for NPF
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
