10th International Aerosol Conference September 2 - September 7, 2018 America's Center Convention Complex St. Louis, Missouri, USA
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Improving Airborne Nanoparticle and Cluster Detection with the Butanol Based Laminar Flow Condensation Nuclei Counters Grimm 5.403 and 5.412
GERHARD STEINER, Manuel Orzan, Ina Nagler, Elena Petrakakis, Mirela Selimovic, Christian Tauber, Frank Tettich, University of Vienna
Abstract Number: 826 Working Group: Instrumentation
Abstract Over the last years, the size range of airborne molecular clusters (< 3nm) has become of highest importance in the field of aerosol sciences since it covers the initial steps of new particle formation in the atmosphere (e.g. Kulmala et al. 2013); therefore having a major climate relevant impact. Also, it was recently shown that a major fraction of traffic produced particles contributes to the sub 3nm size range (Rönkkö et al. 2017). Evidently, also the development of new instrumentation for the classification and detection of sub 3nm particles and clusters is an extremely emerging field.
The detection of charged aerosols and clusters in the size range below 3nm was investigated starting at the turn of the 19th to the 20th century (as reviewed e.g. by Flagan, 1998). The detection of electrically neutral aerosols in this size range is far more challenging and was most probably first made possible in the 1960’s by the development of a mixing type particle size magnifier (PSM) by Kogan & Burnasheva (1960).
Still, the state-of-the-art technique to detect electrically neutral particles by a single-particle count mode is based on the condensational growth of water or various alcohols. New types of condensation particle counters (CPCs) are designed as laminar flow type (e.g. Kuang et al. 2012), mixing type (e.g. Vanhanen et al. 2011) and expansion type (e.g. Winkler et al. 2008) CPCs. These instruments cover prototypes like the vSANC (Pinterich et al. 2016) and commercial products like the A10 Particle Size Magnifier (PSM) from Airmodus Oy and the Nano Enhancer 3777 from TSI Inc.
Accordingly, it appears, that for being able to detect low number concentrations of neutral sub 3 nm particles, one either needs to be expert in the field of the development of new instrumentation or one needs to invest money in a new commercial detector. Following the approach presented by Kangasluoma et al. (2015), this may not be necessary for some applications in laboratory measurements.
Here we present experiments with two n-butanol based CPCs (Grimm 5.403 and 5.412) that were operated with modified settings of their internal temperatures. We show the results of measurements with seed aerosols of different size and chemical composition and demonstrate improved detection of clusters down to 1.47nm (THA+; tetraheptylammonium ion).
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