A Caltech Library Service

A new high-transmission inlet for the Caltech nano-RDMA for size distribution measurements of sub-3 nm ions at ambient concentrations

Franchin, Alessandro and Downard, Andy and Kangasluoma, Juha and Nieminen, Tuomo and Lehtipalo, Katrianne and Steiner, Gerhard and Manninen, Hanna E. and Petäjä, Tuukka and Flagan, Richard C. and Kulmala, Markku (2016) A new high-transmission inlet for the Caltech nano-RDMA for size distribution measurements of sub-3 nm ions at ambient concentrations. Atmospheric Measurement Techniques, 9 (6). pp. 2709-2720. ISSN 1867-8548. doi:10.5194/amt-9-2709-2016.

[img] PDF - Published Version
Creative Commons Attribution.


Use this Persistent URL to link to this item:


Reliable and reproducible measurements of atmospheric aerosol particle number size distributions below 10 nm require optimized classification instruments with high particle transmission efficiency. Almost all differential mobility analyzers (DMAs) have an unfavorable potential gradient at the outlet (e.g., long column, Vienna type) or at the inlet (nano-radial DMA), preventing them from achieving a good transmission efficiency for the smallest nanoparticles. We developed a new high-transmission inlet for the Caltech nano-radial DMA (nRDMA) that increases the transmission efficiency to 12 % for ions as small as 1.3 nm in Millikan–Fuchs mobility equivalent diameter, D_p (corresponding to 1.2  ×  10^(−4) m^2 V^(−1) s^(−1) in electrical mobility). We successfully deployed the nRDMA, equipped with the new inlet, in chamber measurements, using a particle size magnifier (PSM) and as a booster a condensation particle counter (CPC). With this setup, we were able to measure size distributions of ions within a mobility range from 1.2  ×  10^(−4) to 5.8  ×  10^(−6) m^2 V^(−1) s^(−1). The system was modeled, tested in the laboratory and used to measure negative ions at ambient concentrations in the CLOUD (Cosmics Leaving Outdoor Droplets) 7 measurement campaign at CERN. We achieved a higher size resolution (R  =  5.5 at D_p  =  1.47 nm) than techniques currently used in field measurements (e.g., Neutral cluster and Air Ion Spectrometer (NAIS), which has a R  ∼  2 at largest sizes, and R  ∼  1.8 at D_p  =  1.5 nm) and maintained a good total transmission efficiency (6.3 % at D_p  =  1.5 nm) at moderate inlet and sheath airflows (2.5 and 30 L min^(−1), respectively). In this paper, by measuring size distributions at high size resolution down to 1.3 nm, we extend the limit of the current technology. The current setup is limited to ion measurements. However, we envision that future research focused on the charging mechanisms could extend the technique to measure neutral aerosol particles as well, so that it will be possible to measure size distributions of ambient aerosols from 1 nm to 1 µm.

Item Type:Article
Related URLs:
URLURL TypeDescription
Flagan, Richard C.0000-0001-5690-770X
Additional Information:© 2016 Author(s). This work is distributed under the Creative Commons Attribution 3.0 License. Received: 17 February 2015 – Published in Atmos. Meas. Tech. Discuss.: 15 June 2015; Revised: 23 March 2016 – Accepted: 30 May 2016 – Published: 29 June 2016. This research was funded by the European Commission 7th Framework Programme (Marie Curie Initial Training Network “CLOUD-ITN”, grant 215072); the European Research Council (ERC) Advanced Grant Atmospheric nucleation: from molecular to global scale (ATMNUCLE) (grant 227463); from the Austrian Science Fund, FWF (grant number P27295-N20); and the Academy of Finland via the Centre of Excellence Programme (projects 1118615 and 272041). Thanks to Rae Ellen Bichell for proofreading.
Funding AgencyGrant Number
Marie Curie Fellowship215072
European Research Council (ERC)227463
FWF Der WissenschaftsfondsP27295-N20
Academy of Finland1118615
Academy of Finland272041
Issue or Number:6
Record Number:CaltechAUTHORS:20160805-101341458
Persistent URL:
Official Citation:Franchin, A., Downard, A., Kangasluoma, J., Nieminen, T., Lehtipalo, K., Steiner, G., Manninen, H. E., Petäjä, T., Flagan, R. C., and Kulmala, M.: A new high-transmission inlet for the Caltech nano-RDMA for size distribution measurements of sub-3 nm ions at ambient concentrations, Atmos. Meas. Tech., 9, 2709-2720, doi:10.5194/amt-9-2709-2016, 2016
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:69469
Deposited By: Tony Diaz
Deposited On:05 Aug 2016 17:28
Last Modified:11 Nov 2021 04:14

Repository Staff Only: item control page