Performance of diethylene glycol-based particle counters in the sub-3 nm size range

Autor(en)

D. Wimmer, K. Lehtipalo, A. Franchin, J. Kangasluoma, F. Kreissl, A. Kürten, A. Kupc, A. Metzger, J. Mikkilä, T. Petäjä, F. Riccobono, J. Vanhanen, M. Kulmala, J. Curtius

Abstrakt

When studying new particle formation, the uncertainty in determining

the "true" nucleation rate is considerably reduced when using

condensation particle counters (CPCs) capable of measuring

concentrations of aerosol particles at sizes close to or even at the

critical cluster size (1–2 nm). Recently, CPCs able to

reliably detect particles below 2 nm in size and even close to

1 nm became available. Using these instruments, the corrections

needed for calculating nucleation rates are substantially reduced compared to scaling the

observed formation rate to the nucleation rate at the critical cluster

size. However, this improved instrumentation requires a careful

characterization of their cut-off size and the shape of the detection

efficiency curve because relatively small shifts in the cut-off size

can translate into larger relative errors when measuring particles

close to the cut-off size.

Here we describe the development of two continuous-flow CPCs using

diethylene glycol (DEG) as the working fluid. The design is based on

two TSI 3776 counters. Several sets of measurements to characterize

their performance at different temperature settings were carried

out. Furthermore, two mixing-type particle size magnifiers (PSM) A09

from Airmodus were characterized in parallel. One PSM was operated at

the highest mixing ratio (1 L min⁻¹ saturator flow), and the

other was operated in a scanning mode, where the mixing ratios are

changed periodically, resulting in a range of cut-off sizes. The mixing

ratios are determined by varying the saturator flow, where the aerosol flow

stays constant at 2.5 L min⁻¹. Different test aerosols were generated

using a nano-differential mobility analyser (nano-DMA) or a high-resolution DMA,

to obtain detection efficiency curves for all four CPCs. One calibration setup included

a high-resolution mass spectrometer (APi-TOF) for the determination of

the chemical composition of the generated clusters. The lowest cut-off

sizes were achieved with negatively charged ammonium sulfate

clusters, resulting in cut-offs of 1.4 nm for the laminar flow

CPCs and 1.2 and 1.1 nm for the PSMs. A comparison of one of

the laminar-flow CPCs and one of the PSMs measuring ambient and

laboratory air showed good agreement between the instruments.

Organisation(en)

Aerosolphysik und Umweltphysik

Externe Organisation(en)

University of Helsinki, Airmodus Ltd, Johann Wolfgang Goethe-Universität Frankfurt am Main, Universität Zürich (UZH)

Journal

Atmospheric Measurement Techniques

Band

6

Seiten

1793-1804

Anzahl der Seiten

12

ISSN

1867-1381

DOI

https://doi.org/10.5194/amt-6-1793-2013

Publikationsdatum

2013

Peer-reviewed

Ja

ÖFOS 2012

105204 Klimatologie, 105206 Meteorologie, 105904 Umweltforschung

Schlagwörter

Link zum Portal

https://ucrisportal.univie.ac.at/de/publications/be38c36b-9e94-47da-aa80-a129706f9009