AAAR 33rd Annual Conference
October 20 - October 24, 2014
Rosen Shingle Creek
Orlando, Florida, USA
Abstract View
Laboratory Characterization of an Ultrafine Condensation Particle Counter Using a Perfluorinated Compound Working Fluid: Particle Size, Charge, and Composition Dependent Responses down to 1 nm
CHONGAI KUANG, Juha Kangasluoma, Daniela Wimmer, Jian Wang, Markku Kulmala, Tuukka Petäjä, Brookhaven National Laboratory
Abstract Number: 497 Working Group: Instrumentation and Methods
Abstract Recent advances in the development of condensation particle counters (CPCs) have enabled the detection of gas-phase single molecules and molecular clusters down to 1 nm diameter and below through the use of new working fluids and operating conditions. This new capability has enabled the direct measurement of aerosol nucleation from gaseous precursors in both laboratory experiments and the ambient environment, providing information necessary to constrain and probe the nucleation mechanism. While there are CPCs now that are capable of detecting nanoparticles down to 1 nm, the corresponding values for d50 (the particle diameter at which 50% of the sampled particles are counted) display a strong dependence both on particle charge state and particle composition. These strong sensitivities can lead to substantial uncertainties when calculating the actual number concentration of sampled aerosol, especially if the aerosol is of unknown composition. Prior studies have indicated that a perfluorinated compound working fluid could reduce the sensitivity of CPC detection efficiency to particle composition down to 3 nm. In this study, a commercial ultrafine CPC has been adapted to use a perfluorinated compound as the working fluid, with operating conditions optimized for the detection of sub 3 nm aerosol. Characterization results will be presented for compositionally diverse calibration aerosol of both negative and positive charge states.