Detecting Below 3 nm Particles Using Ethylene Glycol-based Ultrafine Condensation Particle Counter
An ethylene glycol based ultrafine condensation particle counter (EGUCPC) was developed by modifying the laminar flow ultrafine condensation particle counter which was originally developed by Stolzenburg and McMurry (1991) . Prior to experiments, theoretical analyses were performed using different working fluids to predict activation efficiency and condensational growth after activation. Ethylene glycol was chosen as the working fluid since it is less toxic than other compounds investigated and it has a predicted 50% cutoff diameter is below 2 nm. Experiments were performed using sodium chloride, ammonium sulfate, and silver as test aerosols. To obtain the activation efficiency from the experimental data we have accounted the size dependence of input particle size distribution and particle penetration within the diffusion-broadened mobility window of transfer function of the DMA. The 50% cutoff sizes of negatively charged particles are 1.3, 1.3, and 1.5 nm mobility diameter for sodium chloride, ammonium sulfate, and silver, respectively. The lower cutoff size for the first two compounds suggests that ethylene glycol vapor heterogeneously nucleates more easily on hygroscopic material.
Keywords Condensation particle counter
KeywordsEthyl Cage Sodium Chloride Ethylene Glycol Fullerene
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