The Nano-Particle Mass Classifier (Nano-PMC): Development, Characterization, and Application for Determining the Mass, Apparent Density, and Shape of Particles with Masses Down to the Zeptogram Range

Abstract

Existing aerosol particle mass classifiers (PMCs) can classify particles having masses down to ca. half an attogram (i.e., 10−18 g), which corresponds to a diameter of ca. 10 nm for spherical particles with standard density (1 g/cm3). Here, we describe an improved design of such a classifier, namely, the nano-PMC, which can classify particles with masses down to 20 zeptograms (10−21 g). The response of the classifier was characterized with spherical polystyrene-latex and ammonium sulfate particles, produced by atomization and mobility classification. Measured responses were compared with predictions by a numerical trajectory-based model that considers particle diffusivity. Measurements and predictions of the mean mass of the particles penetrating the classifier agreed within experimental uncertainty (<6%). Differences in the spectrum width could be attributed to recirculation flows occurring in the classification channel.To demonstrate the capabilities of a nano-PMC, we used it in a tandem configuration w...