miniSPLAT: A Miniaturized Aircraft-Compatible Single Particle Mass Spectrometer for in-situ Quantitative Multidimensional Single Particle Characterization

Description

Characterization of atmospheric aerosol particles presents a significant challenge: ambient aerosol particles are complex, internally and externally evolving mixtures with ranges of concentrations, sizes, and compositions, all of which determine their optical properties, and ability to serve as cloud condensation or ice nuclei. Hence, developing a fundamental understanding of the aerosol effect on climate requires knowing the sizes and chemical compositions of individual aerosol particles. In addition, high instrument sensitivity and temporal resolution are needed to characterize particles with large variations in both composition and size, which all the more important for measurements on-board aircraft. Single particle mass spectrometers (SPMSs) have been developed and deployed on the ground, on-board ships and on-board aircraft to characterize, in-situ and in real-time, the size and composition of individual ambient particles and their spatial and temporal evolution. While SPMSs have undeniably proven to be extremely valuable, improving our understanding of the properties and evolution of atmospheric aerosols, these instruments have also persistently been subject to criticism on a number of fronts. We will present miniSPLAT, our new aircraft-compatible SPMS, that measures in-situ and in real-time many of the attributes of individual small particles (size, composition, number concentration, morphology, density, shape, mass, etc.), to yield comprehensive, quantitative, multidimensional single particle characterization. miniSPLAT has ultrahigh sensitivity, high temporal resolution, precision, and accuracy. When compared to our previous instrument, SPLAT II, miniSPLAT has been significantly reduced in size, weight, and power consumption without loss in performance. We will discuss the results of a recent inter-comparison of 11 SPMSs (KIT, Germany), in which miniSPLAT demonstrated its unmatched analytical capabilities, as it was the only SPMS to correctly identify all three particle types (soot, secondary organic aerosol, and dust) in the blind test. Moreover, miniSPLAT determined quantitative information on their composition-resolved size distributions, relative number fractions, density, shape, mass, and more. In addition to the inter-comparison, miniSPLAT participated in over 50 experiments aimed at understanding ice nucleation activity of various pure and mixed aerosol particles. We will present some preliminary results from these studies.