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Single Particle Mass Spectrometry

The single particle mass spectrometer, miniSPLAT, at the Environmental Molecular Sciences Laboratory is used to characterize in situ and real-time physicochemical properties of individual particles, with unparalleled sensitivity, sizing precision, mass-spectral quality, and temporal resolution. Its analytical capabilities are extended far beyond the basic measurements of particle size and composition. Our researchers have transformed it into a comprehensive quantitative tool that can simultaneously measure a multitude of key individual particles properties.

At present, miniSPLAT provides information on:

  • particle number concentrations
  • size
  • chemical composition
  • mass
  • density
  • porosity or void fraction
  • morphology
  • shape (aspherisity, asymmetry, dynamic shape factors, fractal dimension)
  • phase, viscosity, chemical diffusivity
  • interactions with water vapor (hygroscopicity, activation as cloud condensation and ice nuclei)
  • evaporation kinetics and volatility
  • rates of multiphase reactions as a function of particle size.

MiniSPLAT is compact, robust, and portable, and it can be deployed in the laboratory and in the field, including on-board aircraft. It is used to characterize atmospheric aerosols, nanoparticles, engine exhaust particulate, bioaerosols, soils, and particles generated by high-energy explosives.

To take advantage of the vast amount of multidimensional single particle data generated by miniSPLAT, and analyze these data in the context of measurements acquired by other aerosol, gas-phase, and cloud instruments, researchers developed novel approaches for interactive and intuitive data visualization, classification, and analysis, including

  • visualization expert-driven classification software (ClusterSculptor)
  • data mining and visualization software (SpectraMiner)
  • interactive, visual analytics software (ND-Scope).

This suite of tools was specifically designed to explore millions of single-particle mass spectra, study their size- and shape-dependent properties and behavior, discover correlations, and uncover causal relationships between particle properties and other observables.

a standing square instrument with metal and black parts
EMSL's single particle mass spectrometry (SPLAT) supports research in the Terrestrial-Atmospheric Processes Integrated Research Platform. 

Research application

MiniSPLAT supports EMSL’s Terrestrial-Atmospheric Integrated Research Platform by investigating processes relevant to biosphere-atmosphere interactions that control the atmospheric aerosol lifecycle. This includes aerosol formation and growth, chemical and physical transformations, and aerosol removal processes. The instrument benefits atmospheric research by providing information on the rapidly evolving composition, size distributions, microphysical, optical, and cloud-nucleating properties of atmospheric aerosol particles, their spatial distributions, and seasonal and diurnal variations.

Tips for success

  • Users can supply samples in the form of dry powders, solutions, or particle suspensions. These samples are aerosolized using a powder dispersion generator, atomizers, nebulizers, or an electrospray particle generator.
  • Particles can be generated in situ using a variety of methods that include 1) gas-to-particle conversion during oxidation reactions in Teflon chambers or a flow tube reactor, 2) tube furnace, 3) spark discharge generator, and 4) combustion aerosol generator.
  • The laboratory is also equipped with an inlet for ambient atmospheric particles for real-time characterization and collection for offline analysis.

 

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