ABSTRACT. The importance of atmospheric aerosols in regulating the Earth's climate and their potential detrimental impact on air quality and human health has stimulated the need for instrumentation which can provide real-time analysis of size resolved aerosol, mass, and chemical composition. We describe here an ( ) aerosol mass spectrometer AMS which has been developed in response to these aerosol sampling needs and present results which demonstrate quantitative measurement capability for a laboratory-generated pure component NH NO aerosol. 3The instrument combines standard vacuum and mass spectrometric technologies with recently developed aerosol sampling techniques. A un ique aerodynamic aerosol ( ) inlet developed at the Un iversity of Minnesota focuses particles into a narrow beam and ef ciently transports them into vacuum where aerodynamic particle size ( ) is determined via a particle time-of-ight TOF measurement. Time-resolved particle mass detection is performed mass spectrometrically following particle ash vaporization on a resistively heated surface. Calibration data are presented for aerodynamic particle velocity and particle collection ef ciency measurements. The capability to measure aerosol size and mass distributions is compared ( ) to simultaneous measurements us ing a differential mobility analyzer DMA ( ) and condensation particle counter CPC . Quantitative size classi cation is demonstrated for pure component NH NO aerosols having mass concentrations 4 3 ) ; 0.25 m g m I 3 . Results of uid dynamics calculations illustrating the performance of the aerodynamic lens are also presented and compared to the measured performance. The utility of this AMS as both a laboratory and eld portable instrument is discussed.

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A three-experiment module based on the most widely studied oscillating system, the Belousov-Zhabotinskii (BZ) reaction.