In situ single-particle characterization at Cape Grim

This paper describes operation of the particle analysis by laser mass spectrometry (PALMS) instrument at Cape Grim. Several changes to the instrument improved the uniformity of ionization, simplified data analysis, and reduced the minimum analyzable particle size to 0.16 I-lm Almost all of the particles analyzed by PALMS at Cape Grim during clean marine conditions contained some sea salt. Almost all of the sulfate found during clean marine conditions was mixed with sea salt rather than in separate ammonium sulfate or sulfuric acid aerosols. Metals such as Cr, Fe, and Sn were detected in a few particles even in clean marine air masses. An NO+ peak in the mass spectra was associated with Mg, Ca, and Sr. This association could be caused either by the water retention of various salts or by different reactivities. It provides a reminder that other components of sea salt besides NaCl need to be considered for heterogeneous chemistry.