The chemistry at the air water interface in play in sea spray aerosols is dominated by the surfactants covering the surface.  Palmitic acid is one of the most important species in this regime, and it is known that divalent metals, especially Mg2+, play a key role in controlling the uptake of gaseous molecules across the interface. In this presentation, we describe the results of temperature controlled and size-selected cluster ion spectrosocpy where we follow the vibraitonal spectra of assemblies consisting of metal ion, acid, and water with  systematically varied compositions.  A general them of this work is that in the low hydration regime, the metal bind in a symmetrical fashion to both oxygen atoms on the carboxylate group, but this yields to a single contact when the metal can achieve a hexacoordinated solvation envrionment with water molecules in the first hydration shell. We expect to follow how this motif changes upon introduction of a second acid group into the assembly, and discuss more qualitative results on the mass spectrometric characterization of complex samples that mimic the macroscopic aerosol using DART-based, high resolution mass spectrometry based in a 7T FT ICR.

Spectroscopic signatures of divalent metal binding motifs to long chain acids under microhydration

251st National Meeting (2016)

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