https://phys.org/news/2018-07-carboxylic-acids-superacids-surface.html

For this purpose the researchers used online electrospray ionization (OESI) to generate microdroplets, in a process that was dominated by pneumatically assisted aerosolization of liquid samples at fixed pH. The microdroplets in OESI were impacted by acid molecules from the gas-phase before the ions were generated and detected by a mass spectrometer (MS). The technique enabled the efficient observation of one of the most fundamental chemical reactions, the transfer of protons from the acid molecules to the surface of water.

Marcelo Guzman's group at the University of Kentucky stumbled upon microdroplet acidity enhancement while trying to analyze samples by OESI-MS. The researchers noticed that acetic and pyruvic acid molecules were both stronger acids on the surface of water. "They were presumably more prone to transfer a proton as they reached the surface of water coming from air, even more than 50 and 500 times"," Guzman says. The researchers concluded that the behavior and stability of each acid and base pair at the interface played an important role in this phenomena. The results of this work will help to interpret how common carboxylic acids found in aerosols, clouds and fog waters behave in the atmosphere and contribute to design strategies for reducing air pollution.

                                                            
                                    
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