The growth of aerosol particles is related to chemical reactions in the gas phase, particle phase, and at gas-aerosol particle interfaces. While researches in the gas and particle phases of aerosol particles are well documented, physical properties and chemical reactions at gas-particle interfaces have not been studied extensively. Previous interfacial studies of aerosol particles were mainly involved in samples from fields by transportation. However, in situmeasurements of gas-aerosol particles have not been studied yet. The main reason is a lack of suitable in situinterface-sensitive analytical techniques for direct measurements of interfacial properties. Our early success in in situsecond harmonic scattering (SHS) demonstrated the feasibility of real-time measurements of gas-aerosol particle interfaces. Nevertheless, SHS could not provide spectroscopic information for chemical identifications of aerosol interfaces. Here we developed in situinterface-specific electronic sum frequency scattering (ESFS) to directly identify spectroscopic behaviors of molecules at gas-aerosol particle interfaces. As an example, we used an ESFS probe, malachite green (MG), which has surface and SFS activities. We measured ESFS spectra of aerosol particles with under different polarizations and found that interfacial spectra are different than those in bulk. These experimental results provide first spectroscopic analysis of molecules at gas-aerosol particle interfaces. Moreover, these studies build a solid foundation for further development of vibrational sum frequency scattering (VSFS) technique for chemical structures at gas−aerosol particle interfaces.

In-situ electronic sun frequency scattering (ESFS) spectroscopy of gas-aerosol particle interfaces

ACS Fall 2020 Virtual Meeting

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.