• Minofar, B.
• Liu, Y.
• Desyaterik, Y.
• Dames, E.
• Zhu, Z.
• Cain, J. P.
• Hopkins, R. J.
• Gilles, M. K.
• Laskin, A.
• Jungwirth, P.

Abstract

Internal structures, hygroscopic properties and heterogeneous reactivity of mixed CH(3)SO(3)Na/NaCl particles were investigated using a combination of computer modeling and experimental approaches. Surfactant properties of CH(3)SO(3)(-) ions and their surface accumulation in wet, deliquesced particles were assessed using molecular dynamics (MD) simulations and surface tension measurements. Internal structures of dry CH(3)SO(3)Na/NaCl particles were investigated using scanning electron microscopy (SEM) assisted with X-ray microanalysis mapping, and time-of-flight secondary ion mass spectrometry (TOF-SIMS). The combination of these techniques shows that dry CH(3)SO(3)Na/NaCl particles are composed of a NaCl core surrounded by a CH(3)SO(3)Na shell. Hygroscopic growth, deliquescence and efflorescence phase transitions of mixed CH(3)SO(3)Na/NaCl particles were determined and compared to those of pure NaCl particles. These results indicate that particles undergo a two step deliquescence transition: first at ∼69% relative humidity (RH) the CH(3)SO(3)Na shell takes up water, and then at ∼75% RH the NaCl core deliquesces. Reactive uptake coefficients for the particle-HNO(3) heterogeneous reaction were determined at different CH(3)SO(3)Na/NaCl mixing ratios and RH. The net reaction probability decreased notably with increasing CH(3)SO(3)Na and at lower RH.

Topics

• surface
• phase
• scanning electron microscopy
• simulation
• reactive
• molecular dynamics
• Sodium
• phase transition
• spectrometry
• surfactant
• selective ion monitoring
• secondary ion mass spectrometry