Water Structure and Its Correlation to Heterogeneous Ice Nucleation

Clouds, a mixture of water vapor, condensed liquid droplets, solid crystals and aerosol particles, exert an importance on weather and climate via controlling the amount of precipitation and transportation of radiative fluxes. One of the major processes involved in clouds is heterogeneous ice nucleation, which is nucleation facilitated by the presence of mineral substrates. Understanding the role played by solid surfaces in influencing the structure and dynamics of water and thus regulating ice nucleation paves the road for forecasting long-term climate change and designing surfaces with customer-specified ice nucleation properties. The goal of our research is to be able to predict the nucleating ability of a surface based on the interfacial water structure and dynamics. To investigate this problem, we focus on mica, which has a molecularly smooth nature to begin with, thus eases out the complexity of dealing with surface defects. By combining molecular dynamics (MD) simulations with Fourier-transform infrared spectroscopy (FTIR), we probe the change in interfacial water arrangement, spatial correlation and dynamics on mica surface. The interplay of ion-water, ion-surface, and surface-water interactions affect the interfacial water arrangement along with the hydrogen bond network, which is found to be the crucial part in altering surface nucleating ability