Ion dissolution mechanism and kinetics at kink sites on NaCl surfaces

Significance Ion desolvation limits the rate of elementary ion-attachment steps during ionic crystal growth from aqueous solution. However, the desolvation mechanism and solvent coordinates are unknown, so crystal dissolution/growth rates remain difficult to compute. This work identifies solvent reaction coordinates for detachment/attachment of Cl − and Na + from kink sites on NaCl crystals. We find that the larger Cl − limits the overall rate of NaCl dissolution in water because its size prevents water from accessing the kink site during detachment. Our findings show how ion and solvent characteristics influence the kinetics of NaCl growth and dissolution. This work also provides generalizable solvent coordinates and rate expressions for efficient calculations of crystal growth and dissolution rates.