Charged droplets have been associated with distinct chemical reactivity. It is assumed that the composition of the surface layer plays a critical role in enhancing the reaction rates in the droplets relative to their bulk solution counterparts. We use atomistic modeling to relate the localization of ions in the surface layer to their ejection propensity. We find that ion ejection takes place via a two-stage process. First, a conical protrusion emerges as a result of a global droplet deformation that is insensitive to the locations of the single ions. The ions are subsequently ejected as they enter the conical regions. The study provides mechanistic insight into the ion-evaporation mechanism, which can be used to revise the commonly used ion-evaporation models. We argue that atomistic molecular dynamics simulations of minute nanodrops do not sufficiently distinguish the ion-evaporation mechanism from a Rayleigh fission. We explain mass spectrometry data on the charge state of small globular proteins and the existence of supercharged droplet states that have been detected in experiments.

The composition of outer drop layers has been associated with distinct chemical reactivity. We use atomistic modeling to examine how the composition of the surface excess charge layer (SECL) is related to the ejection mechanisms of ions. Even though the drop disintegration is inherently a non-equilibrium process we find that the equilibrium ion distribution in SECL predicts the ions that are ejected. The escape of the ions in aqueous drops takes place from conical protrusions that are global drop deformations and their appearance is independent of the location of a single ion. Our results agree with the equilibrium partition model, which associates the mass spectrum with the distribution of analytes in the drop’s double electric layer. We present evidence that atomistic simulations of minute nano-drops cannot distinguish Rayleigh fission from the ion evaporation mechanism.

The composition of outer drop layers has been associated with distinct chemical reactivity. We use atomistic modeling to examine how the composition of the surface excess charge layer (SECL) is related to the ejection mechanisms of ions. Even though the drop disintegration is inherently a non-equilibrium process we find that the equilibrium ion distribution in SECL predicts the ions that are ejected. The escape of the ions in aqueous drops takes place from conical protrusions that are global drop deformations and their appearance is independent of the location of a single ion. Our results are consistent with the equilibrium partition model, which associates the mass spectrum with the distribution of analytes in the drop’s double electric layer. We present evidence that atomistic simulations of minute nano-drops cannot distinguish Rayleigh fission from the ion evaporation mechanism.

The composition of outer drop layers has been associated with distinct chemical reactivity. We use atomistic modeling to examine how the composition of the surface excess charge layer (SECL) is related to the ejection mechanisms of ions. Even though the drop disintegration is inherently a non-equilibrium process we find that the equilibrium ion distribution in SECL predicts the ions that are ejected. The escape of the ions in aqueous drops takes place from conical protrusions that are global drop deformations and their appearance is independent of the location of a single ion. Our results agree with the equilibrium partition model, which associates the mass spectrum with the distribution of analytes in the drop’s double electric layer. We present evidence that atomistic simulations of minute nano-drops cannot distinguish Rayleigh fission from the ion evaporation mechanism.

The composition of outer drop layers has been associated with distinct chemical reactivity. We use atomistic modeling to examine how the composition of the surface excess charge layer (SECL) is related to the ejection mechanisms of ions. Even though the drop disintegration is inherently a non-equilibrium process we find that the equilibrium ion distribution in SECL predicts the ions that are ejected. The escape of the ions in aqueous drops takes place from conical protrusions that are global drop deformations and their appearance is independent of the location of a single ion. Our results are consistent with the equilibrium partition model, which associates the mass spectrum with the distribution of analytes in the drop’s double electric layer. We present evidence that atomistic simulations of minute nano-drops cannot distinguish Rayleigh fission from the ion evaporation mechanism.