Ion-Specific Effects under Electric Fields on Ice Nucleation at the Mica Surface

Area of Science:

• Atmospheric chemistry
• Surface science
• Climate science

Background:

• External electric fields impact ice nucleation, crucial for climate and atmospheric systems.
• Mechanisms of heterogeneous ice nucleation (HIN) on mineral surfaces under electric fields with varying ions are not well understood.

Purpose of the Study:

• Investigate ion-specific effects of electric fields on HIN efficiency on mica surfaces with different cations.
• Elucidate the role of cations and electric fields in ice nucleation.

Main Methods:

• Utilized mica surfaces with various cations.
• Applied external electric fields (upward and downward).
• Employed molecular dynamics simulations.

Main Results:

• An upward electric field significantly boosted HIN on Na-mica, raising nucleation temperature by ~6 °C.
• Mica surfaces with other cations or downward fields showed no change in HIN efficiency.
• Molecular dynamics simulations indicated Na+ ions detach more easily under electric fields, exposing the mica lattice.

Conclusions:

• Electric fields exhibit ion-specific effects on heterogeneous ice nucleation.
• Sodium ions play a key role in enhancing ice nucleation on mica surfaces under upward electric fields.
• Findings deepen the understanding of cation and electric field interactions in ice nucleation.