Charge reduction in electrosprays: slender nanojets as intermediates

Area of Science:

• Physical Chemistry
• Computational Physics
• Nanotechnology

Background:

• Electrospraying is a technique used to generate charged droplets.
• Understanding droplet disintegration is crucial for controlling particle formation.
• Macroscopic theories may not accurately describe nanoscale phenomena.

Purpose of the Study:

• To investigate charge reduction mechanisms in electrosprayed liquids.
• To explore the dynamics of nanojet shape relaxation and disintegration.
• To determine the influence of charge on nanojet evolution and droplet formation.

Main Methods:

• Molecular dynamics simulations were employed.
• Cylindrical water nanojets with protonated diglycine molecules were simulated.
• Simulations analyzed nanojet behavior as a function of charge.

Main Results:

• Three nanojet evolution scenarios were observed based on charge levels.
• Moderately charged jets formed spheres; near-limit jets split once.
• Highly charged jets underwent repeated fission, exceeding the Rayleigh limit.
• Surface fluctuations and Maxwell stress influenced disintegration.
• Charged jets exhibited stiffer behavior and longer relaxation times than neutral jets.

Conclusions:

• Nanojet behavior deviates from macroscopic predictions due to fluctuations.
• The Rayleigh limit overestimates maximum charge, leading to higher nanodroplet efficiency.
• This study provides insights into nanoscale droplet formation and charge dynamics.