Origin of long-ranged attraction between like-charged particles at water-air interface

The nature of electrostatic interaction between like-charged particles at water-air interface is analyzed in this paper. We show that long-ranged electrostatic dipolar attraction between these objects generally exists. Our result provides a natural mechanism to explain the experimental observations of attraction between like-charge species trapped at water-air interface. We speculate that a similar (but presumably weaker) mechanism also exists for particles near water-solid interface.