ELECTROSTATIC PRESSURE AND LINE TENSION IN A LANGMUIR MONOLAYER

We present a Brewster angle microscopy study of the domains of liquid condensed phase (L(2)) in the liquid expanded phase (L(1)) in a Langmu ir monolayer of a long-chain fatty acid. A strong deformation of the d omains is observed when they are close to each other, indicating the p resence of long-range repulsive dipolar interactions between them. The line tension of the L(1)/L(2) interface is deduced from the balance b etween the Line tension and the electrostatic forces. The latter were deduced from surface potential measurements.