Spatially patterned static roughness superimposed on thermal roughness in a condensed phospholipid monolayer

Imaging of diffuse light scattering in reflection from a phospholipid monolayer at the air/water interface has revealed a previously undetected separation of the monolayer into two regions distinguishable by the intensity of their scattering. In monolayers of L-dipalmitoyl phosphatidylcholine in the condensed phase, chiral-shaped domains are surrounded by a brighter region that covers approximately half the monolayer. While the scattered intensity from both regions increases with surface pressure in a manner consistent with scattering from thermally induced capillary waves, the additional scattering from the brighter region indicates a static surface roughness superimposed on the thermal roughness.