Brewster Angle Microscopy

Abstract Brewster angle microscopy (BAM) is the technique of choice for imaging monolayers of supramolecular systems at the water–air interface. BAM is based on the optical principle of the Brewster angle, in whichp‐polarized light incident on the water surface at the Brewster angle is nearly completely extinguished. The presence of a monolayer violates this condition and provides the basis for imaging. BAM is a general method for imaging either spread or adsorbed monolayers. BAM can be applied to study phase transitions, characterize domain microstructure, study phase separation in mixed monolayers, follow changes due to complex formation, and observe collapse or multilayer formation. The method is also sensitive to the presence of optical anisotropy in monolayer films due to variations in molecular orientation. BAM has been applied to monolayers of a range of macrocyclic compounds, especially calixarene and cyclodextrin derivatives. BAM has been applied to study chiral phase separation in monolayers of chiral amphiphiles. It is possible to apply BAM in a quantitative manner to estimate variations in monolayer thickness.