Structures of Fatty Acid Monolayers Transferred to Glass Substrates from Various Langmuir Monolayer Phases

Langmuir-Blodgett monolayers of heneicosanoic acid were transferred to glass substrates from three phases of monolayers on water, whose structures are known to be (a) distorted-hexagonal with molecules tilted toward a near neighbor, (b) untilted distorted-hexagonal, and (c) untitled hexagonal. Specular X-ray reflectivity data show that all three transferred films have the same thickness, and X-ray diffraction data show that all three structures are untilted hexagonal. However, there are small differences in the in-plane diffraction peak positions and in the off-specular reflectivity that may be vestiges of the original structure.