Vibrational Spectroscopic Investigation of the Phase Diagram of a Biomimetic Lipid Monolayer

Abstract
The phase behavior of a biomimetic monolayer consisting of diphospholipid molecules on water is investigated using vibrational sum-frequency generation and fluorescence microscopy. In addition to the transition from the—molecularly disordered—liquid phase to the highly ordered and oriented condensed phase, a novel, extremely sharp transition is observed at low compression, which is attributed to the uncurling of the hydrophobic alkane chains upon compression.