Coupling between a first-order gas-liquid phase transition and a second-order orientational transition in Langmuir monolayers

摘要

The Ginzburg-Landau theory is developed to investigate coupling between a gas-liquid first-order phase transition (FOPT) and an orientational second-order phase transition (SOPT) in Langmuir monolayers. It is found that the coupled SOFT and FOPT takes place simultaneously if the uncoupled FOPT occurs prior to the SOFT with compression, and that in the opposite case, the coupling makes the FOPT take place at a lower pressure, but still behind the SOFT. Gas-liquid phase separation always leads to a decrease in the averaged order parameter of the orientational phase transition, which is qualitatively consistent with experimental data. [S1063-651X(99)08411-1]. [References: 17]