Development of a Temperature Programmable Langmuir Trough and Measurements of A-T Isobars of Myristic Acid Monolayers

Abstract

A temperature programmable Langmuir trough using a larg e number of Peltier elements has been developed. Surface temperature of the subphase water in the trough can be changed at a maximum rate of 8°C/min linearly with time in both heating and cooling. Fluc tuation of the surface temperature was within ;± 0.0 2 °C at a constant temperature control. heatingrate dependence and surface-pressure dependence of A-T isobars of myristic acid mo nolayers at the air/water interface were measured with this instrument. The first-order ph ase transition from liquid-condensed to liquid-expanded state of monolayers considerably depend ed on the heating rate. The transition temperature also depended on the surface pressure. This trough will be especially useful for making defect-free LB films by the "isobaric ther mal treatment" of monolayers.