Construction of Computer Controlled Langmuir Trough and Its Performance Test

A fully computer controlled normal type Langmuir trough was successfully constructed. The constructed Langmuir trough is consisted of a PTFE trough, servomechanisms for the barrier and the dipper and a commercial electronic balance modified for the surface pressure measurement. Surface pressure was measured and controlled with an accuracy of 0.025mN/m. It was successfully used for various supplementary experiments measuring surface potential of a monolayer at the air/water interface and contact angle during monolayer transfer onto a substrate. The trough was used for obtaining the surface pressure-area isotherm or barium stearate and transferring the floating monolayer of barium stearate. The bi-layer thickness of transferred Langmuir-Blodgett film was obtained from XRD. Extrapolated area of at zero surface pressure for solid phase occupied by a molecule, linear decrease of monolayer area during the transfer and the bilayer thickness of demonstrate that the constructed Langmuir trough is suitable for the measuring the isotherm and the transferring the floating monolayers.