Design and Interfacing of an Automated Langmuir-Type Film Balance to an FT-IR Spectrometer

Abstract

We report the design of a surface analysis accessory that allows for the use of external reflection FT-IR spectroscopy to investigate the structure of insoluble monolayer films in situ at the air/water interface. The Langmuir film balance constructed for this purpose is optimized to contain the monolayer film at the focal point of the infrared beam, as well as to generate high surface pressures within the film. The optical interfacing of the film balance to an FT-IR spectrometer is also described. Results are presented for a representative surface pressure/molecular area isotherm and infrared spectrum for a phospholipid monolayer film.