Polarization-Modulation Emission FT-IR Measurement of Thin Organic Films on Metal Surfaces

A polarization-modulation technique has been combined with Fourier transform infrared (FT-IR) spectrometry to eliminate the large background radiation which interferes with the infrared emission from thin organic films on metal surfaces. A step scan and a continuous scan interferometer which were combined with a photoelastic modulator were also studied, and the step scan system was found to be stabler and have a better S/N. The spectrum of a 12-nm perfluoropolyether film was obtained at 120°C by this system.