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| Poly (perfluoropropyleneoxide), i.e., PPFPO, is a viscous liquid used extensively in the electronics industry as a lubricant. In a study reported in Applied Spectroscopy (Jan. 1986), the infrared reflectance spectra properties of PPFPO were examined. The optical density (y) for the prominent infrared absorption of PPFPO was recorded for different experimental settings of band frequency (x,) and film thickness (x2) in a Perkin-Elmer Model 621 infrared spectrometer. The results are given in the accompanying table. OPTICAL DENSITY BAND FREQUENCY FILM THICKNESS X1, cm-1 X2, milligrams 231 740 1.1 .107 740 .62 .053 740 31 805 805 .129 1.1 .069 .62 .030 805 31 1.005 980 1.1 559 980 .62 321 980 31 1.1 1,235 1,235 1,235 2.948 1.633 .62 31 934 Source: Pacansky, J., England, C. D., and Waltman, R. "Infrared Spectroscopic Studies of Poly (Perfluoropropyl- eneoxide) on Gold Substrates: A Classical Dispersion Anal- Inder" Anplicd Spectroscopy, Vol. 40,