Optical absorption, fluorescence, and quantitative 13C NMR spectroscopy have been used to study the degradation of mineral gearbox oil. Samples of used oil were collected from field service. Measured absorption, fluorescence, and quantitative 13C NMR spectra of used oils show characteristic changes from the spectra of a fresh oil sample. A clearly observable, ~20-nm blueshift of the fluorescence emission occurs during the early stages of oil use and correlates with changes in intensity of some specific 13C NMR resonance lines. These changes correlate with oil age because of the connection between the blueshift and breaking of the larger conjugated hydrocarbons of oil as a result of use.
© 2004 Optical Society of America
(120.4290) Instrumentation, measurement, and metrology : Nondestructive testing
(120.4630) Instrumentation, measurement, and metrology : Optical inspection
(300.1030) Spectroscopy : Absorption
(300.6280) Spectroscopy : Spectroscopy, fluorescence and luminescence
Jarmo Vanhanen, Marcus Rinkiö, Jukka Aumanen, Jouko Korppi-Tommola, Erkki Kolehmainen, Tuula Kerkkänen, and Päivi Törmä, "Characterization of Used Mineral Oil Condition by Spectroscopic Techniques," Appl. Opt. 43, 4718-4722 (2004)