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Phosphorus contamination from engine oil additives has been associated with reduced performance of vehicle-aged exhaust gas catalysts. Identifying phosphorus species on aged catalysts is important for understanding the reasons for catalytic performance degradation. However, phosphorus is present only in small quantities, which makes its detection with bulk analytical techniques difficult. Raman microscopy probes small regions (a few microns in diameter) of a sample, and can detect both crystalline and amorphous materials. It is thus ideal for characterizing phosphates that may have limited distribution in a catalyst. However, suitable Raman spectra for mixed-metal phosphates that might be expected to be present in contaminated catalysts are not generally available.

The pretreatment of aluminum sheet material in preparation for further paint application can be challenging due to the presence of a thick oxide layer. The composition of the oxide layer is primarily aluminum oxide, but it may also contain magnesium that is typically dispersed unevenly throughout the oxide layer. Zinc-phosphate systems remove much of the oxide layer on aluminum, but questions remain on the extent of removal of the oxide layer by zirconium oxide-based pretreatments and how these oxide layers may affect the zirconium oxide-based pretreatment deposition on aluminum. Several methods have been used to characterize the coating of zirconium oxide-based pretreatments on aluminum. Scanning electron microscopy at very high magnification reveals a coating on aluminum that is significantly different in morphology than the same coating chemistry on steel substrates.