Excitation Frequency Dependence and Fluorescence in the Raman Spectra of Al ₂ O ₃

Raman spectra of aluminum oxide, Al 2 O 3 , have been a subject of interest over the last two decades. The origin of the fluorescence background in the Raman spectra of Al 2 O 3 is still a subject of discussion. It has been believed to be due to hydrocarbon, iron ion impurities, or hydroxy groups on the surface of Al 2 O 3 . In this paper, Raman spectra of Al 2 O 3 are reported that were acquired with different excitation frequencies as well as different spectrometers and different temperatures. It is shown that, whereas at an excitation frequency of 1064 nm a strong fluorescence background is observed, a sample of Al 2 O 3 heated at 1250 °C when excited with a 632.8-nm frequency exhibits strong and remarkable fluorescence ne structure. It is concluded that the origin of the fluorescence background in the Raman spectra of Al 2 O 3 is iron, and Fe impurity, and the intensity of this fluorescence depends upon the structure of Al 2 O 3 and the excitation frequency used.