Analytical Infrared Spectra of Particulate Alpha-Aluminas
A class study was performed of the infrared spectra of various powdered alpha-aluminas dispersed in KBr pellets, from which a typical infrared spectrum is established for qualitative analytical purposes. By reference to the polarized reflection spectra of single-crystal corundum and ruby it is demonstrated that reflection losses at the surfaces of the particles dominate the overall form of the powder transmission spectrum, and that in the case of this material the spectral features cannot be regarded as simple absorption bands. It also is shown that the fundamental vibrational frequencies of the corundum crystal lattice do not necessarily coincide with the minima in the transmission spectrum of its powder. A possible explanation for some of the minor spectral features is advanced.
KeywordsReflection Loss Powder Spectrum Boric Oxide Crystallite Surface Cesium Iodide
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