Laser spectroscopy of nanocrystals of aluminum and silicon oxides

The specific features of the spectra of secondary radiation (photoluminescence and Raman scattering) in nanocrystalline samples of aluminum oxide and fused silica are reported. The photoluminescence (PL) spectrum of nanocrystalline aluminum oxide was found to be strongly modified with the wavelength of exciting radiation. Spectra of secondary radiation were excited using a xenon lamp, a pulsed nitrogen laser (with a wavelength of 337.1 nm), a pulse-periodic copper vapor laser (510.6, 578.2 or 255.3 nm), and a solid-state continuous wave laser (532 nm). The numerical calculation of the photoluminescence spectrum of nanocrystalline aluminum oxide doped with chromium under various excitation conditions was performed. The results were compared with the experimental curves. The photoluminescence decay kinetics of nanocrystalline Al2O3 was measured. Modification of the photoluminescence spectra of nanocrystalline Al2O3 was found under the action of ultraviolet and radioactive radiation. The presence of near-ultraviolet bands was found in the photoluminescence spectra of fused silica of the QV type. The form of Raman and photoluminescence spectra of fused silica was shown to be dependent on its microstructure and impurities. Infrared reflectivity spectra of materials of di_erent structures based on SiO2 were obtained. It was shown that the Raman spectra of nanocrystalline samples of aluminum and silicon oxides differed essentially from those of the bulk samples. A characteristic boson peak was revealed in the nanomaterials with the position and width related to the nanoparticles’ sizes.