Optical absorption by a nanosystem with dielectric quantum dots
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Optical absorption by a nanosystem with dielectric quantum dots Sergey I. Pokutnyia Department of Theoretical Physics, Chuiko Institute of Surface Chemistry, National Academy of Sciences of Ukraine, 17 General Naumov Str., Kiev 03164, Ukraine Received: 24 April 2018 / Accepted: 7 May 2020 © Società Italiana di Fisica and Springer-Verlag GmbH Germany, part of Springer Nature 2020
Abstract The mechanisms of formation of the spectra of interband optical absorption in nanosystems containing aluminum oxide quantum dots, placed in the matrix of vacuum oil, are presented. It is shown that the electron transitions in the band of the electron–hole pair states cause absorption in the ultraviolet wavelengths and cause the experimentally observed significant blurring of the absorption band.
1 Introduction In experimental studies [1–5], the optical properties of heterogeneous liquid nanophase composites based on wide-gap insulating aluminum oxide quantum dots (QDs) were explored. The unique properties of such nanosystems containing wide-gap aluminum oxide QDs (with the band gap E g 3.7 eV) make possible the experimental detection of energy levels and bands in the band gap of the nanoparticles at room temperature from the room-temperature absorption and transmittance spectra. These levels and bands are responsible for the efficient absorption of radiation in the visible, near-infrared and ultraviolet wavelength regions and define the experimentally observable significant blurring of the absorption edge [1–3]. The nanosystems on aluminum oxide QDs basis also have unique photoluminescent properties, the ability to emit in the visible, near-infrared and ultraviolet wavelength regions at room temperature. The linear dimensions a of QD contained in the nanosystem are comparable to the de Broglie wavelength of the electron and the hole, and their Bohr radii. This leads to the fact that the phenomenon of spatial size quantized of charge carriers plays an important role in optical, nonlinear optical and electro-optical processes in such nanosystems [1–4]. Thus, these processes are largely determined by the energy spectrum of a spatially bounded electron–hole pairs (excitons) [6, 7]. In experimental works [1–3], studied the nonlinear optical properties of dielectric nanosystems based on aluminum oxide QDs with an average radius of not greater than a 25 nm in the dielectric matrix. In particular, it is found that in such nanosystems aluminum oxide QDs have a broad absorption band in the visible, near-infrared and ultraviolet wavelength regions. It is shown that in the band gap of the aluminum oxide QDs are energy quantum-size
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Eur. Phys. J. Plus
(2020) 135:398
levels and regions (similar impurity), which results in significant absorption of the radiation at these wavelengths and determines the experimentally observed significant blurring of the absorption edge. Unfortunately, the interband optical absorption of aluminum oxide Q
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