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Journal of Applied Spectroscopy, Vol. 87, No. 4, September, 2020 (Russian Original Vol. 87, No. 4, July–August, 2020)

PREPARATION AND OPTICAL PROPERTIES OF ISOPROPANOL SUSPENSIONS OF ALUMINUM NANOPARTICLES A. A. Ramanenka,a* A. A. Lizunova,b A. K. Mazharenko,b M. F. Kerechanina,b V. V. Ivanov,b and S. V. Gaponenkoa

UDC 544.77;535.341;533.951;546.62

A method is proposed for the production of stabilized suspensions of aluminum nanoparticles with a wide distribution of sizes in isopropanol, and their morphological, physicochemical, and optical characteristics are studied. The spectral dependence of the extinction cross section of the nanoparticle suspensions was calculated according to the Mie theory and compared with the experimental data. The growth of the natural oxide shell of nanoparticles was studied. Keywords: nanoplasmonics, aluminum nanoparticles, extinction spectra, ultraviolet spectral range, Mie theory, electrical explosion of wire. Introduction. Nanoplasmonics is one of the actively developing trends of research in modern nanophotonics [1]. The plasmonic properties of aluminum were discovered in 1959 [2], and these researches are some of the pioneering works in the field of nanoplasmonics as a whole. However, the more pronounced plasmonic properties of silver and gold in the visible area of the spectrum have for many years made these metals the main materials of nanoplasmonics [3]. At the same time in the UV region, which is important for many applications (biosensors, photovoltaics, etc.), these metals are not suitable on account of high optical losses. For certain metals and for aluminum in particular the plasmon resonance frequency lies in the UV region [4]. For this reason and also in connection with availability, low cost, simplicity of use, nontoxicity, and compatibility with existing technologies in optoelectronics has been investigated vigorously in recent years aluminum as one of the most promising plasmon materials in the UV region [5, 6]. Various approaches have been developed and proposed for the production of aluminum nanoparticles (NPs) and nanostructures [7]: electron-beam lithography, laser ablation, chemical synthesis, etc. In the present work, a method is proposed for the production of stabilized suspensions of nanoparticles synthesized by electrical explosion of a conductor in isopropanol, and their morphological, physicochemical, and optical characteristics are investigated. Experimental and Calculation. Preparation of Samples. Aluminum nanopowder, produced by electrical explosion of a conductor at the Institute of Electrophysics, Urals Branch of the Russian Academy of Sciences, was used to prepare suspensions of the NPs [8]. Citric acid (of chemical purity, Khimmed, Russia) was used as stabilizer to secure aggregation and sedimentation stability for the NPs in suspensions since its ions ensure long-term stability for Al2O3 NPs in water [9], and in the present work the NPs were coated with a natural Al2O3 shell. A buffer solution was prepared from chromatographically pure isopropano