Прегледај по Аутор "Pelemiš, Svetlana"

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    Adaption and application of the Green function method to research on molecular ultrathin film optical properties
    (IOP Publishing, 2009) Setrajčić, Jovan P; Ilić, Dušan I.; Markoski, Branko; Setrajčić, Ana J.; Vučenović, Siniša M; Mirjanić, Dragoljub Lj.; Škipina, Blanka; Pelemiš, Svetlana
    Interest in the study of the exciton subsystem in crystalline structures (in this case nanostructures, i.e. thin films) occurred because dielectric, optical, photoelectric and other properties of materials can be explained by means of it. The basic question to be solved concerning theoretical research into the spatially strongly bounded structures is the inability to apply the standard mathematical tools: differential equations and Fourier analysis. In this paper, it is shown how the Green function method can also be efficiently applied to crystalline samples so constrained that quantum size effects play a significant role on them. For the purpose of exemplification of this method’s application, we shall consider a molecular crystal of simple cubic structure: spatially unbounded (bulk) and strongly bounded alongside one direction (ultrathin film).
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    Influence of sumanene modifications with boron and nitrogen atoms to its hydrogen adsorption properties
    (Royal Society of Chemistry, United Kingdom, 2016) Armaković, Stevan; Armaković, Sanja J.; Pelemiš, Svetlana; Mirjanić, Dragoljub
    We have investigated the influence of the sumanene modifications to the adsorption properties towards hydrogen molecule. Benzylic positions of sumanene were substituted with boron and nitrogen atoms, which changed its hydrogen storage properties. H2 binding energies have been calculated with LMP2, DFT and DFT-D3 approaches with several exchange-correlation functionals and the results indicate physisorption mechanism. The physisorption was confirmed by fragment analysis and a special attention was paid to the noncovalent interactions. All non-covalent interactions, based on reduced density gradient surfaces, have been identified and calculated, for better understand of adsorption mechanism. Also the significance of charge separation by inducing boron and nitrogen atoms was emphasized and a special attention was paid to the z-component of dipole moment of sumanene derivatives.
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    Zeolites as Adsorbents and Photocatalysts for Removal of Dyes from the Aqueous Environment
    (MDPI, 2022) Rakanović, Marina; Vukojević, Andrijana; Savanović, Maria M.; Armaković, Stevan; Pelemiš, Svetlana; Živić, Fatima; Sladojević, Slavica; Armaković, Sanja J.
    This study investigated the potential of zeolites (NH4BETA, NH4ZSM-5, and NaY) to remove two frequently used dyes, methylene blue (MB) and rhodamine B (RB), from an aqueous environment. The removal of dyes with zeolites was performed via two mechanisms: adsorption and photocatalysis. Removal of dyes through adsorption was achieved by studying the Freundlich adsorption isotherms, while photocatalytic removal of dyes was performed under UV irradiation. In both cases, the removal experiments were conducted for 180 min at two temperatures (283 K and 293 K), and dye concentrations were determined spectrophotometrically. Additionally, after photodegradation, mineralization was analyzed as chemical oxygen demand. A computational analysis of the structures of MB and RB was performed to gain a deeper understanding of the obtained results. The computational analysis encompassed density functional theory (DFT) calculations and analysis of two quantum-molecular descriptors addressing the local reactivity of molecules. Experimental results have indicated that the considered zeolites effectively remove both dyes through both mechanisms, especially NH4BETA and NH4ZSM-5, due to the presence of active acidic centers on the outer and inner surfaces of the zeolite. The lowest efficiency of dye removal was achieved in the presence of NaY zeolite, which has a lower SiO2/Al2O3 ratio. A more efficient reduction was completed for RB dye, which agrees with the computationally obtained information about reactivity