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dz2 Orbitals Mediated Bound Magnetic Polarons in Ferromagnetic Ce Doped BaTiO3 Nanoparticles and its Enriched Two Photon Absorption Cross Section
摘要： Enriched ferromagnetism and two photon absorption (TPA) cross section of perovskite BaTiO3 nanoparticles are indispensible for magnetic and optical data storage applications. In this work, the hydrothermally synthesized Ce doped BaTiO3 nanoparticles exhibit the maximum room temperature ferromagnetism (4.26×10-3 emu/g) at 4 mol% due to the increase of oxygen vacancies as evidenced by X-ray photoelectron, electron spin resonance spectroscopies and density functional theory (DFT) calculations. Hence, the oxygen vacancy constituted bound magnetic polaron (BMP) model has been invoked to explain the enhancement of ferromagnetism. BMP theoretical model indicates the increase of BMP magnetization (M0, 3.0 to 4.8×10-3 emu/g) and true spontaneous moment per BMP (meff, 4 to 9.88×10-4 emu) on Ce doping. DFT calculations show that BMPs mediate via Ti d orbitals leading to the ferromagnetism. Besides, it is understood that the magnetic moment induced by Ce at Ba site is higher than Ce at Ti site in the presence of oxygen vacancies. Open aperture Z-scan technique displays the highest TPA coefficient β (7.08×10-10 m/W) and TPA cross section σTPA (455×104 GM) at 4 mol% of Ce as a result of robust TPA induced excited state absorption. A large σTPA is attributed to the longer excited state lifetime τ (7.63 ns) of charge carriers created by oxygen vacancies and Ce ions which encounter several electronic transitions in the excited sub-states.
关键词： Ce doping,oxygen vacancies,bound magnetic polarons,two photon absorption,DFT calculations,Z-scan technique,BaTiO3 nanoparticles,ferromagnetism
更新于2025-11-19 16:56:35
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A Spectroscopic Study of Tautomeric Equilibrium of Salicylideneaniline in ZSM-5 Zeolites
摘要： Salicylideneaniline (SA) sorbed in cation-exchanged M-ZSM-5 (M = H+, Li+, Na+, K+, Rb+, Cs+ and Zn2+) zeolites was studied by spectroscopic techniques assisted by quantum-chemical calculations. The nature of extra-framework cations present in the zeolite void was found to affect the spectral signature of the sorbed SA molecule that points to the shift of tautomeric equilibrium between the enol and keto forms. Small size cations, such as H+ and Li+, stabilize a cis-keto SA tautomer along with a enol one in the zeolite structure. The calculations indicate that the sorbed cis-keto tautomer may have the dipole large enough to be considered as a zwitterion. New features appearing in the spectra with the increase of the cation size were attributed to the presence of trans-keto SA tautomer, which up to now has been observed only in time-resolved spectroscopic experiments. A strong interaction of the molecule with cations in Zn-ZSM-5 zeolite results in the chelation of enol SA with the divalent Zn2+ ions. The results of the study suggest that the tautomeric equilibrium of molecules belonging to the Schiff base family can be tuned by the con?nement in the nanoporous materials via a choice of topology of zeolite framework and the nature of extra-framework cations.
关键词： spectroscopy,tautomer,DFT calculations,ZSM-5,equilibrium,salicylideneaniline,zeolite
更新于2025-11-19 16:56:35
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Structural, photophysical and electrochemical properties of a novel cardanol-based salophen ligand and its Mn(II) complex
摘要： A new cardanol-based salophen (hpbp) ligand and its manganese complex [Mn(hpbp)] were obtained by microwave-assisted synthesis method, with yields and reaction times of 65% in 20 min and 85% in 5min, respectively. The structural features of compounds were confirmed by electronic (UV-vis and fluorescence), infrared and NMR (1H, 13C) spectroscopic techniques. The photophysical study of the ligand showed ketoenamine-enolimine tautomeric equilibrium, which was discussed based on the excited state intramolecular proton transfer (ESIPT) mechanism and was dependent on the solvent, concentration and molecular structure. The energy of the HOMO and LUMO orbitals (-5.41 and -2.12 eV, respectively), determinated by cyclic voltammetry and UV-Vis, the energy was very close to the values determined by the theoretical calculations. The studies revealed that the hpbp is a tetradentate ligand bonded to the metal ion by phenolic oxygens and by azomethine nitrogens. Therefore, this work contributes to the science of salophen compounds, in addition to stimulating the synthesis of new ligands from renewable sources for the coordination chemistry.
关键词： Cardanol-based salophen,Solvent effect,Manganese complex,Theoretical calculations
更新于2025-11-19 16:46:39
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Defective ZnS nanoparticles anchored in situ on N-doped carbon as a superior oxygen reduction reaction catalyst
摘要： Defect engineering has been used to develop low-cost and effective catalysts to boost oxygen reduction reactions. However, the development of catalysts that use metal cation vacancies as the active sites for oxygen reduction reaction is lacking. In this study, ZnS nanoparticles on N-doped carbon serve as an oxygen reduction reaction catalyst. These catalysts were prepared via a one-step method at 900 °C. Amazingly, the high-resolution transmission electron microscope image revealed obvious defects in the ZnS nanoparticles. These facilitated the catalyst synthesis, and the product displayed good electrocatalytic performance for the oxygen reduction reaction in an alkaline medium, including a lower onset potential, lower mid-wave potential, four electron transfer process, and better durability compared with 20 wt% Pt/C. More importantly, the density functional theory results indicated that using the Zn vacancies in the prepared catalyst as active sites required a lower reaction energy to produce OOH ? from ?OO toward oxygen reduction reaction. Therefore, the proposed catalyst with Zn vacancies can be used as a potential electrocatalyst and may be substitutes for Pt-based catalysts in fuel cells, given the novel catalyst’s resulting performance.
关键词： Density functional theory calculations,Oxygen reduction reaction,Zn vacancy,Electrocatalyst,Defective ZnS nanoparticle
更新于2025-11-14 17:03:37
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0D/2D AgInS2/MXene Z-scheme heterojunction nanosheets for improved ammonia photosynthesis of N2
摘要： In order to explore efficient photocatalysts for N2 reduction reaction (NRR), 0D AgInS2 nanoparticles and 2D MXene (Ti3C2) nanosheets with different mass ratios are employed for building Z-scheme heterostructures. The resultant hybrids exhibit excellent interfacial charge transfer ability according to their optical and photo-electro properties. As a result, the obtained composite (30 wt% AgInS2) shows significant improvement on the photocatalytic performance for N2 fixation with a high ammonia yield rate of 38.8 μmol/(g·h) under visible-light illumination (> 400 nm). Meanwhile, the DFT calculations show that the activation of N2 in a dinuclear end-on bound structure could lead to high adsorption energy (Ead = -5.20 eV). Moreover, the mechanism of enhanced photocatalytic activity was proposed in terms of the quantum calculation between Ti3C2 and N2. This work provides new systems for enhanced NRR performance.
关键词： N2 reduction,DFT calculations,AgInS2/MXene heterojunction,Photocatalysis
更新于2025-11-14 15:28:36
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Photo-physical properties of substituted 2,3-distyryl indoles: Spectroscopic, computational and biological insights
摘要： The structural dependence of the photo-physical properties of substituted 2,3-distyryl (23DSI) indoles were studied using several spectroscopic techniques including steady-state UV-VIS spectroscopy, steady-state fluorescence spectroscopy, steady-state excitation spectroscopy, time correlated single photon counting (TCSPC) spectroscopy, and time-resolved fluorescence upconversion spectroscopy (TRFLS). Each of 23DSI derivatives investigated showed distinct fluorescence emission and UV-VIS spectra, indicating strong structural dependence of the emission and the excitation. The UV-VIS spectra of the 23DSI derivatives showed three main identical absorption bands with minor deviations in the absorbance caused by substituent groups on the distyryl rings. The time-resolved fluorescence up-conversion studies indicated that the fluorescence undergoes a mono-exponential decay whereas the calculated fluorescence lifetime showed relatively short fluorescence lifetimes of approximately 1 ns. All of the 23DSI derivatives showed two-photon absorption upon direct excitation of 1.6 W laser pulses at 800 nm. These studies suggest that the substituents, attached to distyryl core, are capable of boosting or hindering fluorescence intensities by distorting the π-conjugation of the 23DSI molecule. Our studies showed that 23DSI (p-F) has the highest fluorescence emission quantum yield. Theoretical calculations for the ground state of 23DSI derivatives confirmed differences in electron densities in 23DSI derivatives in the presence of different substituent attachments. The excellent fluorescence emission, high fluorescence quantum yield and two-photon absorption properties of these 23DSI molecules make them attractive candidates for potential applications in the fields of biological imaging, biomedicine, fluorescent probes, and photodynamic inactivation (PDI). B. subtilis samples, treated with micro molar solutions of 23DSI (p-OCH3) and 23DSI (p-CH3), showed very effective photodynamic inactivation (PDI) upon irradiation with white light.
关键词： Two photon absorption,Time-resolved fluorescence upconversion laser spectroscopy,Photodynamic inactivation,Gaussian calculations,Photo-physical properties,Light-activation
更新于2025-11-14 15:26:12
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First titanium square fragment {Ti4(μ4-Se)(μ2-Se2)4} in its selenoiodide: Synthesis and structure of Ti4Se9I6
摘要： The first titanium selenoiodide Ti4Se9I6 was synthesized as black crystals by heating of Ti, Se, and I2 at 250 °C in 5:9:5 M ratio. The crystal structure of the compound was solved by X-ray single-crystal diffractometry (sp. gr. P-1, a = 7.9652(10), b = 10.3390(15), c = 15.692(2) ?; α = 79.116(7)°, β = 75.861(7)°, γ = 71.437(7)°; Z = 2) with final R1 = 0.0397. The structure includes square {Ti4(μ4-Se)(μ2-Se2)4} fragment coordinated by four terminal and four bridging μ2-I atoms. Ti4+ has d0 configuration, and stability of the structure fragments is provided by metal to ligand bonding which was confirmed by DFT calculations.
关键词： Metal chalcohalides,Titanium,Square complex,Synthesis,Selenide,X-ray crystal structure,Chain structure,DFT calculations,Iodide
更新于2025-11-14 15:14:40
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Spectroscopic and theoretical studies of potassium sodium l-(+)-tartrate tetrahydrate and l-tartaric acid used as precursors for in situ laser-induced deposition of the catalytically active copper microstructures
摘要： In this work we study the influence of l-(+)-КNaC4H4O6 × 4H2O (KNaT) and l-H2C4H4O6 (H2T) on the complexation processes occurring during in situ laser-induced catalytic destruction of the organic components of the aqueous solutions with formation of the unsaturated hydrocarbons. For that purpose, ATR-FTIR, Raman, IR, and NIR spectroscopy as well as quantum chemical calculations were implemented. It was observed that hydration of T2? anion via carboxylate groups is stronger than that via hydroxyl groups. We also established the changes in the spectral characteristics of the absorption bands corresponding to vibrations of T2?, HT?, and H2T, at solid state-liquid and acid-salt transitions, depending on concentration of the solution components and the [OH?]/[H2T] ratio. Finally, it was shown that ethylene is a main product of the catalytic destruction of the copper tartrate complexes.
关键词： IR,Laser-induced copper deposition,DFT calculations,Tartaric acid,ATR-FTIR,Catalysis,NIR,Raman spectroscopy,Sodium potassium tartrate tetrahydrate
更新于2025-10-22 19:40:53
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Molecular structure, NBO analysis, ?rst hyper polarizability, and homo-lumo studies of π-extended tetrathiafulvalene (EXTTF) derivatives connected to π-nitro phenyl by density functional method
摘要： In these study we have been obtained the structural properties of (exTTF) derivatives 1-4 by using B3LYP/6-31G(d,p) of Density Functional Theory (DFT) utilizing Becke three exchange functional and Lee Yang Paar correlation functional. The calculation of first hyperpolarizability shows that the molecules are attractive molecules for future applications in non-linear optics. Molecular electrostatic potential (MEP) at a point in the space around a molecule gives an indication of the net electrostatic effect produced at that point by the total charge distribution of the molecule. The calculated HOMO and LUMO energies show that charge transfer occurs within these molecules.
关键词： Density Functional Theory,Quantum Chemical Calculations,Computational Chemistry,Electronic Structure,Tetrathiafulvalenes
更新于2025-09-23 15:23:52
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Computational Study on Interfaces and Interface Defects of Amorphous Silica and Silicon
摘要： The amorphous SiO2/Si interface is arguably the most important part in semiconductor technology, strongly influencing the device reliability. Its electronic structure is affected by the defects, majorly the dangling bonds known as Pb-type defects, which have been studied for decades. These defects are usually passivated by hydrogen atoms in device processing, which eliminates the defect levels in the silicon bandgap and thus removes their electric activity. However, when the interface is exposed to ionization radiation, the passivated defects can be reactivated by the protons generated by radiation, which significantly affects the device performance and causes reliability issues. In this review, computational studies on the amorphous SiO2/Si interface and interface defects are summarized, including the modeling of the interface, the main interface defects, and their depassivation, and compared to experimental results. The hyperfine parameters are emphasized, because they are essential to identify the structures of the interface defects. The defect levels and depassivation of the defects are also emphasized, because the former directly affect the device performance and the latter directly generates the dangling bonds in the interface.
关键词： depassivation,ionizing damage,interface defects,amorphous interfaces,first-principles calculations
更新于2025-09-23 15:23:52