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Optical spectroscopy of the Au4+ cluster: Resolved vibronic structure indicates an unexpected isomer**
摘要： The knowledge of the geometric and electronic structure of gold clusters and nanoparticles is vital for understanding their catalytic and photochemical properties at the molecular level. Herein, we report the vibronic optical photodissociation spectrum of cold and mass-selected Au4+ clusters measured at a resolution high enough to allow for comparison with Franck-Condon simulations of the excited state transitions based on time-dependent density functional theory calculations. The three vibrational frequencies identified for the lowest-lying optically accessible excited state at 2.17 eV stem from the Y-shaped isomer (C2v) and not from the rhombic isomer (D2h) that is considered to be the ground state structure of Au4+. This study demonstrates that an analysis of low-resolution electronic spectra by calculations of vertical transitions alone is not sufficient for a reliable isomer assignment of such metal clusters.
关键词： gold,UV/Vis spectroscopy,structure elucidation,cluster compounds,electronic structure
更新于2025-09-23 15:23:52
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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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The influence of nitrogen doping on the electronic structure of the valence and conduction band in TiO <sub/>2</sub>
摘要： X-ray emission spectroscopy (XES) and X-ray absorption spectroscopy (XAS) provide a unique opportunity to probe both the highest occupied and the lowest unoccupied states in matter with bulk sensitivity. In this work, a combination of valence-to-core XES and pre-edge XAS techniques are used to determine changes induced in the electronic structure of titanium dioxide doped with nitrogen atoms. Based on the experimental data it is shown that N-doping leads to incorporation of the p-states on the occupied electronic site. For the conduction band, a decrease in population of the lowest unoccupied d-localized orbitals with respect to the d-delocalized orbitals is observed. As confirmed by theoretical calculations, the N p-states in TiO2 structure are characterized by higher binding energy than the O p-states which gives a smaller value of the band-gap energy for the doped material.
关键词： TiO2 doping,X-ray absorption spectroscopy,electronic structure analysis,X-ray emission spectroscopy
更新于2025-09-23 15:23:52
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Electronic Structure of Chlorophyll a Solution Investigated by Photoelectron Yield Spectroscopy
摘要： Various bio-related processes are driven by electron transfer reactions. Therefore the electronic structures of bio-molecules in their living environment are keys of their functionalities. One significant example photosynthesis which has attracted much attention due to urgent necessity of clean energy source. In this study, we carried out photoelectron yield spectroscopy (PYS) measurements to demonstrate the electronic structures of oligomerizedChl-a molecules, which is known as an essential reaction center of the photosystem in general green plants, under the atmospheric environment. The ionization energies of the Chl-a aggregates are successfully derived.
关键词： Photoelectron Yield Spectroscopy,Polarization energy,Light harvesting antenna,Photosynthesis,Photosystem,Electronic structure,Ionization energy,Reaction center,Chlorophyll a
更新于2025-09-23 15:23:52
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Graphdiyne: A promising nonlinear optical material modulated by tetrahedral alkali-metal nitrides
摘要： A new series of the functionalized graphdiyne (GDY) material was designed by adsorbing the tetrahedral Li3NM molecules on the largely delocalized π-conjugated GDY surface, namely Li3NM@GDY (M = Li, Na, K), and its structure, chemical stability, electronic property, and the first hyperpolarizability were investigated by using the density functional theory computations. Our results reveal that the Li3NM molecules can interact with three triangular holes on the GDY surface, in which the van der Waals interactions play a crucial role in enhancing the structural stability. Meanwhile, the total NPA charges on the Li3NM molecules are gradually increased from Li to K, and the Li3NM molecules can transfer an electron to GDY, forming intramolecular electron donor and acceptor pairs. All of studied complexes exhibit the giant static first hyperpolarizabilities (βtot), up to ~2.88 × 105 a.u. for Li3NK@GDY, which can be explained by two-level expression from the TDDFT calculations. This study will inevitably stimulate further synthesis of the novel graphdiyne-based nonlinear optical materials.
关键词： Graphdiyne,Electronic structure,TDDFT,Charge transfer,Nonlinear optical property
更新于2025-09-23 15:23:52
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Optoelectronic Properties of Zinc Oxide: A First-Principles Investigation Using the Tran-Blaha Modified Becke-Johnson Potential
摘要： In this work, density functional theory (DFT) is used to investigate the influence of semi-local exchange and correlation effects on the electronic and optical properties of zinc oxide. It is found that the inclusion of such effects using the Tran–Blaha modified Becke–Johnson potential yields an excellent description of the electronic structure of this material giving an energy band gap which is systematically larger than the one obtained with standard local functionals such as the generalized gradient approximation. The discrepancy between the experimental and theoretical band gaps is then significantly reduced. We also calculated the dielectric functions of ZnO and find a violet shift to the absorption edge which is in good agreement with experimental results.
关键词： zinc oxide,electronic structure,optical properties
更新于2025-09-23 15:23:52
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Investigation of Structural and Elastic Stability, Electronic, Magnetic, Thermoelectric, Lattice-Dynamical and Thermodynamical Properties of Spin Gapless Semiconducting Heusler Alloy Zr2MnIn Using DFT Approach
摘要： In recent times, spin gapless semiconductors (SGS) have attracted much attention as a promising candidate for spintronics and thermoelectric applications due to their high carrier concentration and good thermoelectric figure of merit. In this paper, we have carried out a systematic theoretical investigation of the structural, elastic, thermal, electronic, magnetic, thermoelectric, lattice dynamical and thermodynamical properties of Zr2MnIn using density functional theory (DFT) based first principle calculations. The band structure calculation shows indirect band gap in a spin down channel and zero band gap in a spin up channel of valence and conduction bands confirming the spin gapless semiconducting nature of Zr2MnIn. The structural and dynamical stability of the antiferromagnetic phase of Zr2MnIn has also been investigated. Magnetization in Zr2MnIn originates due to the d state electrons of Zr atoms, which follows the Slater Pauling rule: Mt = Zt (cid:2) 18. Phonon dispersion curves exhibit real frequency of phonon modes throughout the Brillouin zone, which confirms the dynamical stability of the antiferromagnetic phase of Zr2MnIn. Thermodynamical properties including specific heat and Debye temperature have been calculated using phonon density of states. A higher value of the thermoelectric figure of merit 1.25, predicts that this alloy as good thermoelectric properties with better output efficiency.
关键词： Spin gapless semiconductor (SGS),magnetic moment,structural and elastic stability,thermoelectric and lattice dynamical properties,electronic structure
更新于2025-09-23 15:23:52
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First-principles study of the electronic structure and optical properties of Eu2+–M (M = Mn2+, Mg2+, Li+) co-doped γ-AlON phosphor
摘要： In our recent work we found γ-AlON:Eu2+ phosphors to hold promise for application in white light-emitting diodes (LEDs). To obtain further insight into Eu2+–M (M = Mn2+, Mg2+, Li+) co-doped γ-AlON, the crystal structure and the electronic and photoluminescence properties of γ-AlON:Eu2+–M (M = Mn2+, Mg2+, Li+) phosphors were studied using first-principle calculations under the framework of density functional theory. Based on the experimental and calculated results, the structure of Eu2+–M (M = Mn2+, Mg2+, Li+) co-doped γ-AlON was established. The calculated results demonstrate that Eu2+ and M (= Mn2+, Mg2+, Li+) can effectively improve the absorption of ultraviolet light by γ-AlON:Eu2+. The absorption coefficient of AlON:Eu2+–Li+ in the ultraviolet blue region of 275–415 nm reached 67,266 cm–1, and the absorption coefficients of AlON:Eu2+–Mn2+ and AlON: Eu2+–Mg2+ at the same doping concentration were 51,219 and 60,575 cm–1, respectively. Our calculations therefore show that the performance of AlON:Eu2+–Li+ is better than AlON:Eu2+–M (M = Mn2+, Mg2+).
关键词： γ-AlON,First principles,Electronic structure,Optical property
更新于2025-09-23 15:23:52
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Multi-active sites derived from a single/double perovskite hybrid for highly efficient water oxidation
摘要： The oxygen evolution reaction (OER) plays a crucial role in the application of water splitting, which is a highly competitive option for a sustainable energy future. Thus, it is vital to design highly active and durable electrocatalyst for OER. Herein a hybrid with the nominal composition of Ba2Co1.5Mo0.25Nb0.25O6-d (denoted as BC1.5MN) electrocatalyst consisting of both double perovskite and single perovskite structures is synthesized by a solid-state reaction method. When tested as an electrocatalyst for OER, the BC1.5MN electrocatalyst requires a current density of 10 mA cm-2 at an overpotential of 400 mV, an onset overpotential of 260 mV, and a Tafel slope of 70 mV dec-1, which are superior to that of precious metal oxide IrO2 catalyst. Chronoamperometric and cyclic voltammetry studies demonstrate that the BC1.5MN electrocatalyst has outstanding durability in alkaline solution. The synergistic effect between multi-active sites derived from a single/double perovskite hybrid structure results in one of the most active perovskite-based OER electrocatalysts in alkaline solution.
关键词： hybrid,oxygen evolution reaction,double perovskite,single perovskite,electronic structure
更新于2025-09-23 15:23:52
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state of RbCs
摘要： We perform a high-resolution Fourier-transform spectroscopic study of the (4) 1Σ state of the RbCs molecule by applying two-step (4) 1Σ ← A 1Σ+ ～ b 3Π ← X 1Σ+ optical excitation followed by observation of the (4) 1Σ → X 1Σ+ laser-induced fluorescence (LIF) spectra. In many LIF progressions the collision-induced satellite rotational lines are observed, thus increasing the amount of term values and allowing us to estimate the Λ-doubling effect in the (4) 1Σ state. The direct potential fit (DPF) of experimental term values of 777 rovibronic levels of both 85RbCs and 87RbCs isotopologues is performed by means of the robust weighted nonlinear least-squares method. The DPF analysis based on the adiabatic approximation and analytical expanded Morse oscillator potential reveals numerous regular shifts in the measured level positions. The spectroscopic studies of the (4) 1Σ state are supported by the electronic structure calculations including the potential energy curves of the singlet- and triplet-state manifold and spin-allowed transition dipole moments. The subsequent estimates of radiative lifetimes and corresponding vibronic branching ratios elucidate a dominant contribution of the (4) 1Σ → A ～ b channel into the total radiative decay of the (4) 1Σ state. The relative intensity distributions simulated for (4) 1Σ → X 1Σ+ LIF progressions agree well with their observed counterparts even for the profoundly shifted levels of the entirely perturbed (4) 1Σ state. To get insight into the origin of the intramolecular perturbations, the relevant spin-orbit- and L-uncoupling electronic matrix elements are evaluated.
关键词： electronic structure calculations,Fourier-transform spectroscopy,RbCs molecule,perturbed state,direct potential fit,laser-induced fluorescence,radiative properties
更新于2025-09-23 15:23:52