Energies Of Electronic States Research Articles

(Invited) Luminescence Nanothermometers: Using Light to Detect Temperature

Rare earth doped nanoparticles have recently emerged as versatile luminescent probes for a number of biological applications resulting from their interesting photophysical properties. These nanoparticles can be excited with near-infrared (NIR) light, which is a strict requirement for biomedical applications due its light penetration capabilities. Furthermore, rare earth doped nanoparticles possess a multitude of 4f electronic energy states and excitation with NIR light can therefore lead to different excitation mechanisms. For example, following NIR excitation, the nanoparticles can undergo upconversion where multiple emissions are observed with energies higher than the excitation wavelength. Also, they can undergo conventional luminescence where emission at lower energies than the excitation wavelength can be observed (known as downshifted luminescence). Here, we show that it is possible to harness these various emissions (upconverted and downshifted) to design luminescence nanothermometers capable of detecting temperature in living organisms.

Ground State Electron Energies in sp3 Hybridized Si and C atoms in C-terminated 4H-SiC

Ground State Electron Energies in sp3 Hybridized Si and C atoms in C-terminated 4H-SiC

Molecular spectroscopy as a laboratory experiment: Measurement of important parameters of sodium diatomic molecules

We present an inexpensive sodium molecular spectroscopy experiment for use in an advanced undergraduate laboratory course in physics or chemistry. The molecules were excited predominantly from the ground X1Σg+(v″ = 15) state to the B1Πu(v′ = 6) state using a commercially available 532-nm broadband diode laser. The laser-induced molecular fluorescence was measured using a miniature fiber-coupled spectrometer at a resolution of 0.5 nm. The spectral peak assignments were done by comparing the observed spectrum with the calculated Franck–Condon values. Important molecular constants such as fundamental frequency, anharmonicity, bond strength, and dissociation energy of the ground electronic state were determined by using the Birge–Sponer extrapolation method. The presence of highly visible blue glowing molecules along the green laser beam creates an engaging laboratory experience. Emphasis is placed on students developing their understanding of the molecular structure, practicing molecular spectroscopic techniques, and applying knowledge of light–matter interactions to a physical system.

First Principles Calculation of Compatibility between Environmentally Friendly Insulating Gas C5F10O and CuW Contacts

The insulating gas and contacts in the arc extinguishing chamber of high‐voltage circuit breakers are the focus of research. In practical applications, the gas may react with the surface of the contacts. In this paper, C5F10O environmental friendly insulating gas, which has one of the potential alternatives, is selected as the research object. The compatibility of C5F10O and its decomposition products with CuW contacts was studied. This article uses the Dmol3 program based on density functional theory. The adsorption energy, transfer charge, and density of electronic states of C5F10O and selected typical decomposition products on the Cu (111) surface and Cu‐W surface were calculated, respectively. It was found that the original CuW metal properties were not changed before and after adsorption. The carbonyl O atom in C5F10O is easily adsorbed on the top of the Cu (111) surface, forming a stable CuO bond, which belongs to chemical adsorption. The interaction of the other three adsorption sites is weaker than that of the top site adsorption, which belongs to physical adsorption. C5F10O exhibits more active charge transfer and forms active W‐O chemical bonds when adsorbed on CuW surfaces than SF6. C5F10O has poorer compatibility with CuW alloy than SF6. C2F4 and C3F6 in the decomposition gas are chemically adsorbed on the Cu‐W surface. CO2, CF4, C2F6, and C3F8 do not form chemical bonds on the CuW surface. The adsorption stability of COF2 is weaker than that of CF4, C2F6, and C3F8. Compared with SF6 adsorption, the compatibility of C5F10O and CO2 on the surface of CuW contact is inferior to that of Cu contact. CF4, C2F6, C3F8, and COF2 in the decomposition gas can be compatible with the surface of the CuW contact. C2F4 and C3F6 cannot be well compatible with the surface of CuW contacts. © 2023 Institute of Electrical Engineer of Japan and Wiley Periodicals LLC.

Lanthanide‐Doped Nanomaterials for Tumor Diagnosis and Treatment by Second Near‐Infrared Fluorescence Imaging

AbstractLanthanides have unique electronic configurations and stepped energy states of [Xe]4fN, which endows them with advantages including stable luminescence, large stokes shift, wide excitation spectral bands, and long fluorescence lifetime. NIR‐II fluorescence imaging overcomes the strong tissue absorption, scattering, and spontaneous fluorescence interference of traditional fluorescence and can achieve deeper tissue penetration and higher spatial and temporal resolution in vivo imaging. Lanthanides hold great potential for in vivo biosensing and bioimaging. In this work, the design and preparation of nanomaterials doped with different lanthanide elements are reviewed in this paper. Applications of lanthanide‐doped nanomaterials to different tumor therapeutics through NIR‐II fluorescence imaging and the unique potential of NIR lanthanide nanomaterials in tumor diagnosis and therapy are also discussed.

Organic Excitonic State Management by Surface Metallic Coupling of Inorganic Lanthanide Nanocrystals

AbstractThe ability to harness charges and spins for control of organic excitonic states is critical in developing high‐performance organic luminophores and optoelectronic devices. Here we report a facile strategy to efficiently manipulate the electronic energy states of various organic phosphors by coupling them with inorganic lanthanide nanocrystals. We show that the metallic atoms exposed on the nanocrystal surface can introduce strong coupling effects to 9‐(4‐ethoxy‐6‐phenyl‐1,3,5‐triazin‐2‐yl)‐9H‐carbazole (OCzT) and some organic chromophores with carbazole functional groups when the organics are approaching the nanocrystals. This unconventional organic–inorganic hybridization enables a nearly 100 % conversion of the singlet excitation to fast charge transfer luminescence that does not exist in pristine organics, which broadens the utility of organic phosphors in hybrid systems.

Organic Excitonic State Management by Surface Metallic Coupling of Inorganic Lanthanide Nanocrystals.

The ability to harness charges and spins for control of organic excitonic states is critical in developing high-performance organic luminophores and optoelectronic devices. Here we report a facile strategy to efficiently manipulate the electronic energy states of various organic phosphors by coupling them with inorganic lanthanide nanocrystals. We show that the metallic atoms exposed on the nanocrystal surface can introduce strong coupling effects to 9-(4-ethoxy-6-phenyl-1,3,5-triazin-2-yl)-9H-carbazole (OCzT) and some organic chromophores with carbazole functional groups when the organics are approaching the nanocrystals. This unconventional organic-inorganic hybridization enables a nearly 100 % conversion of the singlet excitation to fast charge transfer luminescence that does not exist in pristine organics, which broadens the utility of organic phosphors in hybrid systems.

Linearized Pair-Density Functional Theory for Vertical Excitation Energies.

Multiconfiguration pair-density functional theory (MC-PDFT) is a computationally efficient method that computes the energies of electronic states in a state specific or state average framework via an on-top functional. However, MC-PDFT does not include state interaction among these states since the final energies do not come from the diagonalization of an effective model-space Hamiltonian. Recently, multistate extensions such as linearized PDFT (L-PDFT) have been developed to accurately model the potentials near conical intersections and avoided crossings. However, there has not been any systematic study evaluating their performance for predicting vertical excitations at the equilibrium geometry of a molecule, when the excited states are generally well separated. In this paper, we report the performance of L-PDFT on the extensive QUESTDB data set of vertical excitations using a database of automatically selected active spaces. We show that L-PDFT performs well on all these excitations and successfully reproduces the performance of MC-PDFT. These results further demonstrate the potential of L-PDFT, as its scaling is constant with the number of states included in the state-average manifold, whereas MC-PDFT scales linearly in this regard.

Fragmentation of Multiply Charged C10H8 Isomers Produced in keV Range Proton Collision

The dissociation of multiply charged C10H8 isomers produced in fast proton collisions (velocities between 1.41 and 2.4 a.u.) is discussed in terms of their fundamental molecular dynamics, in particular the processes that produce different carbon clusters in such a collision. This aspect is assessed with the help of a multi-hit analysis of daughter ions detected in coincidence with the elimination of H+ and CHn+ (n = 0 to 3). The elimination of H+/C+ is found to be significantly different from CH3+ loss. The loss of CH3+ proceeds through a cascade of momentum-correlated dissociations with the formation of heavy ions such as C9H5+, C9H52+ and C7H3+. The structure of such large fragment ions is predicted with the help of their calculated ground state electronic energies and the multi-hit time-of-flight (ToF) correlation between the second and third hit fragments if detected. Furthermore, we report experimentally the super-dehydrogenation of naphthalene and azulene targets, with evidence of complete dehydrogenation in a single collision.

Super-strong Zn and S atomic terminals in an organic/inorganic hybrid S-scheme polyimide based heterojunction for efficient photocatalytic treatment of mixed pollutant wastewater

Integrated oxidation and reduction reactions in the field of wastewater treatment with mixed high concentrations of sewage achieved by photocatalysis are highly desirable but still challenging. The construction of the S-scheme heterojunction system is expected to be a promising strategy to provide carriers with strong redox ability for oxidation of oxytetracycline hydrochloride (OTC) with simultaneous reduction of hexavalent chromium (Cr(VI)). Reduced graphene oxide (rGO) and ZnIn2S4 (ZIS) were successively assembled on perylene diimide polymer (PDIP) nanorods to form the S-scheme ZIS/rGO/PDIP heterojunction. The construction of organic–inorganic systems achieves wide light absorption, enhanced exciton dissociation and accelerated charge separation. A non-radiation-quenched electron transport path is formed in the ZIS/rGO/PDIP system from the conduction band of PDIP through rGO to the valence band of ZIS. The electronic energy state of the S-scheme ZIS/rGO/PDIP heterojunction was changed, and the Zn and S atomic terminals can realize strong adsorption of OTC and Cr(VI).

Molecular modelling of fused heterocycle-based asymmetric non-fullerene acceptors for efficient organic solar cells

Heterocycle substitution plays a key role in designing an ultra-narrower bandgap (ultra-NBG) small molecule-based (SM) non-fullerene acceptors (NFAs) for organic solar cells (OSCs). The NFAs molecules have great significance because of their ability to improve efficiency, narrow band gap, better charge separation, higher absorption spectra, and overall device performance. However, the impact of heterocycles such as benzoselenadiazole (BSe) on optoelectronics characteristics is still unclear. Herein, seven asymmetric NFAs based on BSe electron-deficient fused-ring core were designed from the reference (R) BTP-Se. All seven NFAs exhibited a strong absorption phenomenon from visible to near-infrared (NIR) region, corresponding to the ultra-NBG and lower excitation energy (Ex). These designed asymmetric materials (BTP1-BTP7) along with R are fully characterized theoretically with various advanced quantum chemical techniques. The optical and optoelectronics features were explored with density functional theory (DFT) and time-dependent (TD-DFT) simulations. The in-depth calculations related to density of state (DOS), transition density of state (TDM), open-circuit voltage, fill factor, and reorganization energy of electrons and holes are performed intensively. BTP3 has an optical band gap narrow of 1.76 eV and an outstanding absorption maximum of 906.85 nm. For charge transfer, a donor:acceptor complex study of BTP3:PBDBT is carried-out. We hope that this may provide a favourable strategy for building highly efficient near infrared (NIR)-based OSCs.

Theoretical Study on the Spectroscopic Properties and Photodissociation Mechanism of Dibromocarbene.

Detailed calculations on the electronic states of dibromocarbene (CBr2) herein are presented. First, the spectroscopic properties of the electronic states including geometry parameters, harmonic vibrational frequencies and transition energies of the lowest electronic states of the neutral radical were calculated in detail using the internally contracted multireference configuration interaction methods including Davidson correction (icMRCI+Q) with correlation consistent basis sets of aug-cc-pVXZ (X = T, Q, 5). Second, as CBr2 including two Br atoms, the Spin-Orbit Coupling (SOC) effect on the spectroscopic parameters and the one-dimensional cuts of the potential energy surface (PESs) of the lowest three states were studied. The barrier to linearity and dissociation of the singlet state were discussed. Third, the one-dimensional cuts along with the vertical transition energy (VTE), the oscillator strength, and so on of the electronic states related to the several lowest dissociation limits of CBr2 were calculated at the icMRCI+Q/aug-cc-pVTZ level. Based on the computed results of the electronic states of the radical, the photodissociation mechanism in the UV region were discussed in detail. The ab initio calculations are compared with the previous theoretical and experimental data and are in good agreement. The present work will provide a comprehensive understanding on the electronic structures and dissociation dynamics for the electronic states of the CBr2 radical.

Theoretical Study of Hydrostatic Pressure and Temperature Effect on a Multi-Quantum well ZnO/Zn<sub>1-X</sub>Mg<sub>x</sub>O Containing a Staircase Defect for Sensing Application

This work describes a theoretical and analytical study of a temperature and pressure sensor based on II-VI semiconductors with a simple multi-quantum wells (MQWs) structure. The proposed sensor operates by detecting changes in the intensity (transmission coefficient) and energy of localized electronic states inside gaps under external perturbations of hydrostatic pressure and temperature. Specifically, the proposed MQWs structure is ZnO/Zn1-XMgXO with 10 cells, each containing two materials that form the wells and barriers, respectively. The structure is perturbed by a staircase defect consisting of three defects of the same material or geomaterial. The Green function method is used to study the transmittance of the structure, with cleavage and coupling operators employed. The objective of the work is to explore a new type of defect for use in sensing applications such as multi-quantum well sensors. Key parameters for evaluating the sensor's performance include full width at half maximum (FWHM), sensor sensitivity (S), quality factor (QF), detection limit (DL), signal-to-noise ratio (SNR), dynamic range (DR), detection accuracy (DA), the figure of merit (MF), and standard deviation. These parameters can be optimized by adjusting structural parameters such as the thickness of the staircase or material concentration. The study found that a geomaterial staircase defect provides higher sensitivity to pressure and temperature changes. Additionally, the step (δx) of the staircase defect influences the sensitivity of the localized states: with increasing steps, δx improves sensitivity to temperature and decreases sensitivity to pressure.

H2 formation via non-Born-Oppenheimer hydrogen migration in photoionized ethane

Neutral H2 formation via intramolecular hydrogen migration in hydrocarbon molecules plays a vital role in many chemical and biological processes. Here, employing cold target recoil ion momentum spectroscopy (COLTRIMS) and pump-probe technique, we find that the non-adiabatic coupling between the ground and excited ionic states of ethane through conical intersection leads to a significantly high yield of neutral H2 fragment. Based on the analysis of fingerprints that are sensitive to orbital symmetry and electronic state energies in the photoelectron momentum distributions, we tag the initial electronic population of both the ground and excited ionic states and determine the branching ratios of H2 formation channel from those two states. Incorporating theoretical simulation, we established the timescale of the H2 formation to be ~1300 fs. We provide a comprehensive characterization of H2 formation in ionic states of ethane mediated by conical intersection and reveals the significance of non-adiabatic coupling dynamics in the intramolecular hydrogen migration.

Stark control of multiphoton ionization through Freeman resonances in alkyl iodides.

Multiphoton ionization (MPI) of alkyl iodides (RI, R = CnH2n+1, n = 1-4) has been investigated with femtosecond laser pulses centered at 800 and 400nm along with photoelectron imaging detection. In addition, the ultraviolet (UV)-vacuum ultraviolet (VUV) absorption spectra of gas-phase RIs have been measured in the photon energy range of 5-11eV using the VUV Fourier transform spectrometer at the VUV DESIRS beamline of the synchrotron SOLEIL facility. The use of high-laser-field strengths in matter-radiation interaction generates highly non-linear phenomena, such as the Stark shift effect, which distorts the potential energy surfaces of molecules by varying both the energy of electronic and rovibrational states and their ionization energies. The Stark shift can then generate resonances between intermediate states and an integer number of laser photons of a given wavelength, which are commonly known as Freeman resonances. Here, we study how the molecular structure of linear and branched alkyl iodides affects the UV-VUV absorption spectrum, the MPI process, and the generation of Freeman resonances. The obtained results reveal a dominant resonance in the experiments at 800nm, which counter-intuitively appears at the same photoelectron kinetic energy in the whole alkyl iodide series. The ionization pathways of this resonance strongly involve the 6p(2E3/2) Rydberg state with different degrees of vibrational excitation, revealing an energy compensation effect as the R-chain complexity increases.

Excited dipole bound electronic states of potassium iodide anions: A theoretical perspective

The information about electronic excited states of molecular anions is of pivotal importance for understanding electron attachment/detachment processes. Here, we present a high-level theoretical study on electronic states of potassium iodide anions (KI−). By the evaluation of different basis sets, we present accurate spectroscopic constants of the anionic ground electronic state using the multireference configuration interaction with Davidson correction method. The equation-of-motion electron-attachment coupled-cluster singles and doubles method is carried out to calculate electron binding energies (EBEs) of electronic states. With the addition of different s-/p-/d-diffusion functions in the basis set, we have identified possible excited dipole bound states (DBSs) of KI−. The results indicate that, owing to the large dipole moment of KI molecules, the anions can hold three excited DBSs, i.e., two σ-type DBSs and one π-type DBS, with the EBEs of 39 meV (σ-DBS1), 4.7 meV (π-DBS), and only 1.8 meV (σ-DBS2) below the neutral ground state. Molecular orbitals, potential energy curves, and spectroscopic constants of DBSs are presented. Our study would shed some light on the electronic states of potassium iodide molecular anions.

Commercial 3D resin blended with TTA functionalized CaWO4:Eu (III), synthesis route and a luminescence study

Synthesis and characterization of calcium tungstate-based micro-nanophosphors are reported in the present work. These materials were synthesized by spray pyrolysis technique. According to Scanning Electron Microscopy measurements, CaWO4 and CaWO4:Eu (III) have quasi-spherical shape. CaWO4 presents blue luminescence whose origin is an electron transition within unperturbed WO42− complexes, while CaWO4:Eu (III) luminescent properties are generated by the presence of Eu (III) ions, which produced light emissions at 591, 615, 655, and 702 nm. Such emissions are due to radiative transitions from the excited state 5D0 to 7Fj (j = 1, 4) inter-level transitions within Eu (III) electronic energy states. These phosphors were blended with a commercial 3D print photocurable resin (Sain Smart 101-90-840TS) and their luminescent properties were transferred to resin. Besides in this case, blended 3D resin has an intrinsic blue luminescence due to its π and π* bonds which is activated under 380 nm excitation wavelength, however blended 3D resin can be also activated under 465 nm excitation which only activates Eu (III) ions producing a red emission 3D luminescent photocurable resin.

High-performance selective NO2 gas sensor based on In2O3–graphene–Cu nanocomposites

The control of atmosphere content and concentration of specific gases are important tasks in many industrial processes, agriculture, environmental and medical applications. Thus there is a high demand to develop new advanced materials with enhanced gas sensing characteristics including high gas selectivity. Herein we report the result of a study on the synthesis, characterization, and investigation of gas sensing properties of In2O3–graphene–Cu composite nanomaterials for sensing elements of single-electrode semiconductor gas sensors. The nanocomposite has a closely interconnected and highly defective structure, which is characterized by high sensitivity to various oxidizing and reducing gases and selectivity to NO2. The In2O3-based materials were obtained by sol–gel method, by adding 0–6 wt% of pre-synthesized graphene–Cu powder into In-containing gel before xerogel formation. The graphene–Cu flakes played the role of centers for In2O3 nucleation and then crystal growth terminators. This led to the formation of structural defects, influencing the surface energy state and concentration of free electrons. The concentration of defects increases with the increase of graphene–Cu content from 1 to 4 wt%, which also affects the gas-sensing properties of the nanocomposites. The sensors show a high sensing response to both oxidizing (NO2) and reducing (acetone, ethanol, methane) gases at an optimal working heating current of 91–161 mA (280–510 °C). The sensor with nanocomposite with 4 wt% of graphene–Cu additive showed the highest sensitivity to NO2 (46 ppm) in comparison with other tested gases with an absolute value of sensing response of (− ) 225 mV at a heating current of 131 mA (430 °C) and linear dependence of sensing response to NO2 concentration.

HARİCİ ELEKTRİK ALANI ETKİSİ ALTINDA 〖Ga〗_(1-x) 〖Al〗_x As/GaAs KUANTUM KUYU TEL ÖRGÜSÜNDEKİ ENERJİ DURUMLARI

HARİCİ ELEKTRİK ALANI ETKİSİ ALTINDA 〖Ga〗_(1-x) 〖Al〗_x As/GaAs KUANTUM KUYU TEL ÖRGÜSÜNDEKİ ENERJİ DURUMLARI

First-Principles Investigation of Electronic and Related Properties of Cubic Magnesium Silicide (Mg2Si)

We present results from ab initio, self-consistent calculations of electronic, transport, and bulk properties of cubic magnesium silicide (Mg2Si). We employed a local density approximation (LDA) potential to perform the computation, following the Bagayoko, Zhao, and Williams (BZW) method, as improved by Ekuma and Franklin (BZW-EF). The BZW-EF method guarantees the attainment of the ground state as well as the avoidance of over-complete basis sets. The ground state electronic energies, total and partial densities of states, effective masses, and the bulk modulus are investigated. As per the calculated band structures, cubic Mg2Si has an indirect band gap of 0.896 eV, from Γ to X, for the room temperature experimental lattice constant of 6.338 Å. This is in reasonable agreement with the experimental value of 0.8 eV, unlike previous ab initio DFT results of 0.5 eV or less. The predicted zero temperature band gap of 0.965 eV, from Γ to X, is obtained for the computationally determined equilibrium lattice constant of 6.218 Å. The calculated value of the bulk modulus of Mg2Si is 58.58 GPa, in excellent agreement with the experimental value of 57.03 ± 2 GPa.