Electronic Transitions Research Articles

Influence of Curvature on the Physical Properties and Reactivity of Triplet Corannulene Nitrene.

Although nitrene chemistry is promising for the light-induced modification of organic compounds, the reactivity of large polycyclic aromatic compounds and the effects of their curvature remain unexplored. Irradiation of azidocorannulene (1) in methanol/acetonitrile followed by HCl addition produced diastereomers 5 and 5'. Azirine 2 is apparently trapped by methanol to form diastereomeric acetal derivatives that are hydrolyzed with HCl to yield 5 and 5'. ESR spectroscopy in a glassy matrix at 77 K showed that irradiation of 1 yields corannulene nitrene 31N, which has significant 1,3-biradical character. Irradiation of 1 in a glassy matrix resulted in a new absorption band in the region of 360-440 nm, with λmax at 360 and 410 nm, attributed to 31N, as supported by time-dependent density function theory calculations, which placed the major electronic transitions of 31N at 367 nm (f = 0.0407) and 440 nm (f = 0.0353). Laser flash photolysis of 1 revealed a similar absorption spectrum. Nitrene 31N had a lifetime of only a few hundred nanoseconds and was efficiently quenched by oxygen, because of its 1,3-biradical character. CASPT2(12,11)/6-311G** calculations revealed small energy gap (7.2 kcal/mol) between singlet and triplet configurations, suggesting that 31N is formed by intersystem crossing of 11N to 31N. Spin-density, nucleus-independent chemical shift, and anisotropy of the induced current density calculations verified that 31N is a triplet vinylnitrene with unpaired electrons localized on the C═C-N moiety; decaying by intersystem crossing to 2, which is more stable owing to its aromaticity, as supported by calculations (SA-CASSCF/QD-NEVPT2/CBS).

Optical and photoelectric properties of nanostructured SnS films obtained by spraying ink using a nanoparticle suspension

Abstract In this work, SnS films were prepared using spraying ink with a nanoparticle suspension. The average size of the synthesized nanoparticles was (18-20) nm. The structural, optical and photoelectric properties of SnS films were investigated using different characterization techniques. XRD and EDX results show that the investigated films exhibited an orthorhombic SnS phase with a composition close to the stoichiometry (CS/CSn = 0.99) and low level of microdeformation (ε = 1.8×10-3). In addition, the hexagonal SnS2 and tetragonal SnO2 phases were also observed. The presence of SnS and SnS2 phases is confirmed by Raman characteristics. The band gap of the SnS, SnS2, and SnO2 phases was determined using the novel ACFD method based on the analysis of the spectra of the first derivative of the absorption coefficient, which directly determines the energy of both band-to-band optical transitions and transitions involving defect`s levels. These results correlate very well with data obtained using photoconductivity spectra. The nature of the electronic optical transitions as well as the type and energy position of various defect levels were established. It was shown that the energy of direct and indirect band-to-band optical transitions of SnS compound correspond to 1.72 eV and 1.16 eV, respectively. At the same time, the band gap of SnS2 phase equal to 2.05 eV. The ionization energy of the acceptor (233 meV) and donor (100 meV) levels that determine the p- and n-type conductivity of SnS and SnS2 compounds, respectively were defined. Due to its properties, SnS films may be suitable for the development of novel effective solar cells with SnS absorber layers.

Evaluating the Importance of Conformers for Understanding the Vacuum-Ultraviolet Spectra of Oxiranes: Experiment and Theory.

Vacuum-ultraviolet (VUV) absorption spectroscopy enables electronic transitions that offer the unambiguous identification of molecules. As target molecules become more complex, multifunctional species present a great challenge to both experimental and computational spectroscopy. This research reports both experimental and theoretical studies of oxiranes. Computationally, the nuclear ensemble approach has been used to accurately predict experimental spectra for a variety of molecules. However, this approach incurs great computational cost, as ensembles generally consist of thousands of geometries. The present study aims to drastically reduce the ensemble by evaluating the significance of the conformers to the predicted spectra. This approach was applied to 11 substituted oxiranes using the Conformer Rotamer Ensemble Sampling Tool (CREST) of Grimme to generate an ensemble of unique conformers determined by their Boltzmann populations. Five TD-DFT functionals (BMK, CAM-B3LYP, M06-2X, MN15, ωB97X-D) and EOM-CCSD were used to simulate the spectrum of each substituted oxirane ensemble. Computed spectra were then compared to the experiment using both qualitative and quantitative metrics. Based on these metrics, it was observed that certain conformers may not be necessary to characterize this set of oxiranes despite the temperature (323 K) of the experiment. A single conformer can then be used with TD-DFT and EOM-CCSD to replicate the experimental spectra of these medium-sized combustion species.

Synthesis and Optical and Nonlinear Optical Properties of Linear and Two-Dimensional Charge Transfer Chromophores Based on Polyoxometalates.

We present the first study of arylimido-polyoxometalate nonlinear optical (NLO) chromophores with two-dimensional (2D) structures, and a comparison with one-dimensional analogues, through the synthesis of a family of arylimido-hexamolybdate derivatives where one or two polyoxometalate (POM) acceptors are connected to a tolyl-amino donor through phenyl bridges. Electronic absorption spectra and TD-DFT calculations reveal significant red-shifts in ligand-to-polyoxometalate charge transfer (LPCT) absorption bands for the 2D species compared to linear, dipolar analogues, consistent with the involvement of a larger conjugated (bridge + POM) system in the transitions. Electrochemical measurements indicate reversible, one-electron processes for the POM acceptors with class II mixed valence behavior observed where the POMs are connected to the same aryl ring and electronic isolation of the acceptors when they are on separate rings. Molecular first hyperpolarizabilities β have been determined using hyper-Rayleigh scattering at 1064 and 1200 nm: for the most active compound, the HRS measurements and depolarization studies reveal a strongly 2D, off-diagonal response (β0,zzz = 190 × 10-30 esu; β0,zyy = -56.5 × 10-30 esu), consistent with the wide A-D-A angle and TD-DFT computed electronic transitions, which show both phenyl bridges and POMs equally involved in the acceptor orbitals.

Classification of Fungal Pigments by Simulating Their Optical Properties Using Evolutionary Optimization

Modern developments in data analysis techniques and evolutionary optimization algorithms have made it possible to analyze large amounts of unstructured digital data sets. Based on the differential evolution algorithm and semiclassical quantum simulations, we have recently proposed a method for classifying and analyzing the optical properties of organic pigments. In this paper, we present the results of modeling the absorption spectra of five carotenoids synthesized during the vital activity of the ascomycetous fungi: neurosporaxanthin, neurosporene, torulene, γ-carotene, and ζ-carotene. We calculated the absorption spectra for each pigment using the multimode Brownian oscillator theory, which allows us to evaluate the influence of molecular vibrations on the electronic transitions in the pigment. We applied a generalized spectral density function method to our modeling, taking into account the contributions of 13 vibrational modes with frequencies varying between 100 cm−1 and 3000 cm−1. This approach allowed us to gain a deeper understanding of how molecular vibrations affect the absorption spectra of these organic compounds. Thus, each absorption spectrum was associated with a unique set of Huang–Rhys factors (which represent the effective electron–phonon interaction). This set can be considered as a kind of “fingerprint” that characterizes the optical response of the pigment in the solvent.

Comparative study of Alpha, Beta, and Omicron spike protein by computing the IR/Raman frequencies and UV-Vis adsorption – A computational analysis through DFT

The outbreak of COVID-19 coronavirus disease around the end of 2019 was a pandemic. The virus has been mutated and so many strains like Alpha, Beta, and Omicron are present in different parts of the world. Hence, timely detection technique is important to overcome the diagnostic challenges. Considering the need for this pandemic situation, we used a spectroscopy test methodology to distinguish different strains of Covid-19 by computing the infrared & Raman frequencies and the optical absorption data. Optimization of spike protein of Alpha, and Omicron mutations showed the high value of dipole moment (4.44, and 4.36) Debye, and polarizability [Alpha (233.62), Omicron (228.65)] indicating more bioactivity of Alpha and Omicron instead of Beta. Molecular electrostatic potential map exhibits the presence of electrophilic and nucleophilic region suggesting charge transfer of spikes to accept/donate electrons and hence the system increased reactiveness. UV-Vis absorption analysis also shows electronic transitions (σ to π* and π to π*) due to that protein probe mechanism of Alpha and Omicron becomes increasingly become unsaturated thus confirming its easy binding ability to the target human protein as compared to binding affinity of Beta spike protein.

Suppression of core temperature fluctuations by edge cooling in the J-TEXT tokamak

Abstract The suppression of core temperature fluctuations due to edge cooling in the J-TEXT tokamak is presented. The supersonic molecular beam is injected into the low density plasmas and the core temperature rise appears. The staggered time correlation technique is utilized to infer the temperature fluctuations from an electron cyclotron emission radiometer (ECE). The existing correlation ECE (CECE) also enables the observation of the temperature fluctuations simultaneously. A significant flattening of the density gradients appears almost in the whole plasmas after the cold pulse injection. The behaviors of the temperature fluctuations from both ECE and CECE show a good agreement, except for the fluctuation level, which exhibits a relative variation of approximately 10% − 50%. The relative intensity of temperature fluctuations decreases within the surface of r / a ∼ 0.8 due to the edge cooling. The cross-power analysis and the agreement in measurements suggest that temperature fluctuations from turbulence inferred from a single ECE channel may be possible. Linear simulations suggest the drop in temperature fluctuation intensity may relate to the trapped electron mode turbulence stabilization. This paper also demonstrates the evolution of both gradients and fluctuations before and after supersonic molecular beam injection with density scans.

Computational studies molecular structure investigation and experimental characterization of Bis(2-aminothiazolium): quantum chemical analysis, electronic transitions, interaction mechanisms, and molecular dynamics

Bis(2-aminothiazolium) succinate succinic acid (ATSA), was synthesized and evaluated using standard spectroscopic studies. Density Functional studies were employed for the theoretical investigation of the substance, aiding in the determination of the chemical molecule’s structure and form. The molecule’s structural stability and the flow of charges within and between molecules were explored using natural bond orbital calculations. The primary binding sites and subtle interactions of the molecule were identified through topological analyses analysis endorse the ultimate charge transfer (CT) within the molecule. In the calculation of a chemical’s potential as a therapeutic candidate, pharmacological research is undertaken. This assessment encompasses molecule’s drug-likeness, pharmaceutical profile, and environmentally friendly toxicity contemplations. A molecular docking technique was used toward ligand spanning different antimicrobial targets, and the associated characteristics were imparted. When likened with positive controls and other pathogens, studies on antimicrobial activity expose that the compounds linked to Enterococcus faecalis, Staphylococcus aureus, Rhizopus stolonifer, and Penicillium notatum exhibit notable antimicrobial efficacy.

Temperature-dependent optical and surface electrical properties of Pb(Zr0.3Ti0.7)O3 /p-GaN film

Understanding the temperature-dependent optical and electrical properties of PZT, a multifunctional ferroelectric thin film with temperature sensitivity, is crucial for its applications. This study systematically investigated the microstructure, optical, and surface electrical features of Pb(Zr0.3Ti0.7)O3 thin film deposited on p-GaN substrate (PZT/p-GaN), with an emphasis on their response to temperature variations. Band gap energy (3.643 eV) and the three interband electronic transitions (3.528 eV, 4.662 eV, 6.582 eV) were extracted from optical measurements, which govern the photoelectron transmission behavior of the PZT/p-GaN. Additionally, we identify three phase-transition temperatures (450 K, 550 K, and 620 K) through temperature-dependent optical behavior analysis. With increasing temperature, the electronic transitions and bandgap show a redshift trend, and the bandgap change follows the O'Donnell equation with a significant electron-phonon coupling coefficient (S = 10.284), revealing a strong electron-phonon coupling effect in PZT/p-GaN. The temperature-dependent kelvin piezoelectric force microscopy (KPFM) shows that the surface potential and work function of PZT/p-GaN exhibit different linear variations over three temperature ranges divided by the phase transition temperature point as a demarcation. Furthermore, we observed that the optical and surface electrical properties exhibit anomalous trends at the phase transition point. These findings offer a theoretical reference for the application of PZT thin films in optoelectronics and electronic devices.

Asymmetrically Fused Nanographene‐Porphyrin Architectures

AbstractA strategy to combine three standalone aromatic building blocks in one coherent, fully conjugated molecule is presented. Namely, benzene, pyrene, and hexa‐peri‐hexabenzocoronene (HBC) are assembled around a central porphyrin core in an ABAC type of geometry and interconnected under oxidative Scholl conditions to achieve merging of the individual π‐systems. The three asymmetric porphyrin conjugates obtained this way exhibit intriguing absorption features, namely strongly red‐shifted and broadened spectra. The presented series of molecules demonstrates the ability to control and influence these optical properties with high precision by altering the size of the aromatic system in a controlled manner. Density functional theory calculations gave more profound insights into the electronic structure and optical transitions of the investigated fused architectures.

Enhancing up-conversion luminescence in Yb/Er co-doped CsPbCl3 single crystals

The search for and fabrication of materials for the near-infrared range of the spectrum, including telecommunication windows, is an extremely important task in modern technology. This work presents the results of studies on the photoluminescence of CsPbCl3 single crystals with varying contents of ytterbium and erbium impurities, grown using the Bridgman method. The existence of electrically neutral Yb3+–VPb–Er3+ complexes within the crystal structure was confirmed. Resonant absorption of excitation radiation λ = 980 nm by Yb3+ ions reveals a three-step energy transfer channel from Yb3+ to Er3+ ions within a single complex. The estimated quantum yield of up-conversion luminescence at λ = 524 nm (0.02%) associated with erbium ions indicates the presence of electronic transitions to higher energy levels, with the possibility of subsequent emission within the third telecommunication window.

Linear and Nonlinear Optical Characteristics of Basic Fuchsin-Doped Polyvinyl Alcohol Films for Flexible Optoelectronics

Abstract Polyvinyl alcohol (PVA) containing different levels of basic fuchsine (BF) was prepared using the solution casting method. Characterization via Fourier-transform infrared spectroscopy detailed changes in functional groups within the PVA/BF composites, indicates the hydrogen bonding between OH group of PVA and BF molecules. Optical investigations spanning the 190-2500 nm range demonstrated UV blocking properties in prepared PVA/BF composites (fromn 2.05 to 2.56 eV and from 4.08 to 6.32 eV). Moreover, the studies on optical band gap indicated a decrease with increased BF concentrations, reflecting altered electronic transitions within the prepared composites. The study also employed the single oscillator model provided by Wemple-DiDomenico to elucidate refractive index variations. After incorporating BF dye into the PVA polymer, the values of the dielectric constant as the frequency approaches infinity (ε∞), the dielectric constant of lattice (εL), dispersion energy (Ed), and oscillator energy (Eo) in PVA/BF composite samples showed an increase. Moreover, the nonlinear optical properties, including optical susceptibility and nonlinear refractive index were investigated and discussed. These findings underscore the versatility of PVA doped with BF for various applications including optical filters, and solar cell devices.

Research on the Construction of Electrical and Electronic Experimental Teaching Platforms in Higher Vocational Colleges

With the advancement of vocational education reform, education informationization, and digitalization have become the important direction of the reform of electrical and electronic teaching in high vocational colleges. In this context, intelligent product development of professional electrical and electronic teaching should also do a good job in practice and innovation, especially in actively building a digital experimental teaching platform and promoting the reform of experimental teaching mode, so that students can learn more useful knowledge and skills in the new platform, and cultivate more applied and skilled talents for society. While analyzing the problems existing in the traditional electrical and electronic experimental teaching mode, this paper analyzes the significance and practical path of the construction of electrical and electronic experimental teaching platforms in higher vocational colleges which can be of reference in future research.

Coulomb impurities in graphene driven by fast ions

We provide a theoretical model for electronic transitions in a two-dimensional (2D) artificial atom in a graphene monolayer. The artificial atom is due to the presence of a charged adatom (Coulomb impurity) in the layer and interacts with a fast ultrarelativistic ion moving parallel to the layer. We compute the probability and cross-sections for the corresponding electronic transitions by means of an exact solution of the time-dependent 2D Dirac equation describing the interaction of the planar atom with the electromagnetic field of the ultrarelativistic projectile.

Multiple stimuli-responsive double perovskite structured Ca2MgWO6: x % Eu3+ (x = 1–11 mol) red-emitting luminescent systems to combat counterfeiting

The rapid escalation of counterfeiting activities in recent years has posed significant challenges across diverse fields, such as pharmaceuticals, currency, luxury goods, and electronics. In response, inorganic phosphors have emerged as promising tools to combat counterfeiting due to their inherent durability and stability. The present work focuses on the synthesis of Ca2MgWO6:x % Eu3+ (x = 1–11 mol) luminescent systems via a gel-combustion route. The structural analysis of the synthesized luminescent systems confirmed a monoclinic crystal phase with a P21/n space group. The morphological study of the luminescent system revealed a network-like structure comprising interconnected particles. Photoluminescence emission spectra show a prominent red emission peak at 616 nm, corresponding to the 5D0→7F2 4f–4f electronic transition of Eu3+ ions in the host matrix. The emitted red light demonstrates a color purity and quantum efficiency of 93.1 % and 77.41 %, respectively. The anti-counterfeiting security patterns were developed using the Ca2MgWO6:x % Eu3+ (x = 9 mol) luminescent system showcase virtually invisible under normal light. However, developed patterns exhibit vivid red luminescence when exposed to multiple stimuli UV light at 365 and 395 nm, which envisages the versatility of the systems for enhancing product authentication and protecting against fraudulent activities across multiple industries. The aforementioned results demonstrated the efficacy of Ca2MgWO6: Eu3+ luminescent systems for integration into advanced security measures.

OCS2 Isomers in the Venusian Atmospheric Chemistry: Spectroscopic Characterization and Photochemistry

The atmosphere of Venus exhibits absorption in the 300–500 nm wavelength range, which is driven by unknown chemical processes. In our study, we explore electronic transitions in molecules that may exist in the Venusian atmosphere, specifically focusing on the photoabsorption cross sections and the lowest singlet and triplet electronic states of the OCS2, SSCO, and OSCS isomers using highly accurate ab initio methods. Our analysis suggests that the SSCO isomer is a strong candidate for explaining the unknown UV absorption. Furthermore, these isomers may serve as significant astrochemical reservoirs in the atmosphere of Venus, where photodissociation could produce atomic sulfur in both its ground and excited states along with OCS and CS2, offering a plausible mechanism for the sulfur cycle dynamics and the formation of S x species. This study provides valuable insights into the complex sulfur chemistry within the atmosphere of Venus.

Biomass-based MnO2 Composite for Efficient Microwave Absorption Performance: Strong Interfacial Polarization and Electron Transition Effects

In this study, we explored the effectiveness of enhancing microwave absorption capabilities of biomass-derived porous carbon by introducing MnO2 through thermochemical techniques. The results showed that the MnO2-C exhibited higher values in both the real and imaginary parts of the dielectric constant compared to the Control, indicating that the addition of MnO2 significantly enhanced the energy storage and dissipation capabilities. Although the magnetic loss properties of the composite were relatively weak, the increase in conductive and dielectric losses compensated for this aspect. Moreover, the loading of MnO2 optimized the dielectric losses and promoted the reconstruction of charge, enabling MnO2-C to demonstrate superior microwave absorption performance, particularly in the high-frequency range. This is attributed to the multiple polarization mechanisms present in MnO2-C, including interfacial and dipolar polarization, which play a crucial role in enhancing dielectric losses. Additionally, a multilevel porous structure significantly enhanced the scattering and reflection of microwaves, further improving the absorption effectiveness. Consequently, these characteristics contribute to the MnO2-C achieving a minimum reflection loss value of -46.2dB and an expanded effective absorption bandwidth. Overall, the MnO2-C composite, with its optimized electromagnetic properties and complex microstructure, provides valuable insights for the development of new, highly efficient microwave absorption materials.

Influence of Spin-Orbit Coupling on the Optical and Thermoelectric Properties of Lateral MoSe2-WSe2 Heterostructure

In this letter, the spin-orbit coupling (SOC) effect in lateral MoSe2-WSe2 heterostructure was theoretically investigated. The results demonstrate that the SOC effect induces band splitting, narrows the band gap, and reduces the effective mass of electrons. These alterations indicates the enhanced probability of electron transitions from the valence band to the conduction band. Additionally, the SOC effect leads to red shift in the absorption peaks and the presence of SOC effect has transformed the heterostructure from being originally a p-type thermoelectric material to a n-type thermoelectric material, increasing its thermoelectric figure of merit (ZT). Our work not only contributes to a deeper understanding of its physical mechanisms , but also provides a reference for its potential applications in the field of thermoelectric and optical devices.

Ag-doped PDA interface strategy for selective electron transition integrating EMI shielding and anti-corrosion performance

Metal-based electromagnetic interference (EMI) shielding composites are essential for ensuring electromagnetic compatibility but are often compromised by susceptibility to corrosion, especially in harsh environments. Existing strategies to mitigate coupling corrosion typically involve physical barriers, which inevitably hinder conductivity. In this study, we introduce a novel interface doping approach to fabricate lightweight Graphite@PDA/Ag@Ag composites that simultaneously enhance EMI shielding and corrosion resistance. The PDA/Ag layer selectively regulates electrons with different migration directions and energies to migrate, increasing charge transfer resistance at Ag/graphite interfaces and ensuring conductivity through a tunneling effect. This design achieves an ultralow corrosion rate of 4.313 × 10-8 μm/yr (a billionth that of 316L stainless steel) alongside superior EMI shielding effectiveness of 109 dB in the X-band at 1.5 mm thickness. Remarkably, the composite maintains over 90 dB shielding efficiency after 7 d in NaCl solutions across various pH levels. Furthermore, simulated corrosion under South China Sea conditions predicts a coating loss of less than 0.026 μm over 7 years. This work presents a transformative approach to mitigating coupling corrosion in EMI shielding materials, offering a practical route to high-performance, corrosion-resistant composites without the need for a protective topcoat.

Research on Enterprise E-commerce Mode Based on Intelligent Management

With the rapid development of Internet technology and e-commerce, the traditional e-commerce management mode has been unable to adapt to the fast-paced development of e-commerce enterprises, and the management mode of e-commerce is facing new changes. The application of intelligent management technology can improve the efficiency and competitiveness of enterprises, and make the enterprise operation more transparent and efficient. Therefore, the article through the concept of intelligent management technology, the characteristics of the development of enterprise electronic commerce intelligent management, combined with the point of view at home and abroad scholars and existing theoretical basis, research based on intelligent management of enterprise electronic commerce mode, improve the level of enterprise e-commerce management, promote the sustainable development of the enterprise.