Electric Dipole Transition Research Articles

Hard-scattering approach to strongly hindered electric dipole transitions between heavy quarkonia

The conventional wisdom in dealing with electromagnetic transition between heavy quarkonia is the multipole expansion, when the emitted photon has a typical energy of order quarkonium binding energy. Nevertheless, in the case when the energy carried by the photon is of order typical heavy quark momentum, the multipole expansion doctrine is expected to break down. In this work, we apply the “hard-scattering” approach originally developed to tackle the strongly hindered magnetic dipole (M1) transition [Y. Jia , ] to the strongly hindered electric dipole (E1) transition between heavy quarkonia. We derive the factorization formula for the strongly hindered E1 transition rates at the lowest order in velocity and αs in the context of the nonrelativistic QCD, and conduct a detailed numerical comparison with the standard predictions for various bottomonia and charmonia E1 transition processes. Published by the American Physical Society 2024

A novel red-emitting InScW3O12:Eu3+ phosphor with anti-thermal-quenching performance for high-power WLED applications

A series of red-emitting InScW3O12:Eu3+ (ISWO:Eu3+) phosphors with anti-thermal-quenching performance were successfully synthesized by conventional solid-state reaction. The phase structure and luminescent properties of ISWO:Eu3+ were systematically studied. The photoluminescence excitation (PLE) spectrum showed that ISWO:Eu3+ phosphor can be effectively matched with commercial ultraviolet (UV), violet and blue light chips. The main emission peak of the phosphor was located at 613 nm, which was attributed to the electric dipole transition 5D0 → 7F2. Under the optimal excitation, the prepared ISWO:0.08Eu3+ phosphor showed excellent anti-thermal-quenching performance, its photoluminescence (PL) intensity at 180 °C reached 157.4 % of initial intensity at room temperature. At 465 nm excitation, it also exhibited the anti-thermal-quenching property and the PL intensity remained 115.1 % at 150 °C of that at room temperature. In situ XRD analysis revealed that the lattice contraction resulting in an increase in structural rigidity as the temperature rising, which caused the change of Eu3+ local environment and improved the PL intensity. Finally, a series of warm white LED devices under varying power density conditions with stable output were prepared using the red ISWO:0.08Eu3+ phosphor, indicating that the ISWO:Eu3+ phosphor with excellent anti-thermal-quenching performance has potential application prospects in high-power white light-emitting diodes (WLEDs).

Violet Light Excitable BaLiZn3(PO4)3: Eu3+ Orange-red-emitting Phosphor towards White LED Application

White light-emitting diode (WLED) has been widely used as solid-state lighting in recent years, with the advantages of energy saving, high luminous efficiency, and safety. Red phosphors are crucial to the color rendering index of WLED, and Eu3+-activated red phosphors can significantly improve the chromaticity performance of WLED. In this work, a series of new orange-red emitting BaLiZn3(PO4)3: Eu3+ phosphors were synthesized through high-temperature solid-state reaction method. The phase composition, crystal structure, morphology and photoluminescence properties of BaLiZn3(PO4)3: Eu3+ samples were investigated. The phosphors can be effectively excited by the violet light at 394 nm and emit orange-red lights corresponding to the electric dipole transition (5D0→7F1) at 594 nm. The optimal doping concentration of Eu3+ ions was about 5 mol%. The concentration quenching was caused by the electric dipole-dipole interaction between Eu3+ ions. Temperature-dependent PL spectra indicate that BaLiZn3(PO4)3: Eu3+ has excellent emission and color stability at high temperatures. The color coordinates were calculated and fall in the orange-red luminescent area. The color purity is about 98.3%, and the correlated color temperature is 1710K. These results indicate that the new orange-red phosphor BaLiZn3(PO4)3: Eu3+ has potential application prospects in WLED.

Eco-friendly synthesis of Nd³⁺-doped Eu₂O₃ nanoparticles for enhanced dye-sensitized solar cells utilizing oxalis Corniculata leaf extract

An environmentally friendly synthesis of Nd³⁺-doped Eu₂O₃ nanoparticles (NPs) was developed using Oxalis Corniculata leaf (OCL) extract to enhance the performance of dye-sensitized solar cells (DSSCs). The as-synthesized NPs were annealed at 600 °C to improve their crystallinity. X-ray diffraction and field-emission scanning electron microscopy revealed high crystallinity and a sub-100 nm spherical morphology. Annealing reduced the NP size from ∼85 nm to ∼45 nm and decreased the bandgap from 4.97 eV to 4.62 eV, enhancing low-energy photon absorption. Fourier-transform infrared spectroscopy showed changes in the chemical bonding environment, with a higher presence of dangling bonds in the as-prepared NPs compared to the 600 °C-annealed NPs, likely due to the OCL extract. Photoluminescence spectra confirmed strong red emission peaks at 580 nm and 612 nm, with a slight reduction in the full width at half maximum of the electric dipole transition after annealing. Integrating these NPs into TiO₂ matrices in DSSCs improved power conversion efficiency to 8.58%, outperforming both as-prepared NPs (6.88%) and bare TiO₂ cells (5.05%). This green synthesis approach offers a sustainable pathway for slightly enhancing performance of photovoltaic devices, with additional potential for UV-shielding applications when incorporated into PVA films.

Mie metasurfaces for enhancing photon outcoupling from single embedded quantum emitters

Abstract Solid-state quantum emitters (QE) can produce single photons required for quantum information processing. However, their emission properties often exhibit poor directivity and polarisation definition resulting in considerable loss of generated photons. Here we propose and numerically evaluate Mie metasurface designs for outcoupling photons from an embedded and randomly-positioned QE. These Mie metasurface designs can provide over one order of magnitude enhancement in photon outcoupling with only several percent of photons being lost. Importantly, the Mie metasurfaces provide the enhancement in photon outcoupling without the need for strict QE position alignment and without affecting the intrinsic QE emission rate (Purcell enhancement). Electric dipole modes are key for achieving the enhancement and they offer a path for selective outcoupling for photons emitted with specific polarisation, including the out-of-plane polarisation. Mie metasurfaces can provide an efficient, polarisation-selective and scalable platform for QEs.

Spectral characteristics and luminescence applications of Eu3+-activated fluorosilicate Na2MgGd2[SiO3]4F2

This work reports the luminescence spectra and application of novel Eu3+-doped Na2MgGd2[SiO3]4F2 phosphor. The X-ray powder diffraction confirmed the pure phase formation of the samples with the monoclinic space group P21/c (No:14). The phosphors demonstrated efficient red emission at 613 nm from the electric dipole transitions 5D0→7F2. The optimal doping concentration was found to be approximately 25 mol%. Na2MgGd2[SiO3]4F2:0.25Eu3+ exhibits a high quantum efficiency (QE) of 57 % with excellent thermal stability and pure chromaticity. Red- and the white light-emitting diode devices were packaged using InGaN chips and Na2MgGd2[SiO3]4F2:0.25Eu3+. The fabricated WLED has CIE coordinates of (x = 0.33, y = 0.34), which are very close to the white point in the National Television System Committee (x = 0.33, y = 0.33). The color rendering index (CRI, Ra) and correlated color temperature (CCT) of the WLED are 91 and 4400 K, respectively. The results show that as a red luminescent phosphor, it is a potential candidate for the preparation of near-UV/blue InGaN-based WLEDs.

Synthesis, Structural Features and Fluorescent Properties of Terbium Acylpyrazolone Complexes

AbstractThree 8‐coordinated terbium acylpyrazolone complexes [Tb(DMBPMP)3(H2O)2] (Tb1), [Tb(DMBMCPMP)3(H2O)2] (Tb2), and [Tb(DMBPTMP)3(H2O)2] (Tb3) with a distorted bicapped trigonal prismatic structure were synthesized (where, 3,5‐dimethylbenzoyl 1‐(phenyl = DMBPMP/m‐chlorophenyl = DMBMCPMP/p‐tolyl = DMBPTMP) 3‐methyl 5‐pyrazolone). The structures of the complexes were comprehensively analyzed using mass ESI, FTIR, UV–vis, powder XRD, and TG‐DTA methods. Single‐crystal analysis of Tb3·H2O confirmed an eight‐coordinate structure (TbO8) with a distorted bicapped trigonal prismatic geometry. In the on‐state emission spectrum, the 5D4 → 7F5 transition exhibits hypersensitivity in the green region of the visible spectrum (∼540–560 nm). The differences between electric dipole (ED) and magnetic dipole (MD) transitions indicate a small degree of asymmetry. The examination of solid‐state emission spectra included the assessment of intensity, G/B ratio, green color purity, and the antenna effect energy diagram.

The luminescent behaviors and J-O theory analysis of red phosphor Ca1-xGeO3:xEu3+

The luminescent material Eu3+-doped CaGeO3 has been synthesized using a high-temperature solid-state reaction technique. The crystal structure was analyzed using X-ray diffraction (XRD). The results showed that the samples belonged to the triclinic crystal system with the space group P1̅. The luminescent properties including photoluminescence excitation (PLE), Photoluminescence emission (PL) spectra, and lifetime, thermal stability, and diffuse reflectance spectroscopy (DRS) have been investigated. Under near-ultraviolet excitation at 390 nm, the phosphor emits red light with the highest intensity around 611 nm, which is dominated by the 5D0→7F2 electric dipole transitions. It indicates that Eu3+ is in the inversion center of the crystal. The concentration quenching occurs at about 6 % doping from the concentration-dependent luminescence behavior. The energy transfer mechanism was analyzed to be mainly the energy transfer between neighboring ions. The thermal stability was 82.16 % at 423 K. The chromaticity coordinates are in the red area and the color purity approaches 99 %. Furthermore, the J-O theoretical results are used to confirm the experimental result. It suggests that Ca1-xGeO3:xEu3+ is an effective red luminescent material for illumination and backlight display applications.

Enhancing Circularly Polarized Luminescence Dissymmetry Factor of Chiral Cylindrical Molecules to -0.56 through Intramolecular Short-Range Charge Transfer.

High-performance circularly polarized luminescent (CPL) materials have received wide attention recently by virtue of broad application in circularly polarized light-emitting diodes, 3D display, and encryption. Reaching both high luminescence efficiency and strong luminescence dissymmetry factor (glum) is still a challenging goal that requires continuous efforts. Herein, we performed a systematic theoretical investigation on the chiroptical properties of helical cylindrical molecules (-)-[4]cyclo-2,6-anthracene [(-)-[4]CA2,6] and (P)-[4]cyclo-2,8-chrysenylene [(P)-[4]CC2,8], and found that the unique and symmetric cylindrical structure could make the transition dipole moment components offset along the cylindrical surface but concentrated along the vertical central axis. This structural superiority contributes the collinear electric and magnetic transition dipole moment vectors and thus the large glum. Based on the results of decomposed transition dipole moment vectors to individual atoms, an effective strategy to enhance the glum through introducing intramolecular short-range charge transfer by embedding B,N atoms is proposed. The decreased electric transition dipole moment and well-kept magnetic transition dipole moment enable the glum of B,N-embedded designed molecules (-)-[4]CA2,6-4BN and (P)-[4]CC2,8-4BN up to -0.31 and -0.56, respectively. This molecular-insight investigation deepens the understanding of the structure-property relationship and provides efficient guidance for improving glum of CPL materials.

Blue to Red Emission Tunable Bi3+ co-doped YPO4:Eu3+: Host Emission and Phase Change.

Bi3+(0, 1, 3, 5, 7, 10, 12 and 15 at.%) co-doped YPO4:Eu3+ have been hydrothermally synthesized. Bi3+ (x ≥ 1 at.%) co-doping in YPO4:Eu3+ renders mixed crystalline phase of tetragonal to hexagonal. Pure tetragonal phase of Bi3+ co-doped YPO4:Eu3+ could be achieved upon annealing at 900°C. The luminescence intensity is improved significantly upon annealing at 900°C. This is due to the reduction of quenching pathways such as water molecules, dangling bonds, etc. The probability of magnetic dipole and electric dipole transitions is observed to be altered. As-prepared samples show near blue emission, while 900°C annealed samples exhibit red emission, which could be a potential candidate for display, sensing and biological labelling, etc.

Unveiling the Versatility of Coumarin-Integrated with Phenanthroline/Thiabendazole-Based EuIII Complexes for Smart LEDs, Vapoluminescence, and Bioimaging Applications.

Narrow band red-emitting phosphors based on organo-Eu(III) complexes prove their energetic features with surprising performance in smart red/white LEDs, sensing, and biological fields. In this report, a series of unique Eu(III) complexes have been synthesized with coumarin integrated with a class of phenanthroline(Phen)/thiabendazole(TBZ) based ancillary ligands and dibenzoyl methane (DBM)/2-theonyl trifluoroacetone (TTA) as an anionic ligand. The computational study reveals that the TBZ/Phen-based neutral ligands are superior energy harvesters to those other reported analogue neutral ligands. All the Eu-complexes demonstrated outstanding red emission due to electric dipole (ED) transition (5D0 → 7F2) in solid, solution, and thin film with high quantum yield (QY). Theoretical analysis (TD-DFT) and experimental findings describe that the energy transfer (ET) from the ligand's triplet level to the Eu(III) ion is completely occurring. The Eu(III) complexes can potentially be used to fabricate intense hybrid white and red LEDs. All of the fabricated red LEDs revealed high luminous efficiency of radiation (LER) values. The fabricated blue LED based hybrid white LEDs displayed remarkable performance with a low correlated color temperature (5634 K), high color rendering index 88%, and CIE values (x = 0.33; y = 0.342) for 3Eu. By interaction with acid-base vapors, Eu-complexes displayed effectively alterable on-off-on luminescence. Further, cellular imaging shows that Eu-complexes can be a potential biomarker for cancer cell lines.

Magneto-optical metasurfaces for high-Q perfect absorption with quasi-bound states in the continuum.

We present a novel, to the best of our knowledge, magneto-optical (MO) metasurface composed of a bismuth iron garnet (BIG) nanocube array, designed to achieve near-perfect absorption through quasi-bound states in the continuum (QBICs). This metasurface supports a stable QBIC mode induced by MO-induced permittivity terms that break the symmetry of the permittivity tensors, corresponding to a longitudinal electric dipole (ED) mode. By integrating graphene to introduce material loss, the absorption reaches 99.6% at a wavelength of 1512.3 nm with a Q factor of 9440, despite monolayer graphene's inherent absorption being only 2.3%. The inherent transverse ED background mode, with high reflection and low Q, helps decrease the radiative loss of the QBIC mode, allowing the structure to surpass the 50% absorption limit. This approach offers a simplified pathway for designing high-Q metasurface perfect absorbers, with potential applications in optical switches and modulators.

Full-Stokes polarization mid-wave infrared photodetector based on the polarization-converting metasurface

It is very challenging to achieve direct capture of the circular polarization due to the complex mechanism of the chiral materials. We numerically demonstrate a circular polarization photodetector composed of the silicon (Si) metasurfaces rotated 45° clockwise presenting as the phase delayer and the grating-coupled quantum well infrared photodetectors (QWIP) chip detecting the transverse magnetic (TM) mode. The circular dichroism and extinction ratio of the circular polarization (CP) photodetector are 0.25 and 20 dB at 4 μm operation wavelength, respectively. In addition, the linear dichroism (LD) and extinction ratios (ER) of the linear polarization device are 0.22 and 60 dB, respectively. The excellent LD performance is caused by the Fano resonance of the Si/SiO2 linear grating corresponding to the interference of the bright electric dipole mode and the dark electric quadrupole mode. The full Stokes pixel of the six-image-element technique can almost accurately obtain arbitrary polarized light at 4 μm operation wavelength. The errors of the degree of linear polarizations (Dolp) and the degree of circular polarizations (Docp) are less than −30 dB and −20 dB, respectively.

Inverse Faraday Effect in Ferrite–Garnet Films in the Near-Infrared Range

The magneto-optical Faraday effect is determined by the electric dipole and magnetic dipole transitions in a transparent magnetic material. At the same time, the inverse Faraday effect is still described by an expression that includes only electric dipole transitions. The magnetic dipole contribution to the inverse Faraday effect is considered theoretically, and the dependence of the inverse Faraday effect on the wavelength in the near-infrared range (where the magnetic dipole contribution becomes significant) is obtained by the example of a ferrite–garnet film. It is shown that, although both contributions to the inverse Faraday effect always take place for homogeneous films, only the magnetic-dipole inverse Faraday effect manifests itself for films with a periodic nanostructure upon excitation by a TE waveguide mode, which may be useful for its experimental observation.

Theoretical investigation of the electronic structure of the Rhodium Halides molecules RhF and RhCl with dipole moment calculation

The current study involves an ab initio exploration of the ground and low-lying excited electronic states of the rhodium halide molecules RhF and RhCl using the complete active space self-consistent field (CASSCF) with multireference configuration interaction (MRCI+Q) method including single and double excitations and with Davidson corrections. We investigated the potential energy curves, the transition and permanent electric dipole moments, the electronic energy relative to the ground state Te, the harmonic frequency ωe, the internuclear distance Re, and the rotational constant Be corresponding to each of the bounded states. Our findings demonstrate good agreement with the available experimental data. Notably, this work represents the inaugural theoretical investigation of the excited states of RhF and RhCl molecules, identifying the ground state of both to be X3Π, as observed in the sole two experimental investigations.

Study of η′ → π+π−l+l− decays at BESIII

With a sample of (10087 ± 44) × 106J/ψ events accumulated with the BESIII detector, we analyze the decays η′ → π+π−l+l−(l = e, μ) via the process J/ψ → γη′. The branching fractions are measured to be B\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$ \\mathcal{B} $$\\end{document}(η′ → π+π−e+e−) = (2.45 ± 0.02(stat.) ± 0.08(syst.)) × 10−3 and B\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$ \\mathcal{B} $$\\end{document}(η′ → π+π−μ+μ−) = (2.16 ± 0.12(stat.) ± 0.06(syst.)) × 10−5, and the ratio is Bη′→π+π−e+e−Bη′→π+π−μ+μ−=113.4±0.9stat.±3.7syst.\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$ \\frac{\\mathcal{B}\\left({\\eta}^{\\prime}\ o {\\pi}^{+}{\\pi}^{-}{e}^{+}{e}^{-}\\right)}{\\mathcal{B}\\left({\\eta}^{\\prime}\ o {\\pi}^{+}{\\pi}^{-}{\\mu}^{+}{\\mu}^{-}\\right)}=113.4\\pm 0.9\\left(\ extrm{stat}.\\right)\\pm 3.7\\left(\ extrm{syst}.\\right) $$\\end{document}. In addition, by combining the η′ → π+π−e+e− and η′ → π+π−μ+μ− decays, the slope parameter of the electromagnetic transition form factor is measured to be bη′ = 1.30 ± 0.19 (GeV/c2)−2, which is consistent with previous measurements from BESIII and theoretical predictions from the VMD model. The asymmetry in the angle between the π+π− and l+l− decay planes, which has the potential to reveal the CP-violation originating from an unconventional electric dipole transition, is also investigated. The asymmetry parameters are determined to be ACPη′→π+π−e+e−=−0.21±0.73stat.±0.01syst.%\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$ {\\mathcal{A}}_{CP}\\left({\\eta}^{\\prime}\ o {\\pi}^{+}{\\pi}^{-}{e}^{+}{e}^{-}\\right)=\\left(-0.21\\pm 0.73\\left(\ extrm{stat}.\\right)\\pm 0.01\\left(\ extrm{syst}.\\right)\\right)\\% $$\\end{document} and ACPη′→π+π−μ+μ−=0.62±4.71stat.±0.08syst.%\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$ {\\mathcal{A}}_{CP}\\left({\\eta}^{\\prime}\ o {\\pi}^{+}{\\pi}^{-}{\\mu}^{+}{\\mu}^{-}\\right)=\\left(0.62\\pm 4.71\\left(\ extrm{stat}.\\right)\\pm 0.08\\left(\ extrm{syst}.\\right)\\right)\\% $$\\end{document}, implying that no evidence of CP-violation is observed at the present statistics. Finally, an axion-like particle is searched for via the decay η′ → π+π−a, a → e+e−, and upper limits of the branching fractions are presented for the mass assumptions of the axion-like particle in the range of 0 − 500 MeV/c2.

Interaction of Hermite–Gaussian Beams with a Macroscopic Atomic Target

AbstractA theoretical analysis is presented on the photoexcitation of a macroscopic atomic target by a Hermite–Gaussian (HG) beam within the framework of density matrix theory. Special emphasis is paid to the influence of the incoming HG mode on the population of an excited state and the emitted fluorescence radiation. In particular, a general expression for the alignment parameter of the excited state is derived, which depends on the beam parameters of the HG mode. Although the developed theory can be applied to any atomic system, here the electric dipole transition in neutral sodium atoms is investigated when driven by three , and modes. For this optical (valence‐shell) excitation, it is demonstrated that the population of the excited state is sensitive to the beam waist and the mode index of the HG beam. Furthermore, the influence of beam parameters on the angular distribution and linear polarization of the emitted fluorescence radiation is discussed.

Modeling the γ spectrum from d−t collisions

Motivated by possible industrial fusion applications of spectroscopy of the γ rays accompanying d−t collisions we develop the first model calculations of the minor branching ratio of the d+t reaction, d+t→α+n+γ. The model exploits the most relevant physics feature—spin conservation in electric dipole transitions—which leads to a peculiar mechanism of this reaction: γ emission via bremsstrahlung from an intermediate α−n state. We highlight that, as a consequence of the bremsstrahlung, the γ spectrum contains nonzero contributions at all energies, thus making inclusive dtγ cross section measurements sensitive to the low-energy cutoff of the detected γ events. Comparison of our predictions to existing d+t→α+n+γ measurements in accelerators, employing cutoffs of 13 and 14 MeV, and inertial confinement fusion facilities, with a low-limit cutoff of 0.4 to 10 MeV, suggests a possible contradiction between results from these two types of experiments. Our predictions agree well with accelerator measurements and corroborate the cutoff dependence observed in inertial confinement experiments. These predictions are sensitive to the wave function details inside the short-range area of the α−n interaction, with uncertainty comparable to that of available experimental data, but become model independent below 4–5 MeV. This part of the γ spectrum features a previously unexpected rise, which below 0.5 MeV surpasses the main 17-MeV γ peak in strength. The reactivity of the d+t→α+n+γ branch was found to be proportional to its cross section. It strongly depends on the d−t plasma temperature, which opens the possibility of not only total d+t reactivity measurements but also advanced plasma temperature diagnostics. Published by the American Physical Society 2024

Large-scale multiconfiguration Dirac-Hartree-Fock calculations of atomic data, Landé gj -factors and hyperfine constants of the neutral Rn-211 isotope

We computed the atomic data of ns[K]J ( n = 7, 8, 9), np[K]J ( n = 7, 8, 9), nd[K]J ( n = 6, 7, 8, 9), and nf[K]J ( n = 5, 6, 7, 8) and 5g[K]J autoionized Rydberg spectra of the neutral radon-211 isotope. The computations are carried out by using the Multiconfiguration Dirac-Hartree-Fock method (MCDHF) together with the relativistic configuration (RCI) approach. The convergence of the obtained results is monitored by incorporating relativistic electron-electron correlation, the Breit-interaction effect, self-energy, and vacuum-polarization corrections. As a result, we acquired the energy levels, transition rates, oscillator strengths, Landé gJ -factors and magnetic dipole hyperfine constants. The transition parameters between the levels belonging to different series are computed for all allowed electric dipole transition selection rules. The present results are in very good agreement with other experimental and theoretical data available in the literature database. The present data could be useful in predicting spectral lines of radon via astrophysics and stellar spectroscopy.

Structural and Spectroscopic Analysis of Reddish-Orange Emitting (Y1−x)2WO6:xEu3+ (0 ≤ x ≤ 0.11) Nanophosphors for Anti-Counterfeiting Application

Exploring luminescent materials that meet the necessary specifications for anti-counterfeiting applications has been the focus of extensive research. In this study, we delve into a double perovskite-structured material, (Y1−x)2WO6:xEu3+ (0 ≤ x ≤ 0.11), synthesized via a chemical combustion method. The crystallographic studies using the X-ray diffraction pattern confirm the crystallization of the nanophosphors into the monoclinic phase with a P2/c space group. The Raman and Fourier transform infrared spectroscopy studies provide insights into the nature of chemical bonding within the material. UV visible spectra are analysed to determine the optical energy gap. Notably, the photoluminescence emission spectra of the Eu3+ incorporated phosphors exhibit a distinct emission peak at 609 nm, corresponding to the 5D0 → 7F2 electric dipole transition of the Eu3+ ions. The optimal photoluminescence intensity is observed for the x = 0.07 nanophosphor, with estimated chroma coordinates of (0.500, 0.316), placing it in the reddish-orange region of the chromaticity diagram. The incorporation of Eu3+ enhances magnetization, attributed to the presence of Eu3+ ions in the 7F2 state. The luminance stability is a critical factor for long-term performance, the x = 0.07 phosphor was analysed under rigorous physical and chemical testing and is found to be stable, making it a favourable candidate as a luminescence pigment for anti-counterfeiting applications.