Strong Field Research Articles

Interfacial [S─Cu─C] Bonds Induced π-d Electron Coupling Toward Modulating Charge Transfer for Efficient Solar Water Oxidation.

Regulating the interfacial electric field to achieve rapid charge transfer is crucial for superior photoelectrochemical water splitting. Herein, the ultra-thin hydrogen-substituted graphdiyne (HsGDY) is precisely assembled on the surface of CdS nanorod array (Cu-CdS-HsGDY) by an in situ polymerization strategy. The strong π-d electron coupling is aroused by the delocalized π electrons of HsGDY and the delocalized d electrons of CdS through the interfacial [S─Cu─C] bonds. The strong interfacial electric field can effectively promote the charge localization distribution and reduce the charge transfer resistance. The optimized Cu-CdS-HsGDY photoanode obtain a photocurrent density as high as 4.83 mA cm-2 at 1.23 V versus reversible hydrogen electrode in neutral electrolyte solution under AM 1.5G illumination, which is 6.8 times that of the pristine CdS. Moreover, the photoanode maintains an initial photocurrent density of 84% within 4 h without any assistance of sacrificial agents, which is a rather competitive performance of similar sulfide photoanodes. The mechanism of strong π-d electron coupling on interfacial charge transfer and surface reaction kinetics is investigated by transient spectroscopy measurements, density functional theory calculation, and finite element simulation analysis. This work provides new insights into designing a reasonable interface structure to regulate charge transfer for achieve efficient PEC water splitting.

Orientation-independent quantification of macromolecular proton fraction in tissues with suppression of residual dipolar coupling.

Quantitative magnetization transfer (MT) imaging enables noninvasive characterization of the macromolecular environment of tissues. However, recent work has highlighted that the quantification of MT parameters using saturation radiofrequency (RF) pulses exhibits orientation dependence in ordered tissue structures, potentially confounding its clinical applications. Notably, in tissues with ordered structures, such as articular cartilage and myelin, the residual dipolar coupling (RDC) effect can arise owing to incomplete averaging of dipolar-dipolar interactions of water protons. In this study, we demonstrated the confounding effect of RDC on quantitative MT imaging in ordered tissues can be suppressed by using an emerging technique known as macromolecular proton fraction mapping based on spin-lock (MPF-SL). The off-resonance spin-lock RF pulse in MPF-SL could be designed to generate a strong effective spin-lock field to suppress RDC without violating the specific absorption rate and hardware limitations in clinical scans. Furthermore, suppressing the water pool contribution in MPF-SL enabled the application of a strong effective spin-lock field without confounding effects from direct water saturation. Our findings were experimentally validated using human knee specimens and healthy human cartilage. The results demonstrated that MPF-SL exhibits lower sensitivity to tissue orientation compared with , , and saturation-pulse-based MT imaging. Consequently, MPF-SL could serve as a valuable orientation-independent technique for the quantification of MPF.

Viscous heating and instabilities in the partially ionized solar atmosphere

Abstract In weak magnetic fields (≲ 50 G), parallel and perpendicular viscosities, mainly from neutrals, may exceed magnetic diffusivities (Ohm, Hall, ambipolar) in the middle and upper chromosphere. Ion-driven gyroviscosity may dominate in the upper chromosphere and transition region. In strong fields (≳ 100 G), viscosities primarily exceed diffusivities in the upper chromosphere and transition region. Parallel and perpendicular viscosities, being similar in magnitude, dampen waves and potentially compete with ambipolar diffusion in plasma heating, potentially inhibiting Hall and ambipolar instabilities when equal. The perpendicular viscosity tensor has two components, ν1 and ν2, which differ slightly and show weak dependence on ion magnetization. Their differences, combined with shear, may destabilize waves, though magnetic diffusion introduces a cutoff for this instability. In configurations with a magnetic field B having vertical (bz = Bz/|B|) and azimuthal (by = By/|B|) components, and a wavevector k with radial ($\hat{k}_x=k_x/|{\bf k}|$) and vertical ($\hat{k}_z=k_z/|{\bf k}|$) components, parallel viscosity and Hall diffusion can generate the viscous-Hall instability. Gyroviscosity further destabilizes waves in the upper regions. These findings indicate that the solar atmosphere may experience various viscous instabilities, revealing complex interactions between viscosity, magnetic fields, and plasma dynamics across different atmospheric regions.

Additive and subtractive hybrid manufacturing assisted by femtosecond adaptive optics

Advanced micro–nano devices commonly require precise three-dimensional (3D) fabrication solutions for pre-designing and integrating 0D to 3D configurations. The additive–subtractive hybrid manufacturing strategy dominated by femtosecond laser direct writing has become an increasingly interesting technical route for material processing. In this study, a novel approach termed femtosecond adaptive optics-assisted hybrid manufacturing was proposed, which integrates subtractive (femtosecond laser ablation) and additive (two-photon polymerization) fabrication. In this hybrid manufacturing method, the introduction of adaptive optics offers parallel direct writing and wide-area material processing capabilities. To demonstrate the validity of the hybrid approach, on-chip surface plasmon polariton waveguides with strong sub-wavelength field confinement and enhanced functionality were successfully fabricated. In comparison with the terahertz-wave devices fabricated based on the focused ion beam technique, the functional tests in terahertz near-field microscopy show a rival performance fabricated with our hybrid approach. Besides, our cost-effective solution also dramatically reduces the fabricating time of excitation regions by a factor >16. Our work provides a new inspiration in integrated photonics.

Interface-Engineered CuxO@Bi2MoO6 Heterojunctions to Inhibit Piezoelectric Screening Effect and Promote Double-Nanozyme Catalysis for Antibacterial Treatment.

Sonodynamic therapy is confronted with the low acoustic efficiency of sonosensitizers, and nanozymes are accompanied by intrinsic low catalytic activity. Herein, to increase the piezopotential of N-type piezoelectric semiconductors, the P-N heterojunction is designed to inhibit the piezoelectric screening effect (PSE) and increase electron utilization efficiency to enhance nanozyme activity. P-type CuxO nanoparticles are in situ grown on N-type piezoelectric Bi2MoO6 (BMO) nanoflakes (NFs) to construct heterostructured CuxO@BMO by interface engineering. CuxO deposition leads to lattice distortion of BMO NFs to improve piezoelectric response, and the strong interface electric field (IEF) suppresses PSE and increases piezopotential. The nonlocal piezopotential, local IEF, and glutathione (GSH) inoculation enhances electron-hole separation and increases peroxidase (POD)-like activity of BMO and GSH oxidase (GSHOx)-like activity of CuxO with high selectivity. The heterojunction formation causes the transfer and rearrangement of interface electrons, and the increased piezopotential accelerates electron transfer at interfaces with bacteria, thus increasing the production of reactive oxidative species and interfering with adenosine triphosphate synthesis. The heterostructured nanozymes produce abundant intracellular ·OH and achieve 4log magnitude reductions in viable bacteria and effective biofilm dispersion. This study elucidates integral mechanisms of nanozyme and acoustic catalysis and opens up a new way to synergize high piezopotential and nanozyme-catalyzed therapy.

Unveiling Frequency-Dependent Electromechanical Dynamics in Ferroelectric BaTiO3 Nanofilm with a Core-Shell Structure

Diverse domain patterns significantly influence the nonlinear electromechanical behaviors of ferroelectric nanomaterials, with polarization switching under strong electric fields being inherently a frequency-dependent phenomenon. Nevertheless, research in this area remains limited. In this study, we present a phase-field investigation of frequency-dependent electromechanical dynamics of a polycrystalline BaTiO3 nanofilm with a core-shell structure, subjected to applied frequencies ranging from 1 to 80 kHz. Our findings elucidate the microstructural mechanisms underlying the electromechanical behaviors observed in these materials. The effect of the grain size and the strains effect are also taken into account. Hysteresis and butterfly loops exhibit a marked change in shape as the frequency changes. We discuss the underlying domain-switching dynamics as a basis for evaluating such frequency-dependent properties. In addition, we examine the scaling behaviors of the dynamic hysteresis and the influence of grain boundaries on the domain structure. We can also observe from hysteresis loops that the remnant polarization and coercive field significantly diminish when grain sizes decrease from 60 to 5 nm. A smaller grain size of the nanofilm yields a larger percentage of the dielectric grain boundary, which “dilutes” the overall ferroelectricity of the film. A vortex domain structure is more likely to form at low frequency and a small grain size.

Construction of a MoOx/MoS2 Heterojunction via the Surface Sulfurization of the Oxide and Its Photocurrent-Switching Characteristics in the Range of the Broadband Light Spectrum

In order to utilize the longer wavelength light, the surface sulfurization of MoO3 was carried out. The photocurrent responses to typical 650, 808, 980, and 1064 nm light sources with Au gap electrodes were investigated. The results showed that the surface S–O exchange of MoO3 improved the interfacial charge transfer in the range of the broadband light spectrum. The S and O can be exchanged on the surface of MoO3 nanosheets under the hydrothermal condition, leading to the formation of a surface MoOx/MoS2 heterojunction. The interfacial interaction between the MoO3 nanosheets and MoS2 easily generated free electrons and holes, and it effectively avoided the recombination of photogenerated carriers. Meanwhile, the surface S-doping of MoO3 also resulted in the generation of an oxygen vacancy and sulfur vacancy on MoO3−xS2−y. The plasmonic characteristics of MoO3−x contributed to the enhancement of the interfacial charge transfer by photoexcitation. Otherwise, even with zero bias applied, a good photoelectric signal was still obtained with polyimide film substrates and carbon electrodes. This indicates that the formation of the heterojunction generates a strong built-in electric field that drives the photogenerated carrier transport, which can be self-powered. This study provides a simple and low-cost method for the surface functionalization of some metal oxides with a wide bandgap.

Effects of Ion Valence States and Radii on the Performance of Solid-State PEDOT:PSS Electrochromic Devices.

Ion transport is a critical factor influencing the performance of electrochromic devices (ECDs). In this work, the effects of the valence state and ionic radius of six cations, Li+, Na+, K+, Mg2+, Zn2+, and Al3+, on the performance of poly(3,4-ethylenedioxythiophene)-polystyrene sulfonic acid (PEDOT:PSS)-based ECDs are investigated. Both ion migration and diffusion are discussed as processes that were analyzed, with results indicating that the primary contributor to the response of ECDs is ion migration. The response time decreases with increasing ionic valence and ionic radius, with the valence state having the predominant effect on response speed. Multivalent ions, due to strong electric field forces, migrate more rapidly and intercalate fewer ions at equivalent reaction charges, thereby facilitating a faster response. ECDs with larger-radius ions, which exhibit slower diffusion rates, also achieve faster response speeds. Among the tested ECDs with various electrolytes, the Al3+-based ECD demonstrates the fastest colored/bleached response time of 0.36/0.4 s. In addition, ions with larger radii introduce greater steric hindrance and structural damage during insertion and extraction, leading to ion retention issues and reduced cycling stability. After 500 cycles (2025 s) under a square wave voltage of ±1.5 V, the peak current of ECDs with Li+ (0.60 Å) electrolyte decreased by only 5.07/5.66%, whereas for K+ (1.33 Å) electrolyte, the decrease was 11.55/12.37%. ECDs utilizing small-radius, higher-valence ions, such as Al3+, achieved both fast response and high cycling stability, with peak current reductions of only 6.98/5.01%. Additionally, the charge storage dynamics were examined by analyzing the contributions from surface-controlled and diffusion-controlled charges, further confirming that ion migration dominates in ECDs. The high contribution of surface-controlled charges (80%) supports the fast response of ECDs and contributes to the high coloration efficiency (592.6 cm2/C for Al3+-based devices).

Antithermal-Quenching Near-Infrared Emitting Lu2SrAl4SiO12:Cr3+ Garnet-Type Phosphor for High-Resolution Nonvisual Imaging.

Near-infrared (NIR) light allows fast and nondestructive detection with deep penetration into biological tissues and is widely used in food inspection, biomedical imaging, night vision security, and other fields. Cr3+-doped NIR first region (NIR-I) phosphors have many interesting features that have attracted a lot of attention recently. However, practical issues, such as low photoluminescence quantum efficiency and poor thermal stability, need to be addressed. We synthesized Cr3+-doped Lu2SrAl4SiO12 garnet-type phosphors using a high-temperature solid-state reaction method. Under blue-light (@ 430 nm) excitation, the phosphors exhibited broadband NIR-I emission in the range of 600-1000 nm, with an emission peak at 710 nm. This system is unique, as the emission had multipeak sharp-line superposition and the Cr3+ ions were situated in a relatively strong crystal field environment, as opposed to a weak crystal field environment for other matrix. The optimal doping content of Cr3+ ions was 2 mol %, and its internal quantum efficiency was ∼76.8%. Surprisingly, this NIR phosphor showed an antithermal quenching effect, and the integrated luminescence intensity of NIR-I emission measured at 573 K was 206.3% of that measured at 303 K. We found that the antithermal quenching of NIR-I luminescence was caused by the extremely low thermal expansion coefficient and rigid structure of the Lu2SrAl4SiO12 matrix in the temperature range, as well as the weakening of electron-phonon coupling with increasing temperature. The optimized phosphor was packaged with a blue chip into a NIR phosphor-converted light-emitting diode device. The light source device showed an output power of 119.02 mW and an electro-optical conversion efficiency of 11.02% under a driving current of 300 mA. The application potential of this NIR phosphor was demonstrated in the field of high-resolution nondestructive imaging.

Microscale Templating of Functional Particles Using Self-Limiting Electrospray Deposition.

Electrospray deposition (ESD) uses strong electric fields applied to solutions and dispersions exiting a capillary to produce charged monodisperse droplets driven toward grounded targets. Self-limiting electrospray deposition (SLED) is a phenomenon in which highly directed, uniform, and even 3D coatings can be achieved by trapping charge in the deposited film, redirecting the field lines to uncoated regions of the target. However, when inorganic particles are added to SLED sprays, the buildup of charge required to repel incoming material is disrupted as particle loading increases. Due to its fibril gelling behavior, methylcellulose (MC) SLED can form nanowire morphologies. These wires, when used as a binder, can separate particles and prevent percolation. In this work, a variety of conductive and insulating particles are explored using patterned and un-patterned substrates. This exploration allows us to maximally load particles for high-concentration and highly controlled self-limiting functional sprays. This is demonstrated using Ti3C2Tx MXene to functionalize an interdigitated electrode for use as a supercapacitor.

Enhancement strategy of thermal stability and photoluminescent intensity of Cr3+ doped Li3+xZn2–2xGaxSbO6 phosphor in a strong crystal field

Near-infrared phosphor-converted light-emitting diodes (pc-LEDs) have shown enormous influence in various applications such as night vision, non-destructive detection，especially in the realm of plant cultivation. However, the role of phosphors presently employed in plant cultivation is typically limited, serving primarily for the purpose of illumination. In this work, a series of near-infrared phosphors Li3+xZn2–2xGaxSbO6: 0.02Cr3+(LZGS: 0.02Cr3+) under 450 nm excitation was successfully synthesized by high-temperature solid-state method. Through precise modulation of Ga3+ ions, a blue shift in the emission spectrum was observed, demonstrating excellent overlap with the absorption spectrum of Phytochrome. To explain two phenomena of spectral blue shift and the enhancement in luminescence intensity, density functional theory calculations have been performed. Additionally, a crystal field strength Dq/B of 3.48 was achieved, which represents the highest value currently reported for Cr3+-doped phosphors. The results offer potential applications of LZGS: 0.02Cr3+ in temperature sensing, enabling precise detection of the environmental temperature for plant growth. Finally, pc-LED devices were made by combining LZGS: 0.02Cr3+ with 450 nm blue light chips and applied to plant lighting, temperature measurement, and anti-counterfeiting, demonstrating the potential of LZGS: 0.02Cr3+ in multifaceted applications.

Fabrication and Mechanism Insight of Multidimensional Coupled Metal-Free van der Waals Heterostructures for Enhanced Photocatalytic Hydrogen Evolution.

It is an arduous issue to significantly improve the charge separation efficiency of polymer photocatalysts due to their inherently high exciton binding energy. Herein, based on an interfacial coupling and atom diffusion strategy, a metal-free 3D/2D van der Waals (VdW) heterojunction is fabricated through the modification of rich-vacancy wrinkle-like S8 (Vs-S8) microspheres on the surface of S-doped polymeric carbon nitride (S-PCN) nanosheets. The insight into the mechanism reveals that the interfacial coupling effect induces a strong built-in electric field from S-PCN to Vs-S8, and the carrier transfer behavior abides by the type-II charge transfer pathway, thereby dramatically improving the separation efficiency and transport kinetics of photogenerated carriers. As a result, the as-prepared metal-free 3D/2D Vs-S8/S-PCN VdW heterojunction is endowed with more superior photocatalytic hydrogen evolution (PHE) performance than PCN. The highest average PHE rate is about 11.3 times higher than that of PCN, and the apparent quantum efficiency reaches 30.1% at 400 nm on the optimal 3%-Vs-S8/S-PCN sample. This work contributes a new design strategy for a metal-free VdW heterojunction and provides a feasible avenue for improving the carrier separation efficiency of polymer photocatalysts.

Construction of 2D/2D Pd Metallene/COFs System with Strong Internal Electric Field for Outstanding Solar Energy Photocatalysis.

Due to the severe recombination of charge carriers, the photocatalytic activity of covalent organic frameworks (COFs) materials is limited. Herein, through simple ultrasound and stirring processes, the Pd metallene (Pde) is successfully combined with 2D COFs to form Pde/TpPa-1-COF (Pde/TPC) composites. Obviously, a strong internal electric field (IEF) is successfully formed in Pde/TPC hybrid materials, which significantly boosts the separation of photogenerated charges. In addition, the matched 2D structure of the two materials can also lead to electronic coupling effects, plentiful active sites, and shortened carrier migration paths. Thus, the Pde/TPC hybrid materials own extraordinary carrier separation ability with a longer carriers lifetime (3.3 ns for Pde/TPC and 2.7 ns for TPC), which can be proved series of photoelectrochemical and spectroscopic tests. Benefiting from the formation of IEF and the matched 2D structure, the 8% Pde/TPC demonstrates the highest photocatalytic H2 evolution efficiency, with H2 production rate reaching up to 5.85 mmolg-1h-1, which is over 25 times greater than that of pristine COFs, also exceeding that of many reported COFs-based photocatalysts. This research provides new perspectives and innovative approaches to further research on enhancing the internal electric field of COFs to promote their photocatalytic performance.

DBD plasma induced SMOSI and encapsulation for regulation of Brønsted-Lewis acid sites of Cr-MOFs@ZrO2

Dielectric barrier discharge (DBD) plasma for the synthesis of Zr-MOFs followed by the calcination and combination with Cr-MOFs was presented to prepare a Brønsted-Lewis bifunctional catalyst for the conversion of glucose to 5-hydroxymethylfurfural (HMF). The strong electric field on the catalyst surface formed by DBD plasma induced the enhancement of strong metal oxide support interaction (SMOSI), which could be indicated by XPS. SMOSI could change the embedding degree of metal micro-particles. SMOSI accompanied with the encapsulation of Zr metal nanoparticles could regulate the acid sites of the catalysts. Lewis acid played an important role in the isomerization of glucose to fructose, while Brønsted acid played a key role in the further conversion of glucose. The strong Brønsted acid sites determined the conversion of glucose to HMF. Cr-MOFs@ZrO2-D with the DBD plasma method afforded a higher Brønsted to Lewis acid ratio, compared with Cr-MOFs@ZrO2-S with the hydrothermal method. Glucose conversion of 97.9 % and HMF yield of 38 % were obtained with DMF solvent system and Cr-MOFs@ZrO2-D at 150 °C for 2h. This research provided a new method for preparing Zr-MOFs by DBD plasma and a new idea to comprehensively understand the role of Brønsted and Lewis acid sites in glucose conversion.

Plasmon-Exciton Strong Coupling in Colloidal Au Nanocubes with Layered Molecular J-Aggregates.

Strong coupling between light and matter forms hybrid states, such as exciton-polaritons, which are crucial for advancements in quantum science and technology. Plasmonic metal nanoparticles, with their ultrasmall mode volumes, are effective for generating these states, but the coupling strength is often limited by surface saturation of excitonic materials. Additionally, cubic nanoparticles, which can generate strong local fields, have not been systematically explored. This study investigates strong coupling in Au nanocubes (AuNCs) coupled with J-aggregates, observing spectral splitting in both extinction and scattering spectra. Our findings suggest that smaller AuNCs, with higher-quality resonances and reduced mode volumes, achieve stronger coupling. Furthermore, a layer-by-layer (LBL) coating of J-aggregates on AuNCs results in a ∼21% increase in coupling strength. Simulations reveal the mechanism behind the enhanced coupling and confirm that the layering method effectively increases coupling, surpassing the limitations of the finite surface area of nanoparticles.

Evidence of the Quantum Optical Nature of High-Harmonic Generation

High-harmonic generation is a light up-conversion process occurring in a strong laser field, leading to coherent bursts of extreme ultrashort broadband radiation [Lewenstein , Phys. Rev. A , 2117 (1994)]. As a new perspective, we propose that ultrafast strong-field electronic or photonic processes such as high-harmonic generation can potentially generate nonclassical states of light well before the decoherence of the system occurs [Gorlach , Nat. Commun. , 4598 (2020); Stammer ., Phys. Rev. Lett. , 123603 (2022)]. This could address fundamental challenges in quantum technology such as scalability, decoherence, or the generation of massively entangled states [Lewenstein , Luca Argenti Michael Chini, 27 (2024)]. Here, we report experimental evidence of the nonclassical nature of the harmonic emission in several semiconductors excited by a femtosecond infrared laser. By investigating single- and double-beam intensity cross-correlation [Loudon, Rep. Prog. Phys. , 913 (1980)], we measure characteristic nonclassical features in the single-photon statistics. We observe two-mode squeezing in the generated harmonic radiation, which depends on the laser intensity that governs the transition from super-Poissonian to Poissonian photon statistics. The measured violation of the Cauchy-Schwarz inequality realizes a direct test of multipartite entanglement in high-harmonic generation [Wasak, Phys. Rev. A , 033616 (2014)]. This result is supported by the theory of multimodal detection and the Hamiltonian from which the effective squeezing modes of the harmonics can be derived [Gonoskov , Phys. Rev. B , 125110 (2024); Christ New J. Phys. , 033027 (2011)]. With this work, we show experimentally that high-harmonic generation is a new quantum bosonic platform that intrinsically produces nonclassical states of light with unique features such as multipartite broadband entanglement or multimode squeezing. The source operates at room temperature, using standard semiconductors and a standard commercial fiber laser, opening up new routes for the quantum industry, such as optical quantum computing, communication, and imaging. Published by the American Physical Society 2024

Sensitive imaging of actinide materials in shielded radioactive waste

This paper reports on the development of a method for enhanced non-destructive assay (NDA) of radioactive waste using the novel technique neutron-gamma emission tomography (NGET). The technique relies on the detection of correlated fast neutrons and gamma rays emitted in spontaneous or induced fission. It is based on fast organic scintillators and enables sensitive detection and three-dimensional (3D) localization of the fission events. The technique is passive and does not require moving components. In this work, we apply the NGET technique to the category of radioactive waste which is often referred to as historic or legacy waste. This can include mixed wastes encased in shielded containers many decades ago, before the advent of detailed waste description criteria. These low or intermediate level wastes are often associated with lacking, limited or conflicting documentation. This poses a challenge when assigning the waste to the proper disposal route as well as in deciding whether the waste needs to undergo sorting and conditioning to fulfil waste acceptance criteria both with regards to safe interim storage and to its ultimate disposal. Actinides, such as isotopes of uranium and plutonium, with their typically long half-lives and decay chains are of special interest in this regard since they may challenge the long-term safety assessment in repositories predicated on mainly shorter half-life radionuclides if undetected. Accurate identification and localisation of actinides is also important from a safeguards perspective, especially since they are generally difficult to detect and localise by established passive means due to their relatively weak radiation emissions, in particular in shielded containments and in the presence of strong radiation fields from other radioactive materials. In this paper we present findings of measurements on shielded containments of long-lived radioactive waste performed at the Studsvik site in Sweden, as well as measurements on a laboratory assembly simulating a grouted waste drum. Similarities and differences between the novel NGET technique and a commercially available gamma imaging system are also briefly discussed.

Thermo-optic tuning of quasi bound state in continuum in lithium niobate thin film hetero-nanograting

Lithium niobate (LN) is difficult to etch precisely due to its stable physical and chemical properties. In recent years, more and more research has focused on etchless thin film lithium niobate (TFLN). Here, a one-dimensional SiO2 nanograting structure fabricated on lithium niobate on insulator (LNOI) platform is designed in this study. This nanograting can generate one-dimensional diffraction waves. Then quasi-bound state in the continuum (q-BIC) can be introduced by aligning with the waveguide mode supported by the TFLN, which can achieve a high-quality factor and strong field enhancement, thus improving the interaction between light and matter. Furthermore, we validate the polarization characteristics of the nanograting structure, and measure the thermo-optical tuning sensitivity of the device to be 26.67 pm/K. This finding opens up potential avenues for realizing multi-dimensional tunable and dynamic photonic devices.

Rethinking Assumptions: Assessing the Impact of Strong Magnetic Fields on Luminescence Thermometry.

Luminescence (nano)thermometry has exploded in popularity, offering a remote detection way to measure temperature across diverse fields like nanomedicine, microelectronics, catalysis, and plasmonics. A key advantage is its supposed immunity to strong electromagnetic fields, a crucial feature in many environments. However, this assumption lacks comprehensive experimental verification as most of the proposed luminescent thermometers rely on magnetic ions, such as lanthanides. Here, we address this gap by critically examining the thermometric response of the luminescent molecular thermometer [Tb0.93Eu0.07(bpy)2(NO3)3] (bpy = 2,2'-bipyridine) under high magnetic fields (up to 58 T). Our findings reveal that the conventional intensity-based method for Tb/Eu luminescent thermometers fails even under weak magnetic fields. However, careful data analysis identified specific transitions with minimal magnetic correlation, enabling the thermometer to operate across the entire temperature range up to 20 T, and with larger fields for temperatures exceeding 120 K. This study highlights the strong dependence of thermometric performance on material properties, urging caution, but also offers a path forward for developing robust luminescent thermometers in such environments.

She’s Got Her Mother’s Hair: Unveiling the Origin of Black Hole Magnetic Fields through Stellar to Collapsar Simulations

Abstract Relativistic jets from a Kerr black hole (BH) following the core collapse of a massive star (“collapsar”) is a leading model for gamma-ray bursts (GRBs). However, the two key ingredients for a Blandford–Znajek-powered jet—rapid rotation and a strong magnetic field—seem mutually exclusive. Strong fields in the progenitor star’s core transport angular momentum outward more quickly, slowing down the core before collapse. Through innovative multidisciplinary modeling, we first use MESA stellar evolution models followed to core collapse to explicitly show that the small length scale of the instabilities—likely responsible for angular momentum transport in the core (e.g., Tayler–Spruit)—results in a low net magnetic flux fed to the BH horizon, far too small to power GRB jets. Instead, we propose a novel scenario in which collapsar BHs acquire their magnetic “hair” from their progenitor proto–neutron star (PNS), which is likely highly magnetized from an internal dynamo. We evaluate the conditions for the BH accretion disk to pin the PNS magnetosphere to its horizon immediately after the collapse. Our results show that the PNS spin-down energy released before collapse matches the kinetic energy of Type Ic-BL supernovae, while the nascent BH’s spin and magnetic flux produce jets consistent with observed GRB characteristics. We map our MESA models to 3D general-relativistic magnetohydrodynamic simulations and confirm that accretion disks confine the strong magnetic flux initiated near a rotating BH, enabling the launch of successful GRB jets, whereas a slower-spinning BH or one without a disk fails to do so.