Dynamic Polarization Research Articles

Machine Learning for Polaritonic Chemistry: Accessing Chemical Kinetics.

Altering chemical reactivity and material structure in confined optical environments is on the rise, and yet, a conclusive understanding of the microscopic mechanisms remains elusive. This originates mostly from the fact that accurately predicting vibrational and reactive dynamics for soluted ensembles of realistic molecules is no small endeavor, and adding (collective) strong light-matter interaction does not simplify matters. Here, we establish a framework based on a combination of machine learning (ML) models, trained using density-functional theory calculations and molecular dynamics to accelerate such simulations. We then apply this approach to evaluate strong coupling, changes in reaction rate constant, and their influence on enthalpy and entropy for the deprotection reaction of 1-phenyl-2-trimethylsilylacetylene, which has been studied previously both experimentally and using ab initio simulations. While we find qualitative agreement with critical experimental observations, especially with regard to the changes in kinetics, we also find differences in comparison with previous theoretical predictions. The features for which the ML-accelerated and ab initio simulations agree show the experimentally estimated kinetic behavior. Conflicting features indicate that a contribution of dynamic electronic polarization to the reaction process is more relevant than currently believed. Our work demonstrates the practical use of ML for polaritonic chemistry, discusses limitations of common approximations, and paves the way for a more holistic description of polaritonic chemistry.

Physical insight into optical spectroscopy of chiral covalent organic pillars as molecular nanotubes

In this paper, we theoretically investigate chiral covalent organic pillars synthesized by connecting rim-desymmetrized macrocycle, stimulated by recent experimental synthesis [Nat. Synth. 2023, 2, 395–402]. Transition densities reveal physical mechanism of spectral intensity in one-photon absorption (OPA) and two-photon absorption (TPA), and solvent effect strongly influence the spectral profile and intensity in TPA, but little influence the spectrum in OPA. The intra-unit and inter-unit charge transfer are visualized in five phenylenediamine linkers. The chirality of covalent organic pillars is revealed by electronic circular dichroism (ECD) spectroscopy, and interpreted by the visualized transition electric and magnetic dipole moments. Molecular vibrational information is demonstrated by normal and resonance Raman spectra and vibrational modes. The visualization of static and dynamic (hyper) polarization can reveal the physical mechanisms of polarization dependent normal and resonance Raman scattering. Our results provide deeper understanding on the physical mechanism of chiral covalent organic pillars as molecular nanotubes.

Quantitative Characterization of Passivation Process of Steel Reinforcement in Concrete towards Durability against Anticorrosion Based on Electrochemical Methods

The passivation behavior of steel reinforcements in concrete is significantly influenced by the environment, concrete pore solution, and the passive film formed on the steel surface. The present study used electrochemical methods to successfully characterize the passivation process of steel reinforcements in concrete. The passivation behavior of commonly used HRB400 steel reinforcement material in concrete was studied using various electrochemical parameters quantitatively. As the soaking test time increased, the OCP gradually increased and stabilized after 5 days, indicating that the steel electrode transitioned from an active state to a passive state in the simulated liquid environment of concrete. The steel reinforcement developed a protective passive film that reduced its tendency to corrode. According to EIS, after soaking for one day, the steel electrode showed significant early passivation, indicated by an increase in its arc diameter. The WE arc gradually increased in the first 5 days of immersion, suggesting dynamic passive film formation and development. Beyond 5 days, the passive film stabilized with minimal further changes in its impedance spectrum, indicating carbon steel electrode passivation. The working electrode’s impedance increased significantly on the fifth day, and gradually increased slightly after 10 days, indicating comprehensive coverage by the oxide film. Attributed to the growth and development of the oxide film, the electrode resistance reached a relatively stable state after the fifth day. The shift in corrosion potential offers an indication of the level of passivation of the steel reinforcements. The decrease in the anode Tafel slope and increase in the corrosion potential indicate the formation and stabilization of an oxide film on the steel surface, which is beneficial for its long-term durability in concrete structures. By analyzing the OCP, EIS, and dynamic potential polarization curve method data, it is possible to gain insights into the passivation behavior of steel reinforcements in concrete structures. This study aims to provide a basis for optimizing the corrosion protection of steel reinforcements in concrete structures. The significance of this study lies in a deep understanding of the passivation behavior of steel bars in concrete, providing a theoretical basis for improving the durability and lifespan of steel bars in concrete structures.

Underwater dynamic polarization imaging without dependence on the background region.

Active-polarization imaging holds significant promise for achieving clear underwater vision. However, only static targets were considered in previous studies, and a background region was required for image restoration. To address these issues, this study proposes an underwater dynamic polarization imaging method based on image pyramid decomposition and reconstruction. During the decomposition process, the polarized image is downsampled to generate an image pyramid. Subsequently, the spatial distribution of the polarization characteristics of the backscattered light is reconstructed by upsampling, which recovered the clear scene. The proposed method avoids dependence on the background region and is suitable for moving targets with varying polarization properties. The experimental results demonstrate effective elimination of backscattered light while sufficiently preserving the target details. In particular, for dynamic targets, processing times that fulfill practical requirements and yield superior recovery effects are simultaneously obtained.

Switchable multi-wavelength coherent polarization manipulation component based on single-layered hollowed S-shaped metasurface

High-performance metasurface polarization manipulation components have important applications in the fields of polarization imaging, polarization detection, and communication. Single-layered metasurface components have attracted a great deal of interest, but it is still a challenge to realize high-efficiency and dynamic polarization manipulation. Combined with coherent control techniques, we propose a single-layered hollowed S-shaped metasurface design that may accomplish multi-wavelength polarization switching in the optical to near-infrared band. The single-layered metasurface enables a real-time switchable effect between dual-wavelength and single-wavelength polarization properties by controlling the phase difference between two coherent counter-propagating lights. The physical mechanism of switchable multi-wavelength coherent polarization manipulation is elucidated based on the electric field distribution of the hollowed S-shaped structure. The effect of metal layer thickness on the switchable coherent polarization properties is investigated in detail. The proposed hollowed S-shaped metasurface significantly improves the polarization performance of the single-layered structure, which is expected to facilitate the development of switchable and compact polarization components.

Synthesis, Corrosion Inhibition Efficiency in Acidic Media, and Quantum Chemical Studies of Some Hydrazine Derivatives

In this work, four hydrazone Schiff base derivatives N-(2,4-Dinitro-phenyl)-N’-(1H-pyrrol-2-ylmethylene)-hydrazine (1a), N-Benzo [1,3] dioxol-5-ylmethylene-N’-(2,4-dinitro-phenyl)-hydrazine (1b), (E)-5-((2-(2,4-dinitrophenyl)hydrazono)methyl)-2-hydroxybenzoic acid (1c) and (E)-1-(2,4-dinitrophenyl)-2-(2-methoxybenzylidene)hydrazine (1d) were synthesized by reaction of four aldehydes namely pyrrole-2-carboxaldehyde, piperonal, 5-formylsalicylic acid, and o-vanillin with 2,4-dinitrophenyl hydrazine to produce the final compounds 1a, 1b, 1c, and 1d, respectively. These four compounds were investigated as corrosion inhibitors in aqueous mild acidic static solution. FTIR, HNMR, and elemental analysis were used to elucidate the chemical structure of the synthesized inhibitors. Using potential dynamic polarization measurements, these inhibitors’ efficiency in preventing C-steel corrosion in 1.00 M HCl was studied. The results of the experiments revealed that 1×10−3 M is the ideal concentration for 1a, 1b, 1c, and 1d, and that the corresponding inhibition efficiencies for these subunits were 80.70%, 91.30%, 91.34, and 88.80%, respectively. The best corrosion inhibitors were compounds 1b and 1c. Furthermore, studies suggested that these substances are mixed-type inhibitors and that the efficiency of the inhibition is strongly correlated with their quantity. Quantum paraments included Dipole moment, energy band gap (ΔE), value of energy of lowermost unoccupied molecular orbital (ELUMO), and energy of high most occupied molecular orbital (EHOMO) using Molecular Operating Environment MOE, Gaussian, and HyperChem software packages were determined which demonstrated strong agreement between algorithmic and practical findings.

How Permanent Are the Permanent Macrodipoles of Anthranilamide Bioinspired Molecular Electrets?

Dipoles are ubiquitous, and their impacts on materials and interfaces affect many aspects of daily life. Despite their importance, dipoles remain underutilized, often because of insufficient knowledge about the structures producing them. As electrostatic analogues of magnets, electrets possess ordered electric dipoles. Here, we characterize the structural dynamics of bioinspired electret oligomers based on anthranilamide motifs. We report dynamics simulations, employing a force field that allows dynamic polarization, in a variety of solvents. The results show a linear increase in macrodipoles with oligomer length that strongly depends on solvent polarity and hydrogen-bonding (HB) propensity, as well as on the anthranilamide side chains. An increase in solvent polarity increases the dipole moments of the electret structures while decreasing the dipole effects on the moieties outside the solvation cavities. The former is due to enhancement of the Onsager reaction field and the latter to screening of the dipole-generated fields. Solvent dynamics hugely contributes to the fluctuations and magnitude of the electret dipoles. HB with the solvent weakens electret macrodipoles without breaking the intramolecular HB that maintains their extended conformation. This study provides design principles for developing a new class of organic materials with controllable electronic properties. An animated version of the TOC graphic showing a sequence of the MD trajectories of short and long molecular electrets in three solvents with different polarities is available in the HTML version of this paper.

Detailed analysis of the 6Li breakup in the field of the 209Bi nucleus

Abstract At energies between 24 and 50 MeV, the angular distributions of 6Li + 209Bi elastic scattering are reanalyzed phenomenologically as well as microscopically. The performed analysis adds to previous studies and aims to further explore the cluster nature of the 6Li nucleus by examining the associated breakup effects on the elastic scattering channel, in addition to probing the consistency of the different implemented potentials in reproducing the considered data. The strong coupling to the breakup channel has a strong influence on elastic data and reproduces a repulsive dynamical polarization potential (DPP), which dramatically reduces the real potential strengths. Such an observed effect was simulated by introducing a semi-microscopic repulsive DPP as well as by applying the continuum discretized coupled channels (CDCC) method. The analysis was extended to check the effect of direct deuteron stripping 209Bi(6Li,d)211Po on the elastic 6Li + 209Bi channel.

Passivation mechanisms of CoCrFeNiMox (x = 0, 0.1, 0.2, 0.3) high entropy alloys and MP35N in 3.5 wt% NaCl aerated aqueous solutions

The passivation mechanisms of CoCrFeNiMox alloys and MP35N in 3.5 wt% NaCl aerated aqueous solutions during dynamic polarization are investigated. Mo oxides in the passivation film can stabilize Cr-rich oxides and/or hydroxides. Furthermore, the formation of CoMoO4 and NiMoO4 expands passivation region Ⅰ. Fe-rich compounds replace Cr-rich ones for CoCrFeNiMox (x = 0.1, 0.2), leading to passivation region Ⅱ which is never found for MP35N. The model based on density function theory indicates that Mo is easier attacked than the other metals by Cl and plays a sacrificial role for Cr, supported by results of the released ion concentrations.

Study on the Corrosion Resistance of Supersonic Plasma Spraying Al2O3 Thin Layer and SiO2 Sealer Alternately Deposited Coating

The longevity of thermally sprayed ceramic coatings is often difficult to achieve in corrosive environments. In this paper, an alternating sealing coating technology was used to seal supersonic plasma sprayed Al2O3 coatings. Scanning electron microscopy (SEM) and X-ray diffraction (XRD) were used to characterize the coating microstructure of Al2O3 coatings and seal coats. The corrosion behavior of alternating sealing coating, traditional sealed coating, and spray coating at 5 wt.% NaCl was studied by the electrochemical test method (dynamic polarization) and immersion corrosion experiments. The results show that the alternating sealing coating is better in preventing the production of through holes and hindering the inward diffusion of corrosive media than traditional sealed coatings, and further increases the thickness of the sealing layer. Compared with the traditional sealing coating, the porosity of alternating sealing coating is decreased by 70.5%, the corrosion potential is increased by 74 mV, and the corrosion current density is decreased by about 78%, which confers better long-term corrosion resistance.

Isotope engineering for spin defects in van der Waals materials.

Spin defects in van der Waals materials offer a promising platform for advancing quantum technologies. Here, we propose and demonstrate a powerful technique based on isotope engineering of host materials to significantly enhance the coherence properties of embedded spin defects. Focusing on the recently-discovered negatively charged boron vacancy center ([Formula: see text]) in hexagonal boron nitride (hBN), we grow isotopically purified h10B15N crystals. Compared to [Formula: see text] in hBN with the natural distribution of isotopes, we observe substantially narrower and less crowded [Formula: see text] spin transitions as well as extended coherence time T2 and relaxation time T1. For quantum sensing, [Formula: see text] centers in our h10B15Nsamples exhibit a factor of 4 (2) enhancement in DC (AC) magnetic field sensitivity. For additional quantum resources, the individual addressability of the [Formula: see text] hyperfine levels enables the dynamical polarization and coherent control of the three nearest-neighbor 15Nnuclear spins. Our results demonstrate the power of isotope engineering for enhancing the properties of quantum spin defects in hBN, and can be readily extended to improving spin qubits in a broad family of van der Waals materials.

Low-loss integrated dynamic polarization controller based on silicon photonics

<sec>A dynamic polarization controller (DPC) is an important component in fiber optic communication, optical imaging, and quantum technologies. The DPC can transform any input state of polarization (SOP) into any desired SOP to overcome polarization-related impairments resulting from high internally and externally induced birefringence. In this work, a low-loss silicon photonics-integrated DPC is designed and demonstrated experimentally. The whole chip is fabricated by using industry-standard silicon-on-insulator technology. Using the edge-coupling method, the coupler loss is reduced to less than 2 dB, and the total loss of DPC is reduced to 5.7 dB. Using a variable-step simulated annealing method, for a low-noise photodetector and high-static-extinction-ratio device, a dynamic polarization extinction ratio can reach more than 30 dB. The size of the DPC on the chip is 5.20 mm × 0.12 mm × 0.80 mm.</sec><sec>The DPC utilizes a 0°/45°/0°/45° structure, which can realize arbitrary polarization-based coordinate conversion with endless polarization control. The 0° and 45° transform structures and matrices are presented, and the principle of the 0° and 45° structures is explained in detail by using the Poincaré sphere.</sec><sec>A simulation using Lumerical is conducted to optimize the polarization rotator-splitter, which can transform the TM<sub>0</sub> mode light in one waveguide into the TE<sub>0</sub> mode light in the other waveguide while the TE<sub>0</sub> mode light in one waveguide remains unchanged. Based on the optimized structure, the static polarization extinction ratio of DPC can be measured to be a value greater than 40 dB.</sec><sec>The thermal phase shift (TPS) is characterized by using a Mach–Zehnder modulator. The length of the TPS is 400 μm, and the resistance of the metal heater is 2.00 kΩ. The maximum power consumed by the four TPSs is a total of 0.2 W. The modulation bandwidth of the DPC designed by our group is approximately 30 kHz. By considering an applied voltage of 5.6 V in the case of the TPS, the bandwidth–voltage product is 5.6 × 30 = 168 kHz·V.</sec><sec>To optimize the DPC parameters, such as the step length, electronic noise, and static polarization extinction ratio, numerical simulation results of the simulated annealing approach are analyzed in detail.</sec><sec>In conclusion, a low-loss silicon photonics-integrated DPC is designed and demonstrated experimentally. A dynamic polarization extinction ratio is obtained to be greater than 30 dB by using the variable-step simulated annealing method. The DPC is expected to be utilized in fiber or quantum communication systems to minimize size and further decrease costs.</sec>

Low-loss integrated dynamic polarization controller based on silicon photonics

<sec>A dynamic polarization controller (DPC) is an important component in fiber optic communication, optical imaging, and quantum technologies. The DPC can transform any input state of polarization (SOP) into any desired SOP to overcome polarization-related impairments resulting from high internally and externally induced birefringence. In this work, a low-loss silicon photonics-integrated DPC is designed and demonstrated experimentally. The whole chip is fabricated by using industry-standard silicon-on-insulator technology. Using the butting coupling method, the coupler loss is reduced to less than 2 dB, and the total loss of DPC is reduced to 5.7 dB. Using a variable-step simulated annealing method, for a low-noise photodetector and high-static-extinction-ratio device, a dynamic polarization extinction ratio can reach more than 30 dB. The size of the DPC on the chip is 5.20 mm × 0.12 mm × 0.80 mm.</sec><sec>The DPC utilizes a 0°/45°/0°/45° structure, which can realize arbitrary polarization-based coordinate conversion with endless polarization control. The 0° and 45° transform structures and matrices are presented, and the principle of the 0° and 45° structures is explained in detail by using the Poincaré sphere.</sec><sec>A simulation using Lumerical is conducted to optimize the polarization rotator-splitter, which can transform the TM<sub>0</sub> mode light in one waveguide into the TE<sub>0</sub> mode light in the other waveguide while the TE<sub>0</sub> mode light in one waveguide remains unchanged. Based on the optimized structure, the static polarization extinction ratio of DPC can be measured to be a value greater than 40 dB.</sec><sec>The thermal phase shift (TPS) is characterized by using a Mach–Zehnder modulator. The length of the TPS is 400 μm, and the resistance of the metal heater is 2.00 kΩ. The maximum power consumed by the four TPSs is a total of 0.2 W. The modulation bandwidth of the DPC designed by our group is approximately 30 kHz. By considering an applied voltage of 5.6 V in the case of the TPS, the bandwidth–voltage product is 5.6 × 30 = 168 kHz·V.</sec><sec>To optimize the DPC parameters, such as the step length, electronic noise, and static polarization extinction ratio, numerical simulation results of the simulated annealing approach are analyzed in detail.</sec><sec>In conclusion, a low-loss silicon photonics-integrated DPC is designed and demonstrated experimentally. A dynamic polarization extinction ratio is obtained to be greater than 30 dB by using the variable-step simulated annealing method. The DPC is expected to be utilized in fiber or quantum communication systems to minimize size and further decrease costs.</sec>

Synergistic Control on Co/Cu Galvanic Corrosion and Its Application for Co Barrier Chemical Mechanical Planarization in Alkaline Slurry

Selective chelation and protective film formation were synergistically combined to achieve Co/Cu galvanic corrosion control. Chelating agent imionodisuccinic acid and protective film formation agent benzotriazole are strategically chosen for fulfilling the above proposed task in alkaline solution for Co barrier chemical mechanical planarization (CMP). Chronopotentiometry and linear dynamic potential polarization methods are used to investigate the thermodynamics and kinetics of Co and Cu corrosion. A synergistic control of Co/Cu corrosion was accomplished by judiciously balancing the power of selective chelation and protective film formation. This systematic approach can be expanded to systematically design other metal CMP slurries to fulfil the desired polishing performance.

Charge target collection from different triboelectrification domains by electrostatic induction and polarization enabled air discharges

New channels of dynamic dielectric polarization enabled discharges (DPD) are proposed and combined with electrostatic induction enabled discharges (EID) to achieve charge target collection from different triboelectrification domains.

Elucidation of the exchange interaction in photoexcited three-spin systems - a second-order perturbational approach.

Photogenerated three-spin systems show great potential for applications in the field of molecular spintronics. In these systems, the exchange interaction in the electronically excited state dictates their magnetic properties. To design such molecules for specific applications, it is thus important to understand how the sign and magnitude of the exchange interaction can be controlled. For this purpose, we developed a perturbational approach, based on previous work by the groups of de Loth and Malrieu, that allows for the direct calculation of the exchange interaction and its individual contributions up to the second order and implemented it within the ORCA program package. Within this manuscript, we present the derivation of the individual second-order contributions, provide an overview of the implementation of the code and illustrate its performance. We show that, using this perturbational approach in combination with state-averaged orbitals from minimal active space calculations, accurate values for the exchange interaction can be computed for organic nitroxides. Further, we demonstrate that the weight of the ionic determinants in the orbital optimisation of the CASSCF procedure is crucial for the computation of accurate exchange couplings. In the case of photoexcited chromophore-radical systems, we find that the dynamic spin polarisation effect constitutes the most important contribution to the exchange interaction, whereby the sign of this contribution determines the sign of the exchange interaction.

Unveiling autophagy and aging through time-resolved imaging of lysosomal polarity with a delayed fluorescent emitter.

Detecting the lysosomal microenvironmental changes like viscosity, pH, and polarity during their dynamic interorganelle interactions remains an intriguing area that facilitates the elucidation of cellular homeostasis. The subtle variation of physiological conditions can be assessed by deciphering the lysosomal microenvironments during lysosome-organelle interactions, closely related to autophagic pathways leading to various cellular disorders. Herein, we shed light on the dynamic lysosomal polarity in live cells and a multicellular model organism, Caenorhabditis elegans (C. elegans), through time-resolved imaging employing a thermally activated delayed fluorescent probe, DC-Lyso. The highly photostable and cytocompatible DC-Lyso rapidly labels the lysosomes (within 1 min of incubation) and exhibits red luminescence and polarity-sensitive long lifetime under the cellular environment. The distinct variation in the fluorescence lifetime of DC-Lyso suggests an increase in local polarity during the lysosomal dynamics and interorganelle interactions, including lipophagy and mitophagy. The lifetime imaging analysis reveals increasing lysosomal polarity as an indicator for probing the successive development of C. elegans during aging. The in vivo microsecond timescale imaging of various cancerous cell lines and C. elegans, as presented here, therefore, expands the scope of delayed fluorescent emitters for unveiling complex biological processes.

Effect of rotational shear on the dielectric dispersion of a nematic liquid crystal above the Freedericksz threshold field.

Rheo-dielectric studies of soft materials provide important information on the dynamic structure and electric polarization. We study the dielectric dispersion of a nematic liquid crystal by applying a high AC probe field without a DC bias and a low AC probe field with a high DC bias under steady rotational shear. The dielectric anisotropy of the nematic is positive and the applied electric field is parallel to the velocity gradient with a magnitude larger than the Freedericksz threshold field. We find that the dielectric dispersion and the relaxation frequencies are strongly shear rate dependent. The analysis of the results based on a simple physical model shows that the effective dielectric constant of the nematic with non-uniform director tilt in the shear plane can be modelled as a series combination of parallel and perpendicular components. Our experiments demonstrate changes in dielectric dispersion are due to molecular reorientation under the influence of the competing effects of hydrodynamic and dielectric torques.

Research on dynamic polarization control in continuous variable quantum key distribution systems

In a commercial fiber-based quantum key distribution system, the local and signal optical fields are transmitted through long distance fibers by using time division multiplexing and polarization multiplexing. The state of polarization of the optical field is inevitably disturbed by random birefringence of the standard single-mode fiber caused by external complex environments. This drift of the state of polarization significantly affects the balanced homodyne detection results and the secret key rate. Therefore, the key technology of the dynamic polarization control unit is crucial for the system in a large-scale commercial application. We theoretically analyze and prove that the polarization control unit only needs the combination of two degrees of freedom when considering the result of an arbitrary polarization extinction ratio at the receiver of the system. To overcome the influence of polarization variations, we propose a chaotic monkey algorithm based on Bayesian parameter estimation method and implement intelligence algorithm on field programmable gate array (FPGA) hardware under pulsed light with an integral-type detector for the dynamic polarization control unit. The simulation results show that the optimal combination is four degrees of freedom and the optimal prior distribution is an exponential distribution among various distributions in the dynamic polarization control unit. According to the simulation results, the experimental results show that the achieved polarization extinction ratio is over 30 dB and the average time of polarization control is 400 μs for a single random polarization scrambling. By combining the dynamic polarization control unit with the system, we demonstrate the continuous variable quantum key distribution (CV-QKD) under a continuous polarization scrambling scope of 0－2 krad/s and verify its effectiveness. In addition, the methods presented will improve the performance of the system and expand the range of applications even under strong external disturbance.

Parameters of Dynamic Polarization of As Nuclei in Silicon at Low Temperatures and Strong Magnetic Fields

Parameters of Dynamic Polarization of As Nuclei in Silicon at Low Temperatures and Strong Magnetic Fields