Effective Polarizability Research Articles

Tailoring Optical Performance of Polyvinyl Alcohol/Crystal Violet Band-Pass Filters via Solvent Features

Optical filters are essential components for a variety of applicative fields, such as communications, chemical analysis and optical signal processing. This article describes the preparation and characterization of a new optical filter made of polyvinyl alcohol and incremental amounts of crystal violet. By using distinct solvents (H2O, dimethyl sulfoxide (DMSO) and H2O2) to obtain the dyed polymer films, new insights were gained into the pathway that underlies the possibility of tailoring the material’s optical performance. The effect of the dye content on the sample’s main properties was inspected via UV–VIS spectroscopy analysis combined with colorimetry, refractometry and atomic force microscopy experiments. The results revealed that the colorimetric parameters are affected by the dye amount and are dramatically changed when the solvent used for film preparation is different. The rise in the refractive index upon polymer dyeing was due to the synergistic effect of the larger polarizability of the dye and the occurrence of hydrogen bonds among the system components. Spectral data evidenced that samples prepared in H2O and DMSO preserve the absorption characteristics of the added dye, whereas H2O2 acts as an oxidizing agent and enhances transparency. Also, for the first two solvents, multiple absorption edges were noted as a result of dye incorporation, which was responsible for the occurrence of new exciton-like states, hence the band gap reduction. The films processed in H2O were able to block radiations in the 506–633 nm range while allowing other wavelengths to pass with a transmittance above 90%. The samples attained in DMSO presented similar properties, with the difference that the domain of light attenuation was shifted towards higher wavelengths. Atomic force microscopy showed the dye’s effect on the level of surface roughness uniformity and morphology isotropy. The dyed polymer foils in non-oxidizing agents have suitable features for use as band-pass filters.

Infrared photoinduced force near-field spectroscopy of silicon carbide

Silicon carbide (SiC) is a promising microelectronic semiconductor with an infrared response that depends on factors such as polytype, growth conditions, and structuring. Recent advances in infrared nano-imaging techniques provide new opportunities to characterize thin films at the nanoscale. We performed tip-enhanced near-field spectral characterization on various 4H-SiC sample surfaces using photoinduced force microscopy (PiFM). The near-field spectra feature a peak associated with a surface phonon polariton (SPhP) resonance, which proves to be highly sensitive to the material’s surface quality. Interestingly, we found that the power absorption at the tip-sample junction, enhanced by the effective tip polarizability, can account for these PiFM spectra, resulting in a blend of both dispersive and dissipative spectral line shapes. As a potential application, a junction-field effect transistor was imaged to evaluate the technique’s ability to map the surface of different p- and n-doped areas, demonstrating high sensitivity and spatial resolution compared to Raman analysis.

New spin structure constraints on hyperfine splitting and proton Zemach radius

The 1S hyperfine splitting in hydrogen is measured to an impressive ppt precision and will soon be measured to ppm precision in muonic hydrogen. The latter measurement will rely on theoretical predictions, which are limited by knowledge of the proton polarizability effect Δpol. Data-driven evaluations of Δpol have long been in significant tension with baryon chiral perturbation theory. Here we present improved results for Δpol driven by new spin structure data, reducing the long-standing tension between theory and experiment and halving the dominating uncertainty in hyperfine splitting calculations.

Effective M3Y-P2 interaction of study nuclear energy levels for 48Ti in fp shell model

In the fp-shell area of the 48Ti isotope (Z=22, N=26), examine the nuclear excitation energies using the nuclear shell model. The energy levels, total angular momentum, and parity of the nucleons outside the locked core 40Ca are calculated using the OXBASH algorithm for GX2, GX1A, KB3, and effective M3Y-P2 interactions. mixing together two orbital configurations. There was a good agreement between the model space vectors and energy levels and experimental data, but the agreement decreased when the realistic M3YP-2 interaction was used. The core polarisability effect has been used to accommodate the rejected space: core and higher organization via the L-S shell with an effective M3Y-P2 interaction. A comparison of the theoretical and experimental results has been conducted.

Solvatochromism, preferential solvation and excited state dipole moments of flufenamic acid in different solvent polarities

The influence of pure solvent and binary solvent mixtures on the optical properties of non-steroidal anti-inflammatory drug (NSAID) molecule, specifically flufenamic acid (FLA), has been studied using absorption and fluorescence spectroscopic techniques. A bathochromic shift is observed in the emission wavelength of FLA with an increase in the solvent polarity of pure solvents, attributed to the highest stability of the excited state. The spectral properties are correlated with Lippert–Mataga, solvent polarity parameter, Kamlet, and Catalan solvent polarity parameters, suggesting that both general and specific solvent effects influence the spectral properties, with general solvent effects dominating over specific solvent effects. Preferential solvation studies have been carried out in tetrahydrofuran (THF) and water solvent mixture, revealing variations in the preference for solvation of FLA as a function of the mole fraction of water. Solvatochromic data are utilized to estimate the excited state dipole moment in pure solvents using different solvatochromic methods, revealing that the excited state dipole moment of FLA is higher than its ground state counterpart. The increase in dipole moment in the excited state compared to the ground state is explained based on intramolecular charge transfer (ICT), with elaboration and discussion on the possible resonance structure corresponding to ICT, inferring the more polar nature of the excited state compared to the ground state. The effect of solute polarizability on the excited state dipole moment and change in dipole moment is also discussed.

Electro-inductive Effects and Molecular Polarizability for Vibrational Probes on Electrode Surfaces.

A microscopic understanding of electric fields and molecular polarization at interfaces will aid in the design of electrocatalytic systems. Herein, variants of 4-mercaptobenzonitrile are designed to test different schemes for breaking the continuous conjugation between a gold electrode surface and a nitrile group. Periodic density functional theory calculations predict applied potential dependencies of the CN vibrational frequencies similar to those observed experimentally. The CN frequency response decreased more when the conjugation was broken between the benzene ring and the nitrile group than between the electrode and the benzene ring, highlighting molecular polarizability effects. The systems with continuous or broken conjugation are dominated by electro-inductive effects or through-space electrostatic effects, respectively. Analysis of the fractional charge transfer between the electrode and the molecule as well as the occupancy of the CN antibonding orbital provides further insights. Balancing the effects of molecular polarizability, electro-induction, and through-space electrostatics has broad implications for electrocatalyst design.

Influence of crystal system, bond valence and ionic polarizability on the microwave dielectric properties of BaIn2O4 ceramic

BaIn2O4 ceramics with the monoclinic crystal system of the P21/c space group were synthesized using a solid-state reaction method. The sample sintered at 1250 °C exhibits a relative density (94.3 %) and the following microwave dielectric properties: εr = 16.3, Q × f = 49,500 GHz, τf = −73.1 ppm/°C. The bond valence results shows that the deviation of permittivity (24.9 %) between the experimental (εr = 16.3) and calculated values (εrC-M = 13.05) obtained using the Clausius−Mosotti equation may be ascribed to the rattling effect of Ba2+ and In3+. Compared with orthorhombic CaIn2O4 and SrIn2O4 ceramics, BaIn2O4 ceramics have lower Q × f values possibly because of the intrinsic loss caused by nonharmonic lattice vibration. The Edc value (0.43 eV) of BaIn2O4 demonstrates that the defects are caused by the single ionized oxygen vacancies. The intrinsic εr (14.7) and Q × f (105,600 GHz) values of the BaIn2O4 ceramic was inferred through infrared reflectivity spectroscopy. All results demonstrate that the dielectric properties are affected not only by density, ionic polarizability, and rattling effect of cations, but also by the crystal system, and particularly the intrinsic factors.

Whispering gallery mode sensing through the lens of quantum optics, artificial intelligence, and nanoscale catalysis

Ultra-sensitive sensors based on the resonant properties of whispering gallery modes (WGMs) can detect fractional changes in nanoscale environments down to the length and time scales of single molecules. However, it is challenging to isolate single-molecule signals from competing noise sources in experiments, such as thermal and mechanical sources of noise, and—at the most fundamental level—the shot noise limit of classical light. Additionally, in contrast to traditional bulk refractive index measurements, analyzing single-molecule signals is complicated by the localized nature of their interactions with nanoscale field gradients. This perspective discusses multifaceted solutions to these challenges, including the use of quantum light sources to boost the signal-to-noise ratio in experiments and leveraging the power of supercomputers to predict the electronic response of molecules to WGM optoplasmonic fields. We further discuss the role of machine learning in WGM sensing, including several advanced models that can predict molecular polarizability and solvent effects. These advancements in WGM spectroscopy and computational modeling can help to decipher the molecular mechanics of enzymes, enable studies of catalysis on the nanoscale, and probe the quantum nature of molecules.

Effective polarizability of vegetable oils

Effective polarizability of vegetable oils

Dielectric relaxation spectroscopy of hybrid insulating nanofluids in time, distribution, and frequency domain

Improving the dielectric properties of insulating liquids belongs to the modern motivation to optimize the operation of high-voltage devices. Hybrid nanofluids can provide the mentioned improvement, and thus, it is necessary to reveal their hidden potential. This study investigates hybrid nanofluids with different concentrations of magnetite and fullerene nanoparticles, a separate fullerene and magnetic nanofluid, and a base carrier fluid based on gas-to-liquid technology. The investigated samples are subjected to dielectric relaxation spectroscopy analysis at three applied electric field intensities in the time, distribution, and frequency domain. The lack of information about the studied parameters of the mentioned nanofluids is another reason for our experimental measurements. A significant dispersion of the charging current characteristics of nanofluids with magnetic nanoparticles is observed. At lower electric field intensities, the increasing fullerene concentration of the hybrid nanofluids reduces the charging currents up to a charging time of 200 s. Magnetic nanofluid shows the highest values of conductivity currents. Experiments show that the suspension of fullerene in the base oil causes a higher charging current and a more pronounced relaxation response than pure base oil. Significant relaxation information in the low-frequency band is detected from the distribution spectra. At higher electric field intensities in the low-frequency spectrum, the relaxation peaks decrease when the concentration of fullerene in hybrid nanofluids increases. The distribution area shows the effect of higher polarizability of magnetite nanoparticles. Compared to lower electric field intensities, at the value of 333.3 kV/m, several polarization processes are captured in the entire frequency spectrum. The frequency-dependent complex permittivity confirms the findings from the time and distribution domains. Comparing the distribution domain with the frequency domain shows higher sensitivity and accuracy in capturing relaxation processes in the distribution domain.

Density dependence for the dielectric permittivity of simple gases and liquids

The present work is devoted to the analysis of polarization effects in atomic systems of the argon type. Special attention is given to the manifestation of the polarizabilities of two particles in the density dependence of the dielectric permittivity of a system and its effective molecular polarizability. It is shown that the effective polarizability of a molecule in the liquid state of a system is mainly caused by deviation of the molecular distribution in the first coordination layer from the spherical one. Due to this, the atomic polarizability inherent to rarefied gas increases practically twice near the triple point. The interconnection between the atomic polarizability and the proper volume of an atom is discussed in detail. It is established that the optimal size of an atom follows from the kinematic shear viscosity measurements.

Strongly Bound Excitons and Anisotropic Linear Absorption in Monolayer Graphullerene.

Graphullerene is a novel two-dimensional carbon allotrope with unique optoelectronic properties. Despite significant experimental characterization and prior density functional theory calculations, unanswered questions remain as to the nature, energy, and intensity of the electronic and optical excitations. Here, we present first-principles calculations of the quasiparticle band structure, neutral excitations, and absorption spectra of monolayer graphullerene and bulk graphullerite, employing the GW-Bethe-Salpeter equation (GW-BSE) approach. We show that strongly bound excitons dominate the absorption spectrum of monolayer graphullerene with binding energies up to 0.8 eV, while graphullerite exhibits less pronounced excitonic effects. Our calculations also reveal a strong linear polarization anisotropy, reflecting the in-plane structural anisotropy from intermolecular coupling between neighboring C60 units. We further show that the presence of Mg atoms, crucial to the synthesis process, induces structural modifications and polarizability effects, resulting in a ∼1 eV quasiparticle gap renormalization and a reduction in the exciton binding energy to ∼0.6 eV.

Effects of Heavy p‐Block Elements on Photophysical Properties of π‐Conjugated Complexes and Organoelement Compounds

π‐Conjugated compounds exhibit remarkable photophysical properties, such as strong light absorption and emission, and are applicable to organic devices, bioimaging, and sensing systems. The introduction of p‐block elements into π‐conjugated systems is presumable as a critical strategy for modulating their properties. Nevertheless, the type of utilized elements has been limited to the second and third‐period ones because it is difficult to construct critical electronic interactions between heavier atoms and carbon‐based π‐conjugated scaffolds. On the other hand, it has been recently suggested that the heavier p‐block elements are able to induce significant changes in the optoelectronic properties of π‐conjugated systems thanks to their large size, high polarizability, and heavy atom effect. Although there are much room to explore effects of heavy‐atom substitution on physical and electronic properties of conjugated systems, various characters have been discovered. Hence, this review mainly focuses on the relationships between the types of p‐block elements and the optical properties of their representative complexes and organoelement compounds, particularly light absorption and emission.

Melting points of compounds of the heavier Group 14 elements: the influence of the polarizability effect

Melting points of compounds of the heavier Group 14 elements: the influence of the polarizability effect

The distortion and misinterpretation of TEM responses caused by the IP effect

Abstract Transient electromagnetic surveys are commonly conducted to map the distribution of resistivity, a key physical property in mineral exploration and other geological prospecting problems. However, the responses obtained in regions associated with chargeable minerals are always distorted by the induced polarization effects. In this study, the distorted responses are initially simulated in the frequency domain employing the Cole–Cole complex resistivity model and subsequently converted into the time domain through a time-frequency transformation method. A uniform half-space model is employed to validate the algorithm and illustrate the distortion characteristics of the responses in polarizable formations. A three-layer model is designed to estimate the misinterpretation of slightly complicated models. An actual misinterpretation is demonstrated by field responses containing induced polarization effects collected in the Wulong Gold Mine. The results show that the distortions under different geoelectrical conditions are consistent, enhancing the responses in the early stage and counteracting the responses in the late stage. The strong induced polarizable effects distort the responses by causing explicit sign reversals, whereas the weak induced polarizable effects only distort the decay rate of the responses. These distortions are prone to causing misinterpretations and resulting in excessively intricate geological structures.

An innovative method for predicting oxidation reaction rate constants by extracting vital information of organic contaminants (OCs) based on diverse molecular representations

The reaction rate constant (k) of oxidants with organic contaminants (OCs) is an important parameter to assess the efficiency of oxidants in removing contaminants. In this study, the degradation of OCs in three oxidation systems was evaluated. The modeling process applied three molecule representations (molecular descriptors (MD), quantum chemical descriptors (QCD) and MACCS fingerprints) and their variable integrations. Models based on integration molecule representations show significant performance improvements. Eventually, the optimal models for ozone, chlorine dioxide and hypochlorite were found to be (MD+QCD)-XGBoost (R2tra = 0.982, Q2tra = 0.715), (MD+QCD+MACCS)-XGBoost (R2tra = 0.982, Q2tra = 0.778), and (MD+QCD+MACCS)-CatBoost (R2tra = 0.856, Q2tra = 0.709) model, respectively. Here, we introduced a new perspective that differed from focusing on machine learning (ML) algorithm optimization. This perspective centered on the input variables (i.e., molecular representations) of models to improve model performance by capturing the key properties of OCs comprehensively. Furthermore, the key effects of pH, ionization potential, orbital energy, polarizability and electronegativity on the oxidation reaction in different oxidation systems were clarified. We hope that the mechanism explanation in this study can provide valuable insights for understanding the mechanism of various oxidation reactions of complex OCs.

Nonlinear Optical Refraction and Absorption Features of Methyl Orange Dye in Polar Solvents.

Herein, we report the nonlinear optical (NLO) refraction and absorption features of azo dye namely, methyl orange (MO) dissolved in ethanol, methanol, acetone, 1-propanol, DMF and DMSO. The UV-Visible absorption study reveals that the maximum absorption spectrum of MO dye appeared towards longer wavelength by increasing the solvent polarizability is the result of red shift or bathochromic shift. The Z-scan method is utilized to measure the third-order NLO features of MO dye in different polar solvents. A continuous wave laser with 5-mW power and an excitation wavelength of 405nm is employed in the Z-scan technique. The NLO features including nonlinear index of refraction (n2), nonlinear coefficient of absorption (β) and third-order NLO susceptibility (χ3) are calculated to be the order of 10-7 cm2/W, 10-2cm/W and 10-7 esu, respectively. The NLO index of refraction shows peak-valley transmittance is the result of self-defocusing and NLO absorption coefficient exhibits both positive and negative nonlinearity owing to saturable absorption (SA) and reverse saturable absorption (RSA). The effect of solvent polarizability and dipole moment on third-order NLO susceptibility of MO dye is discussed. Based on the experimental results, an azo dye MO appears to be a promising option for NLO applications in the future.

Characterizing chiroptical properties of 2D/3D structures based on an improved coupled dipole theory.

To reveal the difference/connection between two-dimensional and three- dimensional (2D and 3D) chiroptical properties and their relation with 2D/3D symmetry/breaking, we develop an improved coupled dipole theory (ICDT) based on a model system of nanorod (NR) dimer. Our analytical ICDT can overcome the shortcoming of the traditional coupled dipole theory and points out the important role of scattering circular dichroism (SCD) in characterizing 2D chirality. The ICDT, supported by finite-difference time-domain (FDTD) simulation, reveals the physical origin of 2D chiroptical response: the interaction induced asymmetric effective polarizability for two identical NRs in a symmetry broken configuration. By tuning the NR's position/inter-particle distance, we find an optimal structure of maximum SCD due to the competition between geometric symmetry breaking and interaction. In addition, the interplay between 2D in-plane mirror symmetry breaking and three-dimensional (3D) mirror symmetry breaking leads to a symmetry broken system with zero SCD. The relation between chirality and reciprocity has also been addressed.

Polarization characteristics and structural modifications of Cu nanoparticles under high electric fields

High electric fields affect the diffusion dynamics of atoms on a metal surface, causing biased surface diffusion that possibly leads to the growth of intensively field emitting protrusions and consequent vacuum breakdown (VBD). The scientific understanding of this process, as well as other fundamental VBD initiation mechanisms, is far from complete. Here we investigate the exact atomic behaviour of metal surfaces exposed to extremely high electric fields using density functional theory (DFT). Previous theories describe the field-surface dynamics in terms of the effective dipole moments and polarizability of surface atoms, disregarding higher-order (hyperpolarizability) terms. The validity of this approximation has been evaluated only for electric fields up to 3 GV/m, due to computational limitations of the plane-wave DFT basis used in previous works. In this work, we test the validity of this approximation for a much wider field range, relevant for VBD and field emission (FE), using Cu nanoparticles as our test structures. We find that although such high fields can change the entire structure of Cu nanoparticles, their energetics are described very precisely by the permanent dipole moment and polarizability terms. Thus, we show that neglecting the hyperpolarizability terms is valid even for field values that exceeds the range that is relevant for intense FE and VBD. This work lays a solid foundation for further developing atomic-level simulation models for electric field-induced surface diffusion on metal surfaces and its effects on protrusion growth and VBD initiation.

QED of Bernabéu-Tarrach sum rule for electric polarizability and its implication for the Lamb shift

We attempt to rehabilitate a sum rule (proposed long ago by Bernabéu and Tarrach) which relates the electric polarizability of a particle to the total photoabsorption of quasireal longitudinally polarized photons by that particle. We discuss its perturbative verification in quantum electrodynamics (QED), which is largely responsible for the skepticism about its validity. The failure of the QED test can be understood via the Sugawara-Kanazawa theorem and is due to the nonvanishing contour contribution in the pertinent dispersion relation. We show another example where this contribution is absent and the perturbative test works exactly. On the empirical side, we show that the sum rule gives a reasonable estimate of the πN-channel contribution to the proton electric polarizability. If this sum rule is valid indeed, there should be a sum rule for the so-called “subtraction function” entering the data-driven calculations of the polarizability effects in the Lamb shift. We have written down a possible sum rule for the subtraction function and verified it in a perturbative calculation. Published by the American Physical Society 2024