- 标题
- 摘要
- 关键词
- 实验方案
- 产品
-
Faraday Effect and Magnetic Circular Dichroism in Media with Magneto-Plasmonic Nanoparticles and Two-Particle Clusters
摘要： The Faraday rotation and magnetic circular dichroism (MCD) in media containing spherical layered nanoparticles with a ferromagnetic core and a plasmon shell or two-particle clusters consisting of ferromagnetic and plasmonic nanoparticles are studied theoretically. Optical absorption spectra, MCD spectra, the orientation angle of the polarization ellipse, and the ellipticity of the light wave are calculated for these systems in the quasistatic approximation of electrodynamics. It is shown that the magneto-optical response of media with magneto-plasmon inclusions depends on the size of the ferromagnetic component of the inclusion. Moreover, this dependence is more pronounced for layered particles, and the response in the region of plasmon resonance of the noble metal is greater than for two-particle clusters.
关键词： magnetic circular dichroism,Faraday rotation,two-particle cluster,magneto-optical phenomena,magneto-plasmonic nanoparticle,dipole dynamic polarizability
更新于2025-09-12 10:27:22
-
Vacuum-annealed and oxygen plasma treated ellipsometric investigations on molybdenum bronzes and measurements of their thermo optic coefficients and electronic polarizability coefficients
摘要： In this investigation, we have measured the optical constants (n, k) of vacuum evaporated MoO3 thin films and of ZxMoO3 (Z = H+, Li+) bronze thin films being annealed at different temperatures and with different concentrations (x) over the range 298–453 K without and within an oxygen plasma environment using manual ellipsometry. We have also measured mass densities, thermo optic coefficients (TOCs), electronic polarizability coefficients (EPCs) and the coefficients of temperature dependence of density of MoO3 thin film and of its bronzes over the same temperature range. It was found that the change in density and porosity of MoO3 thin film (when annealed at 453 K for 36 h) was not more than 6.4% and 15% respectively from the room temperature data. In the case of bronzes, when the samples H0.203MoO3, Li0.076MoO3 and Li0.133MoO3 were annealed at 453 K within an oxygen plasma over different periods of times, it was found that the overall increase in mass density and decrease in the porosity was not more than 4% and 11%, respectively from the initial data at room temperature. Comparably, when the samples H0.211MoO3 and Li0.27MoO3 were annealed at 453 K within an oxygen plasma over different periods of time, the respective decrease in density and increase in porosity was found not more than 3.4% and 6% from the room temperature data. All these results are mostly due to evolution of H2O which causes diffusion of oxygen leading to shallow and deep localised states in the oxide bronze layers. TOCs and EPCs of samples HxMoO3 (x = 0.203) and LixMoO3(x = 0.076, 0.133) upon annealing at 453 K (without and within an oxygen plasma) over different periods of times have an increase in TOCs and in EPCs, and that increase is from 0.10 × 10?4 K?1 to 13.5 × 10?4 K?1 and 0.13 × 10?27 cm3 K?1 to 3.2 × 10?27 cm3 K?1, respectively. On the other hand, the thermo optic coefficient and the coefficient of temperature dependence of density of MoO3 thin films decrease from ? 1.2 × 10?4 K?1 to ? 8.86 × 10?4 K?1 and ? 1.86 × 10?4 g cm?3 K?1 to ? 15.13 × 10?4 g cm?3 K?1, respectively. In the case of H0.211MoO3 and Li0.27MoO3 when annealed at 453 K over different periods of time within oxygen plasma, the overall decrease in TOC is from ? 0.3 × 10?4 K?1 to ? 4.62 × 10?4 K?1, and the decrease in coefficient of temperature dependence of density is from ? 0.45 × 10?4 g cm?3 K?1 to ? 8.9 × 10?4 g cm?3 K?1. These results are due to linear thermal expansion effect.
关键词： ellipsometry,thermo optic coefficients,electronic polarizability coefficients,MoO3 thin films,molybdenum bronzes
更新于2025-09-11 14:15:04
-
Growth, Optical, Thermal, Mechanical, Laser Damage Threshold and Electrical Polarizability of Cadmium Chloride Doped l-Alanine (LACC) Single Crystal for Optoelectronic Applications
摘要： L-Alanine doped with cadmium chloride crystal was grown by slow evaporation technique in an optimum condition using de-ionized water as solvent. Single crystal x-ray diffraction analysis was carried out to con?rm the unit cell parameters and cell volume. The presence of amine vibrations and carboxylic acid vibrations af?rm the presence of L-alanine in grown material by Fourier transform infrared (FT-IR) analysis. The ultraviolet visible near-infrared region (UV–Vis-NIR) spectrum revealed that the grown crystal has a lower cut-off wavelength at 246 nm and has high transmission in the entire visible region. Further, energy gap and the refractive index of the crystal were also calculated. Thermo-gravimetric (TG) and differential thermal analysis (DTA) were carried out, and it is estimated that the material is thermally stable up to 233°C and the melting point of the crystal was found to be 298°C. The mechanical strength of the material is estimated for various loads using Vicker’s microhardness and it reveals that material belongs to a soft material category. The electrical polarizability was calculated using known values such as valence electron, molecular weight, energy gap and density of the material. Z-scan technique for nonlinear studies was carried out on a LACC crystal to determine the third order nonlinear absorption (b), nonlinear refractive index (n2) and third order nonlinear susceptibility (v(3)) using continuous wave Nd: YAG laser of 532 nm. Grown crystal shows that the material is very much suitable for second harmonic generation for frequency conversion applications.
关键词： electrical polarizability,LDT,Z-scan technique,X-ray diffraction,FT-IR,microhardness,TG-DTA
更新于2025-09-11 14:15:04
-
Nonequilibrium Environment Dynamics in a Frequency-Dependent Polarizable Embedding Model
摘要： Hybrid quantum mechanical/molecular mechanical (QM/MM) models are some of the most powerful and computationally feasible approaches to account for solvent effects or more general environmental perturbations on quantum chemical systems. In their more recent formulations (known as polarizable embedding) they can account for electrostatic and mutual polarization effects between the QM and the MM subsystems. In this paper, a polarizable embedding scheme based on induced dipoles that is both able to describe electron evolution of the embedded QM system in an efficient manner as well as to capture the frequency dependent behavior of the solvent is proposed, namely ωMMPol. The effects of this frequency dependent solvent on a time-dependent model system — the Rabi oscillations of H+2 in a resonant field — are considered. The solvent is shown to introduce only mild perturbations when the excitation frequencies of the solvent and the solute are off-resonant. However, the dynamics of the H+2 are fundamentally changed in the presence of a near-resonant excitation solvent. The effectiveness of ωMMPol to simulating realistic chemical systems is demonstrated by capturing charge transfer dynamics within a solvated system.
关键词： charge transfer dynamics,polarizable embedding,Rabi oscillations,QM/MM models,frequency-dependent polarizability,electron dynamics
更新于2025-09-10 09:29:36
-
A systematic study of the effects of thionation in naphthalene dimide derivatives to tune their nonlinear optical properties
摘要： In the present study, the number and position of sulfur atoms on naphthalene diimide (NDI) is systematically investigated to tune its nonlinear optical (NLO) response properties. Our DFT calculations for third-order polarizability (γ) show that the thionation significantly influences the nonlinear optical property of NDI as it is seen among its several designed derivatives (NDI-1 to NDI-10). The smallest and the largest γzzzz amplitudes are 503.49×10?36 and 1299.5×10?36 esu for NDI-1 (having tetraone group) and NDI-10 (having tetrathione group), respectively. The increase in γzzzz amplitude for NDI-10 is 796×10?36 esu, which is ~150% from the γzzzz amplitude of NDI-1. A comparison of the γzzzz amplitudes of our designed derivatives are made with para-nitroaniline i.e. a prototype NLO molecule. The γzzzz amplitude of pNA is found to be 42.64×10?36 esu at the same B3LYP/DZVP2 level of theory. Using two-level model, the origin of larger γzzzz amplitudes is traced in lower transition energy of NDI-10. Furthermore, the calculation of vertical ionization potentials (VIPs) shows that the thionation does not affect the stability of designed derivatives, where a slight difference of 0.06 eV is seen between the VIPs of NDI-1 (6.63 eV) and NDI-10 (6.57 eV). Thus, a systematic comparison of the third-order polarizability and other electro-optical properties of our designed derivatives shows that our derivative systems possess good potential for their practical realization in the field of optical and NLO materials.
关键词： Naphthalene Diimide,Nonlinear Optical Properties,Third order-NLO polarizability,Polarizability,Frontier Molecular Orbitals
更新于2025-09-09 09:28:46
-
Non-linear Optical Response of Triphenylamine Dyes with D-A-π-A Structure
摘要： In this study, we have designed new triphenylamine dyes with D-A-π-A structure and calculated their electro-optical and non-linear properties. Computational techniques were used to study the effect of additional acceptor in π-conjugated systems on absorption spectra and non-linear properties. All the dyes show absorbance in visible region. During theoretical examination polarizability (α), hyperpolarizability (β) and electronic transitions were calculated. Results indicated that the selection of appropriate lengths of conjugated bridges in dye is very important to design high efficiency dyes. This theoretical frame work would be useful to design other organic dyes.
关键词： Hyperpolarizability,Organic dyes,DFT,Polarizability
更新于2025-09-09 09:28:46
-
Stark shift of excitons and trions in two-dimensional materials
摘要： The effect of an external in-plane electric ?eld on neutral and charged exciton states in two-dimensional (2D) materials is theoretically investigated. These states are argued to be strongly bound, so that electron-hole dissociation is not observed up to high electric ?eld intensities. Trions in the anisotropic case of monolayer phosphorene are demonstrated to be especially robust under electric ?elds, so that ?elds as high as 100 kV/cm yield no signi?cant effect on the trion binding energy or probability density distribution. Polarizabilities of excitons are obtained from the parabolicity of numerically calculated Stark shifts. For trions, a fourth order Stark shift is observed, which enables the experimental veri?cation of hyperpolarizability in 2D materials, as observed in the highly excited states of the Rydberg series of atoms and ions.
关键词： Stark shift,polarizability,two-dimensional materials,electric field,excitons,trions,hyperpolarizability
更新于2025-09-04 15:30:14