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Spectroscopic Ellipsometry of fluid and gel phase Lipid Bilayers in hydrated conditions
摘要： The biological membranes play a crucial role in the various biological processes due to their characteristic physical properties. The parameters such as membrane composition, thickness undulations, and the influence of external stimuli play a crucial role in the phase state behavior of biological membranes. The supported lipid bilayer (SLBs) systems closely represent cell membranes and are often studied to understand their behavior. In the current study, we have implemented spectroscopic Ellipsometry (SE) technique to explore the optical properties of various single component lipid bilayers having different phase state (fluid and gel) under hydrated or native conditions. The measurement of ellipsometric angles ψ and Δ were obtained from SE and were utilized to realize an explicit phase state dependence. Further, we obtained the thickness (t) and refractive index (n) by modeling of these SE results. These results were found to be inter-related to the phase state and lateral organization. The bilayer thickness is further verified against values obtained from coarse-grained molecular dynamics simulations. The proposed method was tested on various lipid bilayers under their native phase state at room temperature and was found to have a correlation with AFM measurements.
关键词： fluid phase,Optical properties,gel phase,Spectroscopic Ellipsometry,Lipid membranes,Phase state
更新于2025-09-23 15:23:52
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[IEEE 2018 IEEE 4th International Forum on Research and Technology for Society and Industry (RTSI) - Palermo, Italy (2018.9.10-2018.9.13)] 2018 IEEE 4th International Forum on Research and Technology for Society and Industry (RTSI) - Structural and Optical Behaviour of MAPbI<inf>3</inf> Layers in Nitrogen and Humid Air
摘要： The tendency of MA+-containing perovskites to degradation under humid air is still the main challenge which limits the durability of technologies. We indeed frame the behavior of MAPbI3 layer through structural and optical characterization under thermal cycles and using the environmental composition as a variable parameter (humid air, N2, Ar, O2). Within the temperature range explored (RT-80°C) we likely approach the thermal operation of the material under the sun and find that the degradation mechanism is linked to the action of water molecules by the formation of lattice defects. They rise the lattice disorder, especially at the crossover of the tetragonal to cubic transition wherein an acceleration of the degradation kinetics is observed. Nitrogen can help rationalizing solutions to stabilize the materials even at this critical transition step, since it behaves as more than an inert species.
关键词： Spectroscopic Ellipsometry,Photovoltaics,X-ray diffraction,Hybrid Perovskites,Stability,Thermal Cycle
更新于2025-09-23 15:22:29
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Optical response of heterogeneous polymer layers containing silver nanostructures
摘要： This work is focused on the study of the optical properties of silver nanostructures embedded in a polymer host matrix. The introduction of silver nanostructures in polymer thin films is assumed to result in layers having adaptable optical properties. Thin film layers with inclusions of differently shaped nanoparticles, such as nanospheres and nanoprisms, and of different sizes, are optically characterized. The nanoparticles are produced by a simple chemical synthesis at room temperature in water. The plasmonic resonance peaks of the different colloidal solutions range from 390 to 1300 nm. The non-absorbing, transparent polymer matrix poly(vinylpyrrolidone) (PVP) was chosen because of its suitable optical and chemical properties. The optical studies of the layers include spectrophotometry and spectroscopic ellipsometry measurements, which provide information about the reflection, transmission, absorption of the material as well as the complex optical indices, n and k. Finite difference time domain simulations of nanoparticles in thin film layers allow the visualization of the nanoparticle interactions or the electric field enhancement on and around the nanoparticles to complete the optical characterization. A simple analysis method is proposed to obtain the complex refractive index of nanospheres and nanoprisms in a polymer matrix.
关键词： nanospheres,thin film layers,plasmonic nanoparticles,nanoprisms,spectroscopic ellipsometry
更新于2025-09-23 15:22:29
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Advanced Silicon Carbide Devices and Processing || Investigation of SiC/Oxide Interface Structures by Spectroscopic Ellipsometry
摘要： We have investigated SiC/oxide interface structures by the use of spectroscopic ellipsometry. The depth profile of the optical constants of thermally grown oxide layers on SiC was obtained by observing the slope-shaped oxide layers, and the results suggest the existence of the interface layers, around 1 nm in thickness, having high refractive index than those of both SiC and SiO2. The wavelength dispersions of optical constants of the interface layers were measured in the range of visible to deep UV spectral region, and we found the interface layers have similar dispersion to that of SiC, though the refractive indices are around 1 larger than SiC, which suggests the interface layers are neither transition layers nor roughness layers, but modified SiC, e.g., strained and/or modified composition. By the use of an in-situ ellipsometer, real-time observation of SiC oxidation was performed, and the growth rate enhancement was found in the thin thickness regime as in the case of Si oxidation, which cannot be explained by the Deal-Grove model proposed for Si oxidation. From the measurements of the oxidation temperature and oxygen partial pressure dependences of oxidation rate in the initial stage of oxidation, we have discussed the interface structures and their formation mechanisms within the framework of the interfacial Si-C emission model we proposed for SiC oxidation mechanism.
关键词： interface state density,SiC-MOSFET,SiC/oxide interface,SiC oxidation mechanism,spectroscopic ellipsometry
更新于2025-09-23 15:22:29
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Polydimethylsiloxane: Optical properties from 191 to 1688?nm (0.735–6.491?eV) of the liquid material by spectroscopic ellipsometry
摘要： Polydimethylsiloxane (PDMS) is an important polymer with numerous applications. Herein, the authors report the optical function(s) of PDMS from 191 to 1688 nm as determined from reflection spectroscopic ellipsometry (SE) and transmission ultraviolet-visible data. Two commercial samples of liquid PDMS (PDMS700 and PDMS2000) with molecular weights of 700–1500 g/mol and 2000–3500 g/mol, respectively, were analyzed. Both samples were linear polymers terminated with silanol groups. The optical functions determined from the two materials were essentially identical. Both the reflection and transmission measurements obtained from these materials required special experimental considerations. For the reflection SE measurements, these included roughening (frosting) the inside of the vessel that held PDMS and the need to level the instrument instead of the samples. The transmission measurements were obtained via a dual cuvette approach that eliminated the effects of the cuvettes and their interfaces. In addition to analyzing the data from the individual samples, the SE data from the samples were considered together in a multisample analysis (MSA). Because both samples of PDMS were transparent over the measured wavelength range, and because of the relatively wide wavelength range considered, the optical functions here were fit with Sellmeier models. This produced a good fit for the MSA with a mean squared error value of 1.68. The optical functions obtained in this work agreed well with previously reported values. For example, for the MSA, the authors obtained the following nx values, where x is the wavelength in nanometers: n300 = 1.443, n500 = 1.407, and n1000 = 1.393.
关键词： spectroscopic ellipsometry,optical properties,Sellmeier,transmission,optical function,polydimethylsiloxane (PDMS)
更新于2025-09-23 15:22:29
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Synthesis, ellipsometry and non-linear optical features of substituted 1,3,5-triphenylpyrazolines
摘要： Ellipsometric and nonlinear optical properties of new, differently substituted, 1,3,5-triphenylpyrazolines dyes, were studied. Results of theoretical calculation within a framework of density functional theory (DFT) technique were verified by spectroscopic ellipsometry and optical second harmonic generation (SHG) experiment at fundamental laser wavelength 1064 nm. Absorption bands and complex refractive indices were determined. Principal role of 2-thienyl substituent for first order nonlinear optical properties was demonstrated.
关键词： pyrazolines,DFT method,Nonlinear optics,spectroscopic ellipsometry
更新于2025-09-23 15:21:21
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Numerical analysis of earth-abundant Cu2ZnSn(SxSe1-x)4 solar cells based on Spectroscopic Ellipsometry results by using SCAPS-1D
摘要： Mixed chalcogenide CZTSSe with earth abundant elements, inexpensive, environmental-friendly and impressive photovoltaic performance is a promising absorber material for kesterite thin film solar cells of third generation. In this work, a numerical simulation of p-CZTSSe/n-CdS heterojunction solar cells have been presented using one dimensional Solar Capacitance Simulator. The influence of composition, absorber thickness, defect density and working temperature on Voc, Jsc, FF and power conversion efficiency has been investigated. The optimized cell shows 23.16% efficiency with a Voc ~ 0.724 V corresponding to 40% of the ratio.
关键词： Composition and Spectroscopic Ellipsometry,Absorption coefficient,CZTSSe,Thin film solar cell,Third generation,SCAPS,Efficiency
更新于2025-09-23 15:21:01
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Ellipsometry - Principles and Techniques for Materials Characterization || Spectroscopic Ellipsometry - Application on the Classification of Diamond-Like Carbon Films
摘要： Diamond-like carbon (DLC) films have been spreading from their theoretical basis to worldwide industrial applications because of their unique properties. Since their properties depend strongly on the conditions of synthesis, the effective classification of DLC films becomes quite necessary. From the ternary phase diagram to the Japan New Diamond Forum standard, the classification attempts are also accompanied by the continuous development of their applications. Generally, the hydrogen content and sp3/(sp2 + sp3) ratio are the primary parameters for their classification. However, researchers are afraid that currently sp3/(sp2 + sp3) ratio estimated included not only network sp3 but also sp3 hybrid carbons in the hydrogen-terminated cluster. Simultaneously, the above classification methods need to use the large equipment, such as the synchronous radiation source. Therefore, to realize more straightforward to classify DLC films efficiently, the optical constants (refractive index (n) and extinction coefficient (k)) have been proposed in 2013 to be effective method to classify the DLC films, for which a lot of considerable discussion in the past ISO/TC-107 meetings has been made. The purpose of this chapter is to introduce the latest developments of optical constants on the classification of DLC films and explore their relationship with the current standard.
关键词： spectroscopic ellipsometry,diamond-like carbon film,classification
更新于2025-09-23 15:21:01
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Optical properties of HfO <sub/>x</sub> ( <i>x</i> < 2) films grown by ion beam sputtering-deposition method
摘要： The optical properties of the HfOx films of different chemical composition (x < 2) deposited by ion beam sputtering-deposition (IBSD) method were studied. Spectral dependencies of refractive index n(λ) and extinction coefficient k(λ) were determined with ellipsometry in λ = 250–1100 nm wavelength region. The x values (i.e. [O]/[Hf] ratio) for the films were derived from x-ray photoelectron spectroscopy (XPS) data. The spectral dependences of optical constants n(λ) and k(λ) were found to undergo radical changes with x = 1.78–1.82. The films with x < 1.78 demonstrated high extinction coefficient k > 1 with the metallic-like behavior of optical constants spectral dependences. The films with x > 1.82 were found to be transparent, with k = 0 and n(λ) being well approximated by a Cauchy polynomial dependence for dielectrics. Using a sample with a gradient of x, it was established that the transition from the metallic to the dielectric-like behavior of the optical constants occurs not smoothly, but is discontinuous. A sharp jump in the optical constants is observed at x ≈ 1.8. According to XPS data, the transparent films were found to consist of two components only: HfO2 and Hf4O7 suboxide. Cauchy polynomial coefficients for Hf4O7 suboxide and HfO2 were found by using the Bruggeman effective medium approximation.
关键词： IBSD,ReRAM,spectroscopic ellipsometry,HfOx
更新于2025-09-23 15:21:01
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Nanoconfined water vapour as a probe to evaluate plasmonic heating
摘要： Engineering the photothermal effect in plasmonic materials is of paramount importance for many applications such as cancer therapy, chemical synthesis, cold catalysis and more recently for metasurfaces. Evaluation of plasmonic heating at the nanoscale is challenging and generally requires sophisticated equipments and/or temperature-sensitive probes such as fluorescent molecules or materials. Here we propose to use water vapor as probe to evaluate the local heating around plasmonic nanoparticles. We demonstrated the concept for the case of a plasmonic colloidal film composed by a bi-modal nanoporosity. In particular we exploit the thermal and light water liquid-vapor phase transitions taking place into the nanoporous medium that can be triggered by external stimulus such as heating or irradiation to obtain structural and optical variations in the films. Estimation of the local temperature was then obtained by using spectroscopic ellipsometry acquired by a multimodal chamber. More generally, this method offer a simple and general approach to determine local temperature that only requires a nanoporous material and water vapor, such as environmental humidity. In addition this approach can be further generalized to other materials, vapor molecules or optical technique.
关键词： local temperature measurement,spectroscopic ellipsometry,water vapor,nanoporous materials,plasmonic heating
更新于2025-09-23 15:19:57