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Showing 1 to 20 of 20 for “"Kramers-Kronig"”.
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Qed in periodischen und absorbierenden Medien
… Streuern betrachtet, deren Polarisierbarkeit den Kramers-Kronig Relationen gehorcht. Es wurde ein Quantisierungsverfahren nach Knöll, Scheel und Welsch [1] verwendet, das als eine Ergänzung zum mikroskopischen Huttner-Barnett Schema [2] aufgefaßt werden kann und in dem auf der Basis der …
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Highly absorptive thin films for integrated photonic devices
… J-aggregate thin films are analyzed using Kramers-Kronig regression to determine their complex index of refraction, an important parameter involved in photonic device design. Additionally, a soft lithography method is demonstrated for patterning and deposition of LBL J-aggregate thin films. …
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Novel characterization of materials using THz spectroscopic techniques
… are deduced directly without resorting to the Kramers-Kronig Analysis. In this work, THz spectroscopy has been used to characterize different types of materials. Materials investigated consisted of semiconductors, gate dielectric materials, high energetic materials and cyclic olefin polymers. …
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Dielectric measurement based microstrip transmission line
… including its loss factor material based on Kramers-kronig relationship.
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Theory and design of high-index-contrast microphotonic circuits
… structures that are not limited by the Kramers-Kronig amplitude-dispersion tradeoff. A third class provides a general approach to disabling both the amplitude and phase response of resonant systems to achieve a fulltransparency off state. They allow a robust integrated solution to …
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Theory and Modelling of Wavelength Tunable Laser Transmitters With Enhanced Tuning Range and Their Modulation Performance
… and the band-filling effect which uses the Kramers-Kronig (KK) relations (KK effect). It was found that the band-filling effect is heavily underestimated due to the lack of its investigation in published literature as it is the main contributor to the refractive index change instead of the …
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Optical investigation of bismuth selenide (Bi2Se3) and antimony telluride (Sb2Te3).
… cm−1 ) and temperature (13 to 300 K) . Utilizing Kramers-Kronig analysis, complex conductivity is calculated from which other optical properties are obtained. The resistivity of both samples demonstrates metallic behavior with residual resistivity ratios of 1.8 for Bi2Se3 and 7.5 for Sb2Te3, …
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Optical Properties of Organic Semiconductors: from Submonolayers to Crystalline Films
… becomes possible. The results fulfill a priori a Kramers-Kronig consistency and no specific model is needed to express the spectral behavior of the optical constants. Based on our method, we have successfully calculated the optical constants, and therefore the absorption behavior, of films of …
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Low-dimensional purple and blue bronzes: Crystal growth, characterization and optical properties
… plane. The optical conductivity obtained from Kramers-Kronig analysis of reflectance spectroscopy data was in good agreement with the resistivity measurements. The two in-plane metallic axes undergo CDW transitions at two different temperatures Tp, suggesting a distinction in electronic and …
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Investigation of Size Specific Fe2O3 nanoparticles: Towards Single Nanoparticle Resolved Spectro-ptychography
… related to the absorption spectrum through Kramers- Kronig integral. This thesis will use the Fe L2,3 NEXAFS absorption spectra of iron oxide nanoparticles to discuss the relationship between absorption and phase. The measured phase spectra obtained from ptychography are compared with the …
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Improving solar thermal receiver performance via spectral and directional selectivity
… selectivity are investigated by applying the Kramers-Kronig relations to spectrally selective absorbers. Limits to directional selectivity are studied via geometrical limits, and are compared to the limits of concentrating sunlight. Two silica aerogel based solar receivers are presented as …
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Online condition monitoring of lithium-ion and lead acid batteries for renewable energy applications
… monitor the condition of the batteries, Kramers-Kronig relation: linearity, stability and causality as well as the appropriate perturbation amplitude applied during EIS should be adhered to. Regardless of the accuracy of EIS, its lengthy acquisition time makes it impracticable for online …
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Investigation of the optical properties of Bi₂Sr₂Ca<sub>n-1</sub>Cu<sub>n</sub>O<sub>y</sub> (n=1,2) by transmission electron energy loss spectroscopy
… functions of these materials were derived by Kramers-Kronig analysis. A broad excitation centered at 2.7eV was identified as associated with the Cu — O₂ layer by comparing the spectrum of Bi₂Sr₂CaCu₂O₈ with that of Bi₂Sr₂CuO₆. A pseudo gap of 1.2eV in the spectrum of Bi₂Sr₂CuO₆ suggests that …
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Magnetische Streuung an Grenz- und Viellagenschichten
… und der Berechnung der Dispersion über die Kramers-Kronig-Relation. XRMR-Experimente wurden an Pt/Co-Schichtsystemen an den Synchrotronstrahlungsquellen HASYLAB/Hamburg und BESSYII/Berlin durchgeführt, um die Anwendbarkeit der Messmethodik im harten und weichen Röntgenbereich zu …
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Far infrared reflectance and optical properties of organic superconductor (TMTSF)2ClO4 /
… of the expected superconducting energy gap. Kramers-Kronig analysis was carried out to determine the optical conductivity for the slowly cooled sample from the measured reflectance. In order to do so the low frequency data was extrapolated to zero frequency using a Hagen-Ru bens behaviour, …
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A study of cosmic dust in the galactic environment
… abundances of carbon from the model-independent Kramers-Kronig relation which relates the wavelength-integrated extinction to the total dust volume and is less model-dependent. We also derive carbon abundance from fitting the observed UV/optical/near infrared extinction with a mixture of …
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Double Negative Metamaterials in Dielectric Waveguide Configurations
… A causal material model which obeys the Kramers-Kronig relations and which is based on measurements of a realized metamaterial is studied and used in the investigation in order to produce realistic results. The N-layer formulation is then applied to the three-layer (slab) waveguide and …
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Magnetic X-ray Reflectivity
… and then retrieving the real part through the Kramers-Kronig transformation of the measured imaginary part. This is shown in this work for several 3d transition metals and edges. The simulations are sensitive to a variety of different spin configurations: spiral spin structures, magnetic dead …
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Discovery of a Pseudogap Attributed to Charge Density Wave Order at the β-β′ Phase Transition in As2Te3 and the Influence of Cu and Ge Doping on its Properties
In this work, the origin and driving mechanism of the β to β' phase transition of As2Te3 is investigated through primarily resistivity, optical reflectance and heat capacity measurements. From optical reflectivity we identify the formation of a pseudogap concomitant to the β-As2Te3 to β'-As2Te3 …
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Charge structure of a quasiparticle in graphite measured with inelastic X-ray scattering
"The following work consists of three related topics. First, we demonstrate a multi-dimensional, attosecond-resolution, real-space electron density imaging technique. We apply the technique to the energy-loss spectra of graphite, which we measured using inelastic X-ray scattering at the Advanced …