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Metoda wyznaczania współczynników załamania na powierzchniach granicznych warstw dielektrycznych z obwiedni charakterystyk odbiciowych

Krasiński P., Tyszkiewicz C., Skolik M., Błaszczyk T.

Przegląd Elektrotechniczny

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2018

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R. 94, nr 8

51--54

PL

W pracy przedstawiana jest nowa metoda wyznaczania wspólczynników załamania na powierzchniach granicznych warstw dielektrycznych z obwiedni ich widm odbciowych. Podawane są proste wzory na współczynniki załamania na powierzchniach granicznych warstwy, które weryfikowane są teoretycznie i eksperymentalnie. Wyliczone prezentowaną metodą współczynniki załamania używane były w obliczeniach widm odbiciowych, które porównywane są z wyjściowymi widmami eksperymentalnymi.

EN

The presentation shows the new method allowing determination of refractive indices at interfaces of dielectric films. The method is basing on the analysis of envelopes of reflectance spectra. In the presentation there are shown theoretical foundations of simple mathematical formulas, describing refractive index values at film interfaces as well as experimental results that postively verified our method. In the first step, values of the refractive index at films interfaces were determined using our method. In the second step, reflectance spectra were calculated using the values of refractive indices obtained in the first step and compared with measured ones

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Wavelength intervals effect on reflectance spectra reconstruction

Shams-Nateri A

Optica Applicata

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2012

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Vol. 42, nr 4

737--742

EN

The principal component analysis is an important method in reflectance spectra reconstruction. This is a research into the effects of a wavelength interval on the performance of reflectance spectra estimation by the principal component analysis technique. The spectral reflectance is reconstructed by using 20, 10 and 5 nm intervals. The RMS accuracy of reflectance spectra fitting is 0.0079, 0.0074 and 0.0072, respectively for 20, 10 and 5 nm intervals with 6 principal components. As the obtained results indicated, the performance of reflectance estimation increased with decreasing the wavelength interval.

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Remote sensing reflectance of Pomeranian lakes and the Baltic

Ficek D., Zapadka T., Dera J.

Oceanologia

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2011

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No. 53 (4)

959-970

EN

The remote sensing reflectance R_rs, concentrations of chlorophyll a and other pigments C_i, suspended particulate matter concentrations C_SPM and coloured dissolved organic matter absorption coefficient αCDOM(λ) were measured in the euphotic zones of 15 Pomeranian lakes in 2007-2010. On the basis of 235 sets of data points obtained from simultaneous estimates of these quantities, we classified the lake waters into three types. The first one, with the lowest αCDOM(440 nm) (usually between 0.1 and 1.3 m-1 and chlorophyll α concentrations 1.3 < Ca < 33 mg m-3), displays a broad peak on the reflectance spectrum at 560-580 nm and resembles the shape of the remote sensing reflectance spectra usually observed in the Baltic Proper. A set of Rrs spectra from the Baltic Proper is given for comparison. The second lake water type has a very high CDOM absorption coefficient (usually αCDOM(440 nm) > 10 m-1, up to 17.4 m-1 in Lake Pyszne; it has a relatively low reflectance (Rrs < 0.001 sr-1) over the entire spectral range, and two visible reflectance spectra peaks at ca 650 and 690-710 nm. The third type of lake water represents waters with a lower CDOM absorption coefficient (usually αCDOM(440 nm) < 5 m-1) and a high chlorophyll a concentration (usually Ca > 4 mg m-3, up to 336 mg m-3 in Lake Gardno). The remote sensing reflectance spectra in these waters always exhibit three peaks (Rrs > 0.005 sr-1): a broad one at 560-580 nm, a smaller one at ca 650 nm and a well-pronounced one at 690-720 nm. These Rrs(λ) peaks correspond to the relatively low absorption of light by the various optically active components of the lake water and the considerable scattering (over the entire spectral range investigated) due to the high SPM concentrations there. The remote sensing maximum at λ 690-720 nm is higher still as a result of the natural fluorescence of chlorophyll a. Empirical relationships between the spectral reflectance band ratios at selected wavelengths and the various optically active components for these lake waters are also established: for example, the chlorophyll a concentration in surface water layer Ca = 6.432 e4.556X, where X = [max Rrs (695 ≤λ≤720) - Rrs(? = 670)] / max Rrs (695 ? ? ? 720), and the coefficient of determination R^2 = 0.95.

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Optical study of ß”-(bis(ethylenedithio)tetrathiafulvalene)2SF5CH2SO3 Activation of intramolecular modes

Olejniczak I., Barszcz B., Graja A., Schlueter J. A.

Materials Science Poland

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2009

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Vol. 27, No. 3

621--627

EN

We report on the temperature dependences of polarized reflectance spectra of ß”-(bis(ethylenedithio) tetrathiafulvalene)2SF5CH2SO3. The material remains in the charge-ordered state over the whole temperature range. Room temperature infrared spectra display the response characteristic of a quasi-twodimensional organic conductor, with a broad mid-infrared electronic excitation and a number of vibrational features related to intramolecular modes of both the bis(ethylenedithio)tetrathiafulvalene (ET) donor molecule and the SF5CH2SO3 anion. Upon lowering the temperature, unusual activation of intramolecular modes of ET is observed. We suggest that this effect is connected with electronmolecular vibration coupling within a dimerized lattice.