Структура электронных состояний соединений Gd-=SUB=-5-=/SUB=-Sb-=SUB=-3-=/SUB=- и Gd-=SUB=-5-=/SUB=-Ge-=SUB=-2-=/SUB=-Sb по данным зонных расчетов и оптической спектроскопии

Results of investigations of the electronic structure and optical properties of Gd5Sb3 and Gd5Ge2Sb compounds are presented. Calculations of band spectra were carried out in frame of local density approximation with a correction for strong correlation effects in 4f shell of rare-earth ion (DFT+U+SO method). Optical constants of these materials were measured by ellipsometric technique in wide wavelength interval. Energy dependencies of a number of spectral parameters were determined. The nature of quantum light absorption is discussed on the base of comparative analysis of the experimental and calculated spectra of optical conductivity.

APLIKASI UV SPECTROSCOPY DAN METODE SIMCA UNTUK KLASIFIKASI KOPI LIBERIKA TUNGKAL JAMBI DAN KOPI LIBERIKA PROBOLINGGO

Tungkal Composite Jambi Liberika Coffee is one of the top qualities of Indonesian coffees that has received a geographic indication certificate (IGs). With its limited production and high prices, currently Tungkal Jambi Liberika coffee is one of the coffees that is prone to being counterfeited. The counterfeiting of Tungkal Jambi Liberika coffee is increasingly difficult to identify, especially in the form of ground roasted coffee. This study evaluated the potential application of UV spectroscopy technology to classify Tungkal Jambi Liberika coffee (with geographic indications) and normal Probolinggo Liberika coffee (non- geographic indications). A total of 120 samples for each Liberika coffee were prepared weighing 1 gram for each sample. Spectra measurements were carried out in the form of a coffee solution. Spectral data were taken using a UV-visible spectrometer with a wavelength interval of 200-400 nm (Genesys™ 10S UV-Vis, Thermo Scientific, USA). By using the average transformed spectra in the 250-350 nm interval, the differences between the two types of Liberika coffee can be clearly seen, especially at some wavelength peaks, namely 270 nm, 300 nm, 315 nm and 346 nm. The classification accuracy obtained for the SIMCA classification is 100% for both Tungkal Jambi Liberika and Probolinggo Liberika coffee. Keywords: authentication, classification accuracy, Tungkal Jambi Liberika coffee, SIMCA, UV Spectroscopy

Электронная структура и оптические спектры соединений GdFeAl и GdFeSi

Results of investigations of electronic structure and optical properties of GdFeAl and GdFeSi compounds are presented. Spin-plarized density of states and interband optical conductivity spectra were calculated in frame of DFT+U technique with a correction for strong correlation effects in 4f shell of Gd. Optical properties were measured by ellipsometric technique in wavelength interval of 0.22 – 16 μm. Nature of quantum light absorption is discussed on the base of comparative analysis of experimental and calculated spectra. It is shown that main features of frequency dependencies of the optical conductivity are interpret qualitatively by the calculated density of electronic states.

Atmospheric Characterization via Broadband Color Filters on the PLAnetary Transits and Oscillations of stars (PLATO) Mission

<p>We assess broadband color filters for the two fast cameras on the PLAnetary Transits and Oscillations (PLATO) of stars space mission with respect to exoplanetary atmospheric characterization. We focus on Ultra Hot Jupiters and Hot Jupiters placed 25pc and 100pc away from the Earth and warm Super-Earths placed 10pc and 25pc away. Our analysis takes as input literature values for the difference in transit depth between the broadband lower (500-675nm) wavelength interval (hereafter referred to as ”blue“) and the upper (675-1125nm) broadband wavelength interval (hereafter referred to as ”red“) for transmission, occultation and phase curve analyses. Planets orbiting main sequence central stars with stellar classes F, G, K and M are investigated. We calculate the signal-to-noise ratio with respect to photon and instrument noise for detecting the difference in transit depth between the two spectral intervals. Results suggest that bulk atmospheric composition and planetary geometric albedos could be detected for (Ultra) Hot Jupiters up to ~100pc (~25pc) with strong (moderate) Rayleigh extinction. Phase curve information could be extracted for Ultra Hot Jupiters orbiting K and G dwarf stars up to 25pc away. For warm Super-Earths, basic atmospheric types (primary and water-dominated) and the presence of sub-micron hazes in the upper atmosphere could be distinguished for up to a handful of cases up to ~10pc (manuscript accepted in Experimental Astronomy).</p>

Изопериодические гетероструктуры Ga-=SUB=-x-=/SUB=-In-=SUB=-1-x-=/SUB=-Sb-=SUB=-y-=/SUB=-As-=SUB=-z-=/SUB=-P-=SUB=-1-y-z-=/SUB=-/InP для планарных p-n-фотодиодов

Isoperiodic heterostructures GaxIn1-xSbyAszP1-y-z/InP at a 1.06 to 1.6 μm wavelength interval were grown by the method of floating-zone recrystallization with temperature gradient. Absolute spectral sensitivity of ~ 0.59 A/W and a speed of ~ 10 ns were achieved. Threshold sensitivity for the fabricated photodiodes was in the range 2·10^-10 to 5·10^-11 W with a signal-to-noise ratio of 10.