Search results for " spectrum"
showing 10 items of 1439 documents
Long-term evolution of luminescent properties in CdI2 crystals
2016
Fresh and aged melt-grown or gas-phase grown CdI2 crystals are studied by means of low-temperature photoluminescence spectroscopy. Noticeable transformations of emission spectra are observed after long-term aging. The formation of nanostructures containing cadmium oxide and cadmium hydroxide as well as the changes in local surrounding of iodine atoms and the possible growth of polytypic modifications of CdI2 are taken into account when considering the diversity of optical spectra.
Numerical Procedures and their Practical Application in PV Module Analyses. Part IV: Atmospheric Transparency Parameters - Application
2020
Abstract The presented article relates to aspects of PV module testing using natural sunlight in outdoor conditions. It is a continuation of the article Part III: parameters of atmospheric transparency - determining and correlations. This article discusses the practical application of the indexes: atmosphere purity - k Tm , diffused component content - k s/o , beam clear sky index - K b - in testing various modules in outdoor conditions. Their influence on the conversion of modules made from various absorbers and various technologies is demonstrated. Their practical application in module testing in outdoor conditions is described and it - has been demonstrated that the results of the analys…
Synthesis of ZnO–Ag2CO3–Fe3O4@rGO core–shell structure: magnetically separable photocatalyst for degradation of MB using the Box–Behnken design
2020
In this work, a simple microwave method was utilized to prepare ZnO sheet linked with Fe3O4@rGO core–shell and of Ag2CO3 through formation of the quadri-photocatalytic with high activity. The microstructure, morphology, spectroscopic, and magnetic characteristics of the prepared samples were assessed using XRD, SEM, PL, TEM, FT-IR, DLS, and VSM analysis. The photocatalytic activity of the material was evaluated for photodegradation of methylene blue dye under the UV and visible light with home-made photoreactor. The response surface method in a Box–Behnken design was utilized to design the experiments. The parameters affecting the efficiency of the degradation including, pH (5–9), photocata…
Correlations between density distributions, optical spectra, and ion species in a hydrogen plasma (invited)
2016
An experimental study of plasma distributions in a 2.45 GHz hydrogen discharge operated at 100 Hz repetition rate is presented. Ultrafast photography, time integrated visible light emission spectra, time resolved Balmer-alpha emission, time resolved Fulcher Band emission, ion species mass spectra, and time resolved ion species fraction measurements have been implemented as diagnostic tools in a broad range of plasma conditions. Results of plasma distributions and optical emissions correlated with H + , H + 2 , and H + 3 ion currents by using a Wien filter system with optical observation capability are reported. The magnetic field distribution and strength is found as the most critical facto…
Study of the thermochromic phase transition in CuMo1−xWxO4 solid solutions at the W L3-edge by resonant X-ray emission spectroscopy
2021
Abstract Polycrystalline CuMo 1 − x W x O 4 solid solutions were studied by resonant X-ray emission spectroscopy (RXES) at the W L 3 -edge to follow a variation of the tungsten local atomic and electronic structures across thermochromic phase transition as a function of sample composition and temperature. The experimental results were interpreted using ab initio calculations. The crystal-field splitting parameter Δ for the 5d(W)-states was obtained from the analysis of the RXES plane and was used to evaluate the coordination of tungsten atoms. Temperature-dependent RXES measurements were successfully employed to determine the hysteretic behaviour of the structural phase transition between t…
Commissioning of the vacuum system of the KATRIN Main Spectrometer
2016
The KATRIN experiment will probe the neutrino mass by measuring the β-electron energy spectrum near the endpoint of tritium β-decay. An integral energy analysis will be performed by an electro-static spectrometer (``Main Spectrometer''), an ultra-high vacuum vessel with a length of 23.2 m, a volume of 1240 m[superscript 3], and a complex inner electrode system with about 120 000 individual parts. The strong magnetic field that guides the β-electrons is provided by super-conducting solenoids at both ends of the spectrometer. Its influence on turbo-molecular pumps and vacuum gauges had to be considered. A system consisting of 6 turbo-molecular pumps and 3 km of non-evaporable getter strips ha…
Fourier-transform spectroscopy and deperturbation analysis of the spin-orbit coupled A(1)Σ(+) and b(3)Π states of KRb.
2016
Fourier-transform A(1)Σ(+) - b(3)Π → X(1)Σ(+) laser-induced fluorescence spectra were recorded for the natural mixture of (39,41)K(85,87)Rb isotopologues produced in a heatpipe oven. Overall 4200 rovibronic term values of the spin-orbit coupled A(1)Σ(+) and b(3)Π states were determined with an uncertainty of about 0.01 cm(-1) in the energy range [10 850, 14 200] cm(-1) covering rotational quantum numbers J' ∈ [3, 280]. Direct deperturbation analysis of the A ∼ b complex performed within the framework of the A(1)Σ(+) ∼ b(3)ΠΩ=0,1,2 coupled-channel approach reproduced experimental data with a standard deviation of 0.004 cm(-1). Initial parameters of the internuclear potentials and spin-orbit …
Exotic SiO(2)H(2) Isomers: Theory and Experiment Working in Harmony.
2016
Replacing carbon with silicon can result in dramatic and unanticipated changes in isomeric stability, as the well-studied CO2H2 and the essentially unknown SiO2H2 systems illustrate. Guided by coupled-cluster calculations, three SiO2H2 isomers have been detected and spectroscopically characterized in a molecular beam discharge source using rotational spectroscopy. The cis,trans conformer of dihydroxysilylene HOSiOH, the ground-state isomer, and the high-energy, metastable dioxasilirane c-H2SiO2 are abundantly produced in a dilute SiH4/O2 electrical discharge, enabling precise structural determinations of both by a combination of isotopic measurements and calculated vibrational corrections. …
9,10-Phenanthrenedione as Visible-Light Photoredox Catalyst: A Green Methodology for the Functionalization of 3,4-Dihydro-1,4-Benzoxazin-2- Ones thro…
2018
A visible-light photoredox functionalization of 3,4-dihydro-1,4-benzoxazin-2-ones through a Friedel-Crafts reaction with indoles using an inexpensive organophotoredox catalyst is described. The reaction uses a dual catalytic system that is formed by a photocatalyst simple and cheap, 9,10-phenanthrenedione, and a Lewis acid, Zn(OTf)2. 5W white LEDs are used as visible-light source and oxygen from air as a terminal oxidant, obtaining the corresponding products with good yields. The reaction can be extended to other electron-rich arenes. Our methodology represents one of the most valuable and sustainable approach for the functionalization of 3,4-dihydro-1,4-benzoxazin-2-ones, as compared to th…
A novel MALDI-MS approach for the analysis of neutral metallosupramolecular architectures
2011
Matrix assisted laser desorption/ionisation mass spectrometry (MALDI-MS) methods have been developed for the characterisation of neutral [2×2] metallogrids derived fromdiimine, dihydrazone and diacylhydrazone ligands. Such grids may be protonated in solution to give cationic species but in most cases these are labile, so that rather delicate conditions are required for observation of the intact metallogrids as monoprotonated derivatives in the gas phase. As a MALDI matrix, 2,4,6-trihydroxyacetophenone (THAP) is sufficiently acidic to enable monoprotonation of the grids unaccompanied by dissociation, and if the grid sample is initially deposited by a layering technique to avoid any prelimina…