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1.
Atoumane Ndiaye Alle Dioum Corneliu I. Oprea Anca Dumbrava Jeanina Lungu Adrian Georgescu Florin Moscalu Mihai A. Gîru Aboubaker Chedikh Beye Issakha Youm 《Molecules (Basel, Switzerland)》2021,26(1)
The theoretical study of chrysanthemin (cyanidin 3-glucoside) as a pigment for TiO2-based dye-sensitized solar cells (DSSCs) was performed with the GAUSSSIAN 09 simulation. The electronic spectra of neutral and anionic chrysanthemin molecules were calculated by density functional theory with B3LYP functional and DGDZVP basis set. A better energy level alignment was found for partially deprotonated molecules of chrysanthemin, with the excited photoelectron having enough energy in order to be transferred to the conduction band of TiO2 semiconductor in DSSCs. In addition, we used the raw aqueous extracts of roselle (Hibiscus sabdariffa) calyces as the source of chrysanthemin and the extracts with various pH values were tested in DSSCs. The extracts and photosensitized semiconductor layers were characterized by UV-Vis spectroscopy, and DSSCs based on raw extracts were characterized by current density-voltage measurements. 相似文献
2.
Hellmann S Beye M Sohrt C Rohwer T Sorgenfrei F Redlin H Kalläne M Marczynski-Bühlow M Hennies F Bauer M Föhlisch A Kipp L Wurth W Rossnagel K 《Physical review letters》2010,105(18):187401
Femtosecond time-resolved core-level photoemission spectroscopy with a free-electron laser is used to measure the atomic-site specific charge-order dynamics of the charge-density?wave in the Mott insulator 1T-TaS2. After strong photoexcitation, a prompt loss of charge order and subsequent fast equilibration dynamics of the electron-lattice system are observed. On the time scale of electron-phonon thermalization, about 1?ps, the system is driven across a phase transition from a long-range charge ordered state to a quasiequilibrium state with domainlike short-range charge and lattice order. The experiment opens the way to study the nonequilibrium dynamics of condensed matter systems with full elemental, chemical, and atomic-site selectivity. 相似文献
3.
Ward DE Beye GE Sales M Alarcon IQ Gillis HM Jheengut V 《The Journal of organic chemistry》2007,72(5):1667-1674
The aldol reaction of tetrahydro-4H-thiopyranone with 1,4-dioxa-8-thiaspiro[4.5]decane-6-carboxaldehyde (I) gives four possible diastereomeric adducts (II). Aldol reactions of I with each of the diastereomers of II and their corresponding methoxymethyl ethers III via the Ti enolates were investigated. Using racemic reactants, reactions with II proceeded with high levels of mutual kinetic enantioselection (MKE) and double stereodifferentiation (DS) to give one of the eight possible bisaldol adducts. Similar reactions of III proceeded with low levels of MKE and DS and gave two bisaldol adducts, one from each of the possible combinations of enantiomeric reactants. By extension, 11 of the 20 possible diastereomers of the bisaldol adduct could be obtained selectively. These adducts are useful for polypropionate synthesis. 相似文献
4.
B.D. Ngom T. Mpahane O. Nemraoui J.B. Kana M. Maaza A.C. Beye 《Applied Surface Science》2009,255(7):4153-4158
Novel highly c-oriented tungsten-doped zinc oxide (WZO) thin films with 1 wt% were grown by pulsed laser deposition (PLD) technique on corning 1737F glass substrate. The effects of laser energy on the structural, morphological as well as optical transmission properties of the films were studied. The films were highly transparent with average transmittance exceeding 87% in the wavelength region lying between 400 and 2500 nm. X-ray diffraction analysis (XRD) results indicated that the WZO films had c-axis preferred orientation with wurtzite structure. Film thickness and the full width at half maximum (FWHM) of the (0 0 2) peaks of the films were found to be dependent on laser fluence. The composition determined through Rutherford backscattering spectroscopy (RBS) appeared to be independent of the laser fluence. By assuming a direct band gap transition, the band gap values of 3.36, 3.34 and 3.31 eV were obtained for corresponding laser fluence of 1, 1.7 and 2.7 J cm−2, respectively. Compared with the reported undoped ZnO band gap value of 3.37 eV, it is conjectured that the observed low band gap values obtained in this study may be attributable to tungsten incorporation in the films as well as the increase in laser fluence. The high transparency makes the films useful as optical windows while the high band gap values support the idea that the films could be good candidates for optoelectronic applications. 相似文献
5.
B.D. Ngom M. ChakerN. Manyala B. LoM. Maaza A.C. Beye 《Applied Surface Science》2011,257(14):6226-6232
We report on the effects of glass substrate temperature on the crystal structure and morphology of tungsten (W)-doped ZnO nanostructures synthesized by pulsed-laser deposition. X-ray diffraction analysis data shows that the W-doped ZnO thin films exhibit a strongly preferred orientation along a c-axis (0 0 0 L) plane, while scanning electron and atomic force microscopes reveal that well-aligned W-doped ZnO nanorods with unique shape were directly and successfully synthesized at substrate temperature of 550 °C and 600 °C without any underlying catalyst or template. Possible growth mechanism of these nanorods is suggested and discussed. 相似文献
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7.
A.?F?hlisch M.?Beye H.?Redlin S.?Düsterer 《The European physical journal. Special topics》2009,169(1):123-128
Using the high brilliance femtosecond soft X-ray pulses from the Free-Electron LASer at Hamburg (FLASH) the X-ray induced
transient optical reflectivity change of GaAs has been established as a versatile method for femtosecond X-ray/optical cross-correlation
[1].
As the underlying physical mechanism is the X-ray induced dynamics within solids, we present in this work a feasibility study
how transient grating methods could be used to study nanometer scale dynamics in materials, such as the radical diffusion
parameters in photoresist materials for EUV lithography. 相似文献
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9.
J.B. Kana Kana J.M. Ndjaka B.D. Ngom N. Manyala A.C. Beye 《Applied Surface Science》2008,254(13):3959-3963
The novel physical vapor deposition called inverted cylindrical magnetron sputtering (also known as hollow cathode sputtering) is commonly used to coat wires, fibers, ribbons as well as all sides of three-dimensional substrates. It is a reproducible method for the production of nano-structured systems onto complex shapes substrates. This paper reports the first synthesis and feasibility of reliably reproduced stoichiometric pure textured VO2 nano-structures by the rf-inverted cylindrical magnetron sputtering. Morphological, structural, elemental analysis and optical properties of synthesized VO2 under optimized conditions are reported. 相似文献
10.
Deppe M Föhlisch A Hennies F Nagasono M Beye M Sánchez-Portal D Echenique PM Wurth W 《The Journal of chemical physics》2007,127(17):174708
The role of orbital polarization for ultrafast charge transfer between an atomic adsorbate and a substrate is explored. Core hole clock spectroscopy with linearly polarized x-ray radiation allows to selectively excite adsorbate resonance states with defined spatial orientation relative to the substrate surface. For c(4 x 2)S/Ru(0001) the charge transfer times between the sulfur 2s(-1)3p*+1 antibonding resonance and the ruthenium substrate have been studied, with the 2s electron excited into the 3p perpendicular* state along the surface normal and the 3p parallel* state in the surface plane. The charge transfer times are determined as 0.18+/-0.07 and 0.84+/-0.23 fs, respectively. This variation is the direct consequence of the different adsorbate-substrate orbital overlap. 相似文献