Accurate Density Functional Calculations of Near-Edge X-Ray and Optical Absorption Spectra of Liquid Water Using Nonperiodic Boundary Conditions: The Role of Self-Interaction and Long-Range Effects

2008 ◽  
Vol 100 (10) ◽  
Author(s):  
Giuseppe Brancato ◽  
Nadia Rega ◽  
Vincenzo Barone
Keyword(s):  
Optical Absorption ◽  
Boundary Conditions ◽  
Absorption Spectra ◽  
Long Range ◽  
Liquid Water ◽  
Density Functional Calculations ◽  
Density Functional ◽  
Optical Absorption Spectra ◽  
X Ray

scholarly journals Synthesis, Structures and Co-Crystallizations of Perfluorophenyl Substituted β-Diketone and Triketone Compounds

Crystals ◽  
2019 ◽  
Vol 9 (3) ◽  
pp. 175 ◽  
Author(s):  
Takumi Kusakawa ◽  
Shunichiro Sakai ◽  
Kyosuke Nakajima ◽  
Hidetaka Yuge ◽  
Izabela Rzeznicka ◽  
...  
Keyword(s):  
Absorption Spectra ◽  
Elemental Analysis ◽  
Density Functional Calculations ◽  
Density Functional ◽  
Perfluorinated Compounds ◽  
Molecular Conformations ◽  
X Ray

Perfluorophenyl-substituted compounds, 3-hydroxy-1,3-bis(pentafluorophenyl)-2- propen-1-one (H1) and 1,5-dihydroxy-1,5-bis(pentafluorophenyl)-1,4-pentadien-3-one (H22), were prepared in 56 and 30% yields, respectively, and only the enol forms were preferentially obtained among the keto-enol tautomerism. Molecular conformations and tautomerism of the fluorine-substituted compounds were certified based on X-ray crystallographic studies and density functional calculations. The solvent dependency of the absorption spectra was only observed for the fluorinated compounds. The compounds H1 and H22 quantitatively formed co-crystals with the corresponding non-perfluorinated compounds, dibenzoylmethane (H3) and 1,5-dihydroxy-1,5-diphenyl-1,4-pentadien-3-one (H24), respectively, through the arene–perfluoroarene interaction to give the 1:1 co-crystals H1•H3 and H22•H24, which were characterized by X-ray crystallographic and elemental analysis studies.

scholarly journals Optical Studies on KBr:Tl and KCl-Br:Tl Mixed Crystals

2010 ◽  
Vol 7 (2) ◽  
pp. 425-432
Author(s):  
P. Eswaran ◽  
A. Anbagi ◽  
S. Nagarajan
Keyword(s):  
Optical Absorption ◽  
Single Crystals ◽  
Absorption Spectra ◽  
Emission Band ◽  
Mixed Crystals ◽  
Optical Absorption Spectra ◽  
Optical Studies ◽  
Excitation Spectra ◽  
X Ray ◽  
Wavelength Side

Optical absorption spectra of KBr:Tl+(0.0125 mol%) single crystals shows A, B and C bands around 258, 220 and 210 nm respectively. In KCl0.1Br0.9:Tl+(0.0125 mol%) mixed crystals exhibit slightly broadening of the A-band towards lower wavelength side. The broadening of the absorption spectra are suggested to be due to some complex Tl+centers involving Br-and Cl-ions formed in the mixed crystals. When excited at A, B and C-bands of Tl+ions, PL of KBr:Tl+showed emission band around 320 with a prominent shoulder around 365 nm. In KCl0.1Br0.9mixed crystals the shoulder around 365 nm is not prominent due to the perturbing influence of Cl-ions. Addition bands in the excitation spectra are attributed to the presence of Tl+dimmers. PSL observed in X-ray irradiated crystals resembled their respective PL emissions indicating that PSL in them is due to Tl+ions.

The role of dysprosium ions on the physical and optical properties of lithium-borosulfophosphate glasses

2017 ◽  
Vol 31 (13) ◽  
pp. 1750101 ◽  
Author(s):  
Ibrahim Bulus ◽  
S. A. Dalhatu ◽  
R. Hussin ◽  
W. N. Wan Shamsuri ◽  
Y. A. Yamusa
Keyword(s):  
Optical Properties ◽  
Optical Absorption ◽  
Absorption Spectra ◽  
Physical Parameters ◽  
Potential Candidate ◽  
Optical Absorption Spectra ◽  
Absorption Bands ◽  
X Ray ◽  
Nir Absorption ◽  
Optical Applications

Achieving outstanding physical and optical properties of borosulfophosphate glasses via controlled doping of rare earth ions is the key issue in the fabrication of new and highly-efficient glass material for diverse optical applications. Thus, the effect of replacing P2O5 by Dy2O3 on the physical and optical properties of Dy[Formula: see text]-doped lithium-borosulfophosphate glasses with chemical composition of 15Li2O–30B2O3–15SO3–[Formula: see text]P2O5–[Formula: see text]Dy2O3 (where 0.0 mol.% [Formula: see text] mol.%) has been investigated. The glass samples were synthesized from high-purity raw materials via convectional melt-quenching technique and characterized by X-ray diffraction (XRD), energy-dispersive X-ray spectrometry (EDX), density and UV–vis–NIR absorption measurements. The amorphous nature of the prepared glass samples was confirmed by XRD patterns whereas the EDX spectrum depicts elemental traces of O, C, B, S, P and Dy. The physical parameters such as density, refractive index, molar volume, polaron radius and field strength were found to vary nonlinearly with increasing Dy2O3 concentration. UV–vis–NIR absorption spectra revealed seven absorption bands with most dominant peak at 1269 nm (6H[Formula: see text]F[Formula: see text]H[Formula: see text]). From the optical absorption spectra, the optical bandgap and Urbach’s energy have been determined and are related with the structural changes occurring in these glasses with increase in Dy2O3 content. Meanwhile, the bonding parameters ([Formula: see text]) evaluated from the optical absorption spectra were found to be ionic in nature. The superior features exhibited by the current glasses nominate them as potential candidate for nonlinear optical applications.

Band-gap engineering in amorphous/microcrystalline ScxGa1-xN.

2001 ◽  
Vol 693 ◽  
Author(s):  
M. E. Little ◽  
M. E. Kordesch
Keyword(s):  
Optical Absorption ◽  
Band Gap ◽  
Absorption Spectra ◽  
Optical Band Gap ◽  
Optical Absorption Spectra ◽  
X Ray Diffraction ◽  
Band Gap Engineering ◽  
X Ray ◽  
Bilayer Films ◽  
Quartz Substrates

AbstractReactive sputtering was used to grow thin films of ScxGa1-xN with scandium concentrations of 20%-70% on quartz substrates at temperatures of 300-675 K. X-ray diffraction (XRD) of the films showed either weak or no structure, suggesting the films are amorphous or microcrystalline. Optical absorption spectra were taken of each sample and the optical band gap was determined. The band gap varied linearly with increasing Ga concentration between 2.0 and 3.5 eV. Ellipsometry was used to confirm the band gap measurements and provide optical constants in the range 250-1200 nm. ScN and GaN have different crystal structures (rocksalt and wurzite, respectively), and thus may form a heterogeneous mixture as opposed to an alloy. Since the XRD data were inconclusive, bilayers of ScN/GaN were grown and optical absorption spectra taken. A fundamental difference in the spectra between the bilayer films and alloy films was seen, suggesting the films are alloys, not herterogeneous mixtures.

Electronic excitations of stable fullerene-like GaP clusters

2004 ◽  
Vol 854 ◽  
Author(s):  
Giuliano Malloci ◽  
Giancarlo Cappellini ◽  
Giacomo Mulas ◽  
Guido Satta
Keyword(s):  
Optical Absorption ◽  
Absorption Spectra ◽  
Density Functional ◽  
Electronic Excitations ◽  
Optical Absorption Spectra ◽  
Functional Theory ◽  
Quasi Particle ◽  
New Class ◽  
Excitonic Effects ◽  
Homo Lumo

ABSTRACTWe present quasi-particle (QP) corrections to the electronic energies for small GaP fullerenes, a new class of nanoscaled materials predicted to be stable and to show spontaneous formation. Using Time-Dependent Density Functional Theory we also computed the optical absorption spectra. The comparison between single-particle and optical absorption spectra yields strong excitonic effects with bonding energy up to 3.5 eV. The QP corrected HOMO-LUMO energy gaps confirm the high stability predicted for such molecules using ground-state computational schemes. The present results can be useful to identify the successful synthesis of these systems via optical absorption and QP spectra.

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