Search results for " Matter"
showing 10 items of 15893 documents
Methyl 3',5'-dimethoxybiphenyl-4-carboxylate
2013
In the title compound, C16H16O4, the dihedral angle between the benzene rings is 28.9 (2)°. In the crystal, molecules are packed in layers parallel to the b axis in which they are connected via weak intermolecular C-H...O contacts. Face-to-face π-π interactions also exist between the benzene rings of adjacent molecules, with centroid-centroid and plane-to-plane shift distances of 3.8597 (14) and 1.843 (2) Å, respectively.
Methyl 3',4',5'-trimethoxybiphenyl-4-carboxylate
2013
In the title compound, C17H18O5, the dihedral angle between the benzene rings is 31.23 (16)°. In the crystal, the molecules are packed in an antiparallel fashion in layers along the a axis. In each layer, very weak C-H...O hydrogen bonds occur between the methoxy and methyl ester groups. Weak C-H...[pi] interactions between the 4'- and 5'-methoxy groups and neighbouring benzene rings [methoxy-C-ring centroid distances = 4.075 and 3.486 Å, respectively] connect the layers.
1,1,4,4-Tetramethylpiperazinediium dibromide
2009
A small quantity of the title compound, C8H20N22+·2Br−, was formed as a by-product in a reaction between a diamine and an alkyl bromide. The asymmetric unit contains half of a centrosymmetric dication and a bromide anion. In the crystal, weak intermolecular C—H...Br hydrogen bonds consolidate the crystal packing.
Controlling the crystal growth of potassium iodide with a 1,1'-bis(pyridin-4-ylmethyl)-2,2'-biimidazole ligand (L) – formation of a linear [K4I4L4]n …
2018
The crystal growth of potassium iodide was controlled by using the neutral organic 1,1′-bis(pyridin-4-ylmethyl)-2,2′-biimidazole (L) ligand as a modifier. The selected modifier allows the preservation of original cubic [K4I4] units and their arrangement into a linear ligand-supported 1D chain. The supported [K4I4] cubes are only slightly distorted compared to the cubes found in pure KI salt. The N–K binding of the ligand to the KI salt, as well as weak I⋯H, N⋯H, and N⋯I interactions, stabilizes the structure to create a unique 1D polymer of neutral potassium iodide ionic salt inside the [K4I4L4]n complex.
A black-box, general purpose quadratic self-consistent field code with and without Cholesky Decomposition of the two-electron integrals
2021
We present the implementation of a quadratically convergent self-consistent field (QCSCF) algorithm based on an adaptive trust-radius optimisation scheme for restricted open-shell Hartree���Fock (ROHF), restricted Hartree���Fock (RHF), and unrestricted Hartree���Fock (UHF) references. The algorithm can exploit Cholesky decomposition (CD) of the two-electron integrals to allow calculations on larger systems. The most important feature of the QCSCF code lies in its black-box nature ��� probably the most important quality desired by a generic user. As shown for pilot applications, it does not require one to tune the self-consistent field (SCF) parameters (damping, Pulay's DIIS, and other simil…
Review article: recommended reading list of early publications on atomic layer deposition - outcome of the "virtual Project on the History of ALD"
2017
Atomic layer deposition (ALD), a gas-phase thin film deposition technique based on repeated, self-terminating gas-solid reactions, has become the method of choice in semiconductor manufacturing and many other technological areas for depositing thin conformal inorganic material layers for various applications. ALD has been discovered and developed independently, at least twice, under different names: atomic layer epitaxy (ALE) and molecular layering. ALE, dating back to 1974 in Finland, has been commonly known as the origin of ALD, while work done since the 1960s in the Soviet Union under the name "molecular layering" (and sometimes other names) has remained much less known. The virtual proj…
The structural disorder of a silica network probed by site selective luminescence of the nonbridging oxygen hole centre
2011
We studied the inhomogeneous distribution of the luminescence band associated with the nonbridging oxygen hole centre in silica through site selective excitation/detection of the zero phonon line by a tunable laser source. Defects induced in the bulk of synthetic samples by γ and β exposure exhibit an increase of the inhomogeneous width from 0.071 to 0.086 eV on increasing the irradiation dose from 2 × 10(6) to 5 × 10(9) Gy. We also investigated two defect variants stabilized at the surface of the silica nanoparticles, (≡ Si-O)3 Si–O* and (≡ Si-O)2(H-O)Si-O*, whose inhomogeneous width was measured to be 0.042 eV and 0.060 eV, respectively. These results can be accounted for by the structura…
Effect of the Si doping on the properties of AZO/SiC/Si heterojunctions grown by low temperature pulsed laser deposition
2020
Abstract The structural and photoelectrical properties of Al-doped ZnO (AZO)/SiC/p-Si and AZO/SiC/n-Si heterojunctions, fabricated at low temperature by pulsed laser deposition, were investigated by means of a number of techniques. Raman analysis indicates that SiC layers have the cubic 3C-SiC phase, whilst X-ray diffraction measurements show that AZO films exhibit a hexagonal wurtzite structure, highly textured along the c-axis, with average crystallites size of 35.1 nm and lattice parameter c of 0.518 nm. The homogeneous and dense surface morphology observed by scanning electron microscopy was confirmed by atomic force microscopy images. Moreover, UV–Vis-NIR spectra indicated a high trans…
Localized surface plasmon resonance in silver nanoparticles: Atomistic first-principles time-dependent density-functional theory calculations
2015
We observe using ab initio methods that localized surface plasmon resonances in icosahedral silver nanoparticles enter the asymptotic region already between diameters of 1 and 2 nm, converging close to the classical quasistatic limit around 3.4 eV. We base the observation on time-dependent density-functional theory simulations of the icosahedral silver clusters Ag$_{55}$ (1.06 nm), Ag$_{147}$ (1.60 nm), Ag$_{309}$ (2.14 nm), and Ag$_{561}$ (2.68 nm). The simulation method combines the adiabatic GLLB-SC exchange-correlation functional with real time propagation in an atomic orbital basis set using the projector-augmented wave method. The method has been implemented for the electron structure…
Time resolved emission at 1.3 μm of a single InAs quantum dot by using a tunable fibre Bragg grating
2013
Photoluminescence and time resolved photoluminescence from single metamorphic InAs/GaAs quantum dots (QDs) emitting at 1.3 mu m have been measured by means of a novel fibre-based characterization set-up. We demonstrate that the use of a wavelength tunable fibre Bragg grating filter increases the light collection efficiency by more than one order of magnitude as compared to a conventional grating monochromator. We identified single charged exciton and neutral biexciton transitions in the framework of a random population model. The QD recombination dynamics under pulsed excitation can be understood under the weak quantum confinement potential limit and the interaction between carriers at the …