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71.
N. Sharadhi S. Vimala K. Nurjahan B. N. Veerabhadraswamy C. V. Yelamaggad 《Liquid crystals》2020,47(2):211-218
ABSTRACT Blue phase liquid crystals are soft 3D photonic crystals in which the liquid crystal molecules self-assemble to form a cubic structure with lattice spacing of a few hundred nanometers resulting in selective reflection of colours in the visible spectrum. The corresponding wavelength or the ‘photonic band gap’ can be tuned using various external stimuli such as thermal, electric, magnetic and optical fields. Here, we report efficient tuning of photonic band gap by utilising the combination of electric and optical fields in a blue phase liquid crystalline system. The studies indicate that the chirality of the medium has a direct bearing on the direction of the wavelength shift and the extent of the photonic band gap tunability. More importantly, the synergistic effect of the two fields helps in reversible tuning of the band gap. 相似文献
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73.
《Mendeleev Communications》2020,30(5):666-668
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New hybrid nanomaterials, with improved photocatalytic performance in pollutants removal, were obtained through the modification of titanate nanotubes (TNT) with a cobalt porphyrin, the cyanocobalamin, also knowing as vitamin B12 (B12). The nanocrystalline TNT were produced by hydrothermal treatment and after treated with cobalamin to produce B12-TNT materials. The characterization of the new hybrid material was performed by XRD, FTIR, TEM-EDS, DRS, XPS and ICP. The results show that the immobilization of the cobalt containing specie is dependent on the point of zero charge of the TNT and no modifications on the structure and morphology were observed. No significant changes in the optical band gap were observed after B12 incorporation, but an increasing in the visible light absorption, which arises from charge transfer and d–d transitions of the cobalt, was visualized. The samples photocatalytic performance was studied for the hydroxyl radical production and the highest catalytic ability was achieved by the B12-HTNT sample. The catalytic ability of these new hybrid nanomaterials for two model pollutants photodegradation, phenol and rhodamine B (RhB) was investigated. For both pollutants, the best results were achieved using B12-HTNT with a removal of 94% of a 10 ppm RhB and 87% of a 20 ppm phenol solution in 90 min of irradiation (150 mL, 0.2 g catalyst/L). 相似文献
76.
Abstract Color centers in rutile-structured MgF2 single crystals irradiated at 20K/360K by reactor neutrons are investigated spectroscopically at LNT. Four different types of the F-F vacancy bond in MgF2 are possibly identified to the observed absorption bands as due to the F2 centers; instead of previous assignments, the 300nm band to the F2(D2h), the 325nm band to the F2(C1), the 355nm band to the F2(C2v), and the 400nm band to the F2(C2h) centers. 相似文献
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A novel one-step synthesis process was used to prepare CdTe:Cu2+/TiO2 nanotube arrays (TNTAs). X-ray powder diffraction and high-resolution transmission electron microscopy analyses confirmed that the obtained CdTe:Cu2+ quantum dots (QDs) possess cubic structures, which are approximately spherical, and a small particle size (2.95 nm). The photoluminescent and UV–visible absorption spectra of CdTe:Cu2+ QDs also display an obvious redshift, which was attributed to the replacement of Cd2+ with Cu2+. Compared with that of the TNTAs and CdTe/TNTAs, the photoelectric conversion efficiency of CdTe:5% Cu2+/TNTAs increased by 785.7% and 103.3%, respectively. The incident photo-to-current conversion efficiency of CdTe:5% Cu2+/TNTAs was 50.6%, which indicated the potential use of QDs in photochemical solar cells. 相似文献
79.
Dr. Markus Lampimäki Dr. Veronika Zelenay Dr. Adéla Křepelová Dr. Zhi Liu Rui Chang Dr. Hendrik Bluhm Dr. Markus Ammann 《Chemphyschem》2013,14(11):2419-2425
Ozone adsorption and decomposition on metal oxides is of wide interest in technology and in atmospheric chemistry. Here, ozone‐adsorption‐induced band bending is observed on Ti‐ and Fe‐oxide model surfaces under dry and humid conditions. Photoelectron spectroscopic studies indicate the effect of charge transfer to O3, which limits the surface coverage of the precursor to decomposition reactions. This is also consistent with the negative pressure dependence observed in previous studies. These results contribute to our fundamental understanding of ozone adsorption and decomposition mechanisms on metal oxides of environmental and technological relevance. 相似文献
80.
《Soft Materials》2013,11(2-3):109-123
Abstract We have systematically investigated the production of “nanoemulsions,” droplets of one liquid phase in another immiscible liquid phase that have diameters less than 100 nm. Our approach relies on a combination of extreme shear due to multipass, high‐pressure microfluidic injection and systematic control of the emulsion's composition. By repeatedly shearing a silicone oil‐in‐water emulsion in an inhomogeneous extensional shear flow, the multipass approach enables us to reduce the droplet polydispersity and average radius. Using dynamic light scattering, we study the changes in the average radius, ?a?, as a function of the number of passes, driving injection pressure (i.e., shear rate), droplet volume fraction, surfactant concentration, and droplet oil viscosity. The smallest nanoemulsion that we obtain has ?a?=18 nm. At large droplet volume fractions φ≥0.65, we observe phase inversion, rather than a reduction in the droplet size. This provides evidence that droplet coalescence can occur during extreme shear, even when a significant excess of a strongly stabilizing surfactant is present. 相似文献