post-Spin Crossing Dynamics Determine the Regioselectivity in Open-shell Singlet Biradical Recombination

2022 ◽  
Author(s):  
Min Zhu ◽  
Chao Zheng
Keyword(s):  
Organic Chemistry ◽  
Visible Light ◽  
Open Shell ◽  
Radical Recombination ◽  
High Level

Radical recombination is among the fastest reactions in organic chemistry. Achieving high level of selectivities in this type of reactions is rather challenging. In a recent report on visible-light-induced dearomative...

Construction of a push–pull system in g-C3N4 for efficient photocatalytic hydrogen evolution under visible light

2020 ◽  
Vol 8 (26) ◽  
pp. 13299-13310 ◽  
Author(s):  
Cheng-Qun Xu ◽  
Wei-De Zhang ◽  
Kenzo Deguchi ◽  
Shinobu Ohki ◽  
Tadashi Shimizu ◽  
...  
Keyword(s):  
Organic Chemistry ◽  
Visible Light ◽  
Hydrogen Evolution ◽  
One Pot ◽  
Photocatalytic Hydrogen Evolution ◽  
Pull System

A facile “one-pot” method to improve the utilization of visible light using organic chemistry protocols is reported.

scholarly journals First Glimpse

1999 ◽  
Vol 121 (09) ◽  
pp. 68-70
Author(s):  
John DeGaspari
Keyword(s):  
Visible Light ◽  
Leading Edge ◽  
The Other ◽  
Light Spectrum ◽  
Substantial Cost ◽  
Infrared Band ◽  
Testing Protocol ◽  
High Level ◽  
To Receive ◽  
Very High

The Next Generation Space Telescope (NGST) will incorporate leading-edge technology in construction, optics, and deployment. NGST will be composed of a large sunshield and lightweight mirror, which will be deployed in space. Both are depicted in this rendering by TRW Space and Electronic Group. Over the next two years, the teams, one led by Lockheed Martin Missiles & Space, Sunnyvale, CA, and the other led by TRW Space and Electronic Group in Redondo Beach, California, and including Ball Aerospace and Technologies Corp., Boulder, CO, will tackle some daunting engineering challenges. The new telescope will pick up where the Hubble telescope leaves off. Hubble observes objects that are still in the visible light spectrum. NGST will investigate objects that are much more distant in space and will need to be sensitive to the infrared band. The testing protocol is going to receive a very high level of attention during this upcoming phase one effort, because it is one of the substantial cost elements of a program of this nature.

scholarly journals Reversible and Irreversible Color Change during Photo and Thermal Degradation of PolyphenyleneSulfide Composite

Polymers ◽  
2019 ◽  
Vol 11 (10) ◽  
pp. 1579 ◽  
Author(s):  
Victor B. Ivanov ◽  
Vladimir V. Bitt ◽  
Elena V. Solina ◽  
Alexander V. Samoryadov
Keyword(s):  
Visible Light ◽  
Color Change ◽  
Glass Fibers ◽  
Spectral Composition ◽  
Polyphenylene Sulfide ◽  
Reflection Spectra ◽  
Total Radiation ◽  
Arrhenius Law ◽  
High Level ◽  
Short Glass

The effect of the light spectral composition and temperature on the change of color characteristics and reflection spectra during the irradiation of polyphenylene sulfide reinforced by short glass fibers in the SUNTEST apparatus was analyzed. The scales of reversible color change upon successive exposure to total radiation corresponding to the sunlight spectrum and to visible light wereevaluated and the possible mechanisms for the observed effects are discussed. The features of the color change upon visible light irradiation of previously thermally aged samples wereconsidered. Possible causes for deviation from the Arrhenius law during thermal aging of the composite are discussed. It wasdemonstrated that even with a significant change in color, the physicomechanical and electrotechnical characteristics of the composite only changedslightly or remained virtually at the same high level.

Improved visible-light photoactivities of porous LaFeO3 by coupling with nanosized alkaline earth metal oxides and mechanism insight

2019 ◽  
Vol 9 (12) ◽  
pp. 3149-3157 ◽  
Author(s):  
Iltaf Khan ◽  
Ning Sun ◽  
Ziqing Zhang ◽  
Zhijun Li ◽  
Muhammad Humayun ◽  
...  
Keyword(s):  
Visible Light ◽  
Metal Oxides ◽  
Alkaline Earth ◽  
Earth Metal ◽  
Alkaline Earth Metal ◽  
Dual Functional ◽  
Alkaline Earth Metal Oxides ◽  
High Level

It is significant to improve visible-light photoactivities of porous LaFeO3 by coupling with nanosized alkaline earth metal oxides as dual-functional platform for accepting the high level electrons and activating CO2.

Development of Plasmonic Photocatalysts for Environmental Application

2014 ◽  
Vol 93 ◽  
pp. 174-183 ◽  
Author(s):  
Ewa Kowalska ◽  
Zhi Shun Wei ◽  
Baris Karabiyik ◽  
Marcin Janczarek ◽  
Maya Endo ◽  
...  
Keyword(s):  
Visible Light ◽  
Visible Light Irradiation ◽  
Noble Metals ◽  
Light Irradiation ◽  
Environmental Application ◽  
Shape Distribution ◽  
Photocatalytic Activities ◽  
Catalytically Active ◽  
Gold Nps ◽  
High Level

Regarding catalytic and plasmonic properties of gold nanoparticles (NPs), the novel area of research on photocatalytic gold properties has been recently started. In contrast with catalytically active gold NPs, where nanosized gold is recommended, our results showed that polydispersity of deposited gold NPs on semiconducting support was beneficial for photocatalytic activity under visible light irradiation. It is thought that wide size/shape distribution of gold NPs, and thus the ability of absorption of light in a wide wavelengths range is responsible for the high level of photoactivity. Though desirable absorption properties of plasmonic photocatalysts can be easily obtained by preparation of nanoparticles of different sizes and shapes, their photocatalytic activities under visible light irradiation are still low and should be enanced. The improvement of photocatalytic activities under visible light irradiation was achieved by enlargement of interfacial contact between titania and NPs of noble metals, extension of photoabsorption ranges (by preparation of NPs of various sizes and shapes or composed of two kinds of noble metals), and by deposition of noble metals NPs on faceted titania, i.e., octahedral (OAPs) and decahedral (DAPs). Plasmonic photocatalysts composed of titania and NPs of silver, gold or copper showed also high antiseptic properties under visible light irradiation, due to possible synergism of antiseptic properties of noble metals and photodisinfection properties of photocatalyst, since reactive oxygen species or photogenerated holes are formed on the surface of irradiated semiconductor.

scholarly journals The origin of Scythian caldrons in the context of the late Bronze − Early Iron Age of Eurasia

2017 ◽  
Vol 25 (1) ◽  
pp. 201
Author(s):  
Oleksandra Volodymyrivna Romashko
Keyword(s):  
Black Sea ◽  
Iron Age ◽  
Open Shell ◽  
Early Iron Age ◽  
Black Sea Coast ◽  
Method Of Production ◽  
High Level ◽  
Local Traditions ◽  
Very High ◽  
Sea Coast

A detailed analysis of the historiography of the issue is presented, which takes into account works devoted to the antiquities of the early Iron Age. The authors come to the conclusion about the local production of Scythian metal boilers, seeing in this a very high level of development of metalworking of Scythian masters. With regard to the issue associated with the origin of the tradition of manufacturing these products, then in the historiography there were two theories: the Asian (L. N. Chlenova, S. V. Demidenko, V. S. Bochkarev, etc.) and native (O. A. Krivtsova-Grakova and others). In our opinion, the question of the origin of boilers should be considered taking into account the specific features of their morphology. Thus, open-shell boilers that dominate the archaic times (VII−VI centuries BC) are made taking into account the clearly formulated traditions and requirements for products of this category brought from the East to the Northern Black Sea Coast. Regarding the boilers with closed housing, which begin to appear in the VI century BC, we can say the following. Their production originates in the local traditions of the production of boilers, which were formed back in Cimmerian times (riveted boilers). But these traditions do not receive a direct line of development in Scythian time. We see rather complicated processes of formation of the Scythian center for the production of archaic cast caldrons in the Kuban region, where this tradition spreads throughout the Northern Black Sea Coast. In the course of this complex and multifaceted process, new syncretic traditions of the production of boilers are formed, combining the innovative method of production (casting) and the local traditions of perception of the shape of the caldron.

Visible-light-induced water oxidation by a hybrid photocatalyst consisting of bismuth vanadate and copper(ii) meso-tetra(4-carboxyphenyl)porphyrin

2016 ◽  
Vol 52 (18) ◽  
pp. 3665-3668 ◽  
Author(s):  
Shu Nakashima ◽  
Ryo Negishi ◽  
Hiroaki Tada
Keyword(s):  
Visible Light ◽  
Visible Light Irradiation ◽  
Water Oxidation ◽  
Bismuth Vanadate ◽  
Light Irradiation ◽  
Level Of Activity ◽  
High Level ◽  
Surface Modified ◽  
Hybrid Photocatalyst

Copper(ii) meso-tetra(4-carboxyphenyl)porphyrin surface-modified monoclinic scheelite bismuth vanadate (CuTCPP/ms-BiVO4) exhibits a high level of activity for the water oxidation to oxygen (O2) under visible-light irradiation (λ > 430 nm).

scholarly journals Recent Advances on Copper Complexes as Visible Light Photoinitiators and (Photo) Redox Initiators of Polymerization

Catalysts ◽  
2020 ◽  
Vol 10 (9) ◽  
pp. 953 ◽  
Author(s):  
Guillaume Noirbent ◽  
Frédéric Dumur
Keyword(s):  
Organic Chemistry ◽  
Excited State ◽  
Visible Light ◽  
Metal Complexes ◽  
Copper Complexes ◽  
Low Cost ◽  
Iridium Complexes ◽  
Solid Materials ◽  
Photo Polymerization ◽  
Synthetic Approaches

Metal complexes are used in numerous chemical and photochemical processes in organic chemistry. Metal complexes have not been excluded from the interest of polymerists to convert liquid resins into solid materials. If iridium complexes have demonstrated their remarkable photochemical reactivity in polymerization, their high costs and their attested toxicities have rapidly discarded these complexes for further developments. Conversely, copper complexes are a blooming field of research in (photo) polymerization due to their low cost, easy syntheses, long-living excited state lifetimes, and their remarkable chemical and photochemical stabilities. Copper complexes can also be synthesized in solution and by mechanochemistry, paving the way towards the synthesis of photoinitiators by Green synthetic approaches. In this review, an overview of the different copper complexes reported to date is presented. Copper complexes are versatile candidates for polymerization, as these complexes are now widely used not only in photopolymerization, but also in redox and photoassisted redox polymerization processes.

Sign in / Sign up

Export Citation Format

Share Document