Search results for "Visible"

Light Induced Modifications of Langmuir-Blodgett-Multilayer Assemblies Containing Amphotropic Azocopolymer

1994

Abstract Photochromic LB-multilayers of amphotropic copolymers having rod-like azobenzene moieties as side groups which exhibit thermotropic liquid crystalline behaviour in the bulk have been characterized by UV-VIS spectroscopy as well as by angular dependent and energy dispersive SAXS. Upon irradiation with UV-light the initial optical in-plane anisotropy and the vertical layered structure of LB-films can be destroyed. A new layered structure can be rebuilt on irradiation with visible light or by annealing. Using linearly polarized light for the irradiation an optical anisotropy (POA) has been induced or reversibly modified by a photoselection process.

A Bichromophore Based on Perylene and Terrylene for Energy Transfer Studies at the Single-Molecule Level

1999

A functionalized dialkylperylene and a modified terrylenetetracarboxdiimide (TTCDI) were joined by a hexanediyl spacer. The resulting bichromophoric molecule 1 (R = 4-tert-butylphenoxy) is a suitable model system for donor–acceptor energy transfer studies at the single-molecule level.

Synthesis and Electronic Spectra of Substitutedp-Distyrylbenzenes for the Use in Light-Emitting Diodes

2000

The influence of substitution on the absorption and Luminescence spectra of oligo(phenylenevinylene)s has been studied using distyrylbenzene (DSB) as a model compound. The degree, character, and pattern of substitution was varied systematically, altering the electronic properties of the DSB, the wavelength of the emitted light could be tuned over a range of 100 nm. The syntheses of 6b—h were performed by twofold Wittig Horner-olefinations of bisphoshonates 1a, b with substituted benzaldehydes 2a—i, 6ivia Heck-reaction of the dibromosulfonylbenzene 3, 6k by Siegrist-reaction of 4 with N-phenylbenzaldimine and the Knoevenagel-reaction of benzyl cyanide with 5 led to 6l.

Y en a pas un sur cent mais pourtant ils existent : les films militants anarchistes français, un cinéma invisible mais effectif

2007

Regio- and Stereoselective Chloro Sulfoximidations of Terminal Aryl Alkynes Enabled by Copper Catalysis and Visible Light

2021

Advanced synthesis & catalysis 2552-2556 (2021). doi:10.1002/adsc.202100162

Recensione a R. DIXON e A. STONE (a cura di), The Invisible Constitution in Comparative Perspective, Cambridge, Cambridge University Press, 2018

2020

è la recensione al libro curato da R. Dixon e A. Stone. It is a review of the book edited by R. Dixon and A. Stone.

D’émotions paroxystiques en blessures invisibles. Traumas de guerre et cultures sensibles dans les récits combattants du XIXe siècle

2012

International audience

در ﺑﺎب ﻃﺮاﺣﯽ، ﺗﺮﺟﻤﻪ و ﭘﮋوﻫﺶ / Of designing, of translating, of searching

2018

ﺑﺤﺚ در ﺑﺎب ﻃﺮاﺣﯽ ارﺗﺒﺎط ﺑﺼﺮی ﻣﺴﺘﻠﺰم اﯾﻦ اﺳﺖ ﮐﻪ ﻣﺴﺌﻠﻪ ی ﺗﺮﺟﻤﻪ ﻫﻢ ﺑﻪ ﻃﻮر ﻣﺪاوم و ﺑﻪ ﻣﻮازات آن، ﺻﺮف ﻧﻈﺮ از ﻣﺤﺘﻮای ﻣﻮرد ﺑﺤﺚ، ﻣﻄﺮح ﺷﻮد. ﺑﺤﺚ روی ﻃﺮاﺣﯽ ارﺗﺒﺎط ﺑﺼﺮی ﺑﺮای ﻣﻮﺳﯿﻘﯽ ﺷﺎﻣﻞ دو ﻣﺮﺣﻠﻪ ی ﺗﺮﺟﻤﻪ اﺳﺖ، ﭼﺮا ﮐﻪ دو ﻧﻮع ﺗﻐﯿﯿﺮ را اﯾﺠﺎب ﻣﯽ ﮐﻨﺪ؛ ﺗﻐﯿﯿﺮ ﻓﺮم ﺑﯿﺎن ﻣﺤﺘﻮا از ﻓﺮم اﺻﻠﯽ و ﺗﻐﯿﯿﺮ اﺻﻞ ﻣﺎﻫﯿﺖ ﻣﻮﺳﯿﻘﯽ، از اﻧﺘﺰاﻋﯽ و ﻧﺎﻣﻠﻤﻮس، ﺑﻪ ﻋﯿﻨﯽ و ﻣﻠﻤﻮس. در اﯾﻦ ﻓﺮاﯾﻨﺪ، ﮐﻪ ﻣﻤﮑﻦ اﺳﺖ ارزش ﻫﺮﻣﻨﻮﺗﯿﮏ۲ ﺑﻪ ﺧﻮد ﺑﮕﯿﺮد، ﻃﺮاح ﺑﻪ ﻋﻨﻮان ﻣﺘﺮﺟﻢ ﻋﻤﻞ ﻣﯽ ﮐﻨﺪ؛ در اﯾﻦ ﻓﺮاﯾﻨﺪ، او ﺑﺮای اﻧﺘﻘﺎل ﻣﻔﻬﻮم ﯾﺎ ﺑﻪ ﻋﺒﺎرﺗﯽ »ﮔﺬر از ﭘﻞِ ارﺗﺒﺎﻃﯽ« دﺳﺖ ﺑﻪ اﺑﺰارﻫﺎ ﻣﯽ ﺑﺮد و ﺑﺎ ﺗﻐﯿﯿﺮ درو ﻧﻤﺎﯾﻪ ی ﻣﻔﺎﻫﯿﻢ ﺳﻌﯽ ﻣﯽ ﮐﻨﺪ ﺗﺎ ﺗﺮﺟﻤﺎﻧﯽ ﻣﺮﺋﯽ از ﻣﺤﺘﻮاﯾﯽ ﻧﺎﻣﺮﺋﯽ اراﺋﻪ ﮐﻨﺪ. Discussing the design of visual communication entails the constant drawing of parallels with the issue…

Efficient Conversion of Light to Chemical Energy : Directional, Chiral Photoswitches with Very High Quantum Yields

2020

Abstract Photochromic systems have been used to achieve a number of engineering functions such as light energy conversion, molecular motors, pumps, actuators, and sensors. Key to practical applications is a high efficiency in the conversion of light to chemical energy, a rigid structure for the transmission of force to the environment, and directed motion during isomerization. We present a novel type of photochromic system (diindane diazocines) that converts visible light with an efficiency of 18 % to chemical energy. Quantum yields are exceptionally high with >70 % for the cis–trans isomerization and 90 % for the back‐reaction and thus higher than the biochemical system rhodopsin (64 %). T…

Effect of air-absorbed oxygen and moisture on the chemical stability of photoexcitedMg,ZnandEuphthalocyanines in dimethylformamide

2006

Absorption of oxygen and moisture from air by MPc-DMF systems was studied and related to the molecular stability demonstrated by phthalocyanine complexes (unsubstituted MPc's : MgPc , ZnPc and EuPc2; Pc = phthalocyanine ligand, C32H16N8) subjected to UV irradiation. A lower stability of air-exposed dimethylformamide solutions is observed and is due to a specific affinity for molecular oxygen revealed by the Pc macrocycle. SEM results proved oxygen molecules fixed to the phthalocyanine solids by forces strong enough to sustain desorption under vacuum. Absorption curves determined for MPc-DMF systems also indicate oxygen accommodated by the phthalocyanine moiety. This explains the predominant…