Emission quenching of photoexcited ruthenium(II) complexes by dialkylviologens in sodium decylsulfate micellar solution: effect of hydrophobicity on diffusion coefficients on a micelle surface

1989 ◽  
Vol 93 (4) ◽  
pp. 1426-1428 ◽  
Author(s):  
Tokuji Miyashita ◽  
Tadahiro Murakata ◽  
Minoru Matsuda
Keyword(s):  
Diffusion Coefficients ◽  
Micellar Solution ◽  
Sodium Decylsulfate ◽  
Emission Quenching ◽  
Micelle Surface

Frequency-Diffusion Characteristics of Silicic Acid Gels

2005 ◽  
Vol 480-481 ◽  
pp. 629-634
Author(s):  
Yu.I. Sukharev ◽  
V.V. Avdin
Keyword(s):  
Rare Earth ◽  
Rare Earth Elements ◽  
Diffusion Coefficients ◽  
Micellar Solution ◽  
Polymer Structure ◽  
General Nature ◽  
Vibration Frequencies ◽  
Fractal Nature ◽  
Diffusion Characteristics ◽  
Early Assumption

The discreteness of vibration frequencies of diffusion coefficients of rare - earth elements ions in the forming gel of silicon acid is considered. The existence of at least three vibration frequencies being more probable for the gel system in question is established. The agreement of these results with the experiments studying the behaviour of pacemakers in zirconium oxyhydrate gels is shown. This agreement and the frequency discreteness mentioned prove the early assumption [1] that structuring of different gels proceeds through the process of formation and interaction of stable sites in a polymer structure of a discrete size (attractor). The system of attractors is of a fractal nature. The regularities established reflect the general nature of the gelation with any types of a gelforming polymer and ions diffusing in the micellar solution.

Interlayer mixing in GaAs/AlxGa1-xAs heterostructures as a result of Se+ ion implantation

1988 ◽  
Vol 46 ◽  
pp. 908-909
Author(s):  
E.G. Bithell ◽  
W.M. Stobbs
Keyword(s):  
Ion Implantation ◽  
Diffusion Coefficients ◽  
Dark Field ◽  
Atomic Mass ◽  
Composition Profile ◽  
Semiconductor Heterostructures ◽  
Transmission Electron ◽  
Microscope Images ◽  
Damage Process ◽  
Electron Energy Loss

It is well known that the microstructural consequences of the ion implantation of semiconductor heterostructures can be severe: amorphisation of the damaged region is possible, and layer intermixing can result both from the original damage process and from the enhancement of the diffusion coefficients for the constituents of the original composition profile. A very large number of variables are involved (the atomic mass of the target, the mass and energy of the implant species, the flux and the total dose, the substrate temperature etc.) so that experimental data are needed despite the existence of relatively well developed models for the implantation process. A major difficulty is that conventional techniques (e.g. electron energy loss spectroscopy) have inadequate resolution for the quantification of any changes in the composition profile of fine scale multilayers. However we have demonstrated that the measurement of 002 dark field intensities in transmission electron microscope images of GaAs / AlxGa1_xAs heterostructures can allow the measurement of the local Al / Ga ratio.

Catalyst Halogenation Enables Rapid and Efficient Polymerizations with Visible to Near-Infrared Light

2020 ◽  
Author(s):  
Alex Stafford ◽  
Dowon Ahn ◽  
Emily Raulerson ◽  
Kun-You Chung ◽  
Kaihong Sun ◽  
...  
Keyword(s):  
Near Infrared ◽  
Transient Absorption ◽  
Reaction Times ◽  
Infrared Light ◽  
Structure Property ◽  
Light Emitting ◽  
Structure Property Relationships ◽  
Nir Light ◽  
Light Intensities ◽  
Emission Quenching

Driving rapid polymerizations with visible to near-infrared (NIR) light will enable nascent technologies in the emerging fields of bio- and composite-printing. However, current photopolymerization strategies are limited by long reaction times, high light intensities, and/or large catalyst loadings. Improving efficiency remains elusive without a comprehensive, mechanistic evaluation of photocatalysis to better understand how composition relates to polymerization metrics. With this objective in mind, a series of methine- and aza-bridged boron dipyrromethene (BODIPY) derivatives were synthesized and systematically characterized to elucidate key structure-property relationships that facilitate efficient photopolymerization driven by visible to NIR light. For both BODIPY scaffolds, halogenation was shown as a general method to increase polymerization rate, quantitatively characterized using a custom real-time infrared spectroscopy setup. Furthermore, a combination of steady-state emission quenching experiments, electronic structure calculations, and ultrafast transient absorption revealed that efficient intersystem crossing to the lowest excited triplet state upon halogenation was a key mechanistic step to achieving rapid photopolymerization reactions. Unprecedented polymerization rates were achieved with extremely low light intensities (< 1 mW/cm<sup>2</sup>) and catalyst loadings (< 50 μM), exemplified by reaction completion within 60 seconds of irradiation using green, red, and NIR light-emitting diodes.

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