scholarly journals Long wavelength single photon like driven photolysis via triplet triplet annihilation

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Ling Huang ◽  
Le Zeng ◽  
Yongzhi Chen ◽  
Nuo Yu ◽  
Lei Wang ◽  
...  
Keyword(s):  
Single Photon ◽  
Ambient Air ◽  
Electromagnetic Spectrum ◽  
Long Wavelength ◽  
Chemical Structures ◽  
Extensive Range ◽  
Broad Array ◽  
Photoremovable Protecting Groups ◽  
Wavelength Light ◽  
Triplet Triplet Annihilation

AbstractPhotolysis has enabled the occurrence of numerous discoveries in chemistry, drug discovery and biology. However, there is a dearth of efficient long wavelength light mediated photolysis. Here, we report general and efficient long wavelength single photon method for a wide array of photolytic molecules via triplet-triplet annihilation photolysis. This method is versatile and “LEGO”-like. The light partners (the photosensitizers and the photolytic molecules) can be energetically matched to adapt to an extensive range of electromagnetic spectrum wavelengths and the diversified chemical structures of photoremovable protecting groups, photolabile linkages, as well as a broad array of targeted molecules. Compared to the existing photolysis methods, our strategy of triplet-triplet annihilation photolysis not only exhibits superior reaction yields, but also resolves the photodamage problem, regardless of whether they are single photon or multiple photon associated. Furthermore, the biological promise of this “LEGO” system was illustrated via developing ambient air-stable nanoparticles capable of triplet-triplet annihilation photolysis.

scholarly journals Long Wavelength Single Photon Like Driven Photolysis Via Triplet-Triplet Annihilation

2020 ◽  
Author(s):  
Gang Han ◽  
Ling Huang ◽  
Le Zeng ◽  
Yongzhi Chen ◽  
Nuo Yu ◽  
...  
Keyword(s):  
Single Photon ◽  
Ambient Air ◽  
Electromagnetic Spectrum ◽  
Long Wavelength ◽  
Chemical Structures ◽  
Extensive Range ◽  
Broad Array ◽  
Photoremovable Protecting Groups ◽  
Wavelength Light ◽  
Triplet Triplet Annihilation

Abstract Photolysis has enabled the occurrence of numerous discoveries in chemistry, drug discovery and biology. However, there is a dearth of efficient long wavelength light mediated photolysis. Here, we report general and efficient long wavelength single photon method for a wide array of photolytic molecules via triplet-triplet annihilation photolysis (TTAP). This method is versatile and "LEGO"-like. The light partners (the photosensitizers and the photolytic molecules (PPG-Xs)) can be energetically matched to adapt to an extensive range of electromagnetic spectrum wavelengths and the diversified chemical structures of photoremovable protecting groups (PPGs), photolabile linkages, as well as a broad array of targeted molecules. Our TTAP not only surpasses reaction yields, it also resolves the photodamage problem of the existing photolysis methods, regardless of whether they are a single photon or multiple photons associated. Furthermore, we developed ambient air-stable, TTAP nanoparticles to illustrate the biological promise of TTAP “LEGO” systems.

Multiwavelength Control of Mixtures Using Visible Light Absorbing Photocages

2020 ◽  
Author(s):  
Julie A Peterson ◽  
Ding Yuan ◽  
Arthur Winter
Keyword(s):  
Visible Light ◽  
Optical Control ◽  
Protecting Groups ◽  
Materials Synthesis ◽  
Selective Activation ◽  
Long Wavelength ◽  
Photoremovable Protecting Groups ◽  
Deep Uv ◽  
Wavelength Light ◽  
Led Irradiation

Selective deprotection of functional groups using different wavelengths of light is attractive for materials synthesis as well as for achieving independent photocontrol over substrates in biological systems. However, wavelength-selective activation is difficult to achieve with common UV-absorbing photoremovable protecting groups (PRPGs) because it is difficult to separate the chromophore absorption profiles. Moreover, deep UV irradiation of photocages can result in cellular phototoxicity. Here, we investigated the ability of recently-developed visible light absorbing BODIPY-derived PRPGs and a coumarin-derived PRPG to undergo wavelength selective activation in order to identify well-behaved pairs of PRPGs that allow independent optical control over a mixture of photocaged substrates using more biologically benign long-wavelength light. The three pairs of PRPGs tested have complete selectivities for cleaving the longerwavelength absorbing photocage first, and fair to excellent selectivities for releasing the lower-wavelength absorbing PRPG first when mixtures were irradiated in solution. When the PRPGs are attached to the same substrate, irradiating the shorter-wavelength absorbing PRPG results in energy transfer, but the PRPGs can be cleaved in a sequential manner starting by deprotecting the longest wavelength absorbing photocage first and then removing the lower-wavelength absorbing PRPG. A mixture of the three photocages could be sequentially reacted using common red, green, and far-UV (365 nm) LED irradiation. <br>

Multiwavelength Control of Mixtures Using Visible Light Absorbing Photocages

2020 ◽  
Author(s):  
Julie A Peterson ◽  
Ding Yuan ◽  
Arthur Winter
Keyword(s):  
Visible Light ◽  
Optical Control ◽  
Protecting Groups ◽  
Materials Synthesis ◽  
Selective Activation ◽  
Long Wavelength ◽  
Photoremovable Protecting Groups ◽  
Deep Uv ◽  
Wavelength Light ◽  
Led Irradiation

Selective deprotection of functional groups using different wavelengths of light is attractive for materials synthesis as well as for achieving independent photocontrol over substrates in biological systems. However, wavelength-selective activation is difficult to achieve with common UV-absorbing photoremovable protecting groups (PRPGs) because it is difficult to separate the chromophore absorption profiles. Moreover, deep UV irradiation of photocages can result in cellular phototoxicity. Here, we investigated the ability of recently-developed visible light absorbing BODIPY-derived PRPGs and a coumarin-derived PRPG to undergo wavelength selective activation in order to identify well-behaved pairs of PRPGs that allow independent optical control over a mixture of photocaged substrates using more biologically benign long-wavelength light. The three pairs of PRPGs tested have complete selectivities for cleaving the longerwavelength absorbing photocage first, and fair to excellent selectivities for releasing the lower-wavelength absorbing PRPG first when mixtures were irradiated in solution. When the PRPGs are attached to the same substrate, irradiating the shorter-wavelength absorbing PRPG results in energy transfer, but the PRPGs can be cleaved in a sequential manner starting by deprotecting the longest wavelength absorbing photocage first and then removing the lower-wavelength absorbing PRPG. A mixture of the three photocages could be sequentially reacted using common red, green, and far-UV (365 nm) LED irradiation. <br>

scholarly journals Demonstration of epitaxial growth of strain-relaxed GaN films on graphene/SiC substrates for long wavelength light-emitting diodes

2021 ◽  
Vol 10 (1) ◽  
Author(s):  
Ye Yu ◽  
Tao Wang ◽  
Xiufang Chen ◽  
Lidong Zhang ◽  
Yang Wang ◽  
...  
Keyword(s):  
Epitaxial Growth ◽  
Light Emitting Diodes ◽  
Nitrogen Plasma ◽  
Biaxial Stress ◽  
Organic Chemical ◽  
Graphene Surface ◽  
Light Emitting ◽  
Long Wavelength ◽  
Pre Treatment ◽  
Wavelength Light

AbstractStrain modulation is crucial for heteroepitaxy such as GaN on foreign substrates. Here, the epitaxy of strain-relaxed GaN films on graphene/SiC substrates by metal-organic chemical vapor deposition is demonstrated. Graphene was directly prepared on SiC substrates by thermal decomposition. Its pre-treatment with nitrogen-plasma can introduce C–N dangling bonds, which provides nucleation sites for subsequent epitaxial growth. The scanning transmission electron microscopy measurements confirm that part of graphene surface was etched by nitrogen-plasma. We study the growth behavior on different areas of graphene surface after pre-treatment, and propose a growth model to explain the epitaxial growth mechanism of GaN films on graphene. Significantly, graphene is found to be effective to reduce the biaxial stress in GaN films and the strain relaxation improves indium-atom incorporation in InGaN/GaN multiple quantum wells (MQWs) active region, which results in the obvious red-shift of light-emitting wavelength of InGaN/GaN MQWs. This work opens up a new way for the fabrication of GaN-based long wavelength light-emitting diodes.

scholarly journals The Low-Frequency Array (LOFAR): Opening a New Window on the Universe

2002 ◽  
Vol 199 ◽  
pp. 474-483
Author(s):  
Namir E. Kassim ◽  
T. Joseph W. Lazio ◽  
William C. Erickson ◽  
Patrick C. Crane ◽  
R. A. Perley ◽  
...  
Keyword(s):  
Angular Resolution ◽  
Broad Band ◽  
Low Frequency ◽  
Electromagnetic Spectrum ◽  
Interferometric Imaging ◽  
Very Large Array ◽  
Long Wavelength ◽  
Calibration Techniques ◽  
Long Baselines ◽  
The Universe

Decametric wavelength imaging has been largely neglected in the quest for higher angular resolution because ionospheric structure limited interferometric imaging to short (< 5 km) baselines. The long wavelength (LW, 2—20 m or 15—150 MHz) portion of the electromagnetic spectrum thus remains poorly explored. The NRL-NRAO 74 MHz Very Large Array has demonstrated that self-calibration techniques can remove ionospheric distortions over arbitrarily long baselines. This has inspired the Low Frequency Array (LOFAR)—-a fully electronic, broad-band (15—150 MHz)antenna array which will provide an improvement of 2—3 orders of magnitude in resolution and sensitivity over the state of the art.

scholarly journals Photoprotection and Skin Pigmentation: Melanin-Related Molecules and Some Other New Agents Obtained from Natural Sources

Molecules ◽  
2020 ◽  
Vol 25 (7) ◽  
pp. 1537 ◽  
Author(s):  
Francisco Solano
Keyword(s):  
Human Skin ◽  
Uv Light ◽  
Stratospheric Ozone ◽  
Skin Pigmentation ◽  
Antioxidant Properties ◽  
Sun Exposure ◽  
Marine Organisms ◽  
Electromagnetic Spectrum ◽  
Chemical Structures ◽  
Skin Lightening

Direct sun exposure is one of the most aggressive factors for human skin. Sun radiation contains a range of the electromagnetic spectrum including UV light. In addition to the stratospheric ozone layer filtering the most harmful UVC, human skin contains a photoprotective pigment called melanin to protect from UVB, UVA, and blue visible light. This pigment is a redox UV-absorbing agent and functions as a shield to prevent direct UV action on the DNA of epidermal cells. In addition, melanin indirectly scavenges reactive oxygenated species (ROS) formed during the UV-inducing oxidative stress on the skin. The amounts of melanin in the skin depend on the phototype. In most phenotypes, endogenous melanin is not enough for full protection, especially in the summertime. Thus, photoprotective molecules should be added to commercial sunscreens. These molecules should show UV-absorbing capacity to complement the intrinsic photoprotection of the cutaneous natural pigment. This review deals with (a) the use of exogenous melanin or melanin-related compounds to mimic endogenous melanin and (b) the use of a number of natural compounds from plants and marine organisms that can act as UV filters and ROS scavengers. These agents have antioxidant properties, but this feature usually is associated to skin-lightening action. In contrast, good photoprotectors would be able to enhance natural cutaneous pigmentation. This review examines flavonoids, one of the main groups of these agents, as well as new promising compounds with other chemical structures recently obtained from marine organisms.

Light Trapping in Thin Film Silicon n-i-p Solar Cells - Gains and Losses

2008 ◽  
Vol 1101 ◽  
Author(s):  
Ruud E.I. Schropp ◽  
Hongbo Li ◽  
Jatin K. Rath ◽  
Ronald H. Franken
Keyword(s):  
Thin Film ◽  
Light Trapping ◽  
Structural Defects ◽  
Metallic Surface ◽  
Textured Surfaces ◽  
Long Wavelength ◽  
Thin Film Silicon ◽  
Internal Surfaces ◽  
Gains And Losses ◽  
Wavelength Light

AbstractThin film silicon solar cell technology frequently makes use of rough or textured surfaces in order to enhance light absorption within the thin absorber layers by scattering and total internal reflection (“light trapping”). The rough morphology of the optically functional internal surfaces both in superstrate and substrate cells however, not only has a beneficial effect on light scattering properties, but on the other hand may also have deleterious effects on the microscopic structure of the deposited layers, in particular if these layers are nanocrystalline. The narrow valleys in the surface morphology may lead to structural defects, such as cavities and pinholes. By adjusting the morphology, these defects can be avoided.However, even when structural defects in layers directly deposited on rough interfaces are avoided, the obtained optically defined maximum current density is still much lower than expected. For instance, in n-i-p structures the rough interface (the textured back reflector consisting of nanostructured Ag coated with ZnO) is located at the back of the cell, where only long wavelength light is present. The natively textured Ag film is sputtered at elevated temperature and optimized for diffusely reflecting this long wavelength light. From experiments we infer that the nanostructured metallic surface also gives rise to plasmon absorption in the red and near IR, and that this leads to a parasitic absorption, i.e. at least part of the absorbed energy is not re-emitted to the active layers.

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