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result(s) for
"Luminescence."
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Cold light : creatures, discoveries, and inventions that glow
Learn about cold light -- how some objects and animals make light but not heat.
Book
Thermally and optically stimulated luminescence : a simulation approach
Thermoluminescence (TL) and optically stimulated luminescence (OSL) are two of the most important techniques used in radiation dosimetry. They have extensive practical applications in the monitoring of personnel radiation exposure, in medical dosimetry, environmental dosimetry, spacecraft, nuclear reactors, food irradiation etc., and in geological /archaeological dating.
Thermally and Optically Stimulated Luminescence: A Simulation Approach describes these phenomena, the relevant theoretical models and their prediction, using both approximations and numerical simulation. The authors concentrate on an alternative approach in which they simulate various experimental situations by numerically solving the relevant coupled differential equations for chosen sets of parameters.
Opening with a historical overview and background theory, other chapters cover experimental measurements, dose dependence, dating procedures, trapping parameters, applications, radiophotoluminescence, and effects of ionization density.
Designed for practitioners, researchers and graduate students in the field of radiation dosimetry, Thermally and Optically Stimulated Luminescence provides an essential synthesis of the major developments in modeling and numerical simulations of thermally and optically stimulated processes.
eBook
Advanced Optical Information Encryption Enabled by Polychromatic and Stimuli‐Responsive Luminescence of Sb‐Doped Double Perovskites
The smart materials with multi‐color and stimuli‐responsive luminescence are very promising for next generation of optical information encryption and anti‐counterfeiting, but these materials are still scarce. Herein, a multi‐level information encryption strategy is developed based on the polychromatic emission of Sb‐doped double perovskite powders (SDPPs). Cs2NaInCl6:Sb, Cs2KInCl6:Sb, and Cs2AgInCl6:Sb synthesized through coprecipitation methods exhibit broadband emissions with bright blue, cyan, and orange colors, respectively. The information transmitted by specific SDPP is encrypted when different SDPPs are mixed. The confidential information can be decrypted by selecting the corresponding narrowband filter. Then, an encrypted quick response (QR) code with improved security is demonstrated based on this multi‐channel selection strategy. Moreover, the three types of SDPPs exhibit three different water‐triggered luminescence switching behaviors. The confidential information represented by Cs2NaInCl6:Sb can be erased/recovered through a simple water spray/drying. Whereas, the information collected from the green channel is permanently erased by moisture, which fundamentally avoids information leakage. Therefore, different encryption schemes can be designed to meet a variety of encryption requirements. The multicolor and stimuli‐responsive luminescence greatly enrich the flexibility of optical information encryption, which leaps the level of security and confidentiality. An information encryption strategy is developed based on the polychromatic and hydrochromic luminescence of Sb‐doped double perovskite powders (SDPPs). The confidential information can be decrypted by selecting the correct filter. Moreover, the SDPPs exhibit hydrochromic behaviors, implying the confidential information can be erased/recovered by tuning moisture. Therefore, different encryption schemes can be design for various requirements.
Journal Article
Luminous creatures : the history and science of light production in living organisms
\"Charles Darwin was perplexed by the chaotic diversity of luminous organisms, which he found difficult to reconcile with his evolutionary theory. For other reasons bewilderment confronted many observers watching living lights throughout the ages. It fell on naturalists and scientists to try and make sense of the dazzling luminous displays by fireflies and other organisms. In Luminous Creatures, Michel Anctil shows how the mythical perceptions of bioluminescence gradually gave way to a scientific understanding of its mechanisms, functions and evolution, and to the recognition of its usefulness for biomedical and other applied fields. Naturalists since the Antiquity worked hard at dispelling fanciful ideas about the meaning of living lights by giving as reliable accounts of what they saw as was in their power. But it took the circumnavigations and oceanographic expeditions of the eighteenth and nineteenth centuries, and the rise of the modern scientific method, for biologists to realize how widespread bioluminescence is on the planet and how diverse are its expressions in light organs and ecological imprints. By the end of the nineteenth century an understanding of the chemical nature and physiological control of the phenomenon was at hand. Technological developments led to the recent explosion of knowledge on the ecology, evolution and molecular biology of bioluminescence. Luminous Creatures tracks these historical events and illuminates the lives and trail-blazing accomplishments of the scientists involved. It offers a unique window in the awe-inspiring, phantasmagorical world of light-producing organisms, viewed from the perspectives of the casual observer and science-maker alike.\"-- Provided by publisher.
Book
Thermally Activated Delayed Fluorescence Material: An Emerging Class of Metal‐Free Luminophores for Biomedical Applications
The development of simple, efficient, and biocompatible organic luminescent molecules is of great significance to the clinical transformation of biomaterials. In recent years, purely organic thermally activated delayed fluorescence (TADF) materials with an extremely small single‐triplet energy gap (ΔEST) have been considered as the most promising new‐generation electroluminescence emitters, which is an enormous breakthrough in organic optoelectronics. By merits of the unique photophysical properties, high structure flexibility, and reduced health risks, such metal‐free TADF luminophores have attracted tremendous attention in biomedical fields, including conventional fluorescence imaging, time‐resolved imaging and sensing, and photodynamic therapy. However, there is currently no systematic summary of the TADF materials for biomedical applications, which is presented in this review. Besides a brief introduction of the major developments of TADF material, the typical TADF mechanisms and fundamental principles on design strategies of TADF molecules and nanomaterials are subsequently described. Importantly, a specific emphasis is placed on the discussion of TADF materials for various biomedical applications. Finally, the authors make a forecast of the remaining challenges and future developments. This review provides insightful perspectives and clear prospects towards the rapid development of TADF materials in biomedicine, which will be highly valuable to exploit new luminescent materials. The review focuses on summarizing the current progresses of TADF materials for various biomedical applications, including conventional fluorescence imaging, time‐resolved imaging and sensing, and photodynamic therapy. Moreover, the TADF mechanisms and design strategies of TADF fluorophores in biomedicine are also described. Finally, it provides the insightful perspectives and clear prospects towards the rapid development of TADF materials in biomedicine.
Journal Article
A new strategy to achieve enhanced upconverted circularly polarized luminescence in chiral perovskite nanocrystals
Achieving large luminescence dissymmetry factors (
g
lum
) is challenging in the research field of circularly polarized luminescence (CPL). While various approaches have been developed to construct organic systems with CPL activity, there is still a lack of effective methods for fabricating CPL active inorganic materials. Herein, we propose an approach for endowing upconversion nanoparticles (UCNPs) and perovskite nanocrystal (PKNC) hybrid nanomaterials with upconverted circularly polarized luminescence (UC-CPL) activity. Chiral cesium lead bromides (CsPbBr
3
) PKNCs were synthesized by a chiral-ligand-assistant method. Meanwhile, UCNP could be embedded into the chiral PKNC, enabling a photon upconvesion feature to the PKNC. The embedded UCNPs in PKNCs were confirmed by electron tomography. Consequently, various CPL activities, including prompt CPL, UC-CPL, and energy transfer enhanced circularly polarized luminescence (ET-CPL), were realized. The chiral perovskite nanocrystals could reabsorb the chiral energy generated from UCNPs, showing energy transfer enhanced CPL activity with four times magnification of the circular polarization. These findings provide a meaningful strategy for designing chiral photon upconversion inorganic nanomaterials with highly efficient UC-CPL activity.
Journal Article
Mechanisms for Enhancing Luminescence Yield in KBr Crystals under the Influence of Low-Temperature Uniaxial Elastic Deformation
This study investigates the radiative relaxation of electronic excitations through luminescence spectroscopy techniques applied to high-purity KBr crystals subjected to low-temperature (85 K) uniaxial deformation along the and crystallographic directions. Results demonstrate that the most significant enhancement in the intensity of σ-(4.42 eV) and π-(2.3 eV) luminescence from self-trapped excitons in KBr crystals occurs with elastic deformation along the direction, aligning with the axis of the hole component of the anion self-trapped exciton. Deformation-induced changes in X-ray, tunneling, and thermally stimulated luminescence spectra reveal a new band, denoted as Ex, peaking at approximately 3.58 eV, attributed to tunneling charge exchange between the F’- and VK-centers in their ground state.
Journal Article
Minimising efficiency roll-off in high-brightness perovskite light-emitting diodes
Efficiency roll-off is a major issue for most types of light-emitting diodes (LEDs), and its origins remain controversial. Here we present investigations of the efficiency roll-off in perovskite LEDs based on two-dimensional layered perovskites. By simultaneously measuring electroluminescence and photoluminescence on a working device, supported by transient photoluminescence decay measurements, we conclude that the efficiency roll-off in perovskite LEDs is mainly due to luminescence quenching which is likely caused by non-radiative Auger recombination. This detrimental effect can be suppressed by increasing the width of quantum wells, which can be easily realized in the layered perovskites by tuning the ratio of large and small organic cations in the precursor solution. This approach leads to the realization of a perovskite LED with a record external quantum efficiency of 12.7%, and the efficiency remains to be high, at approximately 10%, under a high current density of 500 mA cm
−2
.
Large drop in efficiency at high brightness has been holding back the development of various light-emitting diodes including halide perovskite. Here Zou et al. achieve high quantum efficiency of 10% under a high current density of 500 mA cm
−2
in perovskite-based diodes by reducing luminescence quenching.
Journal Article
Aggregation induced emission dynamic chiral europium(III) complexes with excellent circularly polarized luminescence and smart sensors
The synthesis of dynamic chiral lanthanide complex emitters has always been difficult. Herein, we report three pairs of dynamic chiral Eu
III
complex emitters (
R/S
-Eu-R-1
, R = Et/Me;
R/S
-Eu-Et-2
) with aggregation-induced emission. In the molecular state, these Eu
III
complexes have almost no obvious emission, while in the aggregate state, they greatly enhance the Eu
III
emission through restriction of intramolecular rotation and restriction of intramolecular vibration. The asymmetry factor and the circularly polarized luminescence brightness are as high as 0.64 (
5
D
0
→
7
F
1
) and 2429 M
−1
cm
−1
of
R
-Eu-Et-1
, achieving a rare double improvement.
R
-Eu-Et-1/2
exhibit excellent sensing properties for low concentrations of Cu
II
ions, and their detection limits are as low as 2.55 and 4.44 nM, respectively. Dynamic Eu
III
complexes are constructed by using chiral ligands with rotor structures or vibration units, an approach that opens a door for the construction of dynamic chiral luminescent materials.
Chiral luminescent materials are of increasing interest in various applications, but achieving a desirable balance of properties can be challenging. Here, the authors report the development of Eu-based complexes with chiral luminescence and aggregation induced emission.
Journal Article