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A THz Receiver with Novel Features and Functionality
摘要： The presented THz receiver is based on an antenna coupled titanium micro-bolometer. A new geometrical design improves the robustness and extends the lifetime of the sensor. A study of sensor lifetime using different biasing currents is presented. The lifetime was verified by several tests and over 1000 operating hours. A new micro-bolometer sensitivity measurement algorithm is presented in the paper and measurement results using the proposed algorithm are shown. The new algorithm was developed to be suitable for ATM production testing. In the paper, a novel feature called “sensitivity boosting” is described, together with its influence on sensitivity and lifetime.
关键词： micro-bolometer lifetime,sensitivity boosting,THz micro-bolometer
更新于2025-09-09 09:28:46
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<i>In vitro</i> and <i>in vivo</i> phasor analysis of stoichiometry and pharmacokinetics using short lifetime near-infrared dyes and time-gated imaging
摘要： We introduce a simple new approach for time-resolved multiplexed analysis of complex systems using near-infrared (NIR) dyes, applicable to in vitro and in vivo studies. We show that fast and precise in vitro quantification of NIR fluorophores? short (sub-nanosecond) lifetime and stoichiometry can be done using phasor analysis, a computationally efficient and user-friendly representation of complex fluorescence intensity decays obtained with pulsed laser excitation and time-gated camera imaging. We apply this approach to the study of binding equilibria by F?rster resonant energy transfer using two different model systems: primary/secondary antibody binding in vitro and ligand/receptor binding in cell cultures. We then extend it to dynamic imaging of the pharmacokinetics of transferrin engagement with the transferrin receptor in live mice, elucidating the kinetics of differential transferrin accumulation in specific organs, straightforwardly differentiating specific from non-specific binding. Our method, implemented in a freely-available software, has the advantage of time-resolved NIR imaging, including better tissue penetration and background-free imaging, but simplifies and considerably speeds up data processing and interpretation, while remaining quantitative. These advances make this method attractive and of broad applicability for in vitro and in vivo molecular imaging, and could be extended to applications as diverse as image guided-surgery or optical tomography.
关键词： Lifetime,Fluorescence,FRET,Mouse,Phasor,in vivo,binding equilibrium,transferrin,pharmacokinetics,Near-infrared
更新于2025-09-09 09:28:46
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Open-source sensor for measuring oxygen partial pressures below 100 microbars
摘要： The ability to measure partial pressures of oxygen below 100 microbars and nanomolar dissolved oxygen concentrations in in situ laboratory systems benefits many fields including microbiology, geobiology, oceanography, chemistry, and materials science. Here, we present an easily constructible open-source design for a networked luminescence lifetime measurement system for in situ measurements in arbitrary laboratory containers. The system is well suited for measuring oxygen partial pressures in the 0–100 μbar range, with the maximum potentially usable upper range limit at around 10 mbar, depending on experimental conditions. The sensor has a limited drift and its detectability limit for oxygen is at 0.02 μbar for short timescale measurements. Each sensor can connect to a Wi-Fi network and send the logged data either over the Internet or to a local server, enabling a large number of parallel unattended experiments. Designs are also provided for attaching the sensor to various commercially available containers used in laboratories. The design files are released under an open source license, which enables other laboratories to build, customize, and use these sensors.
关键词： in situ measurements,luminescence lifetime,oxygen sensor,trace oxygen,open-source
更新于2025-09-09 09:28:46
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Preparation and Two-Photon Photoluminescence Properties of Organic Inorganic Hybrid Perovskites (C6H5CH2NH3)2PbBr4 and (C6H5CH2NH3)2PbI4
摘要： Organic inorganic hybrid perovskites have potential applications in solar cells, electroluminescent devices and radiation detection because of their unique optoelectronic properties. In this paper, the perovskites (C6H5CH2NH3)2PbBr4 and (C6H5CH2NH3)2PbI4 were synthesized by solvent evaporation. The crystal structure, morphology, absorption spectrum, laser power dependence of the photoluminescence (PL) intensity and lifetime were studied. The results showed that the perovskites (C6H5CH2NH3)2PbBr4 and (C6H5CH2NH3)2PbI4 display a layered stacking structure of organic and inorganic components. The absorption peaks are located at 392 nm (3.16 eV) and 516 nm (2.40 eV), respectively. It was observed that the PL intensity and photoluminescence quantum yield (PLQY) increases with increasing laser power, and that the PL lifetime decreases with increasing laser power, which is mainly due to the non-geminate recombination.
关键词： perovskites,photoluminescence lifetime,two-photon excitation,photoluminescence spectrum
更新于2025-09-09 09:28:46
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Applied Nanophotonics || Spontaneous emission of photons and lifetime engineering
摘要： Excited atoms, molecules, and solids emit spontaneously photons, with the rate of emission being dependent both on their intrinsic properties and the properties of ambient space. The latter is capable or not capable of carrying on certain electromagnetic modes. This property of space is described by means of the density of electromagnetic modes or, in quantum language, photon density of states. Photon density of states can be engineered in a desirable way using spatially arranged components with different dielectric permittivity on the wavelength scale. This chapter provides a brief introduction to spontaneous photon emission control in nanostructures based on confinement of electromagnetic waves to get photon density of states’ enhancement or inhibition.
关键词： nanostructures,electromagnetic waves,spontaneous emission,photon density of states,lifetime engineering
更新于2025-09-09 09:28:46
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Visualizing Phase Segregation in Mixed-Halide Perovskite Single Crystals
摘要： Mixed organolead halide perovskites (MOHPs), CH3NH3Pb(BrxI1?x)3, have been shown to undergo phase segregation into I-rich domains under illumination, presenting a major challenge to their development in photovoltaic and light-emitting devices. Recent work suggests phase segregated domains are localized at crystal boundaries, driving investigations into the role of edge structure and the growth of larger crystals with reduced surface area. Herein, a method for growing large (30×30×1 μm) monocrystalline MAPb(BrxI1?x)3 single crystals is presented. The direct visualization of the growth of nanocluster-like I-rich domains throughout the entire crystal revealed grain boundaries are not required for this transformation. Narrowband fluorescence imaging and time-resolved spectroscopy provided new insight into the nature of phase segregated domains and the collective impact on optoelectronic properties.
关键词： perovskite,photoluminescence,lifetime,phase segregation,single crystal
更新于2025-09-09 09:28:46
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Radiative lifetime of localized excitons in transition-metal dichalcogenides
摘要： Disorder derived from defects or local strain in monolayer transition-metal dichalcogenides (TMDs) can lead to a dramatic change in the physical behavior of the interband excitations, producing inhomogeneous spectral broadening and localization leading to radiative lifetime increase. In this study, we have modeled the surface disorder of a monolayer TMD sample through a randomized potential in the layer plane. We show that this model, applied to a monolayer of WSe2, allows us to simulate the spectra of localized exciton states as well as their radiative lifetime. In this context, we give an in depth study of the in?uence of the disorder potential parameters on the optical properties of these defects through energies, density of states, oscillator strengths, photoluminescence (PL) spectroscopy, and radiative lifetime at low temperature (4 K). We demonstrate that localized excitons have a longer emission time than free excitons, in the range of tens of picoseconds or more, the radiative decay time depending strongly on the disorder parameter and dielectric environment. Finally, in order to prove the validity of our model, we compare it to available experimental results of the literature.
关键词： disorder potential,localized excitons,radiative lifetime,transition-metal dichalcogenides,photoluminescence spectroscopy
更新于2025-09-09 09:28:46
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The Invention of an Optical Antenna—A Personal Reminiscence
摘要： The subject of this article is my personal path from the near-field optical (NFO) microscope to the optical antenna and its potential for modern optics.
关键词： breaking the diffraction limit,optical antenna,lifetime of Q-dots,nonlinearities,antenna resonance
更新于2025-09-09 09:28:46
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[ASME ASME 2018 Conference on Smart Materials, Adaptive Structures and Intelligent Systems - San Antonio, Texas, USA (Monday 10 September 2018)] Volume 1: Development and Characterization of Multifunctional Materials; Modeling, Simulation, and Control of Adaptive Systems; Integrated System Design and Implementation - On the Lifetime Performance of a Styrenic Rubber Membrane for Dielectric Elastomer Transducers
摘要： Dielectric Elastomer Transducers (DETs) are solid-state electrostatic devices with variable capacitance that can convert electrical energy into mechanical energy and vice-versa. Recent theoretical and experimental studies demonstrated that DETs made of materials like silicone elastomer and natural rubber can operate at very high energy densities. Practical applicability of DETs is strongly affected by their reliability and lifetime, which depend on the maximum strain and electrical loads that are cyclically applied on such devices. To date, very little knowledge and experimental results are available on the subject. In this context, this paper reports on an extensive lifetime assessment campaign conducted on frame-stretched circular DET specimens made of a commercial styrenic rubber membrane subjected to cyclic electrical loading.
关键词： styrenic rubber membrane,Dielectric Elastomer Transducers,lifetime assessment,DETs,cyclic electrical loading
更新于2025-09-09 09:28:46
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A new approach for determination of free carriers lifetime and density of localised states in disordered semiconductors
摘要： A new method for measuring the free carriers lifetime (tR) and the density of localised states (DOS) in amorphous semiconductors is described. The method is based on the analysis of transient photoconductivity (TPC) data using Laplace transform technique. This technique involves Laplace transform of TPC data, it is a simple analysis of the solution of the basic linearised multiple trapping equations for free and trapped electrons. It is demonstrated by application to simulated and experimental TPC data measured on a typical disordered semiconductor, the hydrogenated amorphous silicon (a-Si:H). An introduced tR in the computing of the TPC using an arbitrarily proposed DOS model is recovered with high accuracy. For the experimental case, the determination of the exact DOS and the estimated tR from the experimental TPC data allow to reconstruct accurately this last. The performance and the limitations of the technique are studied by means of computer simulations. Limitations are essentially the low temperatures of measurement when the recombination phenomenon is not observed at short times.
关键词： recombination lifetime,DOS,Laplace transform,Transient photocurrent
更新于2025-09-09 09:28:46