- 标题
- 摘要
- 关键词
- 实验方案
- 产品
-
Synthesis and luminescent properties of polymer‐silica multilayer‐encapsulated perovskite quantum dots for optoelectronics
摘要： Hydrophobic all-inorganic perovskite quantum dots (IPQDs) CsPbX3 (X = Cl, Br, and I) were synthesized using conventional solution methods. IPQDs are potential materials for lasers, solar cells, and displays because of their narrow full width at half-maximum, optically tunable wavelength, and great photoluminescence quantum yield. Their shortcomings are structurally unstable and moisture sensitive. To overcome the poor stability, we have developed a chemical modification to form GQD + PMAO@SiO2 that enhances their photoluminescence quantum yield (from 60 to ~90%), thermal stability (from 60 to ~90(cid:1)C), and photochemical stability. The combination of the green-emitting GQD + PMAO@SiO2 and red-emitting RQD + PMAO with a 450 nm blue InGaN-based LED chip was used to fabricate a white light emitting diode with the correlated color temperature (CCT) value of 6,943 K and Commission Internationale del'Eclairage of (0.312, 0.290).
关键词： photoluminescence,IPQDs,EL spectrum,white LED,CsPbX3 (X = cl, Br, I)
更新于2025-09-11 14:15:04
-
Hybrid Method of Modal Analysis and Laser Shock Scanning to Visualize the Pyroshock Propagation in a Tension Joint
摘要： The use of pyrodevices in the aerospace industry has been increasing because of their ability to implement separation missions with a small weight, for example, space launchers, spacecrafts, and missiles. During operation, pyrodevices generate pyroshock, which causes failures of electronic devices. Recently, a pyroshock simulation method using laser shock has been developed to evaluate the risk of pyroshock before flight mission. However, depending on the structure, the laser shock showed some difficulty simulating pyroshock in the low-frequency regime accompanying vibration. Therefore, in this study, we developed a hybrid method of numerical modal analysis and laser shock-based experimental simulation to visualize the pyroshock propagation in all the relevant frequency regimes. For the proof of concept of the proposed method, we performed experiments of explosive bolt-induced shock and pyrolock-induced shock in the open-box-type tension joint and compared the hybrid simulation results with actual pyroshock. From the results, we obtained the simulated time-domain signal with an averaged peak-to-peak acceleration difference (PAD) of 11.2% and the shock response spectrum (SRS) with an averaged mean acceleration difference (MAD) of 28.5%. In addition, we were able to visualize the simulation results in the temporal and spectral domains to compare the pyroshock induced by each pyrodevice. A comparison of the simulations showed that the pyrolock had an impulse level of 1/12 compared to the explosion bolt. In particular, it was confirmed that the pyrolock-induced shock at the near field can cause damage to the electronic equipment despite a smaller impulse than that of the explosive bolt-induced shock. The hybrid method developed in this paper demonstrates that it is possible to simulate pyroshock for all the frequency regimes in complex specimens and to evaluate the risk in the time and frequency domain.
关键词： pyroshock,shock response spectrum,modal analysis,pyrodevices,laser shock,hybrid method
更新于2025-09-11 14:15:04
-
[IEEE 2019 Systems of Signal Synchronization, Generating and Processing in Telecommunications (SYNCHROINFO) - Russia (2019.7.1-2019.7.3)] 2019 Systems of Signal Synchronization, Generating and Processing in Telecommunications (SYNCHROINFO) - Investigation of the Influence of the Optical Fiber Structure on the Mandelstam – Brillouin Backscatter Characteristics
摘要： The influence of structure of optical fibers, varieties and concentration of ligating additives, number of layers on the behavior of the Mandelstam – Brillouin scattering in optical fibers is discussed in this paper. The results of analysis and comparison study of the results for different optical fibers are presented.
关键词： Brillouin reflectometry,optical fiber,spectrum profile,acoustic mode,Mandelstam – Brillouin scattering
更新于2025-09-11 14:15:04
-
Plasmonic W18O49/attapulgite nanocomposite with enhanced photofixation of nitrogen under full-spectrum light
摘要： Ammonia (NH3) obtained by traditional Haber–Bosch technique under extreme conditions stimulates the exploration of sustainable approach via nitrogen photofixation process, however, efficient utilization of solar energy remains a great challenge. Herein, a novel plasmonic W18O49 supported on acid modified attapulgite (H-ATP) composite was prepared by microwave hydrothermal method. The impact of the loading fraction of W18O49 on the ammonia production rate was investigated. Results indicate that ATP possesses abundant adsorption sites after modified by phosphoric acid which facilitates the immobilization of W18O49. The 40% W18O49/H-ATP achieves the highest ammonia production rate of 138.76 μmol g?1 h?1 under solar light irradiation, even 78.76 μmol g?1 h?1 under NIR light (λ > 780 nm). The formed Z-scheme heterostructure improves the separation of charge-carriers, and the localized surface plasmon resonance (LSPR) effect of W18O49 broadens the light response range, both of which contribute to the enhanced nitrogen photofixation performance.
关键词： attapulgite,nitrogen,photofixation,W18O49,full-spectrum light,Plasmonic
更新于2025-09-11 14:15:04
-
Growth, spectroscopic, diode-pumped mid-infrared laser properties of Er:GSAG crystal
摘要： A great potential mid-infrared laser crystal of heavily Er3+ doped GSAG crystal with high optical quality is successfully grown by Cz method. The crystal quality of Er:GSAG crystal is determined by XRC. The structure parameters of Er:GSAG crystal are obtained by the X-ray Rietveld refinement method (a=b=c=12.3196?). The absorption cross section at 961nm and 967 nm are 0.381 × 10-21 cm2 and 0.414 × 10-21 cm2, respectively. The 962 nm laser diode end-pumped Er:GSAG laser operated at 2828 nm is demonstrated for the first time. The performance of Er:GSAG laser is investigated in great detail. A maximum output power of Er:GSAG laser is 410 mW when pumped by 962 nm LD at 300 Hz and 0.5 ms. Simulating results display the highest temperatures of Er:GSAG laser spot is 345.8 K, indicating a small thermal lensing effect of Er:GSAG crystal. Besides, the laser performance of Er:GSAG crystals which irradiate by different doses of gamma-ray are used to investigated its potential for working in the radiation resistance environment. The results show the relatively minor differences on the Er:GSAG lasers performance, indicating a great potential of Er:GSAG crystal in radiant environment application.
关键词： Er:GSAG,Mid-infrared laser,Radiation resistant,Crystal structure,Absorption spectrum
更新于2025-09-11 14:15:04
-
Setup of a photomultiplier tube test bench for LHAASO-KM2A
摘要： To ful(cid:12)ll the requirements for testing the photomultiplier tubes (PMTs) of the electromagnetic detector at the Large High Altitude Air Shower Observatory (LHAASO), a multi-functional PMT test bench with a two-dimensional scanning system has been developed. With this 2D scanning system, 16 PMTs can be scanned simultaneously for characteristics tests, including uniformity, cathode transit time di(cid:11)erence, single photo-electron spectrum, gain vs. high voltage, linear behavior and dark noise. The programmable hardware and intelligent software of the test bench make it convenient to use and provide reliable results. The test methods are described in detail and primary results are presented.
关键词： TTS,PMTs,cathode uniformity,LHAASO,CTTD,SPE spectrum,KM2A
更新于2025-09-11 14:15:04
-
Photoinduced reversible isomerization of 9H-fluorene into 1H-fluorene by means of hydrogen-atom migration and the lowest electronically excited triplet state studied by matrix-isolation FTIR spectroscopy
摘要： Photoinduced reversible intramolecular hydrogen-atom migration between 9H-?uorene and 1H-?uorene isolated in an Ar matrix is found by FTIR spectroscopy with an aid of DFT calculation. The forward isomerization from 9H-?uorene to 1H-?uorene occurs upon UV irradiation (λ ≥ 295 nm), while the backward isomerization occurs upon λ ≥ 320 nm light irradiation. The less stable isomer, 1H-?uorene, is identi?ed by comparison of the measured IR spectrum with the corresponding simulated spectral pattern obtained at the B3LYP/6-31++G(d,p) level. In addition, an IR spectrum of 9H-?uorene in the T1 state is measured during UV irradiation (λ ≥ 275 nm).
关键词： Electronically excited T1 state,Fluorene,Matrix-isolation infrared spectrum,Photoinduced hydrogen-atom migration
更新于2025-09-11 14:15:04
-
[American Society of Agricultural and Biological Engineers 2018 Detroit, Michigan July 29 - August 1, 2018 - ()] 2018 Detroit, Michigan July 29 - August 1, 2018 - <i>Feeding Behaviors of Broilers at Chicken-perceived vs. Human-perceived Light Intensities under Two Light Spectrums</i>
摘要： Broilers perceive light intensity differently from human due to differences in spectral sensitivity. Better understanding of broiler behavioral responses to their perceived lighting may inform farm management practices which helps to improve animal welfare and productivity. The objective of this study was to investigate broiler feeding behaviors at chicken- vs. human-perceived light intensities and under broiler specific LED (BLED) vs. conventional LED light spectrums. The treatment combinations of light intensities and light spectrums were randomly assigned to four identical experimental rooms (3.8 ×1.5 m, L×W), each with 60 tagged broilers. Light intensities at bird level were maintained at either 5 clux (chicken-perceived light intensity) or 5 lux (human-perceived light intensity). Ultra-high frequency radio frequency identification (UHF-RFID) systems were used to register broilers at the feeders. Feeding behaviors of individual broilers at each treatment combination were summarized in terms of daily time spent (DTS) at a feeder, daily percentage of time spent (DPTS), daily times of visit (DTV) to a feeder, duration per visit (DV), hourly time spent (HTS) at a feeder, and hourly times of visit (HTV) to a feeder. The results showed that the DTS (mean ± standard deviation ‘SD’, h·bird-1·day-1) were 2.7±0.1 for 5-clux BLED, 2.6±0.1 for 5-lux BLED, 2.3±0.1 for 5-clux LED, and 2.1±0.0 for 5-lux LED, respectively, corresponding to 8.8-11.2% time spent at the feeders within a day. The DTV (mean ± SD, times·bird-1·day-1) and DV (mean ± SD, min·visit-1) were 80±2 and 2.0±0.1 for 5-clux BLED, 88±2 and 1.8±0.1 for 5-lux BLED, 91±3 and 1.5±0.1 for 5-clux LED, and 95±4 and 1.3±0.1 for 5-lux LED, respectively. Numerically, the broilers tended to visit less to feeders but stay longer at feeders under the chicken-perceived light intensity and broiler specific light spectrum. Feeding behaviors (hourly time spent and times of visit) peaked 2-3 h after initiation of the photoperiod and 2-3 h before the end of the photoperiod. These preliminary observations suggest potential effects of light intensity and spectrum on feeding behaviors of individual broilers, thus providing insights in feeding managements under different light properties. More replicates are needed to validate the findings.
关键词： Broiler,broiler specific light spectrum,feeding behaviors,chicken-perceived light intensity,UHF-RFID system
更新于2025-09-11 14:15:04
-
Ultraviolet Absorption Spectra, Solvent Effect and Non-Linear Optical Properties of Tetrahydroxy-1,4-quinone Hydrate by Hartee-Fock and Density Functional Theory
摘要： In present work, the ultraviolet absorption spectrum of tetrahydroxy-1,4-quinone hydrate (TH,1,4-QH) has been carried out experimentally (in water, methanol dimethyl sulfoxide, acetonitrile and chloroform) and theoretically in the range 3500-2300 cm-1 in the solution phase. Predicted electronic absorption spectra from time dependent density functional theory (TD-DFT) calculation have been analyzed and compared with the experimental UV-visible spectrum. The effects of hydroxy group substituent in benzoquinone ring have been analyzed. The electronic properties such as excitation energy, wavelength corresponding to absorption maxima (λmax), oscillator strength (f), HOMO and LUMO energies are calculated by time-dependent density functional theory (TD-DFT) using HF/6-311++G(d,p) and B3LYP/6-311++G(d,p) as basis sets. The electric dipole moment (μ), α (polarizability) and β (first hyperpolarizability) have been computed to evaluate the NLO (non-linear optical) response of the investigated compound by Hartree-Fock (HF) and density functional theory (DFT) with B3LYP basis sets. Mulliken atomic charges of the atoms are calculated by DFT (B3LYP). In addition natural bond orbital (NBO) analysis has been done using TD-DFT with B3LYP/6-311++G(d,p) basis sets.
关键词： Tetrahydroxy-1,4-quinone hydrate,Density Functional Theory,NLO properties,Hartee-Fock,Ultraviolet spectrum
更新于2025-09-11 14:15:04
-
Spectral Methods in Transition Metal Complexes || Electronic Spectroscopy
摘要： The electronic spectrum covers the range from 200 to 800 nm of the electromagnetic spectrum: 200–400 nm is the ultraviolet region and 400–800 nm is the visible region. Hence, the electronic spectrum is also known as the UV-Vis spectrum. The major application of this spectrum to metal complexes is the determination of the geometry of the complex. In order to arrive at this application, we must understand Term Symbols ?rst. If we want to understand these concepts, selection rules, and transitions, we must have a clear understanding of the concepts of the symmetry of molecules, the symmetry elements, symmetry operations, point groups of molecules, character tables, direct product concepts, and so on. Hence, we will discuss these concepts before the term symbols.
关键词： UV-Vis spectrum,symmetry elements,electronic spectrum,character tables,direct product,Term Symbols,symmetry,metal complexes,point groups,geometry,symmetry operations
更新于2025-09-10 09:29:36