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Photo induced trans→cis isomerism studies of heteroleptic iridium complex with 8-quinolinol-5-phenylazo ligand: Photophysical and electrochemical studies and it's theoretical investigations
摘要： Free rotating azo type ligand in different types of metal complexes give trans-cis isomerism in presence of photon irradiation by UV light. For this connection one new iridium complex has been synthesized with 8-hydroxyquinoline-5-phenylazo ligand in which the azo part of the ligand is free from coordination with metal centre. UV light irradiation of the Ir complex with this type of 8-hydroxyquinoline-5-arylazo ligand at room temperature promotes the trans→cis photoisomerization of the N=N bond with formation of a cis-isomer. The complex is characterised by single X-ray diffractometry, IR, mass and 1HNMR spectroscopy method. Here we report on the synthesis, the electrochemical properties and the photophysical characterization of donor-acceptor azobenzene derivative that possess 8-quinolinol group connected to a benzene moiety and it’s cis-trans isomerisation reaction and stability of the isomers. Thoroughly DFT and TD-DFT calculations are performed to correlate experimental and theoretical interpretation.
关键词： Cis-trans isomerism,Iridium(III) complex,Absorption and emission Study,DFT and TDDFT study
更新于2025-09-04 15:30:14
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Double photon emission coincidence imaging with GAGG-SiPM Compton camera
摘要： Compton imaging is a promising gamma-ray imaging method based on the Compton scattering kinematics due to high Compton scattering probability for sub-MeV to MeV gamma-rays. A conventional Compton camera has a disadvantage of low signal-to-background ratio (SBR), which is caused by drawing of multiple Compton cones. A method to solve this fundamental problem is the double-photon emission computed tomography (DPECT), which uses the coincidence detection for cascade gamma-rays and significantly increases the SBR using intersections of two Compton cones. In this study, we demonstrated the DPECT method by using 134Cs radioisotope, which is one of important radioisotopes for the imaging of fuel debris, with two Ce:Gd3(Al,Ga)5O12 (GAGG) scintillator Compton cameras.
关键词： Compton camera,Double photon emission coincidence imaging,Compton imaging,Caesium-134
更新于2025-09-04 15:30:14
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A Conformationally Flexible Macrocyclic Dipyrrin Tetramer and Its Unsymmetrically Twisted Luminescent Zinc(II) Complex
摘要： A macrocyclic dipyrrin tetramer containing flexible m-phenylene linkages and its tetranuclear zinc(II) complex were synthesized. The obtained complex has an unsymmetrical figure-of-eight structure because of the conformational flexibility of the macrocyclic framework. The first μ-hydroxo- and μ-acetato-bridged dinuclear zinc(II) dipyrrin complex structure is realized in the twisted macrocyclic complex. Furthermore, the complex exhibited an efficient emission in toluene and chloroform.
关键词： μ-hydroxo- and μ-acetato-bridged,efficient emission,zinc(II) complex,macrocyclic dipyrrin tetramer,unsymmetrical figure-of-eight structure
更新于2025-09-04 15:30:14
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Construction of a Layered Hydrogen-Bonded Organic Framework Showing High-Contrast Mechanoresponsive Luminescence Turn-On
摘要： This paper probes the mechanoresponsive luminescence and aggregation-induced emission (AIE) properties of N-phenylcarbazole-based thiophene/dicyanovinyl (T?DCV) derivatives. In bis-T?DCV planar molecule 1, a layered hydrogen-bonded organic framework (HOF) structure is formed with the assistance of multiple C?H···N and strong interlayer interactions. The formation of such a layer packing HOF structure can quench the solid fluorescent emission when aggregated as nanosuspensions but guarantees the high-contrast luminescence on?off switching (1.2 × 103 fold) in the solid state. Moreover, the grinding-induced destruction of HOF 1 is reflected by powder X-ray diffraction measurements, in which the destruction of the α and β rings in the planar HOF stripe and the close interlayer stacking could be observed. This work achieves the successful construction of long-wavelength emission AIE molecules (2 and 3) by introducing sufficient steric hindrance rotors to disturb the intermolecular π?π stacking and/or dipole?dipole interactions.
关键词： high-contrast luminescence,aggregation-induced emission,mechanoresponsive luminescence,hydrogen-bonded organic framework,thiophene/dicyanovinyl derivatives
更新于2025-09-04 15:30:14
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Infrared limb emission measurements of aerosol in the troposphere and stratosphere
摘要： Altitude-resolved aerosol detection in the upper troposphere and lower stratosphere (UTLS) is a challenging task for remote sensing instruments. Infrared limb emission measurements provide vertically resolved global measurements at day- and nighttime in the UTLS. For high-spectral-resolution infrared limb instruments we present here a new method to detect aerosol and separate between ice and non-ice particles. The method is based on an improved aerosol–cloud index that identifies infrared limb emission spectra affected by non-ice aerosol or ice clouds. For the discrimination between non-ice aerosol and ice clouds we employed brightness temperature difference correlations. The discrimination thresholds for this method were derived from radiative transfer simulations (including scattering) and Michelson Interferometer for Passive Atmospheric Sounding (MIPAS)/Envisat measurements obtained in 2011. We demonstrate the value of this approach for observations of volcanic ash and sulfate aerosol originating from the Grímsv?tn (Iceland, 64? N), Puyehue–Cordón Caulle (Chile, 40? S), and Nabro (Eritrea, 13? N) eruptions in May and June 2011 by comparing the MIPAS volcanic aerosol detections with Atmospheric Infrared Sounder (AIRS) volcanic ash and SO2 measurements.
关键词： aerosol detection,infrared limb emission,volcanic ash,sulfate aerosol,ice clouds,UTLS
更新于2025-09-04 15:30:14
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Impact of active geomagnetic conditions on stimulated radiation during ionospheric second electron gyroharmonic heating
摘要： Recently, narrowband emissions ordered near the H+ (proton) gyrofrequency (fcH) were reported in the stimulated electromagnetic emission (SEE) spectrum during active geomagnetic conditions. This work presents new observations and theoretical analysis of these recently discovered emissions. These emission lines are observed in the stimulated electromagnetic emission (SEE) spectrum when the transmitter is tuned near the second electron gyroharmonic frequency (2fce) during recent ionospheric modification experiments at the High Frequency Active Auroral Research (HAARP) facility near Gakona, Alaska. The spectral lines are typically shifted below and above the pump wave frequency by harmonics of a frequency roughly 10% less than fcH (≈ 800 Hz) with a narrow emission bandwidth less than the O+ gyrofrequency (≈ 50 Hz). However, new observations and analysis of emission lines ordered by a frequency approximately 10% greater than fcH are presented here for the first time as well. The interaction altitude for the heating for all the observations is in the range of 160 km up to 200 km. As described previously, proton precipitation due to active geomagnetic conditions is considered as the reason for the presence of H+ ions known to be a minor background constituent in this altitude region. DMSP satellite observations over HAARP during the heating experiments and ground-based magnetometer and riometer data validate active geomagnetic conditions. The theory of parametric decay instability in multi-ion component plasma including H+ ions as a minority species described in previous work is expanded in light of simultaneously observed preexisting SEE features to interpret the newly reported observations. Impact of active geomagnetic conditions on the SEE spectrum as a diagnostic tool for proton precipitation event characterization is discussed.
关键词： stimulated electromagnetic emission,parametric decay instability,proton precipitation,HAARP,ionospheric heating
更新于2025-09-04 15:30:14
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The Monte Carlo Ray-Trace Method in Radiation Heat Transfer and Applied Optics || The MCRT Method for Participating Media
摘要： The MCRT Method for Participating Media So far we have only considered energy interactions between rays and surfaces. Two possible outcomes – absorption and reflection – have been identified, and corresponding models have been formulated and used to describe radiation heat transfer among surfaces. When a ray incident to a surface is neither absorbed nor reflected, it is said to be transmitted. Thermal radiation passing through lenses, filters, and the earth’s atmosphere are familiar examples of transmission. This chapter deals with emission, absorption, refraction, and scattering of thermal radiation within a medium through which it is propagating. Such media are said to be “participating.”
关键词： Emission,Thermal Radiation,Refraction,Radiation Heat Transfer,Transmission,Absorption,Reflection,MCRT Method,Scattering,Participating Media
更新于2025-09-04 15:30:14
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Bio‐orthogonal AIE Dots Based on Polyyne‐Bridged Red‐emissive AIEgen for Tumor Metabolic Labeling and Targeted Imaging
摘要： In this work, we aim to develop cancer cell-targeting AIE dots based on the polyyne-bridged red-emissive AIEgen, 2TPE-4E, through the combination of metabolic engineering and bio-orthogonal reactions. Azide groups on tumor were efficiently produced by intravenous injection of Ac4ManNAz and glycol-metabolic engineering. These bio-orthogonal azide groups could facilitate the specific targeting of DBCO-AIE dots to the tumor cells undergoing metal-free click reaction in vivo. The efficiency of this targeting strategy could be improved along with further development of new bio-orthogonal chemical groups with higher reactivity and sufficient AIEgens could be delivered to tumor for diagnosis.
关键词： in vivo,metabolic labeling,aggregation-induced emission,tumor,bio-orthogonal chemistry
更新于2025-09-04 15:30:14
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Conduction mechanisms of the reverse leakage current of 4H-SiC Schottky barrier diode
摘要： A new numerical method for determining the reverse transition voltage between thermionic and tunneling mechanisms has been performed for 4H-SiC Schottky barrier diode. The idea of this method is based on equality between thermionic emission and tunneling process and both of them are combined with barrier lowering model. Application of this method shows a strong discrepancy between our results and that deduced from Padovani-Stratton condition. The reverse transition voltage was found increase linearly with increasing the barrier height, the effective mass and the inverse of doping concentration. In order to predict the reverse transition voltage as a function of temperature, doping concentration and barrier height for 4H-SiC Schottky barrier diode an analytical model has been proposed.
关键词： image force barrier lowering,reverse transition voltage,SiC Schottky diode,thermionic emission,tunneling current
更新于2025-09-04 15:30:14
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Breakdown of the Spectator Concept in Low-Electron-Energy Resonant Decay Processes
摘要： We suggest that low-energy electrons, released by resonant decay processes, experience substantial scattering on the electron density of excited electrons, which remain a spectator during the decay. As a result, the angular emission distribution is altered significantly. This effect is expected to be a common feature of low-energy secondary electron emission. In this Letter, we exemplify our idea by examining the spectator resonant interatomic Coulombic decay of Ne dimers. Our theoretical predictions are confirmed by a corresponding coincidence experiment.
关键词： low-energy electrons,spectator electron,resonant decay processes,Ne dimers,interatomic Coulombic decay,angular emission distribution
更新于2025-09-04 15:30:14