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Rydberg-state ionization dynamics and tunnel ionization rates in strong electric fields
摘要： Tunnel ionization rates of triplet Rydberg states in helium with principal quantum numbers close to 37 have been measured in electric fields at the classical ionization threshold of ～197 V/cm. The measurements were performed in the time domain by combining high-resolution continuous-wave laser photoexcitation and pulsed electric field ionization. The observed tunnel ionization rates range from 105 to 107 s?1 and have, together with the measured atomic energy-level structure in the corresponding electric fields, been compared to the results of calculations of the eigenvalues of the Hamiltonian matrix describing the atoms in the presence of the fields to which complex absorbing potentials have been introduced. The comparison of the measured tunnel ionization rates with the results of these, and additional calculations for hydrogenlike Rydberg states performed using semiempirical methods, have allowed the accuracy of these methods of calculation to be tested. For the particular eigenstates studied the measured ionization rates are ～5 times larger than those obtained from semiempirical expressions.
关键词： Rydberg states,tunnel ionization,electric field ionization,complex absorbing potentials,helium
更新于2025-09-23 15:22:29
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[IEEE IGARSS 2018 - 2018 IEEE International Geoscience and Remote Sensing Symposium - Valencia (2018.7.22-2018.7.27)] IGARSS 2018 - 2018 IEEE International Geoscience and Remote Sensing Symposium - Proposal of Millimeter-Wave Adaptive Glucose-Concentration Estimation System Using Complex-Valued Neural Networks
摘要： This paper presents a novel approach for glucose concentration detection using a complex-valued neural network (CVNN) based on microwave transmission characteristics. The method leverages the dielectric properties of glucose solutions, which vary with concentration, to train a neural network that accurately predicts glucose levels from S-parameter measurements. Experimental results demonstrate high accuracy and robustness across a range of concentrations from 0 to 300 mg/dL.
关键词： complex-valued neural network,dielectric properties,glucose detection,S-parameters,microwave sensing
更新于2025-09-23 15:22:29
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Phasor Quaternion Neural Networks for Singular Point Compensation in Polarimetric-Interferometric Synthetic Aperture Radar
摘要： Interferograms obtained by synthetic aperture radar often include many singular points (SPs), which makes it difficult to generate an accurate digital elevation model. This paper proposes a filtering method to compensate SPs adaptively by using polarization and phase information around the SPs. Phase value is essentially related to polarization changes in scattering as well as propagation. In order to handle the polarization and phase information simultaneously in a consistent manner, we define a new number, phasor quaternion (PQ), by combining quaternion and complex amplitude, with which we construct the theory of PQ neural networks (PQNNs). Experiments demonstrate that the proposed PQNN filter compensates SPs very effectively. Even in the situations where the conventional methods deteriorate in their performance, it realizes accurate compensation, thanks to its good generalization characteristics in integrated Poincare-sphere polarization space and the complex-amplitude space. We find that PQNN is an excellent framework to deal with the polarization and phase of electromagnetic wave adaptively and consistently.
关键词： Complex-valued neural network (CVNN),phase singular point,polarimetric interferometric synthetic aperture radar (PolInSAR),quaternion neural network (QNN),digital elevation model (DEM)
更新于2025-09-23 15:22:29
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Combined multi-waves rational solutions for complex Ginzburg–Landau equation with Kerr law of nonlinearity
摘要： By utilizing the logarithmic transformation and symbolic computation with ansatz functions technique, rational solution and multi-waves interaction solutions are obtained for complex Ginzburg–Landau equation with Kerr law of nonlinearity. Meanwhile, the interaction between rational solutions and the kink wave is also investigated. The dynamics of these obtained solutions are analyzed and described in figures by selecting appropriate values of parameters. Through graphical interpretation, we observe the dynamics and characteristics of lump-kink interaction, soliton–soliton interaction, multi-waves interactions and breathers.
关键词： complex Ginzburg–Landau equation.,logarithmic transformations,multi-waves interactions,Rational solutions
更新于2025-09-23 15:22:29
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Soil Temperature Variability in Complex Terrain Measured Using Fiber-Optic Distributed Temperature Sensing
摘要： Soil temperature (Ts) exerts critical controls on hydrologic and biogeochemical processes, but the magnitude and nature of Ts variability in a landscape setting are rarely documented. Fiber-optic distributed temperature sensing (DTS) systems potentially measure Ts at high density across a large extent. A fiber-optic cable 771 m long was installed at a depth of 10 cm in contrasting landscape units (LUs) defined by vegetative cover at Upper Sheep Creek in the Reynolds Creek Experimental Watershed (RCEW) and Critical Zone Observatory in Idaho. The purpose was to evaluate the applicability of DTS in remote settings and to characterize Ts variability in complex terrain. Measurement accuracy was similar to other field instruments (±0.4°C), and Ts changes of approximately 0.05°C at a monitoring spatial scale of 1 m were resolved with occasional calibration and an ambient temperature range of 50°C. Differences in solar inputs among LUs were strongly modified by surface conditions. During spatially continuous snow cover, Ts was practically homogeneous across LUs. In the absence of snow cover, daily average Ts was highly variable among LUs due to variations in vegetative cover, with a standard deviation (SD) greater than 5°C, and relatively uniform (SD < 1.5°C) within LUs. Mean annual soil temperature differences among LUs of 5.2°C was greater than those of 4.4°C associated with a 910-m elevation difference within the RCEW. In this environment, effective Ts simulation requires representation of relatively small-scale (<20 m) LUs due to the deterministic spatial variability of Ts.
关键词： landscape units,complex terrain,vegetative cover,fiber-optic cable,snow cover,spatial variability,Soil temperature,distributed temperature sensing
更新于2025-09-23 15:22:29
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Abundant manganese complex-anchored BiOI hybrid photocatalyst for visible light-driven CO <sub/>2</sub> reduction
摘要： An abundant manganese complex-anchored BiOI hybrid system for CO2 photocatalytic conversion was constructed. Layered BiOI and tricarbonyl Mn bipyridyl complex with carboxyl acid groups were connected with covalent bonds and used as visible light antenna and CO2 reduction reaction centers, respectively. The covalent connection of this hybrid system benefits the transfer of electrons from the semiconductor to the Mn complex. The anchoring group (carboxyl) is the key to CO2 reduction for the direct coupling of the two units, facilitating the transfer of electrons from BiOI to the manganese complexes. The photocatalytic properties and stability of the tricarbonyl Mn–bipyridyl complex were significantly enhanced with the aid of anchored BiOI. A high turnover number (TON = 74) of HCOO? formation from CO2 could be achieved using this hybrid system under visible light irradiation.
关键词： CO2 reduction,Photocatalysis,BiOI,Mn tricarbonyl bipyridyl complex
更新于2025-09-23 15:22:29
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Synthesis, Crystal Structure and Fluorescent Properties of Dinuclear Zinc Complex
摘要： A dinuclear zinc complex [Zn2(qnal)2(CH3COO)2] (Hqnal: N-(8'-quinolyl)-2-hydroxy-1-naphthaldimine) was synthesized and characterized by X-ray crystallography. The complex crystallizes in monoclinic system, space group C2/c with a = 40.00(3), b = 7.690(5), c = 27.492(16) ?, β = 120.446(11)°, V = 17290(8) ?3, Z = 8. Dc = 1.537 g/cm3, Mr = 843.48, F(000) = 3456, μ(MoKα) = 1.374 mm-1, S = 1.033, R = 0.0403 and wR = 0.1049 for 4454 observed reflections (I > 2σ(I)). It exhibits a 3D supramolecular architecture constructing by π-π stacking interactions between quinolyl and naphthyl rings and shows luminescent property in the yellow region.
关键词： Zinc complex,Dinuclear,Fluorescence,Crystal structure
更新于2025-09-23 15:22:29
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Resonance Raman Spectro-Electrochemistry to Illuminate Photo-Induced Molecular Reaction Pathways
摘要： Electron transfer reactions play a key role for artificial solar energy conversion, however, the underlying reaction mechanisms and the interplay with the molecular structure are still poorly understood due to the complexity of the reaction pathways and ultrafast timescales. In order to investigate such light-induced reaction pathways, a new spectroscopic tool has been applied, which combines UV-vis and resonance Raman spectroscopy at multiple excitation wavelengths with electrochemistry in a thin-layer electrochemical cell to study [RuII(tbtpy)2]2+ (tbtpy = tri-tert-butyl-2,2′:6′,2′′-terpyridine) as a model compound for the photo-activated electron donor in structurally related molecular and supramolecular assemblies. The new spectroscopic method substantiates previous suggestions regarding the reduction mechanism of this complex by localizing photo-electrons and identifying structural changes of metastable intermediates along the reaction cascade. This has been realized by monitoring selective enhancement of Raman-active vibrations associated with structural changes upon electronic absorption when tuning the excitation wavelength into new UV-vis absorption bands of intermediate structures. Additional interpretation of shifts in Raman band positions upon reduction with the help of quantum chemical calculations provides a consistent picture of the sequential reduction of the individual terpyridine ligands, i.e., the first reduction results in the monocation [(tbtpy)Ru(tbtpy?)]+, while the second reduction generates [(tbtpy?)Ru(tbtpy?)]0 of triplet multiplicity. Therefore, the combination of this versatile spectro-electrochemical tool allows us to deepen the fundamental understanding of light-induced charge transfer processes in more relevant and complex systems.
关键词： ruthenium bis-terpyridine complex,resonance Raman,in situ spectro-electrochemistry,TDDFT,UV-vis
更新于2025-09-23 15:22:29
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Retrieval of Chlorophyll a from Sentinel-2 MSI Data for the European Union Water Framework Directive Reporting Purposes
摘要： The European Parliament and The Council of the European Union have established the Water Framework Directive (2000/60/EC) for all European Union member states to achieve, at least, 'good' ecological status of all water bodies larger than 50 hectares in Europe. The MultiSpectral Instrument onboard European Space Agency satellite Sentinel-2 has suitable 10, 20, 60 m spatial resolution to monitor most of the Estonian lakes as required by the Water Framework Directive. The study aims to analyze the suitability of Sentinel-2 MultiSpectral Instrument data to monitor water quality in inland waters. This consists of testing various atmospheric correction processors to remove the influence of atmosphere and comparing and developing chlorophyll a algorithms to estimate the ecological status of water in Estonian lakes. This study shows that the Sentinel-2 MultiSpectral Instrument is suitable for estimating chlorophyll a in water bodies and tracking the spatial and temporal dynamics in the lakes. However, atmospheric corrections are sensitive to surrounding land and often fail in narrow and small lakes. Due to that, deriving satellite-based chlorophyll a is not possible in every case, but initial results show the Sentinel-2 MultiSpectral Instrument could still provide complementary information to in situ data to support Water Framework Directive monitoring requirements.
关键词： atmospheric correction,chlorophyll a,optically complex waters,remote sensing,European Union Water Framework Directive (2000/60/EC),ecological status of water bodies,Copernicus,Sentinel-2 MultiSpectral Instrument
更新于2025-09-23 15:22:29
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Post-synthetic platinum complex modification of a triazine based metal organic frameworks for enhanced photocatalytic H2 evolution
摘要： A triazine-based MOFs [PCN-9(Co)] was synthesized and its photoelectrical, photophysical properties were studied. As a new photocatalyst, PCN-9(Co) displays photocatalytic hydrogen evolution from water under UV–Visible light irradiation. With the introduction of platinum complex, PCN-9-Pt was obtained and platinum complex was believed to coordinate with the N in triazine. The H2 evolution rate of PCN-9-Pt is greatly improved, about 6.8 times higher than that of PCN-9(Co). The reason is due to the fact that platinum complex plays an important role in improving the separation efficiency of photogenerated charge carriers, as verified by PL and EIS results. This result provides a new kind of idea of modifying MOFs materials with molecular complex to improve the photocatalytic activity.
关键词： Post-synthetic,Platinum complex,Photocatalysis,Triazine-based MOFs
更新于2025-09-23 15:22:29