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Junqing Shi - One of the best experts on this subject based on the ideXlab platform.
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inverted energy gap law for the nonradiative decay in fluorescent floppy molecules larger fluorescence quantum yields for smaller energy gaps
Organic chemistry frontiers, 2019Co-Authors: Junqing Shi, Maria A Izquierdo, Soo Young Park, Begona Milianmedina, Daniel Rocasanjuan, Johannes GierschnerAbstract:A data survey on experimental fluorescence quantum yields of (multi)substituted dicyano-distyrylbenzenes in fluid solution evidences that non-radiative decay increases with the Franck–Condon energy (EFC), being opposite to the conventional energy gap law. Quantum-chemistry indicates that this is controlled by access to the conical intersection (CI) following the Bell–Evans–Polanyi principle as a first-Step Approximation for this family of molecules; the variations in EFC among the different compounds are found to be decisive, while those of ECI are estimated to be weaker or even enhancing the effect. The current findings may have significant consequences for the design of molecules for organic solid state emitters.
Peter Simon - One of the best experts on this subject based on the ideXlab platform.
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the single Step Approximation attributes strong and weak sides
Journal of Thermal Analysis and Calorimetry, 2007Co-Authors: Peter SimonAbstract:Mechanisms of the processes in condensed phase tend to occur in multiple Steps that have different rates. Their kinetics is very often described by the single-Step Approximation. The first attribute of the Approximation is the substitution of a generally complex set of kinetic equations describing the complex process by the sole single-Step kinetic equation. The other attributes of the Approximation are the separability of the temperature and conversion functions and the additivity. The temperature function for the best fit of experimental data may not be the Arrhenius relationship. The main strength of the single-Step Approximation is that it enables a mathematical description of the kinetics of solid-state reactions without a deeper insight into their mechanism. The low trustworthiness of far extrapolation is a weak point.
Johannes Gierschner - One of the best experts on this subject based on the ideXlab platform.
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inverted energy gap law for the nonradiative decay in fluorescent floppy molecules larger fluorescence quantum yields for smaller energy gaps
Organic chemistry frontiers, 2019Co-Authors: Junqing Shi, Maria A Izquierdo, Soo Young Park, Begona Milianmedina, Daniel Rocasanjuan, Johannes GierschnerAbstract:A data survey on experimental fluorescence quantum yields of (multi)substituted dicyano-distyrylbenzenes in fluid solution evidences that non-radiative decay increases with the Franck–Condon energy (EFC), being opposite to the conventional energy gap law. Quantum-chemistry indicates that this is controlled by access to the conical intersection (CI) following the Bell–Evans–Polanyi principle as a first-Step Approximation for this family of molecules; the variations in EFC among the different compounds are found to be decisive, while those of ECI are estimated to be weaker or even enhancing the effect. The current findings may have significant consequences for the design of molecules for organic solid state emitters.
Maria A Izquierdo - One of the best experts on this subject based on the ideXlab platform.
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inverted energy gap law for the nonradiative decay in fluorescent floppy molecules larger fluorescence quantum yields for smaller energy gaps
Organic chemistry frontiers, 2019Co-Authors: Junqing Shi, Maria A Izquierdo, Soo Young Park, Begona Milianmedina, Daniel Rocasanjuan, Johannes GierschnerAbstract:A data survey on experimental fluorescence quantum yields of (multi)substituted dicyano-distyrylbenzenes in fluid solution evidences that non-radiative decay increases with the Franck–Condon energy (EFC), being opposite to the conventional energy gap law. Quantum-chemistry indicates that this is controlled by access to the conical intersection (CI) following the Bell–Evans–Polanyi principle as a first-Step Approximation for this family of molecules; the variations in EFC among the different compounds are found to be decisive, while those of ECI are estimated to be weaker or even enhancing the effect. The current findings may have significant consequences for the design of molecules for organic solid state emitters.
Chiacheng Tsai - One of the best experts on this subject based on the ideXlab platform.
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Step Approximation for Water Wave Scattering by Multiple Thin Barriers over Undulated Bottoms
'MDPI AG', 2021Co-Authors: Chang-thi Tran, Jen-yi Chang, Chiacheng TsaiAbstract:This paper investigates the scattering of oblique water waves by multiple thin barriers over undulation bottoms using the eigenfunction matching method (EMM). In the solution procedures of the EMM, the bottom topographies are sliced into shelves separated by Steps. On each Step, surface-piercing or/and bottom-standing barriers can be presented or not. For each shelf, the solution is composed of eigenfunctions with unknown coefficients representing the wave amplitudes. Then applying the conservations of mass and momentum, a system of linear equations is resulted and can be solved by a sparse-matrix solver. If no barriers are presented on the Steps, the proposed EMM formulation degenerates to the water wave scattering over undulating bottoms. The effects on the barrier lengths, barrier positions and oblique wave incidences by different undulated bottoms are studied. In addition, the EMM is also applied to solve the Bragg reflections of normal and oblique water waves by periodic barrier over sinusoidal bottoms. The accuracy of the solution is demonstrated by comparing it with the results in the literature
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Step Approximation of water wave scattering caused by tension leg structures over uneven bottoms
Ocean Engineering, 2018Co-Authors: Chiacheng Tsai, Wei Tai, Taiwen Hsu, Shih Chun HsiaoAbstract:Abstract The scattering of water waves induced by tension leg structures (TLSs) over uneven bottoms is investigated using the eigenfunction matching method (EMM). Both the wave amplitude and the surge-motion displacement were assumed to be small, and the linear wave theory was employed to solve the problem. In the solution procedure of the Step Approximation, the structure and the bottom configuration were sliced into a number of shelves separated by abrupt Steps. Upon applying the conservation of mass and momentum, a system of linear equations was obtained with unknown coefficients that represented the wave amplitude and the horizontal displacement of the TLS. The sparse system of linear equations was then solved by using the sparse matrix solver SuperLU. The solution was validated via the theoretical solution of the wave-scattering problem with a rectangular TLS over a flat bottom. The method was further applied to study wave scattering for different TLS geometries over uneven bottoms. Moreover, a problem with multiple TLSs was studied as well.
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on Step Approximation for roseau s analytical solution of water waves
Mathematical Problems in Engineering, 2011Co-Authors: Chiacheng Tsai, Taiwen Hsu, Yuehting LinAbstract:An indirect eigenfunction marching method (IEMM) is developed to provide Step Approximations for water wave problems. The bottom profile is in terms of successive flat shelves separated by abrupt Steps. The marching conditions are represented by the horizontal velocities at the Steps in the solution procedure. The approximated wave field can be obtained by solving a system of linear equations with unknown coefficients which represents the horizontal velocities under a proper basis. It is also demonstrated that this solution method can be exactly reduced to the transfer-matrix method (TM method) for a specific setting. The combined scattering effects of a series of Steps can be described by a single two-by-two transfer matrix for connecting the far-field behaviors of both sides for this method. The solutions obtained by the IEMM are basically exact for water wave problems considering Step-like bottoms. Numerical simulations were performed to validate the present and commonly used methods. Furthermore, it also shows that the solutions obtained by the IEMM converge very well to Roseau's analytical solutions for both mild and steep curved bottom profiles. The present method improves the converges of the TM method for solving water wave scattering over steep bathymetry.