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11.
U. Täuber C.E.M. Carvalho R.F. dos Santos C.G. Carvalhaes C.E. Fellows 《Applied physics. B, Lasers and optics》2007,87(3):475-481
A six level rate equation system was used to investigate the impact of photodepletion to amplified spontaneous emission (ASE)
of intramolecular proton-transfer (IPT) dyes incorporated into polymeric hosts. The model includes the most important transitions
for the normal and tautomer form of the molecule as well as intersystem crossing and triplet–triplet transitions. The experimentally
observed pulse shape as well as photodepletion phenomena, i.e. a first order exponential decay of the ASE intensity and a
shortening in ASE pulse width, have been simulated successfully. Additionally, the model was used to propose an explanation
of the unexpected high photodepletion of proton-transfer dyes in solids. The results show that the emission cross section
and reabsorption cross section of the tautomer form of the molecule are the most important parameter not only for efficiency
but also for photodepletion. The model was tested by comparison with experimental results of 2-(2’-hydroxyphenyl)benzimidazole
in polymethylmethacrylate (PMMA), polystyrene (PS) and a 1:1 alternating copolymer matrix PS-co-PMMA.
PACS 78.45.th; 42.55.Mv; 42.70.Jk 相似文献
12.
Elon Santos Correa Maria Teresinha A. Steiner Alex A. Freitas Celso Carnieri 《Numerical Algorithms》2004,35(2-4):373-388
Facility-location problems have several applications, such as telecommunications, industrial transportation and distribution. One of the most well-known facility-location problems is the p-median problem. This work addresses an application of the capacitated p-median problem to a real-world problem. We propose a genetic algorithm (GA) to solve the capacitated p-median problem. The proposed GA uses not only conventional genetic operators, but also a new heuristic “hypermutation” operator suggested in this work. The proposed GA is compared with a tabu search algorithm. 相似文献
13.
Humberto César Chaves Fernandes Arthur Rodrigo Barros da Rocha 《International Journal of Infrared and Millimeter Waves》2003,24(7):1171-1176
The use of photonic materials has been used in the theory of optical waves. The PBG (Photonic Band Gap) theory and material, was developed recently for optical frequencies and can be easily applied to millimeter waves, microwaves and planar antenna frequencies. The presence of photonic materials as substrate in antennas has some good characteristics such as, supression of light spontaneous emission and suppression of surface waves, allowing the application in planar antenna array. In this work an elaborate analysis using the full wave Transverse Transmission Line - TTL method, that provides efficient and concise results is applied to the planar antennas array with PBG substrate. 相似文献
14.
This work presents a formulation based on UPML for truncating conductive media by using a local and non-orthogonal coordinate
system to solve Maxwell’s equations by the FDTD method. The detailed procedure for obtaining the UPML equations for this case
is shown and the complete equation set is provided. 相似文献
15.
16.
结合声表面波和光致发光谱在低温(15K)下对非故意掺杂的GaAs(110)量子阱结构的发光特性进行了研究.实验结果表明,由于声表面波的作用GaAs(110)量子阱的发光强度减弱,并且其对应的重空穴能级出现了分裂的现象,当施加的声波强度Prf达到20dBm时,能级分裂ΔE达到了10meV.进一步讨论了声表面波对GaAs(110)量子阱圆偏振光自旋注入的影响.
关键词:
发光
GaAs量子阱
声表面波
自旋极化 相似文献
17.
Gianluigi Luppi Rodrigo J. Corrêa Angelo C. Pinto Quirinus B. Broxterman Claudia Tomasini 《Tetrahedron》2006,62(51):12017-12024
The first total synthesis of (R)-convolutamydine A has been achieved by the organocatalytic addition of acetone to 4,6-dibromoisatin. The absolute configuration was determined by single crystal X-ray diffraction. DFT studies were used to model the transition states for the aldol reaction and equilibrium geometries of the post-aldol reaction intermediates. The DFT study revealed that the aldol bond forming reaction was considerably endothermic. 相似文献
18.
J. L. Souza A. F. Santos L. Polese Marisa S. Crespi C. A. Ribeiro 《Journal of Thermal Analysis and Calorimetry》2007,87(3):673-677
Poly(3-hydroxybutyrate), PHB has been structurally
modified through reaction with maleic anhydride, MA. Transesterification reaction
was carried out fixing the PHB and MA and besides time and temperature the
concentration of the triethylamine (used as catalyst) was changed. Glass transition,
melting and crystallization temperature obtained from DSC curves and thermal
degradation temperatures obtained from TG traces were used to evaluate the
influence of the reaction conditions on the modification of PHB according
to factorial design. On the base of the results the optimum conditions are
to perform the PHB modification reaction with MA reaction at 110°C for
1 h with 5% v/v triethylamine. 相似文献
19.
In this work we show that the energy associated to the linear three-dimensional magneto-elastic system decays polynomially to zero as time goes to infinity, provided the initial data is smooth enough. 相似文献
20.
SbPO4, a phosphate with a layered structure, was tested as an electrode material for lithium cells spanning the 3.0-0.0 V range. Two main electrochemical processes were detected as extensive plateaus at ca. 1.6 and 0.7 V in galvanostatic measurements. The first process was found to be irreversible, thus excluding a potential intercalation-like mechanism for the reaction and being better interpreted as a decomposition reaction leading to the formation of elemental Sb. This precludes the use of this compound as a cathodic material for lithium cells. By contrast, the process at 0.7 V is reversible and can be ascribed to the formation of lithium-antimony alloys. The best electrochemical response was obtained by cycling the cell at a C/20 discharge rate over the voltage range 1.25-0.25 V. Under these conditions, the cell delivers an average capacity of 165 Ah/kg—a value greater than those reported for other phosphates—upon successive cycling. 相似文献