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激光诱导击穿光谱技术是一种新的材料识别及定量分析技术。但是光谱的重复性低限制其由定性分析向定量分析的发展。因此提高激光诱导等离子光谱信号信噪比及等离子体的空间稳定性对于提高光谱信号的可重复性、降低基体效应等不利因素影响有着积极的作用。同时光谱信号信噪比的增强可降低对激光器输出能量的要求,有效降低了激光诱导击穿光谱集成系统的成本,有利于此技术向更多领域拓展。本文对实验中采用的双脉冲或多脉冲增强,放电脉冲再激发,空间限域,磁场束缚和微波辅助增强四大类方法加以总结及概括。在此基础上深入探讨光谱增强的物理机制,从而为进一步提高光谱信号稳定性及定量化分析的精确度提供有力的理论支持。 相似文献
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A Model on the Mn^2+ Luminescence Band Redshift with Mn(Ⅱ) Doping and Aggregation within CdS'Mn Microwires * 下载免费PDF全文
We report the microphoto-luminescence band redshifts with individual and multi-Mn(Ⅱ) ion emissions within CdS microwires. The localized exciton magnetic polaxons (LEMPs) corresponding to the d-d optical transitions of Mn(Ⅱ) account for this shift. This LEMP emission from the double-, three- and four-Mn(Ⅱ) ions with ferromag- netic coupling after photoexeitation can happen in diluted magnetic semiconductors, except for the individual Mn(Ⅱ) doping. In addition, a simple spin-exchange polaronic model is established to account for these emission peaks well. Through this model, we can verify the local geometry of the Mn(Ⅱ) ions in CdS microwires. 相似文献
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In this article, mono-dispersed hexagonal structure CdSe nanocrystals with polyhedron shape were prepared by an open solvent thermal reaction. They show a discrete excitonic transition structure in the absorption spectra and the minimal photoluminescence (PL) peak full-width at half-maximum of 19nm. The PL quantum yield is about 60%. Transmission electron micrographs, high-resolution transmission electron micrographs, x-ray powder diffraction patterns, UV-vis absorption spectra and PL spectra were obtained for the as-prepared CdSe nanocrystals. The size of the CdSe nanocrystals can be tuned by changing the reaction temperature or time. Due to the improved synthesis method, a different growth mechanism of the CdSe nanocrystals is discussed. 相似文献
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Weifeng Ma 《中国物理 B》2022,31(3):37802-037802
The methylammonium lead triiodide (CH3NH3PbI3)-based perovskite shows a great alluring prospect in areas of solar cells, lasers, photodetectors, and light emitting diodes owing to their excellent optical and electrical advantages. However, it is very sensitive to the surrounding oxygen and moisture, which limits its development seriously. It is urgent to spare no effort to enhance its optical and electrical stability for further application. In this paper, we synthesize the MAPbI3 perovskite film on the glass substrate with/without the ionic liquid (IL) of 1-Butyl-3-methylimidazolium tetrafluoroborate (BMIMBF4) by a simple two-step sequential solution method. The additive of BMIMBF4 can improve the quality of crystal structure. Moreover, the photo-luminescence (PL) intensity of MAPbI3 film with BMIMBF4 is much stronger than the pure MAPbI3 film after a week in the air, which is almost ten-fold of the pure one. Meanwhile, under the illumination of 405-nm continuous wave (CW) laser, the fluorescent duration of the MAPbI3 film with BMIMBF4 is approximately 2.75 min, while the pure MAPbI3 film is only about 6 s. In fact, ionic liquid of BMIMBF4 in the perovskite film plays a role of passivation, which prevents the dissolution of MAPbI3 into CH3NH3 and PbI2 and thus enhances the stability of environment. In addition, the ionic liquid of BMIMBF4 possesses high ionic conductivity, which accelerates the electron transport, so it is beneficial for the perovskite film in the areas of solar cells, photodetectors, and lasers. This interesting experiment provides a promising way to develop the perovskite's further application. 相似文献
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自旋是基本粒子(电子、光子)角动量的内在形式.固体中体现自旋特征的集体电子行为如拓扑绝缘体等是当前凝聚态物理领域关注的焦点,是基态行为.激子作为电子空穴对的激发态且寿命很短,可复合发光,它是否能体现自旋极化主导的行为?对此人们的认识远不如针对基态的电子.激子磁极化子(exciton magnetic polaron, EMP)是由磁性半导体微结构中铁磁自旋耦合态与自由激子相互作用形成的复合元激发,但其研究很有限.本文概述了我们在稀磁半导体微纳米结构中的EMP及其发光动态学光谱、自旋极化激子凝聚态的形成方面取得的一些进展,展望了未来可能在自旋光电子器件、磁控激光、光致磁性等量子技术方面的潜在应用. 相似文献
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Atoms under optical and magnetic trapping in a limited space at a very low temperature can lead to Bose-Einstein condensation (BEC),even in a one-dimensional (1D) optical lattice. However,can the confinment of dense excitons in a 1D semiconductor microstructure easily reach the excitonic BEC A lightly Mn(Ⅱ)-doped ZnO nanowire under a femtosecond laser pulse pump at room temperature produces single-mode lasing from coherent bipolaronic excitons,which is much like a macroscopic quantum state due to the condensation of the bipoaronic excitons if not real BEC. In this process,longitudinal biphonon binding with the exciton plays an important role. We revisit this system and propose possibility of bipolaronic exciton condensation. More studies are needed for this condensation phenomenon in 1D microcavity systems. 相似文献