Optical gain in CdSe nanocrystals
Optical gain in CdSe nanocrystals
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DOI：
10.1016/j.jlumin.2006.01.294
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发表时间：
2007
影响因子：
3.6
通讯作者：
K. Kyhm;Sang Min Kim;Jongun Kim;Bumjin Kim;H. Lim;K. Hong;M. Cha;Ho-soon Yang
中科院分区：
文献类型：
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作者：
K. Kyhm;Sang Min Kim;Jongun Kim;Bumjin Kim;H. Lim;K. Hong;M. Cha;Ho-soon Yang
利用变条纹长度法对溶解于甲苯中的CdSe胶体量子点进行了飞秒激发下的光学增益测量。我们发现，在制备量子点时，可以通过排除十八烯（ODE）来代替覆盖zns壳层，从而实现光谱变窄和荧光强度增强。不含ode的CdSe量子点的最大增益（~ 1.5mm−1）与CdSe/ZnS核壳结构相当。尽管尺寸分布均匀（σ=0.25nm），但由于双激子和激子态之间的许多激发能级的重组，两种情况下都出现了宽增益谱。排除ode的CdSe量子点的剩余表面态也有助于增益（1.0mm−1），这涉及到一个三能级过程。
Optical gain measurements with femtosecond excitation were performed in CdSe colloidal quantum dots (QDs) dissolved in toluene using the variable stripe length method. Instead of ZnS-shell overcoating, we found that the spectral narrowing and intensity enhancement of the fluorescence can be achieved alternatively by excluding octadecene (ODE) at the preparation of QDs. The maximum gain (∼1.5mm−1) in the ODE-excluded CdSe QDs is comparable to that of CdSe/ZnS core–shell structures. Despite the uniform size distribution (σ=0.25nm), a broad gain spectrum appears in both cases due to the recombination of many excited levels between biexciton and exciton states. The remaining surface states in the ODE-excluded CdSe QDs also contribute to gain (1.0mm−1), which is involved with a three-level process.