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首页> 外文会议>Conference on Quantum Dots, Nanoparticles, and Nanoclusters; 20040126-20040127; San Jose,CA; US >Picosecond-resolved nonlinear absorption of spin-processible Lead Sulfide (PbS) nanocrystals from 1100 to 1600 nm
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Picosecond-resolved nonlinear absorption of spin-processible Lead Sulfide (PbS) nanocrystals from 1100 to 1600 nm

机译：皮秒分辨的1100至1600 nm自旋可加工硫化铅（PbS）纳米晶体的非线性吸收

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Solution-synthesized nanocrystals which manifest strong quantum-confinement effects enable size-tunability of spectral properties and strong excitonic effects. Lead sulfide (PbS) nanocrystals are especially interesting for applications in telecommunication because their resonance is tunable to wavelengths from 1.3-1.55 μm and beyond. In other quantum dot systems, optically-induced bleaching of absorption has been shown to lead to a strong nonlinearity in the vicinity of the exciton peak wavelength [1][2-4][5-8]. We report herein results of picosecond-resolved transient absorption in spin-processible solution-synthesized PbS nanocrystals across the wavelength range 1100 nm to 1600 nm. The sample was synthesized using the solution phase organometallic method (hot injection technique), which provides good control over the size of the nanocrystals [9]. The sample consisted of nanocrystals with diameter around 5.2 nm resulting in an exciton peak at 1330 nm. Since the Bohr radius for the bulk PbS is 18 nm, these nanocrystals lay within the strong quantum-confinement regime [10]. Time-resolved absorption was studied using the single-wavelength collinear pump-probe setup. From the observed double-exponential decay trace of the transmission, fast and slow time constants were extracted. The fast component of few 10is of ps was attributed to Auger recombination. The slow component is on the order of ns. The saturation intensity was also measured in this wavelength range using the Z-Scan technique [11]. The open aperture signals were fit to the intensity-dependent absorption model. The value of the saturation intensity was found to be 0.6 GW/cm~2 around the exciton peak.
机译：溶液合成的纳米晶体表现出强大的量子约束效应，可实现光谱特性的大小可调和强激子效应。硫化铅（PbS）纳米晶体对于电信应用特别有趣，因为它们的共振可调谐到1.3-1.55μm甚至更高的波长。在其他量子点系统中，已显示光致吸收性漂白会在激子峰值波长[1] [2-4] [5-8]附近导致强烈的非线性。我们在此报告在1100 nm至1600 nm波长范围内可自旋加工的溶液合成的PbS纳米晶体中皮秒分辨的瞬态吸收的结果。使用溶液相有机金属方法（热注射技术）合成了样品，可以很好地控制纳米晶体的尺寸[9]。样品由直径约5.2 nm的纳米晶体组成，在1330 nm处产生激子峰。由于块状PbS的玻尔半径为18 nm，因此这些纳米晶体位于强量子约束范围内[10]。使用单波长共线泵浦探针装置研究了时间分辨吸收。从观察到的传输的双指数衰减迹线中，提取出快速和慢速时间常数。 ps的10is的快速分量归因于Auger重组。慢分量约为ns。还使用Z扫描技术在此波长范围内测量了饱和强度[11]。光圈信号适合强度依赖的吸收模型。发现在激子峰附近饱和强度的值为0.6 GW / cm〜2。

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