单一金纳米棒表面等离子共振增强单一稀土纳米晶上转换发光研究

发布时间：2018-01-16 01:30

本文关键词：单一金纳米棒表面等离子共振增强单一稀土纳米晶上转换发光研究　出处：《华东师范大学》2017年硕士论文　论文类型：学位论文

【摘要】：上转换发光(PL)是一种在低能量的激发光源的照射下产生更高能量的光子发射的过程。与传统的有机染料和半导体纳米材料相比,镧系元素掺杂上转换纳米晶具有优越的化学和光谱性质,吸引了生物医学、纳米光电子学、信息科学等领域的科研工作者的广泛关注。且由于镧系元素掺杂纳米晶的主体和掺杂剂的不同,其上转换光谱可在可见光到近红外区域中调谐。然而,相对较低的上转换效率抑制了其在实际应用中的进一步发展。为了提高稀土掺杂上转换纳米晶的发光效率以满足实际需求,本论文基于表面等离子体共振效应,利用金纳米棒与稀土掺杂纳米颗粒相耦合以增强其上转换发光,并对其发光特性和发光机理进行了探讨。本学位论文研究了单一金纳米棒对单一NaYF_4:Yb~(3+)/Tm~(3+)/Mn~(2+)纳米晶的上转换发光的增强效应。利用原子力显微镜针尖操控方法组装不同直径(27.3和46.7nm)但具有相似纵向表面等离子体共振峰的金纳米棒,分别与单个NaYF_4:Yb~(3+)/Tm~(3+)/Mn~(2+)纳米晶进行耦合。实验结果表明,当金纳米棒-NaYF_4:Yb~(3+)/Er~(3+)/Mn~(2+)纳米晶复合结构中金纳米棒的直径是46.7nm时,上转换发光强度增强达到最大,大约为110倍,这是由于较大直径的金纳米棒(46.7nm)具有更大的散射截面和近场增强。并且,与单个NaYF_4:Yb~(3+)/Er~(3+)/Mn~(2+)纳米晶相比,与金纳米棒耦合后的NaYF_4:Yb~(3+)/Er~(3+)/Mn~(2+)纳米晶的发光强度表现出对激发光偏振方向的强烈依赖性。另外,探测了与金纳米棒耦合前后NaYF_4:Yb~(3+)/Er~(3+)/Mn~(2+)纳米晶的激发和荧光辐射衰减寿命,发现与金纳米棒耦合后纳米晶的寿命均变小。有限差分时域(FDTD)理论模拟结果揭示了金纳米棒的等离子体效应改善了稀土掺杂纳米晶激发和发射速率,与实验结果相吻合。
[Abstract]:Up-conversion photoluminescence (PLL) is a kind of photonic emission process which produces higher energy under the irradiation of low energy excitation light source, compared with traditional organic dyes and semiconductor nanomaterials. Lanthanide doped up-conversion nanocrystals have excellent chemical and spectral properties, which have attracted biomedical and nano-optoelectronics. The upconversion spectra of lanthanide doped nanocrystals can be tuned from visible light to near infrared region due to the difference of the host and dopant of lanthanide doped nanocrystals. In order to improve the luminescence efficiency of rare-earth doped up-conversion nanocrystals to meet the practical requirements, this paper based on the surface plasmon resonance effect. Gold nanorods were coupled with rare earth doped nanoparticles to enhance their up-conversion luminescence. The luminescence characteristics and luminescence mechanism of mono-gold nanorods were studied in this dissertation, and the effects of single gold nanorods on single NaYF_4:Yb~(3 / TM ~ (3 / MN / MN ~ (2)) were investigated. The enhanced effect of up-conversion luminescence of nanocrystals. The au nanorods with different diameters (27.3 and 46.7 nm) were assembled by atomic force microscope (AFM) manipulation method, but with similar longitudinal surface plasmon resonance peaks. The results show that the structure is coupled with a single NaYF_4:Yb~(3 / TMT / MN ~ (2) nanocrystalline. When the diameter of gold nanorods in nanocrystalline composite structure is 46.7 nm, the diameter of gold nanorods is 46.7 nm. The upconversion luminescence intensity increased to about 110 times, which is due to the larger scattering cross section and near field enhancement of the large diameter gold nanorods (46.7 nm). Compared with a single NaYF_4:Yb~(3 / / Ern / MN _ (2) nanocrystalline. After coupling with gold nanorods, the luminescence intensity of the NaYF_4:Yb~(3 / Ern / Ern / MNO _ 2) nanocrystals shows a strong dependence on the polarization direction of excited light. The excitation and fluorescence decay lifetime of NaYF_4:Yb~(3 / Ern / Ern / MNO _ 2) nanocrystals were investigated before and after coupling with gold nanorods. It is found that the lifetime of nanocrystals becomes smaller after coupling with gold nanorods. The results of FDTD theoretical simulation show that the plasma effect of gold nanorods improves the excitation and emission rate of rare-earth doped nanocrystals. The results are in agreement with the experimental results.
【学位授予单位】：华东师范大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：O482.31

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