金纳米环等离激元模式的研究
发布时间：2018-11-16 18:01
【摘要】：金属纳米结构中,局域表面等离激元共振具有亚波长局域和近场增强的特性,在众多领域都有广泛的应用。特别是环形金属纳米结构,由于其具有较大的腔内体积、腔内可以形成均匀稳定电场等特点,非常适合应用于传感、探测以及太阳能电池等领域。因此,对于支持等离激元共振的环形金属纳米结构的研究是目前人们关注的热点领域之一。本文利用时域有限差分算法,结合光辐射电子显微术,对金纳米环表面等离激元模式分布进行了较为全面的研究。利用FDTD solutions软件对不同尺寸金纳米圆环结构的光学响应进行了模拟研究,从激发光入射角度等方面分析了等离激元明、暗模式产生条件。模拟结果表明,平面波光源斜入射激发金纳米环时,可以实现对明、暗模式的同时激发;而垂直入射时只能激发明模式。研究结果同时表明,等离激元共振峰对纳米环厚度与纳米环外直径的比值(T/D)极其敏感,随着T/D比值的减小,会出现等离激元共振峰红移的现象。进一步发现,p偏振入射激发条件下,金纳米环表面电荷分布异常。这种异常分布产生的原因是:当p偏振光激发时,光源存在z方向的电场分量,使得电荷在上下表面以及衬底表面之间发生振荡,导致纳米环单一表面内出现了电荷的异常分布。另一方面,通过模拟激发点的时间响应,揭示出了不同激发点之间的动力学演化关系。研究结果显示,在s偏振光激发条件下,强度较强的两个热点处的电荷是同时振荡的,但两点处电荷的相位在振荡过程中始终是相反的;在p偏振光激发条件下,金纳米环远离光源处的电场增强明显高于近光源处的电场增强,且近光源处的等离激元的振荡早于远离光源处的振荡。在外加光源消失后,纳米环结构的等离激元模式开始自身振荡,各个激发点之间的振荡此时不再存在时间差异。最后,利用光辐射电子显微镜(PEEM)对单一金纳米环的暗模式近场分布进行高分辨率原位成像。研究结果表明,s偏振光斜入射辐照样品时,可以观察到明显的四极分布特性;在p偏振激发条件下,可在结构远光源处观察到一个激发热点。得到的实验结果与理论模拟结果具有很好的一致性。金纳米环具有极高的灵敏度和品质因子,充分地体现了极好的传感性能,对传感等应用领域的发展具有重要的意义。
[Abstract]:In metal nanostructures, local surface isoexcitons resonance has subwavelength localized and near-field enhancement characteristics, and has been widely used in many fields. Especially the ring metal nanostructures are suitable for sensing detection and solar cells because of their large cavity volume and the uniform and stable electric field in the cavity. Therefore, the research of annular metal nanostructures supporting isoexciton resonance is one of the hot topics. Using the finite-difference time-domain (FDTD) algorithm and photoluminescence electron microscopy, the distribution of isopherton modes on the surface of gold nanospheres has been studied in detail. The optical response of gold nanometers with different sizes has been simulated by using FDTD solutions software. The conditions for the generation of the luminous and dark modes have been analyzed from the angle of incidence of excited light. The simulation results show that the light and dark modes can be excited simultaneously by oblique incident of plane wave light source, but only bright mode can be excited at vertical incidence. The results also show that the resonance peak is very sensitive to the ratio of the thickness of the ring to the outer diameter of the ring (T / D). With the decrease of the ratio of T / D, there will be a red shift of the resonance peak. It is further found that the surface charge distribution of gold nanocrystals is abnormal under the condition of p polarization incident excitation. The reason for this abnormal distribution is that when the p-polarized light is excited, the electric field component in z direction exists in the light source, which makes the charge oscillate between the upper and lower surfaces and the substrate surface. This leads to the abnormal distribution of charge on the single surface of the ring. On the other hand, the dynamic evolution of different excitation points is revealed by simulating the time response of excitation points. The results show that the charge at the two hot spots with strong intensity oscillates simultaneously under the condition of s-polarized light excitation, but the phase of the charge at the two points is always opposite during the oscillation process. Under the condition of p-polarized light excitation, the electric field enhancement of gold nanospheres far away from the light source is obviously higher than that of the near light source, and the oscillation of the isotherm near the light source is earlier than that at the distance from the light source. After the disappearance of the external light source, the Isophosphor mode of the nanoscale structure begins to oscillate itself, and there is no time difference between the oscillations between the excitation points. Finally, a high resolution in situ imaging of the dark mode near field distribution of a single gold nanoring is carried out by using photoemission electron microscope (PEEM). The results show that the quadrupole distribution can be observed when the S polarized light is oblique incident on the irradiated sample, and an exciting hot spot can be observed at the far light source under the condition of p polarization excitation. The experimental results are in good agreement with the theoretical simulation results. Gold nanocrystals have high sensitivity and quality factors, which fully reflect the excellent sensing performance, and have important significance for the development of sensing and other applications.
【学位授予单位】：长春理工大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TB383.1;O614.123
本文编号：2336226
[Abstract]:In metal nanostructures, local surface isoexcitons resonance has subwavelength localized and near-field enhancement characteristics, and has been widely used in many fields. Especially the ring metal nanostructures are suitable for sensing detection and solar cells because of their large cavity volume and the uniform and stable electric field in the cavity. Therefore, the research of annular metal nanostructures supporting isoexciton resonance is one of the hot topics. Using the finite-difference time-domain (FDTD) algorithm and photoluminescence electron microscopy, the distribution of isopherton modes on the surface of gold nanospheres has been studied in detail. The optical response of gold nanometers with different sizes has been simulated by using FDTD solutions software. The conditions for the generation of the luminous and dark modes have been analyzed from the angle of incidence of excited light. The simulation results show that the light and dark modes can be excited simultaneously by oblique incident of plane wave light source, but only bright mode can be excited at vertical incidence. The results also show that the resonance peak is very sensitive to the ratio of the thickness of the ring to the outer diameter of the ring (T / D). With the decrease of the ratio of T / D, there will be a red shift of the resonance peak. It is further found that the surface charge distribution of gold nanocrystals is abnormal under the condition of p polarization incident excitation. The reason for this abnormal distribution is that when the p-polarized light is excited, the electric field component in z direction exists in the light source, which makes the charge oscillate between the upper and lower surfaces and the substrate surface. This leads to the abnormal distribution of charge on the single surface of the ring. On the other hand, the dynamic evolution of different excitation points is revealed by simulating the time response of excitation points. The results show that the charge at the two hot spots with strong intensity oscillates simultaneously under the condition of s-polarized light excitation, but the phase of the charge at the two points is always opposite during the oscillation process. Under the condition of p-polarized light excitation, the electric field enhancement of gold nanospheres far away from the light source is obviously higher than that of the near light source, and the oscillation of the isotherm near the light source is earlier than that at the distance from the light source. After the disappearance of the external light source, the Isophosphor mode of the nanoscale structure begins to oscillate itself, and there is no time difference between the oscillations between the excitation points. Finally, a high resolution in situ imaging of the dark mode near field distribution of a single gold nanoring is carried out by using photoemission electron microscope (PEEM). The results show that the quadrupole distribution can be observed when the S polarized light is oblique incident on the irradiated sample, and an exciting hot spot can be observed at the far light source under the condition of p polarization excitation. The experimental results are in good agreement with the theoretical simulation results. Gold nanocrystals have high sensitivity and quality factors, which fully reflect the excellent sensing performance, and have important significance for the development of sensing and other applications.
【学位授予单位】：长春理工大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TB383.1;O614.123
【参考文献】
相关期刊论文 前2条
1 秦将;郎鹏;季博宇;N.K.Alemayehu;陶海岩;高勋;郝作强;林景全;;Imaging Ultrafast Plasmon Dynamics within a Complex Dolmen Nanostructure Using Photoemission Electron Microscopy[J];Chinese Physics Letters;2016年11期
2 秦将;季博宇;郝作强;林景全;;Probing of Ultrafast Plasmon Dynamics on Gold Bowtie Nanostructure Using Photoemission Electron Microscopy[J];Chinese Physics Letters;2015年06期
，本文编号：2336226
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