金納米環(huán)等離激元模式的研究
發(fā)布時間：2018-11-16 18:01
【摘要】：金屬納米結(jié)構(gòu)中,局域表面等離激元共振具有亞波長局域和近場增強的特性,在眾多領(lǐng)域都有廣泛的應(yīng)用。特別是環(huán)形金屬納米結(jié)構(gòu),由于其具有較大的腔內(nèi)體積、腔內(nèi)可以形成均勻穩(wěn)定電場等特點,非常適合應(yīng)用于傳感、探測以及太陽能電池等領(lǐng)域。因此,對于支持等離激元共振的環(huán)形金屬納米結(jié)構(gòu)的研究是目前人們關(guān)注的熱點領(lǐng)域之一。本文利用時域有限差分算法,結(jié)合光輻射電子顯微術(shù),對金納米環(huán)表面等離激元模式分布進行了較為全面的研究。利用FDTD solutions軟件對不同尺寸金納米圓環(huán)結(jié)構(gòu)的光學(xué)響應(yīng)進行了模擬研究,從激發(fā)光入射角度等方面分析了等離激元明、暗模式產(chǎn)生條件。模擬結(jié)果表明,平面波光源斜入射激發(fā)金納米環(huán)時,可以實現(xiàn)對明、暗模式的同時激發(fā);而垂直入射時只能激發(fā)明模式。研究結(jié)果同時表明,等離激元共振峰對納米環(huán)厚度與納米環(huán)外直徑的比值(T/D)極其敏感,隨著T/D比值的減小,會出現(xiàn)等離激元共振峰紅移的現(xiàn)象。進一步發(fā)現(xiàn),p偏振入射激發(fā)條件下,金納米環(huán)表面電荷分布異常。這種異常分布產(chǎn)生的原因是:當(dāng)p偏振光激發(fā)時,光源存在z方向的電場分量,使得電荷在上下表面以及襯底表面之間發(fā)生振蕩,導(dǎo)致納米環(huán)單一表面內(nèi)出現(xiàn)了電荷的異常分布。另一方面,通過模擬激發(fā)點的時間響應(yīng),揭示出了不同激發(fā)點之間的動力學(xué)演化關(guān)系。研究結(jié)果顯示,在s偏振光激發(fā)條件下,強度較強的兩個熱點處的電荷是同時振蕩的,但兩點處電荷的相位在振蕩過程中始終是相反的;在p偏振光激發(fā)條件下,金納米環(huán)遠離光源處的電場增強明顯高于近光源處的電場增強,且近光源處的等離激元的振蕩早于遠離光源處的振蕩。在外加光源消失后,納米環(huán)結(jié)構(gòu)的等離激元模式開始自身振蕩,各個激發(fā)點之間的振蕩此時不再存在時間差異。最后,利用光輻射電子顯微鏡(PEEM)對單一金納米環(huán)的暗模式近場分布進行高分辨率原位成像。研究結(jié)果表明,s偏振光斜入射輻照樣品時,可以觀察到明顯的四極分布特性;在p偏振激發(fā)條件下,可在結(jié)構(gòu)遠光源處觀察到一個激發(fā)熱點。得到的實驗結(jié)果與理論模擬結(jié)果具有很好的一致性。金納米環(huán)具有極高的靈敏度和品質(zhì)因子,充分地體現(xiàn)了極好的傳感性能,對傳感等應(yīng)用領(lǐng)域的發(fā)展具有重要的意義。
[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.
【學(xué)位授予單位】：長春理工大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2017
【分類號】：TB383.1;O614.123
本文編號：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.
【學(xué)位授予單位】：長春理工大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2017
【分類號】：TB383.1;O614.123
【參考文獻】
相關(guān)期刊論文 前2條
1 秦將;郎鵬;季博宇;N.K.Alemayehu;陶海巖;高勛;郝作強;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 秦將;季博宇;郝作強;林景全;;Probing of Ultrafast Plasmon Dynamics on Gold Bowtie Nanostructure Using Photoemission Electron Microscopy[J];Chinese Physics Letters;2015年06期
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