Optical Properties of Ag-Al Nanosphere Heterodimer
CHENG Long1, JIANG Yong-gang1, HUANG Li-qing2*, ZHANG Yu2, WU Ji2, SUN Hao1, LIU Qi1, WANG Jun3
1. Chinese Satellite Maritime Tracking and Control Department, Jiangyin 214431, China 2. College of Science, Xi’an Jiaotong University, Xi’an 710049, China 3. College of Science, Xi’an Polytechnic University, Xi’an 710048, China
Abstract：Metal nanostructure material has attracted great attention due to its surface plasmon resonance. The optical properties of heterodimer metallic nanostructure materials are different compared with that of homogeneous nanostructure materials because their symmetry structure is broken. The symmetry of the original structures will be changed, and the interaction between the two particles will produce Fano resonance. The Fano resonances are the result of the double or more surface plasmon resonances coupling, and be controlled by properly controlling the nanostructures. The electric field enhancement and the radiation characteristics of the nanostructure are further optimized for the Fano resonance controlled. Aluminum nanostructure materials have become the best choice of the surface plasmon resonance in the UV region, because gold, silver and other noble metals have inter-band transition effects. In this work, we study the local field and absorption spectra of heterodimer composed of a silver nanosphere and an aluminum nanosphere by the Finite-Difference Time-Domain (FDTD) theory. Firstly, the effects of the incident polarization, the geometric like, nanospheres separation, nanosphere radius and physical dielectric media on the optical response of silver-aluminum nanospheres heterodimer are analyzed. Secondly, the near field distributions of heterodimer are given in-depth discussion. Due to the destruction of the symmetry of dimer material, heterodimeric optical character is significantly different from homodimer. Fano resonances are produced in UV and visible light in the heterodimer respectively when silver-aluminum nanospheres heterodimer is illuminated by the Y-polarized light. More favorable Fano resonance effects can be obtained by regulating the spacing and size of heterodimer in the given dielectric environment which is also an effect factor certainly. Finally, the absorption of the heterodimer contributed from each nanosphere structure is also analyzed. In this way, the result which is a general and complete description of the optical properties of silver-aluminum nanospheres heterodimer nanostructure in the paper, leads to the suppression and enhancement of the surface plasmon resonance in different frequency bands and may be valuable for the design and development of plasmonic devices and optical tools in UV-visible light and could serve as the basis of the future experimental analysis of surface enhanced spectroscopy, molecular detection and biosensor etc.
[1] Kelly K L, Coronado E, Zhao L L, et al. The Journal of Physical Chemistry B, 2003, 107(3): 668. [2] Le F, Brandl D W, Urzhumov Y A, et al. ACS Nano, 2008, 2(4): 707. [3] Knight M W, King N S, Liu L, et al. ACS Nano, 2013, 8(1), 834. [4] Ding T, Sigle D O, Herrmann L O, et al. ACS Applied Materials & Interfaces, 2014, 6(20): 17358. [5] Ono A, Kikawada M, Inami W. Frontiers of Physics, 2014, 9(1): 60. [6] Encina E R, Coronado E A. The Journal of Physical Chemistry C, 2011, 115(32): 15908. [7] Halas N J, Lal S, Chang W. Chemical Reviews, 2011, 111(6): 3913. [8] Liusman C, Li H, Lu G, et al. The Journal of Physical Chemistry C, 2012, 116(18): 10390. [9] Ahmadivand A, Karabiyik M, Pala N, et al. Optics Communications, 2015, 338(1): 218. [10] Shan D, Huang L, Li X, et al. The Journal of Physical Chemistry C, 2014, 118(41): 23930. [11] Cheng L, Huang L, Li X, et al. The Journal of Physical Chemistry C, 2015, 119(25): 14304. [12] Palik E D. Handbook of Optical Constants of Solids. 3nd ed. New York: Academic Press, 1998. [13] Sposito G. The Environmental Chemistry of Aluminum. Boca Raton: CRC Press, 1995.
