title: Metal-Enhanced Fluorescence of Silver Island Associated with Silver Nanoparticle.
abstract: The coupling plasmon of a hybrid nanostructure, silver island (SI) associated with silver nanoparticle (SNP), on metal-enhanced fluorescence (MEF) was studied theoretically. We used the multiple multipole method to analyze the plasmon-mediated enhancement factor on the fluorescence of a molecule immobilized on SNP and located in the gap zone between SI and SNP; herein, the SI was modeled as an oblate spheroid. Numerical results show that the enhancement factor of the hybrid nanostructure is higher than that of a SNP or a SI alone due to the coupled gap mode. This finding is in agreement with the previous experimental results. In addition, the plasmon band of the structure is broadband and tunable, which can be red-shifted and broadened by flattening or enlarging SI. Based on this property, the hybrid nanostructure can be tailored to obtain the optimal enhancement factor on a specific molecule according to its excitation spectrum. Moreover, we found that there is an induced optical force allowing SNP be attracted by SI. Consequently, the gap is reduced gradually to perform a stronger MEF effect.
authors.affiliation: Department of Mechanical Engineering, Chang Gung University, 259 Wen-Hwa 1st Rd., Kwei-Shan, Taoyuan, 333, Taiwan. markliaw@mail.cgu.edu.tw.|Center for Biomedical Engineering, Chang Gung University, 259 Wen-Hwa 1st Rd., Kwei-Shan, Taoyuan, 333, Taiwan. markliaw@mail.cgu.edu.tw.|Medical Physics Research Center, Institute for Radiological Research, Chang Gung University and Chang Gung Memorial Hospital, Taoyuan, 333, Taiwan. markliaw@mail.cgu.edu.tw.
authors.forename: Jiunn-Woei
authors.initials: JW
authors.lastname: Liaw
authors.affiliation: Institute of Applied Mechanics, National Taiwan University, 1, Sec. 4, Roosevelt Rd., Taipei, 106, Taiwan.
authors.forename: Hsin-Yu
authors.initials: HY
authors.lastname: Wu
authors.affiliation: Institute of Applied Mechanics, National Taiwan University, 1, Sec. 4, Roosevelt Rd., Taipei, 106, Taiwan.
authors.forename: Chu-Chuan
authors.initials: CC
authors.lastname: Huang
authors.affiliation: Institute of Applied Mechanics, National Taiwan University, 1, Sec. 4, Roosevelt Rd., Taipei, 106, Taiwan. mkkuo@ntu.edu.tw.
authors.forename: Mao-Kuen
authors.initials: MK
authors.lastname: Kuo
keywords: Apparent quantum yield; Enhancement factor; Excitation rate; MMP; Metal-enhanced fluorescence; Oblate spheroid; Silver island; Silver nanoparticle; Surface plasmon resonance