Plasmonic-Enhanced Molecular Fluorescence within Isolated Bowtie Nano-Apertures

Guowei Lu, Wenqiang Li, Tianyue Zhang, Song Yue, Jie Liu, Lei Hou, Zhi Li, and Qihuang Gong*

State Key Laboratory for Mesoscopic Physics and Department of Physics, Peking University, Beijing 100871, China

ACS Nano, Article ASAP

DOI: 10.1021/nn2042412

Publication Date (Web): January 16, 2012

Copyright © 2012 American Chemical Society

 

 

We report experimental behaviors of polarization-dependent, plasmonic-enhanced molecular fluorescence within isolated bowtie nano-apertures (BNAs) milled in aluminum films. BNAs provide efficient control of the fluorescent count rate per molecule and the decay lifetime of the molecules and provide an effective detection volume at the nanometer scale by tuning either the excitation light polarization or the BNA size. Interestingly, large BNAs (>300 nm) present high plasmonic-enhanced fluorescence efficiency and can simultaneously confine the detection volume below the subdiffraction limit. Numerical simulations were performed that agreed qualitatively with the experimental results. The BNAs have potential applications, especially for single-molecule biological analysis.