Fano Resonance of Nanocrescent for the Detection of Single Molecules and Single Nanoparticles
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This paper reports a theoretical study on the Fano resonance of a 3D nanocrescent and its application in single molecular detection. The resonance wavelength changes with the crescent radius, gap width and thickness. The Fano resonance is attributed to the interference between the quadrupolar mode supported by the horizontal crescent and the quadrupolar mode supported by the nanotip oscillating along the height direction. The Fano resonance is highly sensitive to a nanoparticle trapped by the nanocrescent. The wavelength shift is larger than 0.5 nm when a single protein nanoparticle with radius only of 1.25 nm is trapped. For a protein with radius of 0.3 nm, the wavelength shift is still larger than 0.03 nm, over the detection limit (10−5 nm) by 3 orders in the magnitude, which indicates that the nanocrescent can be used to detect small molecule with several atoms.
KeywordsLabel-free detection Fano resonance Nanocrescent Quadrupolar mode Surface plasmon polaritons
This work is supported by the National Natural Science Foundation of China (11474097, 11274116, 11374099, 11104178, 51132004), and the Open Fund of the State Key Laboratory of High Field Laser Physics (Shanghai Institute of Optics and Fine Mechanics).
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