J4 ›› 2013, Vol. 30 ›› Issue (5): 513-519.

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Experimental investigation of  fluorescence enhancement or quenching of Rhodamine B molecules caused by silver nano-cubes

Yi Mingfang, Zhang Jie, Zhao Yujie , Ma Yewan, Zhu Dequan, Zhu Zusong, You Jiancun, Xia Qiangsheng   

  1. School of Physics and Electronic Engineering, Anqing Teachers College, Anqing  246133, China
  • Received:2012-09-18 Revised:2012-11-09 Published:2013-09-28 Online:2013-09-17

Abstract:

Silver nano-cubes of about 97nm side-length were synthesized by reducing AgNO3 with ethylene glycol (EG) and used to modulate fluorescence intensity of Rhodamine B (RhB). The RhB (probe molecules) powder were dissolved into PMMA solution with different PMMA concentrations, which were resulted in RhB doped PMMA films of different thickness. The distance between Ag nano-cubes and the fluorescence molecules and the distribution of Ag nano-cubes have important influence on the fluorescence emission. The fluorescence spectrums show the enhancement and quenching effect with different thickness of PMMA film. The largest fluorescence enhancement factor (EF) is 56 for the structure of Ag nano-cubes absorbed on the RhB doped PMMA film as the thickness of PMMA is 10nm. The confocal-images also verified the fluorescence enhancement. The EF is influenced by the distribution of silver nano-cubes on the PMMA film from the confocal-images. So the biggest EF can be obtained by optimizing the distance between silver nano-cubes and the fluorescence molecules or by tuning the distribution of silver nano-cubes, which may be used to single molecule detection. The experiment results have potential application in fluorescence based bio-sensing or bio-imaging.

Key words: spectroscopy, enhanced fluorescence, surface plasmon polaritons, localized field enhancement, silver nano-cubes

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