Large-area Fluorescence Enhancement of R6G Based on a Uniform PVA-Au Plasmonic Substrate.

With the development of surface enhanced fluorescence (SEF) spectroscopy technology, uniform and low-cost SEF substrate is urgently needed. In this paper, the nanocomposite films of poly (vinyl alcohol) (PVA) embedded with in-situ Au particles, their localized surface plasmon resonance (LSPR) bands locate at different wavelengths from 525 nm to 569 nm, were used as substrates to enhance the fluorescence of rhodamine 6 G (R6G). The results shows that the uniform light emission in large area can be measured, and the maximum enhancement factor (EF) is about 13 folds. With increasing concentration of R6G films, the EF first increases and then slowly decreases. It is demonstrated that the EF greatly depends on the matching degree of the emission/excitation of R6G and the LSPR band of PVA-Au substrate. All the results further suggests that the PVA-Au substrate not only realize the fluorescence enhancement but also attenuates the fluorescence quenching at higher concentration. In addition, the local electric distribution of the substrate is simulated by using three-dimensional finite different time-domain (FDTD) to further demonstrate the mechanism of the SEF. This substrate has good development prospects in the fields of fluorescent probes and fluorescence imaging, which can be beneficial to the development of uniform and low-cost SEF substrate.