The fluorescence enhancement of Rhodamine 6G(Rh6G) fluorophore in the close vicinity of porous alumina film with ordered nanohole arrays is investigated.Experimental observations show that the nonmetallic substrate with hole arrays enhances the fluorescence intensity.By comparing the fluorescence emissions that are excited with 325 nm and 532 nm,better fluorescence enhancement is obtained with excitation at a shorter wavelength.The study suggests that higher fluorescence excitation efficiency due to the energy transfer from oxygen vacancies to Rh6G fluorophore molecules is responsible for better fluorescence enhancement.The contribution of the scattering of nanohole arrays to the fluorescence enhancement is also proposed based on the intensity increase and reduced lifetime when the energy transfer from oxygen vacancy is absent.The result of the current study is useful for developing non-metal substrates in the study of spectroscopic enhancement,and is expected to advance the applications of porous alumina to microanalysis.
Fluoride nanoparticles of Ln3+(Ln3+=Pr3+,Nd3+,Sm3+,Gd3+,Tb3+Dy3+,Ho3+,Er3+,Tm3+,Yb3+)/Eu3+:LaOF and Eu3+ :LaOF with rhombohedral crystal structure were prepared by a hydrothermal-sintering method. The red fluorescence emission of Eu3+ ions was found to be enhanced with most of the co-dopant Ln3+ ions. Compared with strong fluorescence emission at 610 nm of Eu3+ :LaOF nanoparticles, the enhancement factors was up to ten times in Ln3+(Ln3+ =Gd3+,Dy3+,Tm3+)/Eu3+ :LaOF co-doped nanoparticles. The results show that the asymmetry of the local environment of Eu3+ ion was reduced by co-doping Ln3+ ion into the nanoparticles, and that energy transfer might occur between Eu3+ and codopant Ln3+ ions, which is suggested as the source of the observed fluorescence enhancement.
A simple,mild,and time-saving method is employed to synthesize Ag-SiO2 composite nanospheres with Ag nanoparticles uniformly distributed on the surface of SiO2 nanoparticles.The chemical elements and the morphology of Ag-SiO2 composite nanospheres were analyzed with transmission electron microscopy(TEM),X-ray power diffraction(XRD),and X-ray photoelectron spectroscopy(XPS).On the surface of Ag-SiO2 composite nanospheres,silane coupling agent(KH-550)is introduced as an intermediary to connect the surfaces of SiO2 nanospheres and Ag nanoparticles,which is also helpful for avoiding the aggregation of Ag nanoparticles.It is found that Ag-SiO2 composite nanospheres have very good catalytic properties for the reduction of organic dyes,which may have potential application in wastewater treatment.
