不同电性的纳米银对甲基橙光谱学性质的影响

通过吸收光谱和荧光光谱等手段研究了正/负电性纳米银对不同pH值的甲基橙(MO)溶液光谱学性质的影响.研究结果表明,正电性纳米银(P-Ag)与甲基橙作用形成新的复合物,吸收光谱表现为复合物体系的性质.负电性纳米银(N-Ag)与甲基橙静电排斥作用,相互作用较弱,吸收光谱仅表现为两者简单叠加.在正电性纳米银-甲基橙体系中,S1→S0荧光明显增强.当溶液pH=2.1时,荧光增强比率最大,当pH=4.8时,荧光增强比率最小;S2→S0荧光减弱,且与体系的pH值关系不大.在负电性纳米银-甲基橙体系中,仅少量纳米银存在条件下,S1→S0荧光略增强.在溶液pH=2.1时,荧光增强比率最大;S2→S0荧光明显减弱,且与体系的pH值关系不大.分析认为,不同电性的纳米银对甲基橙光谱学性质影响不同,与纳米银与甲基橙分子间相互作用、纳米银的局域场增强效应以及无辐射能量转移作用等密切相关.

Effects of Silver Nanoparticles with Different Electrical Properties on the Spectroscopic Properties of Methyl Orange

The effects of positive/negative silver nanoparticles on the spectroscopic properties of methyl orange(MO) in solution at different pH values were studied by UV-visible(UV-Vis) absorption spectroscopy and fluorometry.New complexes were formed by the strong electrostatic interaction between positive silver nanoparticles(P-Ag) and the MO so that UV-Vis absorption spectra showed the performance of the complexes.However,the UV-Vis absorption spectra only showed superposition of component peaks after addition of negative silver nanoparticles(N-Ag) to MO solution because of the weak interaction between N-Ag and MO induced by electrostatic repulsion.S1→S0 was significantly enhanced in the MO solution containing P-Ag.The largest and smallest fluorescence enhancement ratios were observed at pH 2.1 and 4.8,respectively.The fluorescence intensity of S2→S0 decreased and was almost independent of pH.Similar trends were observed for the MO solution containing N-Ag,except that the intensity of S1→S0 was slightly enhanced in the presence of a small amount of N-Ag.The effects of silver nanoparticles with different electrical properties on the spectroscopic properties of MO depend on the interaction between MO and the silver nanoparticles as well as local field enhancement and non-radiative energy transfer.