776nm近红外光激发下NaY(WO_4)_2:Dy^(3+),Ho^(3+)上转换发光粒子的光学特性

采用水热法制备出NaY(WO+4)+2:Dy^(3+),Ho^(3+)上转换荧光材料。通过X线粉末衍射、扫描电子显微镜、激发光谱以及发射光谱对该材料特性进行表征。研究Dy^(3+)与Ho^(3+)的掺杂比例及退火温度对上转换发光效果的影响,并确定了最佳反应条件。探讨Dy^(3+)与Ho^(3+)的能量传递过程及上转换发光机制。研究结果表明:通过776 nm近红外光激发NaY(WO+4)+2:Dy^(3+),Ho^(3+),观察到Dy^(3+)的480 nm处蓝光发射峰以及577 nm处的黄光发射峰。其中蓝光主要来自于Dy^(3+)的~4F_(9/2)→~6H_(15/2)跃迁,黄光由Dy^(3+)的~4F_(9/2)→~6H_(13/2)跃迁产生。

Application of graphite screen printed electrode modified with dysprosium tungstate nanoparticles in voltammetric determination of epinephrine in the presence of acetylcholine

The current work focuses on the development of a sensitive and selective electrochemical device based on a graphite screen printed electrode modified with Dy2（WO4）3 nanoparticles（DWO/SPE） for the analysis of epinephrine in samples also containing acetylcholine. The study proves that the sensor has excellent electron-mediating behavior in the oxidation of epinephrine in a 0.1 mol/L phosphate buffer solution（PBS）（pH 7.0）. The application of the DWO/SPE in differential pulse voltammetry（DPV） is found to lead to distinct response for the oxidation of epinephrine and acetylcholine, with the potentials of the epinephrine and acetylcholine peaks（△Ep） to be 550 mV apart. The detection limits of the method for epinephrine and acetylcholine are 0.5 and 0.7 μmol/L（S/N = 3） and the responses are found to be linear in the concentration ranges of 1.0-900.0 μmol/L and 1.0-1200.0 μmol/L in a PBS buffer（pH = 7.0）respectively. The modified electrode was used for the detection of epinephrine and acetylcholine in real samples and found to produce satisfactory results. These results can be a proof that Dy2（WO4）3 nanoparticles can find promising applications in electrochemical sensors to be used for the analysis of（bio）chemical species.