碱性染料杂多酸多元络合物显色反应的研究——IX.乙基罗丹明B-锗钼杂多酸-聚乙烯醇体系

本文研究了乙基罗丹明B-锗钼杂多酸-PVA显色体系,提出了测定痕量锗新的高灵敏分光光度法.缔合物最大吸收位于584nm,表观摩尔吸光系数ε为3.8×10~5L·mol~(-1)·cm~(-1).缔合物的组成比为Ge(Ⅳ):ERB~+=1:4.红外光谱研究表明,染料阳离子的结构未受缔合物形成的影响.本法用于人参中痕量锗的测定,得到满意结果.

Crystallization Behavior of Poly(tetrahydrofuran-b-methyl methacrylate) Diblock Copolymer

Crystallization behavior of a series of newly synthesized poly (tetrahydrofuran-b-methyl methacrylate) diblock copolymer has been studied by differential scanning calorimetry (DSC) and X-ray scattering and diffraction techniques. The results show that the

THE YELLOW-TO-BLUE INTENSITY RATION (Y/B) OF DY-3+ EMISSION

Various borates, vanadates, niobates, antimonates, titanates, zirconates and CaS doped with Dy3+ were prepared. Factors which have an effect on the yellow-to-blue intensity ratio (Y/B) of Dy3+ emission are reported. Y/B increases with decreasing Z/r or electronegativity of the next-neighbour element M in the complex oxides Dy-O-M. The greater the degree of covalency between Dy3+ and O2-, the greater Y/B is. When Dy3+ is located at a site with an inverse centre and high symmetry, Dy3+ displays no luminescence. It seems that Y/B of Dy3+ located at a site deviated from an inverse centre is greater than that of Dy3+ located at a site without an inverse centre. Y/B does not vary much with the variation in concentration of Dy3+ when Dy3+ is substituted for an element with the same valency, but it does depend on the concentration of Dy3+ when Dy3+ is substituted for an element with a different valency in the matrix, because defects are formed in this case.