基于近红外光谱的维生素C片无损鉴别分析

基于近红外光谱技术与化学计量学方法,建立了一种国内外不同品牌维生素C片的无损鉴别方法。采集了国内外8个品牌的维生素C片共计40个样本的近红外光谱数据,比较了完整样品以及粉末样品的近红外光谱,采用连续小波变换技术消除背景干扰和基线漂移,基于标准偏差与相对标准偏差的变量筛选方法筛选出具有代表性的波数点,结合主成分分析方法对国内外不同品牌维生素C片进行鉴别分析。结果表明:原始光谱存在着明显的背景干扰和基线漂移现象,且粉末样品的重现性要优于完整样品;单纯使用原始光谱无法辨别来自不同品牌的维生素C片;连续小波变换可以有效消除背景干扰,提高模型鉴别能力;完整样品的鉴别准确率优于粉末样品,说明国内外不同品牌维生素C片主要成分基本一致,可能是辅剂和工艺上存在细微差异。通过结合近红外光谱分析技术与化学计量学方法,可实现对国产以及进口不同品牌维生素C片的鉴别分析。     

Synthesis,crystal structure and optical property of manganese (II) halides based on pyridine ionic liquids with high quantum yield

Transition Metal Chemistry - Two novel tetrahedral Mn (II) halide single-crystals [(C7H10N)2][MnCl4] (1) and [(C7H10N)2][MnBr4] (2), based on pyridine ionic liquids, have been successfully...     

The luminescence and energy transfer in Pr3+–Ce3+ co-doped Lu0.8Sc0.2BO3 crystals

Lu_0.8Sc_0.2BO₃ crystals doped with 1 at%Ce³⁺ and co-doped 0.1 at% and 0.5 at%Pr³⁺ were grown by the Czochralski method. The concentrations of Pr³⁺ and Ce³⁺ in crystals were measured by the ICP-AES method. Absorption spectra, VUV–UV spectra, fluorescence decay time and X-ray excitation luminescence spectra were investigated at room temperature. The excitation luminescence spectra of Ce³⁺ emission and decay curves from the lower excited state levels of the 4f¹5d¹ and 5d¹ electronic configurations of the Pr³⁺ and Ce³⁺ conspicuously indicated the non-radiative energy transfer from Pr³⁺ to Ce³⁺. The detailed pathways were shown in the energy level diagram of the respective Ce³⁺ and Pr³⁺ in Lu_0.8Sc_0.2BO₃ host. In addition, the scintillation efficiency data indicated that the energy transfer effect is directly associated with the Pr³⁺ concentration.     

氧气对CsPbBr3单晶电学性能的影响

CsPbBr₃兼具高探测效率和较好的稳定性,是当前高性能高能辐射探测器的热门材料。在使用坩埚下降法制备CsPbBr₃单晶的配料阶段,如果无法有效隔绝原料与氧气的接触,氧气会吸附于原料表面难以排出,在原料熔化后会聚集在密封坩埚的上方,导致所得到的单晶颜色沿生长方向逐渐变深,这一颜色变化不会改变CsPbBr₃的禁带宽度。通过对单晶上端切片进行电学性能测试发现,从单晶的中心到外侧,CsPbBr₃单晶的电阻率逐渐下降,陷阱密度和载流子迁移率逐渐增大,但对X射线的响应度基本不变。本文为研究高质量CsPbBr₃单晶的生长提供帮助。     

Luminescence and point defects in cerium-doped lutetium scandium orthoborate crystals

Cerium-doped lutetium scandium orthoborate single crystals as potential scintillation materials were grown by the floating zone (FZ) method for the first time and the Czochralski (Cz) grown crystal was used for comparison. In this paper, the representative composition Lu_0.5Sc_0.5BO₃:0.5at%Ce (abbreviated as LSBO:Ce) was selected as the research target. The phase structure of FZ-grown LSBO:Ce crystal was characterized by X-ray diffraction and its optical properties were investigated using photoluminescence emission (PL), excitation (PLE), radioluminescence (RL) spectra. The defect properties of LSBO:Ce crystals were studied by thermoluminescence (TL) as a function of temperature (300–600 K). The glow curve of FZ-grown LSBO:Ce crystal shows three TSL peaks, at 350, 400, 552 K, corresponding to a trap depth of 0.99, 1.14 and 1.50 eV, respectively. Based on UV-irradiation TL measurements and air-annealing experiments, the former two kinds of traps could be ascribed to the radiation-induced defects and the third kind originated from the oxygen vacancies formed during crystal growth. These defects also existed in the Cz-grown LSBO:Ce crystal.     

ChemInform Abstract: Effects of Scandium Substitution on the Crystal Structure and Luminescence Properties of LuBO3:Ce3+.

Crystals of Lu_1-xSc_xBO₃:Ce (x = 0.2, 0.5, 0.7) are prepared by the Czochralski method and characterized by single crystal XRD, Raman spectroscopy, and vacuum UV excitation spectroscopy.     

Study of the effects of Ga3+ co-doping on the Lu0.8Sc0.2BO3:Ce scintillation crystals

Transparent Lu_0.8Sc_0.2BO₃ crystals doped with 1 at%Ce³⁺ and co-doped with 1 at% and 3 at%Ga³⁺ were grown by the Czochralski method. We applied absorption spectrum, luminescence spectra under UV and X-ray excitation, fluorescence decay curve, three dimensional thermoluminescene and X-ray absorption near edge spectroscopy to study the effect of Ga³⁺ co-doping on the Lu_0.8Sc_0.2BO₃:Ce scintillation crystals. Experimental results indicated that no positive contribution of the Ga³⁺ ion doping on the scintillation efficiency was found. The causes for the deterioration of scintillation efficiency by co-doping Ga³⁺ were revealed. The decrease of practical cerium content and the Ce³⁺/Ce⁴⁺ ratio in crystals, and the increase of the trap concentrations, although the corresponding trap types still maintained the same, played a joint influence on the degrading of scintillation efficiency of Lu_0.8Sc_0.2BO₃:Ce crystals.     

K2LaBr5∶Pr晶体的生长及发光性能研究

通过高温固相法合成Pr³⁺不同掺杂浓度的K₂LaBr₅多晶料,采用垂直坩埚下降法生长出K₂LaBr₅∶Pr单晶,并对晶体进行一系列加工,得到ø12 mm×5 mm的圆柱透明晶体。该晶体属于正交晶系,晶胞参数为a=1.336 0 nm,b=0.992 7 nm,c=0.846 2 nm,Z=4,晶体密度为3.908 g/cm³,熔点为607 ℃。测试了该晶体的X射线粉末衍射、X射线激发发射光谱、光致发光光谱、透过率等。在紫外光以及X射线的激发下,K₂LaBr₅∶Pr晶体在480~750 nm波长范围内呈现蓝光(³P₁→³H₄)、绿光(³P₀→³H₄,³P₁→³H₅)、橙光(³P₁→³H₆,³P₁→³F₂)、红光(³P₀→³F₂,³P₁→³F₃)、深红光(³P₁→³F₄),及紫光(³P₀→³F₄)等多个可见波长的光输出,表明该晶体具有优良的发光性能。在X射线的激发下,在360~440 nm范围内还观察到一个宽带4f 5d-4f²发射跃迁。稳态瞬态荧光光谱分析仪测出光致衰减时间为10 μs左右,紫外可见分光光度计则测出晶体在可见光波段的透过率达到88%。     

[(Epy)2][MnBr2I2]配合物的合成、晶体结构及发光性能

室温下,以N-乙基吡啶碘盐(Epy)I和四水溴化锰(MnBr₂·4H₂O)为原料合成了一种零维发光材料[(Epy)₂][MnBr₂I₂]。对该配合物进行元素含量分析、红外光谱、单晶X射线衍射、粉末X射线衍射、紫外可见吸收光谱、光致发光光谱及X射线激发发射光谱等测试。单晶X射线衍射结果表明:配合物为单斜晶系,C2/c空间群,中心离子Mn(Ⅱ)为四面体构型,晶胞参数为a=2.825 5(6) nm,b=0.839 71(17) nm,c=1.836 0(4) nm。在332 nm紫外光激发下,配合物发出528 nm的绿光,对应于四面体Mn(Ⅱ)配合物的⁴T₁(G)→⁶A₁特征辐射跃迁,荧光寿命为58.85 μs,荧光量子产率为58.29%。X射线激发光谱表明配合物发光强度较高,具有X射线荧光性能。     

SrAl12O19:Pr3+中1S0能级的电子-振动跃迁

稀土离子Pr^3＋ 4f^2组态中的的高激发态1S0的光谱性质与其他4f^2能级有显著的差别.分析了SrAl12O19：Pr的^1S0→1I6和^1S0→^1D2发射光谱,跃迁分别属于Δ过程和M过程; 指认了其中的零声子线和电子-振动跃迁线.这两组跃迁中,电子-振动跃迁强度与零声子跃迁强度之比大于文献中报道的低激发态中的值,表明^1S0与4f5d态的混杂增强了它的电子-声子耦合.