Synthesis and characterization of Ca2Sn1-xCexO4 with blue luminescence originating from Ce^4＋ charge transfer transition

Ce^4＋-doped Ca2SnO4 with a one-dimensional structure, which emits bright blue light, is prepared by using a solid-state reaction method. The x-ray diffraction results show that the Ce^4＋ ions doped in Ca2SnO4 occupy the Sn^4＋ sites. The excitation and emission spectra of Ca2Sn1-xCexO4 appear to have broad bands with peaks at - 268nm and -442nm, respectively. A long excited-state lifetime （-83μs） for the emission from Ca2Sn1-xCexO4 suggests that the luminescence originates from a ligand-to-metal Ce^4＋ charge transfer （CT）. The luminescent properties of Ca2Snl_xCexO4 have been compared with those of Sr2CeO4, which is the only material reported so far to show Ce^4＋ CT luminescence. More interestingly, it is observed that the emission intensity of Ca2Sn1-xCexO4 with a small doping concentration （x - 0.03） is comparable to that of Sr2CeO4 in which the concentration of active centre is 100%.     

稀有类铥铋离子辐射光谱的相对论识别

用全相对论多组态自洽场方法,计算了高离化类铥铋原子BiXV的1s、2s、2p-、2p、3s、3p-、3p、3d-、3d、4s、4p-、4p、4d-、4d、4f-、4f、5s、5p-、5p、5d-、5d、5f-、5f、5g-、5g、6s、6p-、6p、6d-、6d、6f-、6f、6g-、6g、7s、7p-、7p、7d-、7d、7f-、7f、7g-、7g、8s、8p-、8p、8d-、8d轨道的2249个精细结构能级和辐射寿命以及其他各种跃迁参数.能级和波长的计算值和实验值符合得好.另外还发现了一些辐射寿命较长的亚稳态能级.     

双离子(40Ar+,C2H6+)辐照合成金刚石纳米晶颗粒

用双离子(40Ar+,C1H6+)辐照实验完成了从多壁碳纳米管向金刚石纳米晶颗粒的转变.对转变机理进行了初步探讨.这一探索有望能成为一种金刚石纳米晶合成的新途径.由此可知,多重荷能离子辐照用于其他材料纳米结构的制备也不是凭空设想.     

掺铒铋酸盐玻璃光谱性质的组分依赖性研究

通过测试掺铒铋酸盐玻璃43Bi2O3-xB2O3-（57-x）SiO2（x=10，20，30，40，50mol％）中Er^3＋离子的吸收光谱、荧光光谱、荧光寿命及荧光强度，结合Judd—Ofelt和McCumber理论，对玻璃中Er^3＋离子光谱性质随玻璃组分的依赖关系进行了系统研究．研究结果显示，掺铒铋酸盐玻璃具有较其它玻璃优异的光谱性质．随着玻璃中组分B2O3含量的增加，强度参量Ω6、荧光半高宽和能级^4I15／2→^4I13/2间自发辐射跃迁几率相应增加，而荧光寿命、荧光强度和受激发射峰值截面相应减小，带宽品质因子（σe^pcak×FWHM）在组分B2O3含量30mol％时达到最大．     

Orientation and Structure of Ionic Liquid Cation at Air/[bmim][BF4] Aqueous Solution Interface

The watermiscible room temperature ionic liquid 1butyl3methylimidazolium tetrafluorob orate （[bmim] [BF4]） is a model system for studying the interactions between ionic liquid and water molecules. In this work the orientational structure of the low concentrated aqueous solution of [bmim] [BF4] at the air/liquid interface was investigated by sum frequency gener ation vibrational spectroscopy. It has been found that at very low concentrations, the butyl chain exhibited a significant gauche defect, indicating a disordered conformation; and the cation ring oriented with a fairly small tilting angle at the surface. When the concentration increased, the cation ring tended to lie flat at the surface, and the gauche defects of the butyl chain decreased due to the intermolecular chainchain interactions and the consequent more ordered interfacial molecular arrangement. Additionally, the antisymmetric stretching mode in the PPP and SPS spectra exhibited a peak shift, showing that there exists more than one kind of orientation or chemical environment for the butyl CH3 group. These results may shed new light on understanding the surface behavior of watermiscible ionic liquids as well as the imidazolium based surfactants.     

离子色谱法测定米酒中NO-3和NO-2

研究了用带电导检测器的离子色谱对米酒中阴离子NO3^-、NO2^－进行分离测定的方法。NO3^-、NO2^－的线性范围分别为0．5－80mg/L和0.1-20mg/L，检出限分别为0.5mg/L和0.1mg/L。该法适用于SO4^2-、CI^-的测定。     

三甲基苯基六氟磷酸铵离子液体结构性质的密度泛函研究

离子液体以其独特性质广受关注，人们对其潜在的利用价值做了大量的研究.本文采用密度泛函（DFT）B3LYP/6-31(d)的方法计算了三甲基苯基六氟磷酸铵离子液体的几何和电子结构，对比对了三种不同的优化结构.通过自然键轨道(NBO)分析，得到各原子的电荷分布，并用二阶微扰稳定化能分析了阴阳离子间相互作用.结果发现：阴离子分布在阳离子周围的三个区域，所有离子对中阴阳离子间有电荷的转移，且都存在多重氢键作用，阴阳离子间的电荷转移主要是通过LPF→σ*C-H 相互作用.     

Tm3+掺杂的MFT玻璃蓝色荧光动力学

测量了Tm^3 掺杂的MFT玻璃材料的吸收光谱，J－O计算给出了该材料的光学跃迁强度参数Ωt(t=2,4,6)。测量了355nm激发下该材料的发射光谱，通过测量不同掺杂浓度Tm^3 的^1D2→^3H4和^1G4→^3H6荧光衰减曲线讨论了这两个能级寿命及荧光量子效随浓度的变化关系，计算当Tm^3 浓度的4％时引起^1D2和^1G4荧光猝灭的能量传递效率。指出了^1D2→^3H4的荧光猝灭属于电偶极－电偶极相互作用的能量传递所导致。     

UV Photodissociation Dynamics of Nitric Acid： The Hydroxyl Elimination Channel

Sliced velocity mapping ion imaging technique was employed to investigate the dynamics of the hydroxyl elimination channel in the photodissociaiton of nitric acid in the ultraviolet region. The OH product was detected by （2＋1） resonance enhanced multiphoton ionization via the D^2∑^- electronic state. The total kinetic energy spectra of the OH＋NO2 channel from the photolysis of HONO2 show that both ：NO2（X2A1） and NO2（A2B2） channels are present, suggesting that both 1^1A″ and 2^1A″ excited electronic states of HONO2 are involved in the excitation. The parallel angular distributions suggest that the dissociation of the nitric acid is a fast process in comparison with the rotational period of the HNO3 molecule. The anisotropy parameter β for the hydroxyl elimination channel is found to be dependent on the OH product rotational state as well as the photolysis energy.     

以卟啉吡啶季铵盐为显色剂分光光度法测定水中痕量铜

应用新试剂5-[4-N-(对氯)-苄铵基吡啶基]-10,15,20-三(4-N-吡啶基)卟吩氯化物作显色剂,用分光光度法测定了痕量铜,在pH 3.2的邻苯二甲酸盐缓冲介质中,此试剂与铜离子生成组成比为1比1的稳定配合物,其吸收峰位于428.0 nm波长处,表观摩尔吸光率为1.9×105L·mol-1·cm-1.铜含量在0.1 mg·L-1以内符合比耳定律,其线性回归方程为A=0.0152 0.31 C(r=0.999 1).按所提出的方法测定了3种环境水标准样品中的痕量铜(Ⅱ),测得结果与标准值相符.