共查询到18条相似文献,搜索用时 296 毫秒
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本文用X射线粉末法测定了Li2K(IO3)3与Li2NH4(IO3)3的晶体结构和原子参数。发现Li3K(IO3)3,Li2NH4(IO3)3与Li2Rb(IO3)3同晶型,属单斜晶系,空间群为P21/α,每个单胞含有四个化合式量。室温的点阵常数分别为α=11.198?,b=11.046?,c=8.254?,β=111.53°,及α=11.327?,b=11.078?,c=8.341?,β=111.87°。讨论了二元化合物的形成与离子半径的关系。
关键词: 相似文献
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运用激光拉曼光谱实验和密度泛函理论计算研究了450~1 700 cm-1光谱范围内有机-无机杂化钙钛矿材料(C6H5CH2NH3)2PbBr4的振动模式特性。对比实验所得拉曼光谱和理论计算所得拉曼光谱,发现密度泛函理论计算可以很好的模拟(C6H5CH2NH3)2PbBr4有机部分的分子振动模式。同时通过比较分析密度泛函理论计算和参考文献,对450~1 700 cm-1光谱范围内的拉曼峰的分子振动模式进行了初步的归属,并发现该光谱范围内的拉曼峰主要是由(C6H5CH2NH3)2PbBr4分子中有机部分振动所产生的。 相似文献
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利用XRD、VUV及UV光谱等方法对Ce3+、Tb3+离子掺杂以及Ce3+、Tb3+离子共掺的3种BaCa2(BO3)2荧光粉的相纯度、发光性质、浓度猝灭现象进行研究。结果表明:3种荧光粉在VUV波段有较好的吸收,基质吸收带位于140~190 nm范围。Ce3+在BaCa2(BO3)2的最低4f5d跃迁带位置在360 nm附近,其5d→2FJ(J=5/2, 7/2)发射峰分别位于393,424 nm。Tb3+掺杂的样品在172 nm激发下的发射光谱由4个窄带组成,分别对应5D4→7FJ(J=3,4,5,6)的跃迁,其中占主导位置的是5D4→7F5的跃迁,大约位于543 nm处,主要为绿光发射。在Ce3+,Tb3+离子共掺杂的BaCa2(BO3)2光谱中,观察到Ce3+-Tb3+离子间有能量传递。 相似文献
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测量了碱土金属正磷酸盐Ba3(PO4)2和Sr3(PO4)2常温及高温拉曼光谱, 对拉曼振动模式进行指认, 并分析了晶体拉曼振动光谱及晶体结构在高温下的变化. 在温度升高的过程中, 拉曼振动频率向低频移动且振动峰宽度展宽, 晶体中的P-O平均键长随温度升高而变长, 但O-P-O的键角并未发生变化. 晶体在900 ℃以下无结构相变发生.
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3(PO4)2和Sr3(PO4)2')" href="#">Ba3(PO4)2和Sr3(PO4)2
高温拉曼光谱
振动模式
高温结构 相似文献
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With the K matrix and multichannel quantum defect theory, we have studied the branching ratios of 3p3/2nd (J=1,3) autoionizing series of Mg above the 3p1/2 ion limit. The calculations are compared with the previous experimental spectra, and the unmeasured branching ratios are presented. The conclusion is that 3p3/2nd state prepared by the three-step excitation can form population inversion between the 3p1/2 and 3s1/2 ionic states. 相似文献
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Odd parity autoionizing Rydberg levels of atomic lead in
the energy region above the 6p1/2 ionization threshold have been
investigated using three-step laser excitation in conjunction with an atomic
beam apparatus. The 6p3/2ns (J = 1, 2), 6p3/2nd (J = 1, 2, 3) and
6p3/2ng (J = 2, 3) levels have been observed from the 6p5f 1/2[5/2]2
intermediate level. Energy values and FWHM of forty levels belonging to the
6p3/2ns, 6p3/2nd and 6p3/2ng configurations are presented. Six
levels based on the 6p3/2ng (5, 13 n 15) configurations and
three levels attached to the 6p3/28d configuration are reported for the
first time. The present study of the low-lying autoionizing levels attached
to the 6p3/25g (J = 2, 3) configuration completes the series adjacent to
the 6p1/2 limit. 相似文献
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The nonlinear absorption properties of two organometallic compounds, [(C2H5)4N]2[Cu(C3S5)2] (DCu1) and [(C4H9)4N]2[Cu(C3S5)2] (DCu2), have been investigated using an open-aperture Z-scan technique at 1064 nm with 40 ps pulse width and at 1053 nm with 18 ns pulse width. The reverse saturable absorption (RSA) which was observed in both samples with nanosecond pulse excitation was much larger than that observed with picosecond pulse excitation. The nonlinear absorption properties were analyzed theoretically by a five-level model. Optical limiting based on RSA was performed and limiting thresholds were evaluated for both samples under three conditions. DCu1 exhibited the better limiting characteristics because of its stronger RSA response. 相似文献
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The pyroelectric coefficient p3 in 3La(IO3)3.HIO3.7H2O has an average value 2.0×10-5 Cm-2 in the temperature range 152 to 240 K. The resistivity decreases from 1012 to 1010 ohm-cm between 258 and 338 K. At 298 K, the piezoelectric coefficient d33 19×10-12CN-1. Positive polarity is generated on (001) by increasing temperature or tensile stress. A displacement toward (001) by La3+ or H3O+ ions of 1×10-4 Å per K or 106Nm-2, or rotation of the water molecule or iodate ion dipoles by about 5 arc minutes per K or 106Nm-2, produces the observed polarity. 相似文献
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Synthesis and photoluminescence (PL) investigations of lithium metasilicate doped with Eu3+, Tb3+ and Ce3+ were carried out. PL spectra of Eu-doped sample showed peaks corresponding to the 5D0→7Fj (j=1, 2, 3 and 4) transitions under ultraviolet excitation. Strong red emission coming from the hypersensitive 5D0→7F2 transition of Eu3+ ion suggested the presence of the dopant ion in structurally disordered environment. Tb3+-doped silicate sample showed blue-green emission corresponding to the 5D4→7Fj (j=6, 5 and 4) transitions. Ce-doped sample under excitation from UV, showed a broad emission band in the region 350-370 nm with shoulders around 410 nm. The fluorescence lifetimes of Eu3+ and Tb3+ ions were found out to be 790 and 600 μs, respectively. For Ce3+, the lifetime was of the order of 45 ns. PL spectra of the europium- and terbium-doped samples were compared with commercial red (Y2O3:Eu3+) and green (LaPO4:Tb3+) phosphors, respectively. It was found that the emission from the doped silicate sample was 37% of the commercial phosphor in case of the Tb-doped sample and 8% of the commercial phosphor in case of the Eu-doped sample. 相似文献
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H. Klein H. Elchner H.J. Helten H. Kretzer K. Prescher H. Stehle W.W. Wohlfarth 《Nuclear Physics A》1973,199(1):169-185
The break-up reaction p0 + d → p1 + p2 + n has been studied at E0 = 16 MeV in kinematically complete p1-p2 coincidence experiments with special regard to n-p final-state interactions (f.s.i.) and p1-p2 quasifree scattering (q.f.s.). The absolute differential cross section has been measured for n-p f.s.i. c.m. production angles from 60° to 140° and for four pairs of angles with strong contributions due to q.f.s. Calculations with separable nucleon-nucleon potentials based on the Faddeev equations are in good agreement with the data obtained. In general, the shape of the experimental differential cross section is well reproduced. Discrepancies of up to 30 % in the worst cases arise between the absolute values of the theoretical predictions and the experimental data. 相似文献
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New sodium strontium rare-earth orthophosphates with general formula NaxSr3?2xLnx (PO4)2 (Ln = La, Nd, Gd) have been prepared and characterized. They seem to be of Sr3 (PO4)2 structural type. In NaSrLa1?x?yCexTby (PO4)2, a new green phosphor absorbing in the UV region, high yield results from a Ce3+ → Tb3+ energy transfer. 相似文献