显示用上转换绿色发光材料NaYF4∶Er,Yb及其特性

采用喷射微波燃烧合成法制备了上转换发光显示器中发绿光的上转换发光材料NaYF4∶Er,Yb.测试了该材料的XRD衍射图谱和发光效率.给出了该材料在1 064 nm三种激光功率激发下的发光光谱.分析了该材料的上转换发光机理,得到545 nm和662 nm峰值发光分别是Er3+的4S3/2→4I15/2和4F9/2→4I15/2跃迁产生的.NaYF4∶Er,Yb具有较强的上转换绿光,同时存在的较弱的红光易于用滤色膜滤除,满足显示对三基色中绿色的要求;并且喷射微波燃烧合成法制备的该材料达到了高分辨率显示应用超细粉体的要求.     

Theoretical investigation of a backward wave oscillator

From the linear Vlasov equation,the theoretical investigation on relativistic backward wave osciUator is performed.The relationship between the microwave power and the guiding magnetic field,which accords with the results of the particle simulation and experiments,is deduced.     

Rotational spectra, nuclear quadrupole hyperfine tensors, and conformational structures of the mustard gas simulent 2-chloroethyl ethyl sulfide

Rotational spectra have been recorded for both the ³⁵Cl and ³⁷Cl isotopic forms of two structural conformations of 2-chloroethyl ethyl sulfide (CEES). The rotational constants of the ³⁵Cl and ³⁷Cl isotopomers were used to identify the conformational isomers. A total of 236 hyperfine transitions have been assigned for 47 rotational transitions of the ³⁵Cl isotope of a GGT conformer, and 146 hyperfine have been assigned for 37 rotational transitions of the ³⁷Cl isotopomer. For the second conformer, a total of 128 (110) hyperfine and 30 (28) rotational transitions have also been assigned to the ³⁵Cl (³⁷Cl) isotopes of a TGT conformation. The extensive hyperfine splitting data, measured to high resolution with a compact Fourier transform microwave spectrometer, were used to determine both the diagonal and off-diagonal elements of the ³⁵Cl and ³⁷Cl nuclear quadrupole coupling tensors in the inertial tensor principal axis system. The experimental rotational constant data, as well as the ³⁵Cl and ³⁷Cl nuclear quadrupole coupling tensors, were compared to the results from 27 optimized ab initio (HF/6-311++G^∗∗ and MP2/6-311++G^∗∗) model structures.     

高真空多层绝热容器真空丧失后传热研究综述

高真空多层绝热低温容器突然的真空丧失可能会引发重大的安全事故.文中综述了国内外研究者在高真空多层绝热低温容器突然的真空丧失方面的研究成果,并对未来的研究方向进行了讨论和展望.     

磁过滤器电流对非晶碳薄膜摩擦学特性影响的研究

研究了过滤阴极真空电弧技术中,不同的磁过滤器电流下(5—13 A),制备的四面体非晶碳(ta-C)薄膜对摩擦学特性的影响.通过对薄膜厚度,薄膜结构以及薄膜表面粗糙度随磁过滤电流的变化结果进行了测试,结果表明,随着磁过滤器电流的增大,薄膜的sp³键含量逐渐减少,表面粗糙度从0.13增大到0.38.磁过滤器电流在5 A时,薄膜的摩擦系数最小约为0.08,当电流增大到7 A时,摩擦系数显著增大,磁过滤器电流从7 A增大到13 A时,薄膜的摩擦系数再次减小约为0.1. 关键词： 四面体非晶碳 过滤阴极真空电弧 磁过滤器电流 摩擦系数     

TheB 2Σ-X 2Σ system of the CaF molecule

The spectrum of theB ²Σ-X ²Σ system of the CaF molecule has been photographed in the second order of a 10.6 m concave grating spectrograph with 0.33 Å/mm dispersion. The rotational structure of the (0, 0) and (1, 0) bands has been analysed and the precise molecular constants have been obtained. Using the constants so determined the band origins of a large number of bands with 0 <v′,v″ < 10 have been calculated and used to obtain the accurate vibrational constants forB andX states and these are presented.     

微波烧结Al_2O_3陶瓷的研究

简要介绍了微波烧结的特点,对 Ａｌ２ Ｏ３ 陶瓷的微波烧结过程进行了介绍和分析,并同常规烧结进行了对比实验,在此基础上得出了一些结论,为陶瓷微波烧结提供了实验依据     

连蕊茶花的干燥工艺研究

为研究连蕊茶花的干燥工艺,对其鲜花采用微波杀青和热力杀青、微波干燥和热力干燥的方法进行处理.经过实验处理后,获得连蕊茶花的最佳干燥工艺如下:采摘→清洗→800W微波杀青80s→60℃热力干燥120min→样品保存.得到的连蕊茶干燥花外观好、芳香,具有较大的市场前景,为我国市场增添了一种新的花茶品种.     

北京自由电子激光最近进展──实现饱和振荡

北京自由电子激光(BFEL)装置于1993年底在10.68μm处实现了饱和振荡.输出激光能量为3mJ,饱和平顶宽度2μs.对应饱和振荡平均功率为210kW(宏脉冲),峰值功率约为20MW,比自发辐射高8个量级,单程小讯号净增益为24%,转换效率为0.45%,与理论预期结果相符.光束质量接近衍射极限.目前装置可工作于9-11μm.     

Optical design of a toroidal grating monochromator based beam line on Indus-1

In this paper, we discuss the detailed optical design of a beam line that is under construction on the synchrotron radiation source, Indus-1. Toroidal mirrors are used as pre-and post- focusing elements and a toroidal grating monochromator as a dispersing element. Using three interchangeable gratings, this monochromator will give, at a moderate resolution, a good throughput on the sample in the wavelength range 40 to 1000 Å. Effect of various parameters and their optimization on the resolution and throughput characteristics have been studied by ray tracing calculations, and presented.