晶体学一百年 璀璨的历史

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紫外分光光度法测定海水中季铵盐的含量

提出了紫外分光光度法测定海水中季铵盐含量的方法。通过对不同浓缩倍数的海水进行紫外扫描,确定季铵盐的最大吸收波长为263nm。蒸馏水和海水中季铵盐的质量浓度和其吸光度分别在100mg·mL-1和50mg·mL-1以内呈线性关系。方法的检出限(3S/N)为3.205mg.L-1,平均回收率为94.95%,相对标准偏差(n=5)为1.9%。     

由缺陷引起的Burstein-Moss和带隙收缩效应对CdIn2O4透明导电薄膜光带隙的影响

在Ar+O2气氛，采用射频反应溅射Cd In靶制备CdIn2O4（CIO）薄膜.通过对不同衬底 温度下制备和沉积后在氩气流中退火的薄膜进行透射、反射和Hall效应的测量和分析发现， 随着衬底温度的降低，载流子浓度呈上升趋势，而吸收边呈现先是“蓝移”然后“红移”的 现象.从理论上阐述了高浓度的点缺陷对CIO氧化物薄膜的能带产生的重要影响，这些影响主 要体现在带尾的形成，Burstein Moss(B M)漂移和带隙收缩.另外，衬底温度的变化将对 薄膜的迁移率有重要影响.对于CIO薄膜，由缺陷产生的空穴浓度将对薄膜的带隙收缩产生重 要影响并将直接影响到薄膜的光透性.由于存在吸收带尾，利用传统的“外推法”获得薄膜 的光带隙并不适合简并半导体，而应使用更为准确的“拟合法”. 关键词： 射频反应溅射 CdIn2O4透明导电薄膜 Burstein Moss漂移 带隙收缩 电学性 质 光学性质     

由缺陷引起的Burstein-Moss和带隙收缩效应对CdIn2O4透明导电薄膜光带隙的影响

在Ar+O2气氛,采用射频反应溅射Cd-In靶制备CdIn2O4(CIO)薄膜.通过对不同衬底温度下制备和沉积后在氩气流中退火的薄膜进行透射、反射和Hall效应的测量和分析发现,随着衬底温度的降低,载流子浓度呈上升趋势,而吸收边呈现先是"蓝移"然后"红移"的现象.从理论上阐述了高浓度的点缺陷对CIO氧化物薄膜的能带产生的重要影响,这些影响主要体现在带尾的形成,Burstein-Moss(B-M)漂移和带隙收缩.另外,衬底温度的变化将对薄膜的迁移率有重要影响.对于CIO薄膜,由缺陷产生的空穴浓度将对薄膜的带隙收缩产生重要影响并将直接影响到薄膜的光透性.由于存在吸收带尾,利用传统的"外推法"获得薄膜的光带隙并不适合简并半导体,而应使用更为准确的"拟合法".     

HYBRID REGULARIZED CONE-BEAM RECONSTRUCTION FOR AXIALLY SYMMETRIC OBJECT TOMOGRAPHY

In this paper,we consider 3 D tomographic reconstruction for axially symmetric objects from a single radiograph formed by cone-beam X-rays.All contemporary density reconstruction methods in high-energy X-ray radiography are based on the assumption that the cone beam can be treated as fan beams located at parallel planes perpendicular to the symmetric axis,so that the density of the whole object can be recovered layer by layer.Considering the relationship between different layers,we undertake the cone-beam global reconstruction to solve the ambiguity effect at the material interfaces of the reconstruction results.In view of the anisotropy of classical discrete total variations,a new discretization of total variation which yields sharp edges and has better isotropy is introduced in our reconstruction model.Furthermore,considering that the object density consists of continually changing parts and jumps,a high-order regularization term is introduced.The final hybrid regularization model is solved using the alternating proximal gradient method,which was recently applied in image processing.Density reconstruction results are presented for simulated radiographs,which shows that the proposed method has led to an improvement in terms of the preservation of edge location.