Effects of Impurity on the Ground—State Transitions of a Quantum Dot in Strong Magnetic Field

The low-lying spectra of parabolic quantum dots with or without an impurity at the center are investigated.While it has been known that the electron-electron interaction leads to ground-state transitions on magic values of angular momentum in a magnetic field. We show, in this paper, that the implantation of an impurity ion at the center can either enhance or suppress such transitions, depending on whether it is an acceptor or a donor ion.

Electric-Field Switching of Bright and Dark Excitons in Semiconductor Crossed Nanowires

We investigate theoretically the exciton states in semiconductor crossed nanowires(CNWs)and it is found that the energy spectrum and electro-PL spectrum of the exciton in the CNWs can be tuned by the size of the nanowires using electric fields.An interesting bright-to-dark exciton transition can be found and it significantly affects the photoluminescence spectrum by the electric fields,which can be used to design new types of optoelectronic devices.

控水诊断图

在石油开采中，已研究了一种用于确定过量产水产气机理的新方法，并得到了验证。以油藏水锥和水窜问题的系统数值模拟为基础，人们发现，驱替机理不同，WOR与时间及GOR与时间的双对数图表现出不同的特征，利用WOR或GOR对时间的导数可以判别油井是水锥还是气锥，是高渗层见水还是井底附近水窜。该方法对德克萨斯、加利福尼亚、墨西哥湾岸区和阿拉斯加油田的某些井进行了应用，利用实际生产数据图，确定产生问题的机理。结合油井测试和生产测井资料，利用该方法选择措施井，并对增产措施进行优化，可以加速投资的回收。