用解卷积方法测量亚毫微秒荧光寿命

本文报道了用光电倍增管及取样示波器测量Rh6G和不同浓度的KI混合水溶液的荧光衰变曲线。系统的响应时间是毫微秒量级的,测量得到的衰变曲线是溶液的真实衰变曲线与仪器响应函数卷积的结果。应用相平面法与迭代卷积法相结合来进行解卷积处理,求得溶液的真实荧光寿命,其结果可获得最小时间分辨为130ps,达到仪器的响应函数半宽度的3％。     

贝尔实验室物理学家的论文诸多被撤消

20 0 1年 ,位于新泽西州穆勒山的贝尔实验室物理奇才詹·亨德里克·舒恩以平均每 8天出 1篇的惊人速度写出论文 .现今 ,依据贝尔实验室 9月 2 5日的报告 :舒恩论文存在许多被指控的不轨行为 (Science杂志2 0 0 2年 10月 4日 ,第 30页 ) .论文被撤消的速度同样惊人 .2 0 0 2年 11月 ,Science刊登了关于舒恩与同事所著的 8篇论文的撤消声明 (见《物理》2 0 0 3年第 2期第 138页 ) .Science杂志电子版对舒恩论文发布相关警告 ,并说将尽快发表书面撤消声明 .在最新的一轮撤消声明大战中 ,美国物理学会 (APS)与美国物理联合会 (AIP)在 2 0 0 …     

Formation of Infrared Femtosecond Laser Induced Colour Centres in Tb^3＋－Doped and Tb^3＋／Ce^3＋－Codoped Heavy Germanate Glasses and Tb3＋／Ce3＋－Codoped Heavy Germanate Glasses ＊

The formation of infrared femtosecond laser induced colour centres was observed in Tb^3 -doped and Tb^3 /Ce^3 -codoped heavy germanate glasses. A rectangular scan was made by focusing the laser beam inside the glasssamples. A three-dimensional yellowish block was created from the path and it corresponded to the appearanceof broad absorption bands in the absorption spectra. The irradiation induced absorption coefficient μ(λ) wasused to characterize the distribution of radiation induced colour centres in the samples, whose peak was locatedat 380 nm and extended to the longer wavelength. Ce^3 ions were found not only to inhibit the formation ofcolour centres, but also to enhance the recovery.     

裂纹尖端附近莫尔(Moire)应变测量

本文利用错动变形栅的方法,直接记录位移微分等值线。这一方法在测量双边裂缝拉伸试件中得到应用。得到满意的结果。     

为一位17世纪的科学家鸣冤

胡克，1635年7月18日生于英格兰怀特岛弗雷什沃特村，1702年3月5日卒于伦敦，他是17世纪一位深有造诣的天文学家、发明家、勘探家和建筑设计师，他曾在1666年帮助重建遭遇大火洗礼的伦敦城；他还是一位有独特见解的思想家，他提出的关于进化论的观点要比达尔文早两个世纪。     

Design and numerical analysis for low birefringence silica on silicon waveguides

A new fabrication technology for three-dimensionally buried silica on silicon optical waveguide based on deep etching and thermal oxidation is presented. Using this method, a silicon layer is left at the side of waveguide. The stress distribution and effective refractive index are calculated by using finite element method and finite different beam propagation method, respectively. The results indicate that the stress of silica on silicon optical waveguide fabricated by this method can be matched in parallel and vertical directions and stress birefringence can be effectively reduced due to the side-silicon layer.     

做一颗算盘珠子

我在交通银行北京分行营业部工作两年多了,由于勤奋学习、努力工作,很快就掌握了营业部的业务知识,进入工作角色,现在已经担当大户室部门经理快一年了。加了薪、提了职,领导还把与汽车行业的外商洽谈业务的翻译工作交给了我,我利用只剩一周的时间,     

受激发射的观测

光有两种发射机制-自发发射和受激发射.普通光源的光是由自发发射产生的,而激光器辐射的激光是受激发射产生的放大光.自发发射人们是熟悉的,但是在通常情况下很难观察到受激发射现象.本文介绍一个简单的实验,很容易观察到受激发射现象,并且又能方便地测出受激发射光放大的增益系数. 设物质粒子有上下两个能级E2和E1.要想观察到受激发射现象,必须使上能级 E2上的粒子数N2超过下能级E1上的粒子数N1,也就是使系统处于非热平衡的所谓“粒子数反转状态”.处于粒子数反转状态的物质称为增益介质,这是由于受激发射光通过增益介质何放大作01.如有…     

Fabrication of Microstructures in LiF Crystals by a Femtosecond Laser

We report the space-selective formation of colour centres and refractive index change in LiF crystals at room temperature by an 800nm Ti:sapphire femtosecond laser irradiation. Optical absorption and photoluminescence spectra have been measured for the crystal before and after the laser irradiation. The absorption spectra indicate F and F3^ colour centres are induced in LiF after the laser irradiation. When the temperature of heat treatment reaches 300℃, the absorption peak disappears, indicating that the induced colour centres are bleached. The induced refractive index change is also evaluated. A mechanism for the formation of colour centres and refractive index change is proposed.     

核磁共振与诺贝尔奖

 2003年10月6日,瑞典卡罗林斯卡医学院宣布:2003年诺贝尔生理和医学奖授予美国化学家保罗·劳特布尔和英国物理学家彼得·曼斯菲尔德,以表彰他们在核磁共振成像技术领域的突破性成就。迄今为止,已有10位科学家因在核磁共振技术领域的卓越贡献而荣获诺贝尔奖。