掺C60二氧化钛微晶特性和光催化活性研究

通过热分析、X射线衍射以及光活性测试,分析了不同掺杂量、不同燃烧温度下掺杂C60二氧化钛微晶样品,研究了掺杂对二氧化钛光活性的改善情况,C60掺杂二氧化钛体系中C60的热解温度明显提前,二氧化钛的晶化温度延迟、相变受到抑制且光活性得到一定程度的提高,其微晶参数也有一定规律变化。     

Improved atom number with a dual color magneto-optical trap

We demonstrate a novel dual color magneto–optical trap (MOT), which uses two sets of overlapping laser beams to cool and trap 87 Rb atoms. The volume of cold cloud in the dual color MOT is strongly dependent on the frequency difference of the laser beams and can be significantly larger than that in the normal MOT with single frequency MOT beams. Our experiment shows that the dual color MOT has the same loading rate as the normal MOT, but much longer loading time, leading to threefold increase in the number of trapped atoms. This indicates that the larger number is caused by reduced light induced loss. The dual color MOT is very useful in experiments where both high vacuum level and large atom number are required, such as single chamber quantum memory and Bose–Einstein condensation (BEC) experiments. Compared to the popular dark spontaneous-force optical trap (dark SPOT) technique, our approach is technically simpler and more suitable to low power laser systems.     

湿球温度的修正因子及计算式

一、前言 在干燥、冷藏及某些生产工艺和科学实验中,需要严格控制空气的湿度.通常都是采用干-湿球温度计测出干球温度和湿球温度,然后查湿空气图表得出含湿量、相对湿度、焓等等.湿空气图表中的湿球温度是理论湿球温度,也就是绝热饱和温度.绝热饱和温度是湿空气经过一绝热饱和过程后达到的温度.在一定的湿空气状态下,绝热饱和温度有完全确定的数值,因而它是状态参数.用于实际测量的湿球温度计所处的情况和绝热饱和器中的情况并不相同.因为实测的湿球温度比较接近绝热饱和温度,所以通常就用它来     

脉冲磁控溅射MoS2-Ti涂层常温及高温真空摩擦磨损性能

利用脉冲磁控溅射法,以铝青铜合金(C63200)和硅片为基底,制作不同Ti含量的MoS₂-Ti复合涂层。通过XRD、SEM、EDS、光学显微镜、多环境摩擦试验机等表征了涂层的结构成分和摩擦性能。结果表明：随Ti含量的增加,涂层致密度提升,S、Mo原子比上升。Ti的掺入使涂层由高度结晶态向非晶态转变。Ti含量增加,涂层摩擦磨损性能先上升再下降,常温真空下含3%Ti的涂层拥有稳定和低至0.015的摩擦系数,23%Ti的涂层失去润滑性。温度升高到400℃,涂层摩擦系数由0.015~0.04上升至0.07~0.1,含13%Ti的涂层高温真空下在800s后润滑失效。磨痕形貌显示,含3%Ti的涂层磨痕最窄,温度升高宽度增加不大,含13%Ti的涂层磨损严重,400℃真空环境下很快磨穿,纯MoS₂和13%Ti涂层摩擦时发现大量磨粒和破碎磨屑。     

0.22THz宽带折叠波导行波管设计与实验

为了获得0.22THz宽带折叠波导行波管,对行波管的慢波结构和输入输出窗结构进行了宽带设计。通过理论分析和电磁仿真计算出合适的参数,使慢波结构在0.22THz工作点附近的色散曲线平坦,耦合阻抗变化小,模拟计算得到的慢波结构3dB带宽大于16GHz;通过对盒型窗结构及匹配段的优化计算,得到的输入输出结构在大于30GHz范围内S11参数小于-25dB。根据该设计进行了两轮制管和实验研究,得到了一支3dB瞬时带宽约8.8GHz,另一支3dB瞬时带宽大于12GHz的0.22THz折叠波导行波管,中心频率的峰值功率大于400mW。     

40MeV/u 40Ar与Cu相互作用的靶余核

使用离线y能谱法和厚靶──厚收集箔技术测量了40MeV/u ⁴⁰Ar和Cu相互作用中靶余核的生成截面和前向平均反冲射程FW值.根据电荷分布假设得到了靶余核的质量产额分布.从FW值导出了重离子碰撞中的线性动量转移.与¹²C+Cu和²⁰Ne+Cu的类似结果比较指出,在相同的弹核速度下,相应于中心碰撞的相对线性动量转移随弹核质量增加而减小,但是在⁴⁰Ar离子和Cu的中心碰撞中产生的复合系统的激发能比¹²C和²⁰Ne离子碰撞情况下更高,达到每核子5.3MeV.     

Propagation dynamics of dipole breathing wave in lossy nonlocal nonlinear media

In the framework of nonlinear wave optics,we report the evolution process of a dipole breathing wave in lossy nonlocal nonlinear media based on the nonlocal nonlinear Schr?dinger equation.The analytical expression of the dipole breathing wave in such a nonlinear system is obtained by using the variational method.Taking advantage of the analytical expression,we analyze the influences of various physical parameters on the breathing wave propagation,including the propagation loss and the input power on the beam width,the beam intensity,and the wavefront curvature.Also,the corresponding analytical solutions are obtained.The validity of the analysis results is verified by numerical simulation.This study provides some new insights for investigating beam propagation in lossy nonlinear media.     

Theory of multiphoton photoemission disclosing excited states in conduction band of individual TiO2 nanoparticles

A theory of multiphoton photoemission is derived to explain the experimentally observed monotonic decrease with the wavelength in the electron yield of TiO₂ nanoparticles (NPs) by as large as four orders of magnitude. It is found that the fitting parameter corresponds to the energy position of Ti3d e_g and t_2g states, and the derived theory is a novel diagnostic of excited states in the conduction band, very importantly, applicable to individual NPs. The difference between four-photon slope NPs and three-photon slope NPs is attributed to the difference in defect density. The success of the theory in solving the puzzling result shows that thermal emission from high-lying levels may dominate over direct multiphoton ionization in solids when the photon number larger than four is required.     

0.22THz折叠波导行波管电子光学系统设计与实验研究

设计了一套0.22THz折叠波导行波管电子光学系统,详细介绍了电子枪和周期永磁聚焦系统的设计过程,在电子枪电子束束腰与磁系统不匹配情况下,对磁场过渡区进行了优化设计,以此为基础利用磁场仿真软件对磁场进行模拟和优化,并把磁场位形代入电磁仿真软件进行电子束传输仿真,优化后的电子光学系统发射束流10mA,阴极电压15kV,束流通过率96%。通过实验验证,流通管束流通过率93%,高频样管束流通过率94%,与设计相符。高频样管实现连续波运行,功率大于0.4 W,3dB带宽大于12GHz。     

基于学习力培养的问题驱动式复习课教学设计——以“二次函数的复习(第1课时)”为例

<正>1 基于学习力培养的课程分析1.1 内容解读二次函数是描述现实世界变量之间关系的重要数学模型,也是初中阶段研究的三种基本函数之一.本章学习是以已学的一次函数为基础,首先让学生认识二次函数,掌握二次函数的图象和性质,进而用函数的观点来看待方程和不等式,最后解决一些简单的实际问题.二次函数的学习集数形结合、分类讨论、函数与方程、化归等多种思想于一体,在中学数学中有着非常重要的地位,也为学生后续学习打下良好的基础.