SiO_2／SiO界面能级位移光电发射的研究

芯层光电子能谱（ＸＰＳ）和价带光电子能谱（ＵＰＳ）是研究不同半导体之间界面价带落差的有效手段，由ＳｉＯ２／ＳｉＯ界面处的芯层和价带光电子能谱，我们确定ＳｉＯ２／ＳｉＯ界面能级落差为２．０ｅＶ，覆盖引起能带位移为０．９ｅＶ，同时发现ＳｉＯ和ＳｉＯ２中的化学组分是较复杂的。     

用XPS测量ZnS0.8Te0.2／GaP半导体异质结的价带偏移

应用Ｘ射线光电子能谱(ＸＰＳ）对分子束外延生长的ＺｎＳ(０．８)Ｔｅ(０．２)／ＧａＰ半导体异质结进行直接法测量，得其价带偏移值为１．５ｅＶ；采用芯态能级技术法测量，得其价带偏移值为１．４５ｅＶ在测量误差范围内，两种方法测得的结果相一致．     

光激励发光材料 BaFCl : Eu 的制备及光电子能谱

研究了在不同反应气氛下合成的光激励发光材料ＢａＦＣｌ：Ｅｕ中稀土离子发光中心及发光性质．利用光谱和Ｘ射线光电子能谱的方法，研究了在不同条件下制备的样品ＢａＦＣｌ：Ｅｕ中稀土离子Ｅｕ的性质     

EHMO方法对CaF2晶体能带结构的研究

利用扩展休克尔方法结合特殊Ｋ点方案，采用自包容子程序，计算了离子晶体ＣａＦ２的能带结构，得出了价带位置和能隙宽度。能级结构计算结果表明，能级Г１２位于Г＇之下，一些能级的位置被排斥上移，导带的最小点在Г１，而不是像其他半经验方法计算的那样在Ｘ３。采用的方案计算简便，大大节省了计算时间，所得结果较好地解释了实验光谱数据。     

Pr掺杂对Bi_2Sr_2Ca_(1-x)Pr_xCu_2O_y单晶结构的影响

采用自助熔剂法制备出Ｂｉ２Ｓｒ２Ｃａ１－ｘＰｒｘＣｕ２Ｏｙ系列单晶样品,通过对样品的Ｘ射线衍射（ＸＲＤ）实验的结构分析,利用对称反射和对称透射几何得到沿单晶ａ、ｂ、ｃ方向的多级衍射,由此可以得到晶格参数和调制周期。本文给出了Ｂｉ２Ｓｒ２Ｃａ１－ｘＰｒｘＣｕ２Ｏｙ单晶的晶格参数ａ、ｂ、ｃ和调制周期ｓ随Ｐｒ掺杂量ｘ的变化,并讨论了这种结构细微变化的原因     

F~-离子和Ti~(4+)离子在CaO-Al_2O_3-SiO_2系玻璃晶化时的作用

在ＣａＯ－Ａｌ２Ｏ３－ＳｉＯ２（ＣＡＳ）系玻璃中单独引入Ｆ－离子或Ｔｉ４＋离子,以及同时引入Ｆ－离子和Ｔｉ４＋离子,通过ＤＴＡ（差热分析）、ＸＲＤ（Ｘ－射线衍射）、Ｒａｍａｎ、ＸＰＳ（光电子能谱）和ＳＥＭ（扫描电镜）方法进行了研究。结果表明在ＣＡＳ系玻璃中一部分Ｆ－离子取代非桥氧离子处于玻璃网络内部,另一部分Ｆ－离子处于玻璃网络间隙,Ｆ－离子能促使ＣＡＳ系玻璃分相,在稍高于Ｔｇ的某一温度热处理时,ＣａＦ２晶体首先从玻璃中析出;Ｔｉ４＋离子对玻璃晶化影响不大,在稍高于Ｔｇ的某一温度热处理时,加Ｔｉ４＋离子和不加Ｔｉ４＋离子的玻璃首先析出的晶相均是钙长石（ＣａＡｌ２Ｓｉ２Ｏ８）;在ＣＡＳ系玻璃中同时引入Ｆ－离和Ｔｉ４＋离子时,在稍高于Ｔｇ的某一温度热处理后首先析出的晶体是ＣａＦ２和钙长石（ＣａＡｌ２Ｓｉ２Ｏ８）,Ｆ－离子和Ｔｉ４＋离子混合使用能更好地促进ＣＡＳ系玻璃的晶化。     

离子束外延β—FeSi2／Si薄膜的电子能谱研究和表征

用电子能谱分析方法对低能离子束外延（ＩＢＥ）生长的β－ＦｅＳｉ２进行了详细研究,并对其电子能谱进行了表征。实测出ＸＰＳ价带谱与有关理论计算结果相符,用ＸＰＳ价带谱来表征β－ＦｅＳｉ２比光电子峰更为清晰、可取。同时,对样品纵向分析表明界面处存在有较厚的过渡层。根据分析结果对低能ＩＢＥ生长机理进行了探讨。经研究认为：Ｆｅ,Ｓｉ通过空位机制进行的增强互扩散,在高温下生长出与Ｓｉ晶格相匹配的β－ＦｅＳｉ２     

Ar^＋离子注入对Ge／GaAs（100）异质结能带偏离影响的XP…

用Ｘ光电子能谱（ＸＰＳ）方法研究了界面特性和Ｇｅ／ＧａＡｓ（１００）异质结的能带偏离关系。实验表明，当在清洁的ＧａＡｓ（１００）表面生长Ｇｅ异质结时，其价带偏离（△Ｅｖ）与界面特性无关，而在Ａｒ离子注入的ＧａＡｓ（１００）表面上生长的Ｇｅ异质结，其价带偏离与Ａｒ＾＋离子的浓度分布有关。     

钨砷系列杂多蓝的研究Ⅱ——1：11钨砷双系列稀土杂多蓝

利用控制电位电解的方法合成了４种未见文献报道的杂多蓝，Ｋ１１Ｈ２〔Ｌｎ（ＡｗＷ１Ｏ３９）２〕·ｘＨ２Ｏ（Ｌｎ＝Ｌａ，Ｃｅ，Ｐｒ，Ｎｄ），并利用等离子体原子发射光谱等对其进行了元素组成的分析，利用ＩＲ、ＵＶ、极谱，光电子能谱，电子顺磁共振，热重差热等测试手段，对其结构和性质进行了研究。     

BaFCl:Eu~(2 )的正电子湮没谱研究

利用正电子湮没谱研究了不同离子数（Ｆ）／离子数（Ｃｌ）比ＢａＦＣｌ：Ｅｕ２＋系列粉末样品．实验结果表明：当晶体中的离子数（Ｆ）／离子数（Ｃｌ）＜１时，可以有效地产生Ｆ离子空位缺陷，当离子数（Ｆ）／离子数（Ｃｌ）比值在０．９２附近的空位缺陷浓度最大．     

变化电场作用下Bloch振荡的自发辐射

研究了随时间变化电场作用下超晶格中电子的自发辐射．对超晶格采用最近邻紧束缚近似模型,在单带最近邻框架内讨论一维系统,推导出辐射几率的函数式．分析了Bloch频率与电场频率比值对于辐射几率的影响．结果表明,可以通过调整Bloch频率与电场频率比值得出较大的辐射几率,从而获得较大功率的THz波源．     

High-quality electron beams from a laser wakefield accelerator using plasma-channel guiding

Laser-driven accelerators, in which particles are accelerated by the electric field of a plasma wave (the wakefield) driven by an intense laser, have demonstrated accelerating electric fields of hundreds of GV m(-1) (refs 1-3). These fields are thousands of times greater than those achievable in conventional radio-frequency accelerators, spurring interest in laser accelerators as compact next-generation sources of energetic electrons and radiation. To date, however, acceleration distances have been severely limited by the lack of a controllable method for extending the propagation distance of the focused laser pulse. The ensuing short acceleration distance results in low-energy beams with 100 per cent electron energy spread, which limits potential applications. Here we demonstrate a laser accelerator that produces electron beams with an energy spread of a few per cent, low emittance and increased energy (more than 10(9) electrons above 80 MeV). Our technique involves the use of a preformed plasma density channel to guide a relativistically intense laser, resulting in a longer propagation distance. The results open the way for compact and tunable high-brightness sources of electrons and radiation.     

闭合轨道理论在二层介质中原子自发辐射问题上的应用

利用量子电动力学计算了二层介质中电磁场零点涨落,并用原子物理中发展成熟的闭合轨道理论探讨了原子自发辐射速率随发光原子离开界面的距离的增加而变化的特性.研究结果表明:当发光原子远离界面时,原子自发辐射速率呈现衰减的周期振荡现象.通过傅立叶变换,得到了原子自发辐射速率随发光原子离开界面的距离的增加而振荡的频率,为了解释这些现象,我们首次将闭合轨道理论应用于研究两层介质中原子的自发辐射,给出了一种对原子自发辐射现象新的理解方式.     

非等温空腔法确定固体材料的比辐射率

本文讨论一种确定固体材料比辐射率的方法。在被测材料的表面开一个圆柱形空腔,并在其背面均匀加热。联立求解腔壁的辐射换热和体内的热传导方程,求得温度场分布和腔底的有效辐射。结果表明,腔底的有效辐射是比辐射率、腔深和半径之比以及一个表示温度梯度的参数的函数。文中讨论了能量辐射和光子辐射两种情况。在实验中,用热象仪测量材料表面和腔底的有效辐射。由理论分析结果和实验测定的有效辐射,求得材料的比辐射率。     

Laser acceleration of quasi-monoenergetic MeV ion beams

Acceleration of particles by intense laser-plasma interactions represents a rapidly evolving field of interest, as highlighted by the recent demonstration of laser-driven relativistic beams of monoenergetic electrons. Ultrahigh-intensity lasers can produce accelerating fields of 10 TV m(-1) (1 TV = 10(12) V), surpassing those in conventional accelerators by six orders of magnitude. Laser-driven ions with energies of several MeV per nucleon have also been produced. Such ion beams exhibit unprecedented characteristics--short pulse lengths, high currents and low transverse emittance--but their exponential energy spectra have almost 100% energy spread. This large energy spread, which is a consequence of the experimental conditions used to date, remains the biggest impediment to the wider use of this technology. Here we report the production of quasi-monoenergetic laser-driven C5+ ions with a vastly reduced energy spread of 17%. The ions have a mean energy of 3 MeV per nucleon (full-width at half-maximum approximately 0.5 MeV per nucleon) and a longitudinal emittance of less than 2 x 10(-6) eV s for pulse durations shorter than 1 ps. Such laser-driven, high-current, quasi-monoenergetic ion sources may enable significant advances in the development of compact MeV ion accelerators, new diagnostics, medical physics, inertial confinement fusion and fast ignition.     

Thermal properties of high temperature vacuum receivers used for parabolic trough solar thermal power system

The receiver's emittance and vacuum pressure are the two of great significance issues on the heat-loss which is the main factor reducing the efficiency of the parabolic though systems. In this paper, the thermal steady-state equilibrium method was used to test the receivers heat-loss. The receivers with increasing emittance were tested to study the variation of heat-loss. Meanwhile, the variable vacuum pressure in the annulus that affects the efficiency of the system was investigated. The influence of vacuumizing rate and getters on the vacuum pressure and heat-loss were discussed. The result shows that the emittance and vacuum pressure affect the receiver's heat-loss dramatically, and the emittance is the major influence factor on the thermal properties. The receiver with 0.08 emittance and 10~(-3) Pa vacuum pressure has a satisfactory heat-loss of 215.6 W/m at 400 ℃.The analysis further reveals that the synergistic effect of both emittance and vacuum pressure on the heat-loss can be reflected by the packaging temperature of the glass tube, and a fitting formula has been established to estimate the receivers' heat-loss according to the packaging temperature of the glass tube.     

量子点半导体光放大器的自发辐射特性研究

从导带、价带和浸润层的能级跃迁出发,采用分段模型对量子点半导体光放大器的增益和自发辐射进行了数值研究．物理模型包括自发辐射行波方程和各能级栽流子与光子数速率方程．经过大量数值计算,得到基态电子占用概率随注入光脉冲的变化,以及增益动态过程（饱和与恢复）和输出光脉冲的时域波形畸变．进一步研究了量子点光放大器自发辐射谱和增益平坦性,结果表明自发辐射功率随输入信号功率增大而减小,引入合适的钳制光,可在20nm带宽内获得小于0．3dB的增益平坦度,或者40nm带宽内小于1．0dB．     

Controlling the dynamics of spontaneous emission from quantum dots by photonic crystals

Control of spontaneously emitted light lies at the heart of quantum optics. It is essential for diverse applications ranging from miniature lasers and light-emitting diodes, to single-photon sources for quantum information, and to solar energy harvesting. To explore such new quantum optics applications, a suitably tailored dielectric environment is required in which the vacuum fluctuations that control spontaneous emission can be manipulated. Photonic crystals provide such an environment: they strongly modify the vacuum fluctuations, causing the decay of emitted light to be accelerated or slowed down, to reveal unusual statistics, or to be completely inhibited in the ideal case of a photonic bandgap. Here we study spontaneous emission from semiconductor quantum dots embedded in inverse opal photonic crystals. We show that the spectral distribution and time-dependent decay of light emitted from excitons confined in the quantum dots are controlled by the host photonic crystal. Modified emission is observed over large frequency bandwidths of 10%, orders of magnitude larger than reported for resonant optical microcavities. Both inhibited and enhanced decay rates are observed depending on the optical emission frequency, and they are controlled by the crystals' lattice parameter. Our experimental results provide a basis for all-solid-state dynamic control of optical quantum systems.     

基于STIRPAT及解耦模型的河北省碳排放影响因素分析

运用解耦模型分析了2007年—2014年河北省的解耦状态:从增长性耦合到弱解耦,在波动中实现了强解耦.运用STIRPAT模型分析河北省碳排放影响因素,利用灰色模型GM(1,1)预测河北省2015年—2022年碳排放量,结果显示:产业结构对河北省碳排放影响最大;煤炭消费量、人均GDP、城镇人口占比、人口数对河北省碳排放量有促进作用,能源价格和研究与发展经费支出对河北省碳排放量的影响系数较小;能源结构、能源强度对河北省碳排放量有一定的抑制作用.GM(1,1)模型预测结果显示:应当重视河北省碳排放量的发展趋势,正视低碳发展的压力,通过调整各影响因素实现河北省低碳经济.     

量子阱微腔激光器中TE和TM模自发发射的差异

利用金属镜面微腔激光器中真空场和量子阱中电子态函数,对比了ＴＥ模和ＴＭ模的自发发射谱,发现腔长为半个波长的微腔激光器可以增进ＴＥ模垂直方向的自发发射,同时ＴＭ模却得到很大抑制,并且它们总的自发发射也存在差异。