空间层叠矩形阵列式角多路解码光路设计

根据角多路技术原理,提出了一种矩形阵列空间层叠形式的解码光路结构和先分组解码再组内解码的两步解码方式,并针对本实验室的高功率准分子激光系统给出了具体的解码光路设计实例。该方法具有解码精度高,设计误差小,与光路准直、激光参数测量系统等兼容性好,便于加工制作和安装调试等优点。     

四同芳香性转烯及其羰基硼衍生物

运用G03W程序, 在高精度理论水平(B3P86/6-311＋G**)下, 对母体转烯(Hypostrophene)及其BCO衍生物的单态、三态、开壳层单态的Cope重排体系进行了理论研究: 对体系进行了相应的结构优化和频率计算, 并进一步计算了体系的重排势垒、反应能量、核独立化学位移值等理论参数. 文中首次提出具有四同芳香性的实例: 转烯的Cope重排过渡态. 计算同时表明BCO取代CH的行为使得进行Cope重排的反应物和过渡态的离域性、芳香性以及稳定性都得到很大的促进, 这可以从前线轨道的成键以及延伸方面得到合理的解释. 所得结果进一步验证了BCO基团的稳定性效应.     

Fe原子活化乙烷的微观反应机理

本文采用密度泛函理论B3LYP方法在6-311 G(d,p)基组水平上研究了Fe原子催化乙烷反应的微观反应机理,优化了反应过程中各反应物、中间体、过渡态和产物的构型,并在同一水平上计算了反应中各驻点的振动频率,运用自然键轨道理论(NBO)方法分析了各物质的成键情况和轨道间相互作用。Fe原子对乙烷的活化过程可分为C-C键活化及C-H键活化,分别释放出CH4和H2。     

The effects of pre-equilibrium emission and secondary decay on the determination of freeze-out volume at intermediate energies

The effects of pre-equilibrium emission and secondary decay on the determination of the freeze-out volume are investigated using the isospin-dependent quantum molecular dynamics model accompanied by the statistical decay model GEMINI. Small-mass projectiles and large-mass targets with central collisions are studied at intermediate energies. It is revealed that the proton yields of pre-equilibrium emission are smaller than those of secondary decay. However, the determination of the freeze-out volume from the proton yields is more easily affected by pre-equilibrium emission. Moreover, the percentage of proton yields in the freeze-out stage is found to be approximately 50%.     

多晶体二次电子的角度分布

根据二次电子发射的主要物理过程,推导了内二次电子到达多晶表面并逸出的几率的角度分布、斜射入多晶的高能原电子产生的二次电子的角度分布和由背散射电子产生的二次电子的角度分布。同时,推导了高能原电子轰击多晶产生的二次电子的角度分布公式,该公式表明多晶的二次电子遵循余弦分布,且与原电子的入射角无关。分析结果表明: 在内二次电子最大逸出深度范围内,如果由射入多晶的原电子和背散射电子产生的内二次电子数是常数, 则多晶的二次电子的角度分布遵循余弦分布;如果由射入多晶的原电子和背散射电子产生的内二次电子数越来越少,则多晶的二次电子发射角度分布随出射角减少得比出射角的余弦值更慢;如果由射入多晶的原电子和背散射电子产生的内二次电子越来越多,则多晶的二次电子发射角度分布随出射角减少得比出射角的余弦值更快。     

关于自旋电子的一些为什么——浅谈与超导电性对抗的磁性元素Fe,Co,Ni为什么形成化合物就超导了？

在近20年来的凝聚态物理研究中,人们在铜基氧化物中发现了高温超导电性,在锰基钙钛矿中发现了巨磁电阻效应,以及近年来发现由铁、钴、镍等传统认为与超导对抗的元素组成化合物后可以形成超导.这些不同的体系有着迥然不同的物理行为,却具有一个共同的特征：这些铜、锰、铁、钴、镍基化合物都是3d电子材料.那么,同为3d电子,为什么在不同的环境中表现出完全不同甚至对抗的行为？文章对这些现象提出了一系列为什么,并对其进行了探讨.     

双曲余弦高斯列阵光束通过湍流大气传输的角扩展及方向性

采用积分变换,推导出了双曲余弦高斯（ChG）列阵光束通过湍流大气传输的二阶矩束宽和角扩展的解析公式,给出了ChG列阵光束与一束高斯光束具有相同角扩展的条件。研究表明:相干合成的ChG列阵光束的角扩展比非相干合成的小,但是,非相干合成的ChG列阵光束的角扩展受湍流影响比相干合成ChG光束小;相干合成情况下,ChG列阵光束的角扩展随离心参数、束腰宽度和相对子光束间距的变化均出现振荡,但在湍流中的振荡减弱,非相干合成情况下,ChG列阵光束的角扩展与相对子光束间距和光束数无关。     

高功率准分子激光系统光学设计

回顾并介绍了高功率准分子激光系统设计中需要综合考虑的两项主要技术——像传递技术和角多路技术。讨论了照明方式和激光振荡源的光束整形在激光系统成像光路设计中的重要作用,对多路放大技术及角多路放大技术形式进行了系统分析。多路激光非相干合束是角多路技术和成像技术对高功率准分子激光系统光学设计提出的特殊要求,在简要分析了透射阵列和反射式望远物镜两种实现多路激光合束的打靶光学系统基础上,提出了一种利用反射式打靶光学系统和一套光学延迟线阵列来同时实现角多路编码和解码的新型光路布局,给出了初步设计方案。     

Statistical inference and modelling of momentum in stock prices

The following results are obtained, (i) It is possible to obtain a time series of market data {y(t)} in which the fluctuations in fundamental value have been compensated for. An objective test of the efficient market hypothesis (EMH), which would predict random correlations about a constant value, is thereby possible, (ii) A time series procedure can be used to determine the extent to which the differences in the data and the moving averages are significant. This provides a model of the form y(t)-y(t-l)=0.5{y(t- l)-y(t-2)}+ε(t)+0.8ε(r-1) where ε(t) is the error at time t, and the coefficients 0.5 and 0.8 are determined from the data. One concludes that today's price is not a random perturbation from yesterday's; rather, yesterday's rate of change is a significant predictor of today's rate of change. This confirms the concept of momentum that is crucial to market participants. (iii) The model provides out-of-sample predictions that can be tested statistically. (iv) The model and coefficients obtained in this way can be used to make predictions on laboratory experiments to establish an objective and quantitative link between the experiments and the market data. These methods circumvent the central difficulty in testing market data, namely, that changes in fundamentals obscure intrinsic trends and autocorrelations. This procedure is implemented by considering the ratio of two similar funds (Germany and Future Germany) with the same manager and performing a set of statistical tests that have excluded fluctuations in fundamental factors. For the entire data of the first 1149 days beginning with the introduction of the latter fund, a standard runs test indicates that the data is 29 standard deviations away from that which would be expected under a hypothesis of random fluctuations about the fundamental value. This and other tests provide strong evidence against the efficient market hypothesis and in favour of autocorrelations in the data. An ARIMA time series finds strong evidence (9.6 and 21.6 standard deviations in the two coefficients) that the data is described by a model that involves the first difference, indicating that momentum is the significant factor. The first quarter's data is used to make out-of-sample predictions for the second quarter with results that are significant to 3 standard deviations. Finally, the ARIMA model and coefficients are used to make predictions on laboratory experiments of Porter and Smith in which the intrinsic value is clear. The model's forecasts are decidedly more accurate than that of the null hypothesis of random fluctuations about the fundamental value.     

Spin–Orbit Charge-Transfer Intersystem Crossing (ISC) in Compact Electron Donor–Acceptor Dyads: ISC Mechanism and Application as Novel and Potent Photodynamic Therapy Reagents

Spin–orbit charge-transfer intersystem crossing (SOCT-ISC) is useful for the preparation of heavy atom-free triplet photosensitisers (PSs). Herein, a series of perylene-Bodipy compact electron donor/acceptor dyads showing efficient SOCT-ISC is prepared. The photophysical properties of the dyads were studied with steady-state and time-resolved spectroscopies. Efficient triplet state formation (quantum yield Φ_T=60 %) was observed, with a triplet state lifetime (τ_T=436 μs) much longer than that accessed with the conventional heavy atom effect (τ_T=62 μs). The SOCT-ISC mechanism was unambiguously confirmed by direct excitation of the charge transfer (CT) absorption band by using nanosecond transient absorption spectroscopy and time-resolved electron paramagnetic resonance (TREPR) spectroscopy. The factors affecting the SOCT-ISC efficiency include the geometry, the potential energy surface of the torsion, the spin density for the atoms of the linker, solvent polarity, and the energy matching of the ¹CT/³LE states. Remarkably, these heavy atom-free triplet PSs were demonstrated as a new type of efficient photodynamic therapy (PDT) reagents (phototoxicity, EC₅₀=75 nm ), with a negligible dark toxicity (EC₅₀=78.1 μm ) compared with the conventional heavy atom PSs (dark toxicity, EC₅₀=6.0 μm, light toxicity, EC₅₀=4.0 nm ). This study provides in-depth understanding of the SOCT-ISC, unveils the design principles of triplet PSs based on SOCT-ISC, and underlines their application as a new generation of potent PDT reagents.