多通道反应O(3P)＋CH2F的理论研究

用密度泛函理论研究了氧原子与氟代甲基自由基的反应.反应中出现的所有物种的平衡构型用B3LYP方法在6-311＋＋G（2d, 2p）基组水平上进行了优化，同时对各物种进行了频率分析；在同一理论水平上计算了各反应通道的势能面变化，分析了反应物、中间体、过渡态、产物的振动模式随反应途径的变化关系，阐明了该多通道反应的反应机理.     

多孔硅镶嵌C102的蓝绿发光特性

利用多孔硅(PS)独特的微孔结构、非常大的比表面积、很强的吸附能力和灵敏的表面光学性质等特点,将激光染料香豆素102(C102)镶嵌在多孔硅中,得到多孔硅镶嵌C102的复合膜。研究复合膜的荧光特性,我们发现：镶嵌在多孔硅中的C102荧光光谱与其在无水乙醇溶液中的荧光光谱相似,主要呈现单体发光特性;通过比较镶嵌在不同孔隙率中的C102荧光光谱,得知镶嵌在不同多孔硅中的染料分子主要以同种形式存在。另外还发现,放置一段时间后的镶嵌复合膜,荧光强度明显增强,对称性提高,保留了激光染料发光的很多优点。多孔硅镶嵌C102的荧光特性展示了多孔硅在发展固体激光器方面有一定的应用,并为实现硅基蓝绿发光打开新的途径。     

铜掺杂多孔硅的光致荧光猝灭

采用浸泡镀敷的方法在多孔硅表面形成了一铜镀层,通过对掺铜前后多孔硅的光致发光(PL)谱和傅里叶变换红外(FTIR)吸收光谱的研究,讨论了铜在多孔硅表面的吸附对其光致发光的影响。实验表明,掺铜对多孔硅的光致发光具有明显的猝灭效应,并使多孔硅的发光峰位蓝移。由于多孔硅表面铜的吸附使硅-氢键明显减少,而铜原子和硅的悬挂键成键会形成新的非辐射复合中心,从而使多孔硅的光致发光强度衰减。且浸泡溶液的浓度越高,这种猝灭效应越明显。而多孔硅发光峰位的蓝移,则是由于在发生金属淀积的同时伴随着多孔硅表面Si的氧化过程(纳米Si氧化为SiO2)的缘故。     

Intersubband absorption with difference-frequency generation in GaAs asymmetric quantum wells

An asymmetric quantum well(AQW) is designed to emit terahertz(THz) waves by using difference frequency generation(DFG) with the structure of GaAs/Al 0.2 Ga 0.8 As/Al 0.5 Ga 0.5 As.The characteristics of absorption coefficients are analysed under the parabolic and non-parabolic energy-band conditions in detail.We find that the absorption coefficients vary with the two pump optical intensities,and they reach the maxima when the pump wavelengths are given as λ p1 = 9.70 μm and λ p2 = 10.64 μm,respectively.Compared with non-parabolic conditions,the total absorption coefficient under parabolic conditions shows a blue shift,which is due to the increase in the energy difference between the ground and excited states.By adjusting the two pump optical intensities,the wave vector phase-matching condition inside the AQW is satisfied.     

Rh6G/氧化多孔硅复合膜的荧光光谱

为了发展性能良好的固体染料激光器,多孔介质中镶嵌激光染料是一种可行的途径。将氧化多孔硅作为基质材料,通过浸泡的方式将激光染料Rh6G嵌入其中,形成Rh6G/氧化多孔硅复合膜,对比研究了Rh6G在无水乙醇、多孔硅、多孔氧化硅中的荧光特性。结果表明,经高温氧化后,氧化多孔硅透明度提高,其荧光强度明显变弱,在复合膜中已检测不到其荧光行为。相比于在无水乙醇溶液中,在氧化多孔硅中Rh6G发射光谱的半峰全宽有所展宽,峰值波长略有红移,对称性大为提高,具有类似单体发光特性,这种现象与纳米孔对Rh6G的聚集程度的限制有关。     

双波泵浦非对称量子阱的光学整流效应

为了实现基于光整流方式的室温下宽调谐高效率太赫兹源,设计了一种适于双波长CO2激光器共振子带跃迁泵浦的双阱嵌套形非对称量子阱结构,结构组分为Al0.5Ga0.5As/Ga As/Al0.2Ga0.8As,采用密度矩阵及迭代方法计算了其二阶非线性光整流系数χo(2)表达式,在导带为抛物线形和非抛物线形两种条件下对χo(2)进行对比研究。计算结果表明,其偶极跃迁矩阵元随量子阱总阱宽的增大而逐渐减小。当固定量子阱总阱宽及其中一束泵浦光波长不变时,χo(2)随着另一束泵浦光波长的增加,呈现出先增大后减小的变化趋势。当深阱为7 nm、总阱宽为23 nm、两束泵浦光相等为10.64μm时,χo(2)达到最大值5.925×10-6m/V;随着总阱宽的增大,χo(2)曲线呈现"红移"现象,其原因为量子限制效应导致了不同阱宽条件下的量子阱能级值差不同,从而造成满足泵浦光光子能量与能级差共振条件的变化。导带为抛物线形和非抛物线形两种条件下的χo(2)的最大值对应泵浦光波长基本相同,χo(2)数值上的差异主要由跃迁矩阵元的不同导致。     

太赫兹频段开口环谐振器的可调谐振模式转换

在硅衬底上设计了一种单开口环谐振器，对其太赫兹频段内的透射性质进行了研究。假定通过光注入方式改变衬底硅的电导率，实现了谐振环的双谐振透射率可调。将砷化镓材料生长于该谐振环的开口处，通过光注入方式改变砷化镓材料的电导率，可以实现谐振环的双频LC共振和偶极子共振模式与单频闭合环共振模式之间的转换。这种通过光注入改变半导体材料电导率的方法，可以在不破坏原来谐振器件物理结构的前提下，实现谐振环谐振模式的可逆转换。     

《勾股定理》课堂诊断,反思教与学的成长

本学期我有幸成为省级初中数学骨干教师培训班的一员,并积极承担了一节公开课,旨在锻炼、提升自我.课题为苏科版八年级数学上册第二章第一节《勾股定理》,内容为第1课时——勾股定理.课堂诊断我们的课上下来,先是开课教师说课、谈得失,然后学员交流,专家再逐一点评.笔者认为自己的课并不成功:前松后紧,节奏欠佳,学生探究不充分,认知过程存在脱节,学生的主体性体现不够,反馈不足等.接下来结合大家的意见和建议,诊断如下:一、教学目标从目标制定上看能体现三维目标,但     

Tunable ultra-wideband terahertz filter based on three-dimensional arrays of H-shaped plasmonic crystals

A face-to-face system of double-layer three-dimensional arrays of H-shaped plasmonic crystals is proposed, and its transmission and filtering properties are investigated in the terahertz regime. Simulation results show that our design has excellent filtering properties. It has an ultra-wide bandgap and passband with steep band-edges, and the transmittance of the passband and the forbidden band are very close to 1 and 0, respectively. As the distance between the two face-to-face plates increases, the resonance frequency exhibits a gradual blueshift from 0.88 THz to 1.30 THz. Therefore, we can dynamically control the bandwidths of bandgap and passband by adding a piezoelectric ceramic plate between the two crystal plates. Furthermore, the dispersion relations of modes and electric field distributions are presented to analyze the generation mechanisms of bandgaps and to explain the location of bandgaps and the frequency shift phenomenon. Due to the fact that our design can provide many resonant modes, the bandwidth of the bandgaps can be greatly broadened. This paper can serve as a valuable reference for the design of terahertz functional devices and three-dimensional terahertz metamaterials.     

Tunable ultra-wideband terahertz filter based on three-dimensional arrays of H-shaped plasmonic crystalsTunable ultra-wideband terahertz filter based on three-dimensional arrays of H-shaped plasmonic crystalsTunable ultra-wideband terahertz filter based on three-dimensional arrays of H-shaped plasmonic crystals

A face-to-face system of double-layer three-dimensional arrays of H-shaped plasmonic crystals is proposed, and its transmission and filtering properties are investigated in the terahertz regime. Simulation results show that our design has excellent filtering properties. It has an ultra-wide bandgap and passband with steep band-edges, and the transmittance of the passband and the forbidden band are very close to I and 0, respectively. As the distance between the two face-to-face plates increases, the resonance frequency exhibits a gradual blueshift from 0.88 THz to 1.30 THz. Therefore, we can dynamically control the bandwidths of bandgap and passband by adding a piezoelectric ceramic plate between the two crystal plates. Furthermore, the dispersion relations of modes and electric field distributions are presented to analyze the generation mechanisms of bandgaps and to explain the location of bandgaps and the frequency shift phenomenon. Due to the fact that our design can provide many resonant modes, the bandwidth of the bandgaps can be greatly broadened. This paper can serve as a valuable reference for the design of terahertz functional devices and three-dimensional terahertz metamaterials.