光子晶体反常色散超窄带滤波理论

讨论了利用由反常色散材料构成的二维（2D）光子晶体(PCs)实现超窄带滤波（PCADOF）的原理，并对铯原子蒸气6P3/2←6S1/2谱线的反常色散曲线进行了研究，讨论利用此反常色散曲线通过2D PCs实现超窄带滤波的方法和特点，研究发现这种滤光器的带宽可达到0.002nm，这将为设计一种全新的滤波器提供指导. 关键词： 反常色散 光子晶体 超窄带滤波     

响应面法优化石油烃含量测定的前处理条件

红外光谱法被广泛应用于水体、土壤等样品中石油烃残留的检测,样品预处理是红外光谱法测定水产品中石油烃残留的关键步骤。本文通过响应面分析法,对鱼肉的皂化条件进行优化,建立了回归模型,优化后预处理条件如下:皂化温度30℃,皂化时间20h,6mol/LNaOH溶液16.5mL。在此条件下,鱼肉得到了较为完全的皂化,结合溶剂萃取、柱吸附处理,将红外光谱法成功应用于水产品中石油烃的残留检测。     

Electron field emission characteristics of nano-catkin carbon films deposited by electron cyclotron resonance microwave plasma chemical vapour deposition

This paper reported that the nano-catkin carbon films were prepared on Si substrates by means of electron cyclotron resonance microwave plasma chemical vapour deposition in a hydrogen and methane mixture. The surface morphology and the structure of the fabricated films were characterized by using scanning electron microscopes and Raman spectroscopy, respectively. The stable field emission properties with a low threshold field of 5V/μm corresponding to a current density of about 1μA/cm^2 and a current density of 3.2mA/cm^2 at an electric field of 10V/μm were obtained from the carbon film deposited at CH4 concentration of 8%. The mechanism that the threshold field decreased with the increase of the CH4 concentration and the high emission current appeared at the high CH4 concentration was explained by using the Fowler-Nordheim theory.     

Er3+/Yb3+共掺Gd3Sc2Ga3O12晶体的上转换发光

研究了提拉法生长的Er³⁺/Yb³⁺:Gd₃Sc₂Ga₃O₁₂和Er³⁺:Gd₃Sc₂Ga₃O₁₂晶体在室温下320—1700nm范围的吸收光谱和500—750nm范围内的上转换荧光谱,同时对其上转换荧光的可能发生机制、途径以及上转换过程可能对Er^{3+相似文献}   

超强激光超热电子激发的Kα X射线发射研究

建立了无色散型X射线谱仪. 利用SILEX-I激光装置的超强激光辐照固体物质，分别在靶前、后定量测量了Cu和Mo物质在不同激光功率密度时的X射线谱和Kα光子产额，推导了不同激光强度时的Kα X射线光子转换效率. 实验发现，打靶激光能量越高，靶后出射的Kα产额越高，100μm Mo靶可获得10^-5量级转换效率.     

卷云多角度偏振特性研究

由各种形状冰晶粒子组成的卷云,对全球辐射平衡和气候变化有重要的影响,其影响程度取决于卷云本身的微物理特性和光学特性,如冰晶粒子形状、卷云光学厚度和云顶压强等.在对0.865μm波长处卷云光学特性研究的基础上,采用矢量辐射传输方程模拟分析了含卷云层的总反射率和偏振反射率,并利用卫星观测数据验证了模拟结果.分析研究了卷云微物理特征、光学特征和地表反照率对总反射率和偏振反射率的影响.分析表明,可以综合利用多角度偏振遥感信息反演各种卷云参数.这为利用多角度偏振遥感数据反演卷云各参数提供了理论基础. 关键词： 卷云微物理特征 卷云光学特性 多角度偏振辐射 矢量辐射传输方程     

快冷Fe-Al合金中的原子缺陷弛豫

在多功能内耗仪上用自由衰减和强迫振动方法研究了不同Al含量淬火Fe-Al合金中的两个弛豫型内耗峰.结果显示：P1(180℃)和P2(340℃)两个内耗峰只出现在淬火样品的加热过程中，而在随后的冷却过程中不出现.P1峰是由在α和β(或γ)点阵上的空位组成的最近邻双空位偶极子在应力诱导下的重新取向产生的，其弛豫强度随Al含量非单调地变化，在大约25% Al(原子百分比，以下同)处出现最大值.Al含量较低的Fe-Al合金无     

地基高频加热激励ELF/VLF波对辐射带高能电子的准线性散射

地球内、外辐射带电子通量的变化对于空间飞行器,尤其是中低轨卫星的防护有着非常重要的影响.基于回旋共振波粒相互作用的准线性理论,使用地基高频发射器发射电波调制低电离层背景电流可以人工激励ELF/VLF波,这些波能使辐射带相对论电子发生抛射角散射沉降进入大气层从而降低其生存期.为了定量地分析人工激励ELF/VLF波散射辐射带高能粒子的可行性,针对内、外辐射带,本文选取了两个典型区域：L=4.6和L=1.5.数值计算结果表明,在内、外辐射带由于ELF/VLF波的人工注入而造成的高能电子损失时间尺度很大程度上取决于冷等离子体参量α^*(∝B²/N₀,这里B是背景磁场,N₀是电子数密度)、电波频谱特性和功率,以及与波发生回旋共振的电子能量.一般来讲,在外辐射带人工ELF/VLF哨声波散射相对论电子使之沉降到大气层要容易得多;低能量的高能电子(200keV)要比高能量的相对论电子(500keV)更有效地通过抛射角散射进入大气层.考虑到高频电波加热电离层激励的ELF/VLF波可能会被捕获在磁层空腔中,来回反射从而得到增强,因此在适当的条件下,地基高频加热装置发射足够的电波功率进入电离层诱导大幅度ELF/VLF波注入到内磁层,能够在1至3天的时间尺度内快速散射外辐射带相对论电子使之沉降,也能够在10天量级的时间尺度里散射生存周期一般为100天甚至更长的内辐射带相对论电子. 关键词： 地基高频加热电离层 ELF/VLF波激励 高能电子散射和沉降 共振波粒相互作用     

A scribing laser marking system using DSP controller

Laser marking is an important branch of laser processing technology, and has been widely used in many fields of industry. Digital signal processor (DSP) is an incredibly fast and powerful microprocessor that can deal with signals in real time. Not only it is portable but has the ability to integrate the processing signals of subsystems. In this research, it is emphasized that we designed a scribing laser marking system based on a DSP in galvanometric marking method. To control the rotating angle of the galvanometric scanning mirrors more accurately, we combine the D/A converter of the DSP with the human–machine interface successfully. The whole marking system is not only inexpensive, but also miniaturized.     

Raman spectroscopic study of ceramic Sr2Bi4Ti5O18

Raman spectra of ceramic Sr2Bi4Ti5O18 （SBTi5） are reported to consist of four different Raman bands. Temperature-dependent spectra reveal the relationship between the lattice vibration and the material＇s structure. There appears a relatively large change in structure of the material at about 273K, The anharmonic potential of the material has a great influence on its phonon mode full width at half maximum （FWHM）, which can be expressed by a function of temperature. Theoretical fittings of the FWHMs for the two modes at around 312 cm^-1 and 464cm^-1 indicate that the latter phonon mode is more anharmonic than the former one.