锗酸盐晶体压致非晶化的研究

高压拉曼散射研究表明．ＣｕＧｅＯ３，Ｌｉ２ＧｅＯ３和Ｌｉ６Ｇｅ２Ｏ７三种晶体分别在７，１２和１１ＧＰａ压力下转变为非晶。在高于起始转变压力以上一定范围压致非晶是可逆的，ＣｕＧｅＯ３，Ｌｉ２ＧｅＯ３和Ｌｉ６Ｇｅ２Ｏ７压致非晶的不可逆转变压力分别为１４．１，２０和２０ＧＰａ。压致非晶ＣｕＧｅＯ３的重新晶化温度在６００℃附近。锗酸及系列晶体的压致非晶化与它们的成份和结构有关，随着在这一系列晶体中Ｌｉ２Ｏ含量的增加，压致非晶化的压力趋于减小。     

受激布里渊散射相位共轭效应数值解

本文从联立麦克斯韦方程和介质的声振动方程出发，在缓变振幅近似及小信号近似下得到耦合波振幅方程，以丙酮（Ｃ＿３Ｈ＿６Ｏ）为ＳＢＳ介质，利用计算机进行了受激布里渊散射相位共轭效应数值求解，得到ＳＢＳ阈值、饱和效应及二维情况下的ＳＢＳ相位共轭效应。理论计算表明，在小信号情况下受激布里渊散射具有良好的相位共轭效果。     

β-C_3N_4的制备及若干问题探讨

采用热丝辅助反应溅射和等离子体增强热丝化学气相沉积（ＣＶＤ）的制备方法，获得了含有β－Ｃ３Ｎ４结晶相的ＣＮｘ薄膜．文章将重点介绍制备参数与ＣＮｘ薄膜结构的关系，并进一步讨论与β－Ｃ３Ｎ４结晶相择优生长有关的主要问题     

γ－Fe_2SiO_4在静水压下的压缩行为的测定

采用同步辐射高压原位Ｘ光衍射技术及金刚石对顶压砧高压装置，对γ－Ｆｅ＿２ＳｉＯ＿４进行了静水压条件下等温压缩行为的测定，最高压力达２３ＧＰａ。γ－Ｆｅ＿２ｓｉＯ＿４在０～２３ＧＰａ压力范围内的ｐ、Ｖ数据表明，其等温压缩可分为两个阶段：若设Ｋ＇＿０＝４，在０～１８Ｇｐａ，Ｋ＿０＝１８９±２ＧＰａ；而在１８～２３０Ｐａ，Ｋ＿０＝２１３±２ＧＰａ。我们认为，样品在１８ＧＰａ以下处于较好的静水压状态，压力超过１８ＧＰａ，传压介质的静水压性质变坏，所以Ｋ＿０值偏高。在整个实验过程中并未发现样品有任何发生相变的迹象。最后，对一些虽然使用了液体介质但得不到静水压条件的实验现象进行了讨论。     

自发有序Ga_（0．5）In_（0．5）P合金的喇曼光谱研究

在室温和非共振条件下测量了自发有序Ｇａ０．５Ｉｎ０．５Ｐ合金的喇曼散射谱。测得的３８０，３６０和３３０ｃｍ－１附近的三个散射峰分别归结于合金中的类ＧａＰ的ＬＯ模、类ＩｎＰ的ＬＯ模和ＴＯＭ。发现有序合金的类ＧａＰ的ＬＯ模的声子频率随着合金的带隙能量的降低而增大。认为这与在有序合金中形成沿［１１１］方向的（ＧＳＰ）１／（ＩｎＰ）１单层超晶格有一定联系。在几种偏振配置下测得的有序合金的喇曼谱的偏振特性与通常的闪锌矿结构的半导体材料的偏振特性类似。     

测定核间距的不对称2D NOESY方法2．Cis－Pt（NH＿3）＿2（Guo）＿2Cl＿2的不对称2D NOESY实验研究

应用不对称２ＤＮＯＥＳＨＹ实验方法研究了顺铂配合物Ｃｉｓ－Ｐｔ（ＮＨ＿３）＿２（Ｇｕｏ）＿２Ｃｌ＿２的水溶液中的构象，表明鸟苷同铂配合后其糖环构象发生明显的变化。     

NO＿2ν＿2振动带的CO＿2激光磁共振垂直谱的观测

采用高灵敏度、高分辨率激光磁共振光谱（ＬＭＲ）方法，使用ＣＯ＿２激光器测量了分子ＮＯ＿２ｖ＿２振动带的垂直谱（ΔＭ＿Ｊ＝±１）．观测到了前人没有测过的新谱，在２２支激光谱线下新获得１００支塞曼（Ｚｅｅｍａｎ）跃迁谱线。     

CO_2焊接短路过渡过程的动态分析─短路液桥的动态变化与力学测算

ＣＯ＿２气体保护焊接是一种高效、节能和低成本的焊接方法，在钢结构焊接生产中得到了广泛的应用。但也存在着诸如：金属飞溅、焊缝成形较差等问题，要解决这些问题，必须首先对ＣＯ＿２焊接过程的电弧形态以及熔滴变化情况从理论上深入分析研究。本文以高速摄影与光线示波器同步进行拍摄，记录了ＣＯ＿２悍接短路过渡中熔滴的长大、缩颈、脱落的全过程以及相对应的电流电压波形。利用影片数据分析处理系统对所得影片及记录波形进行了分析处理，得到了熔滴过渡形成金属液桥爆断瞬间的最大电流值及所受合力的大小。从理论上更进一步研究了短路过渡的机理，建立了短路过渡的模型，这对正确调节焊接工艺规范，保证焊接质量具有重大的指导意义，研究结果表明：在常规短路过渡ＣＯ＿２焊接中，抑制飞溅是提高ＣＯ＿２焊接质量的关键，利用焊接规范来调节短路频率和短路峰值电流是抑制飞溅的主要途径。     

连续波化学氧碘激光器O_2（~1Δ_g）／Ⅰ_2最佳配比的理论分析与实验研究

通过对连续波ＣＯＩＬ小信号增益的分析得到，对连续波ＣＯＩＬ，Ｏ＿２（￣１Δ＿ｇ）／Ⅰ＿２存在最佳配比；实验结果表明：Ｏ＿２（￣１Δ＿ｇ）／Ⅰ＿２最佳配比约为５０～６０。通过建立一维预混模型，进一步研究了ＣＯＩＬ小信号增益以及—维空间分布依赖于Ｏ＿２（￣１Δ＿ｇ）／Ⅰ＿２配比的变化规律，当ｇ＿ｍＬ＿ｅ值依赖于Ｏ＿２（￣１Δ＿ｇ）／Ⅰ＿２配比（约４０～６０）而取极大值时，ＣＯＩＬ系统处于最佳工作状态。     

脉冲Ti~（3＋）：Al_2O_3激光器的增益长度

脉冲激光束纵向泵浦Ｔｉ￣（３＋）：Ａｌ＿２Ｏ＿３晶体，根据晶体中增益区的分布情况和脉冲运转的特点，从获取高转换效率考虑，可用“损耗平衡”确定晶体长度。单纵向泵浦时晶体的长度１由式选取。式中α＿ｐ是晶体对泵浦光的吸收系数，β是ＦＯＭ值。双纵向泵浦时，“损耗平衡”表示为：是晶体长度。根据实际光路的调整状态，设双纵向泵浦参数基本对称，对高α＿ｐ晶体取Ｌ＝１．５ｌ。若α＿ｐ较低，且泵浦参数并不对称，则Ｌ在ｌ＜Ｌ＜１．５ｌ范围内取值。这一方法与实验系统运转情况相符。     

Grand canonical Monte Carlo simulations of phase equilibria of pure silicon tetrachloride and its binary mixture with carbon dioxide

Grand canonical histogram-reweighting Monte Carlo simulations were used to obtain the phase behaviour of pure silicon tetrachloride and its binary mixture with carbon dioxide. Two new potential models for pure silicon tetrachloride were developed and parametrized to the vapour-liquid coexistence properties. The first model, with one exponential-6 site and fixed electrostatic charges on atoms, does not adequately reproduce the experimental phase behaviour due to its inability to represent orientational anisotropy in the liquid phase. The second potential model, with five exponential-6 sites for the repulsive and dispersive interactions plus partial charges, accurately reproduces experimental saturated liquid and vapour densities as well as vapour pressures and the second virial coefficient for pure silicon tetrachloride. This model was used in simulations of the phase behaviour of the binary mixture carbon dioxide-silicon tetrachloride. Two sets of combining rules (Lorentz-Berthelot and Kong [1973, J. chem. Phys., 59, 2464]) were used to obtain unlike-pair potential parameters. For the binary system, the predicted phase diagram is in good agreement with experiment when the Kong combining rules are used. The Lorentz-Berthelot rules significantly overestimate the solubility of carbon dioxide in silicon tetrachloride.     

IR spectra of carbon-vacancy clusters in the topochemical transformation of silicon into silicon carbide

Using infrared (IR) spectroscopy and spectral ellipsometry, we experimentally confirmed the previously predicted mechanochemical effect of the stoichiometric composition disorder leading to the formation of carbon-vacancy structures in silicon carbide (SiC) films grown on silicon substrates by the atom substitution method. It was found that a band at 960 cm^–1 in the IR spectra of SiC films on silicon, corresponding to “carbon-vacancy clusters” is always present in SiC films grown under pure carbon monoxide (CO) or in a mixture of CO with silane (SiH₄) on Si substrates of different orientation and doping level and type. There is no absorption band in the region of 960 cm–1 in the IR spectra of SiC films synthesized at the optimum ratio of the CO and trichlorosilane (SiHCl₃) gas pressures. The previously predicted mechanism of the chemical reaction of substitution of Si atoms for carbon by the interaction of gases CO and SiHCl₃ on the surface of the silicon substrate, which leads to the formation of epitaxial layers of single-crystal SiC, is experimentally confirmed.     

Ultrahigh infrared normal spectral emissivity of microstructured silicon coating Au film

We studied infrared normal spectral emissivity on quasi-periodic microstructured silicon, which was prepared by femtosecond laser irradiation in SF6 ambient gas, coated with 100 nm thick Au thin film. The observed emissivity is higher than any reported previously for a flat material with a thickness of less than 0.5 mm, at a temperature range of 200 °C to 400 °C. The emissivity over the measured wavelength region increases with temperature and the spike height. These results show the potential to be used as a flat blackbody source or for applications in infrared thermal sensor, detector, and stealth military technology.     

一种经济简便的红外密封池的研制

用红外光谱法测定精四氯化钛的杂质的关键是要有一个密封性能良好、液池厚度适合、便于清洗又能反复使用的密封池。为此，针对四氯化钛极易水解的特性我们设计了一种能满足上述要求的密封池及一个简易的装样装置，满足了定量和半定量测定精四氯化钛中某些杂质的要求，使得监控四氯化铁的质量方便易行。     

Using liquid and solid state NMR and photoluminescence to study the synthesis and solubility properties of amine capped silicon nanoparticles

Water soluble silicon nanoparticles were prepared by the reaction of bromine terminated silicon nanoparticles with 3-(dimethylamino)propyl lithium and characterized with liquid and solid state nuclear magnetic resonance (NMR) and photoluminescence (PL) spectroscopies. The surface site dependent 29Si chemical shifts and the nuclear spin relaxation rates from an assortment of 1H-29Si heteronuclear solid state NMR experiments for the amine coated reaction product are consistent with both the 1H and 13C liquid state NMR results and routine transmission electron microscopy, ultra-violet/visible, and Fourier transform infrared measurements. PL was used to demonstrate the pH dependent solubility properties of the amine passivated silicon nanoparticles.     

基于近红外光谱技术的瓶装醋定性检测

采用近红外光谱直接对四种瓶装醋进行检测,并与比色皿检测方法获得的谱图进行了比较。结果发现,两种检测方法获得的谱图在近红外区域有明显差别,瓶装醋在1 480和1 900nm附近无吸收峰,而在1 660nm附近有一吸收峰,明显区别于比色皿检测获得的谱图;瓶装醋检测获得的吸光度最大值不超过4,而用比色皿所测值约为6,说明玻璃包装对其检测有一定的影响。本研究采用一阶导数法来消除此影响,并用主成分-神经网络方法建立了瓶装醋的定性分析模型,模型预测精度达到100%,表明一阶导数可以消除玻璃包装对瓶装醋近红外检测的影响,实现定性分析的目的。     

Physical mechanism of silicon ablation with long nanosecond laser pulses at 1064 nm through time-resolved observation

Nanosecond (ns) laser ablation can provide a competitive solution for silicon micromachining in many applications. However, most of the previous studies focus on ns lasers at visible or ultraviolet (UV) wavelengths. The research is very limited for ns lasers at infrared (e.g., 1064 nm) wavelengths (which often have the advantage of much lower cost per unit average output power), and the research is even less if the ns laser also has a long pulse duration on the order of ∼100 ns. In this paper, time-resolved observation using an ICCD (intensified charge-coupled device) camera has been performed to understand the physical mechanism of silicon ablation by 200-ns and 1064-nm laser pulses. This kind of work has been rarely reported in the literature. The research shows that for the studied conditions, material removal in laser silicon ablation is realized through surface vaporization followed by liquid ejection that occurs at a delay time of around 200-300 ns. The propagation speed is on the order of ∼1000 m/s for laser-induced plasma (ionized vapor) front, while it is on the order of ∼100 m/s or smaller for the front of ejected liquid. It has also been found that the liquid ejection is very unlikely due to phase explosion, and its exact underlying physical mechanism requires further investigations.     

Infrared absorption spectrum of neutral magnesium donors in silicon

The infrared absorption spectrum of neutral magnesium donor impurities in silicon has been investigated under the high resolution of a Fourier-transform infrared spectrometer. The absorption spectrum measured at liquid helium temperature are observed to be clearly better than those reported earlier in the literature. Several new lines corresponding to excitation from ground state to higher excited states have been observed and identified.     

多孔硅量子点的受激辐射：陷阱态的作用

 经激光辐照和高温退火后能够在硅基上生成氧化多孔硅结构。用514 nm的激光泵浦,观测到该多孔硅的受激辐射。当激励强度超过阈值时,在650～750 nm区域有很强的受激发光峰。这些受激发光峰的半高宽小于0.5 nm。激光辐照和高温退火后,在样品上能形成某些特殊的氧化结构。在傅里叶红外光谱分析中,显示有硅氧双键或硅氧桥键在硅表面形成。计算结果表明：当硅氧双键或硅氧桥键形成时,电子的陷阱态出现在纳晶硅的带隙中。价带顶和陷阱态之间的粒子数反转是解释这种受激辐射的关键。     

10倍全球面红外变焦光学系统设计

针对320240像素非制冷红外焦平面探测器,设计了一个工作波段为3.7 m~4.8 m的红外变焦光学系统。该系统由6片全球面透镜组成,采用硅和锗两种常见的红外材料,F数为2.5,后工作距为20 mm,可以实现15 mm~150 mm范围内连续变焦。设计评价结果表明:光学系统在探测器奈奎斯特频率16 lp/mm处,变焦范围内全视场MTF大于0.6, 0.7视场MTF接近0.7,整体接近衍射极限。焦平面探测器敏感元能量集中度大于70%,具有大相对孔径、长工作距、全球面的特点。在-20 ℃~60 ℃温度范围内,成像质量满足设计要求。