激光诱导等离子体中电子密度随时间演化的实验研究

通过测定激光等离子体中镁原子和离子谱线Ｓｔａｒｋ展宽的时间演化特性．得到了激光诱导等离子体中电子密度的时间演化行为及其机理。     

Rydberg态Cs原子的Stark效应的实验研究

利用原子束装置，采用双束波长为λ１＝８５２．１ｎｍ和λ２＝５１０ｎｍ激光的两步激发，实验研究了Ｃｓ Ｒｙｄｂｅｒｇ态原子在外加电场为０～６００Ｖ／ｃｍ时的Ｓｔａｒｋ扇形图，观察到在外电场的作用下能级出现τ混合和ｎ混合的现象。     

高功率激光在铯金属蒸气中产生三阶谐波

讨论了在铯（Ｃｓ）原子蒸气中的光学三阶谐波的产生。理论分析表明，铯的非线性极化率系数Ｘ￣（３）（３ω）在λ＝１．０７９０μｍ处存在双光子共振增强效应，给出了为达到位相匹配所需的温度。实验获得了１．０７９０μｍ光波作用于Ｃｓ所产生的三阶谐波谱线（３５９．７ｕｍ）的照片。     

超晶格微带电子态随电场演化过程的电解液电反射谱研究

本文利用电解液电反射谱研究了Ｉｎ０．２Ｇａ０．８Ａｓ／ＧａＡｓ短周期超晶格中微带电子态随电场的演化过程，不仅清楚地观察到弱场Ｆｒａｎｚ－Ｋｅｌｄｙｓｈ效应和强场Ｗａｎｎｉｅｒ－Ｓｔａｒｋ局域化效应，而且观察到了从弱场过渡到强场过程中Ｆｒａｎｚ－Ｋｅｌｄｙｓｈ效应和Ｗａｎｎｉｅｒ－Ｓｔａｒｋ局域化效应互相竞争的现象．     

光致发光纳米晶粒硅薄膜的电子自旋共振研究

用电子自旋共振（ＥＳＲ）方法研究了含纳米晶粒：ａ－Ｓｉ：Ｈ薄膜的缺陷态．这种薄膜是用等离子体增强ＣＶＤ方法制备而成，未经任何后处理过程，在室温观察到可见光范围的光致发光．薄膜的ＥＳＲ谱由三个部分组成：（１）一对轴向对称超精细谱线，其ｇ∥＝１．９９６７，ｇ⊥＝２．００１６，其超精细常数为１．２×１０－２Ｔ；（２）一条各向同性谱线，其ｇ＝２．００５２．线宽△Ｈｐｐ＝１×１０－３Ｔ；（３）一条轴向对称谱线，其ｇ∥＝２．００５７，ｇ⊥＝２．００４２．以上三部分分别来源于三个不同的顺磁中心本文分析了它们的产生，     

GaAs／AlGaAs MQW 子带吸收及其 Stark 效应的理论与实验研究

本文采用Ｋｒｏｎｉｇ－Ｐｅｎｎｅｙ模型及无限深势阶等效法对方势阶结构的子带能级及其Ｓｔａｒｋ效应进行了理论推导和数值计算，并与其它近似法作了比较．实验上，研究了ＧａＡｓ／ＡｌＧａＡｓ方阶结构的子带吸收及其Ｓｔａｒｋ效应，分析了实验结果．     

短周期GaAs／AlAs超晶格的光频介电函数谱理论的实验检验

我们制备了Ｍ＝２，４，６和１０的一系列短周期（ＧａＡｓ）Ｍ／（ＡｌＡｓ）Ｍ厂超晶格样品并测量了其椭偏光谱．对这些样品的光频介电函数港进行了分析，并与夏建白等的理论计算结果作了直接比较上述理论计算是对Ｍ＝４，６和１０的超晶格样品作出的，并给出相应的介电函数谱曲线．在光子能量３．５～４．５ｅＶ范围的Ｅ１峰与瓦峰附近的实验谱的主要特征，与理论计算结果相一致实验谱中的Ｅ１峰比理论谱要强些，不同Ｍ值的超晶格样品之间的Ｅ１峰之差异也大于理论结果。     

弯波导吸收区结构1．3μm InGaAsP／InP超辐射发光二极管的设计

本文用束传播方法（ＢＰＭ）设计了具有弯曲波导吸收区结构１．３μｍＩｎＧａＡｓＰ／ＩｎＰ超辐射发光二极管（ＳＬＤ），分析了不同吸收区长度Ｌａ和弯曲的曲率半径Ｒ对ＳＬＤ特性的影响，给出了直观的结果，并进行了优化设计。在假定吸收区后端面反射率为１，和忽略吸收区内的吸收损耗的条件下，取ｄ＝０．２μｍ，ｗ＝２μｍ，Ｌｐ＝４００μｍ，Ｌａ＝２００μｍ，Ｒ＝５００μｍ，Ｉ＝２００ｍＡ，经吸收区反射耦合回有源区内的光与有源区前端面入射光的强度比率仅为９．５×１０－３。     

用于1．2μmCMOS70MS／sADC阵列中的一种10位5MS／s逐次逼近ADC单元

用于１．２μｍＣＭＯＳ７０ＭＳ／ｓＡＤＣ阵列中的一种１０位５ＭＳ／ｓ逐次逼近ＡＤＣ单元＝Ａ１０－ｂｉｔ５ＭＳ／ｓｓｕｃｃｅｓｓｉｖｅａｐｐｒｏｘｉｍａｔｉｏｎＡＤＣｃｅｌｌｕｓｅｄｉｎａ７０ＭＳ／ｓＡＤＣａｒｒａｙｉｎ１．２μｍＣＭＯＳ［刊，英］／Ｙ...     

LPE法在Si衬底上生长SiGe层的方法及电子特性的研究

本文介绍了在电阻率为（７７～３００）ｋΩ·ｃｍ的ｎ型（１１１）Ｓｉ衬底上用ＬＰＥ法生长高质量Ｓｉ１－ＸＧｅｘ单晶薄层（其厚度一般为１～３μｍ）的生长条件，并对引入的缺陷进行了ＴＥＭ研究，结果表明其缺陷密度和用ＭＢＥ及超高真空ＣＶＤ法生长的同样厚度和组分的Ｓｉ１－ｘＧｅｘ薄层的缺陷密度相等甚至更低．霍尔迁移率μＨ与温度有μＨ∝Ｔｍ的关系，（在Ｔ＝８０～３００Ｋ时，ｍ＝－０．９５）．当ｘ＞０．８５时，μＨ的测量值和由Ｋｒｉｓｈｎａｍｕｒｔｈｙ计算的理论值相符，ｘ＜０．８５，测量值仅为理论值的７０％．由Ｂｉ杂质     

Assigment of the CH2F2laser lines associated with the 9R(34) CO2pumping transition

Two new submillimeter laser transitions are reported for CH2F2optically pumped by the 9R(34) CO2line. The new transitions allow us to assign molecular transitions to the complete group of laser lines observed with that pump transition.     

非线性定标方法在炉渣成分分析中的应用

采用激光诱导击穿光谱技术对炉渣中的Ca、Mg含量进行了定量分析。由于炉渣成分复杂,建立的一元回归关系式往往得不到理想的结果,这时需要考虑多个自变量的回归分析问题。为了分析炉渣中Ca、Mg元素的含量,将炉渣中Mg、Ca、Fe、Si、Al的原子谱线强度以及Mg、Ca的离子谱线强度作为输入向量。由于不同谱线强度相差过大时,会使在计算出的权重系数中,不同谱线所占的比重大不相同。为了消除不同谱线强度差距过大的影响,对光谱强度进行标准化处理,把所有谱线强度的值放在了一个相似的范围。综合对比分析了非线性多元函数定标、BP神经网络定标以及径向基网络（RBF神经网络）定标在炉渣成分分析中的作用,并重点分析了RBF神经网络定标相对于传统非线性定标方法的优势。     

SiC改性Mg_2SiO_4陶瓷微波衰减性能的研究

采用热压烧结工艺在1500℃下保温1h,制备了SiC改性Mg_2SiO_4陶瓷,研究了SiC添加量对Mg_2SiO_4陶瓷烧结性能、显微结构及微波衰减性能的影响。初步探讨了该Mg_2SiO_4陶瓷的微波衰减机制。结果表明:当SiC质量分数从0增加到10%,Mg_2SiO_4陶瓷的表观气孔率逐渐增大,烧结性能下降;Mg_2SiO_4陶瓷的谐振频率随之向低频移动,谐振吸收峰的峰值逐渐减小,有效衰减带宽增大。电阻损耗和介质损耗是Mg_2SiO_4陶瓷主要的微波衰减机制。     

Diode laser measurements of line strengths and collisional half-widths in thev 2band of14NH3 and15NH3

A tunable diode laser spectrometer was used to perform measurements of half-widths and intensities of several rotational lines in v₂-band of ammonia. The intensity measurements of 16 lines of¹⁵NH₃ allowed us to estimate v₂-band strength of this molecule at 298 K to be S_v ⁰=(550±10) cm^?2-atm^?1.     

Effect of site-selective substitution in bulk superconducting Tl2Ba2CaCu2O8

Magnetization measurements were carried out on bulk Tl₂Ba₂CaCu₂O₈ (referred to as Tl-2212) and on various site-selective substituted Tl-2212 samples. At 5K between 0 and 4.5 T, the 5 at. % Mg-doped Tl-2212 (Tl,Mg-2212) samples displayed enhanced pinning as demonstrated by a field dependent increase of the magnetic critical-current density J_c by 18 to 25 percent over that of pristine Tl-2212. Excess Mg (10–15 at. %), however, is deleterious. Rietveld refinement of the x-ray diffraction pattern showed Mg on the Tl sites. Auger electron spectroscopy analysis showed part of the Mg on grain boundaries. The flux-creep activation energies are higher for flux expulsion than for flux penetration in both Tl-2212 and Tl,Mg-2212 samples; the latter displays higher individual values. Our results demonstrate an increase in the number density of flux lines as a result of increased density of atomic-size-structural, defects by Mg (5 at. %) doping. In the Tl_2−yBa₂(Ca_1−zY_z)Cu₂O_8−x(z=0–0.3; single phase; x and y represent oxygen and thallium vacancies) system also studied, the T_c decreases as z increases. At z=0.3, the sample becomes an antiferromagnetic semiconductor.     

Dual‐Salt Mg‐Based Batteries with Conversion Cathodes

Mg batteries as the most typical multivalent batteries are attracting increasing attention because of resource abundance, high volumetric energy density, and smooth plating/stripping of Mg anodes. However, current limitations for the progress of Mg batteries come from the lack of high voltage electrolytes and fast Mg‐insertable structure prototypes. In order to improve their energy or power density, hybrid systems combining Li‐driven cathode reaction with Mg anode process appear to be a potential solution by bypassing the aforementioned limitations. Here, FeS _x (x = 1 or 2) is employed as conversion cathode with 2–4 electron transfers to achieve a maximum energy density close to 400 Wh kg^?1, which is comparable with that of Li‐ion batteries but without serious dendrite growth and polysulphide dissolution. In situ formation of solid electrolyte interfaces on both sulfide and Mg electrodes is likely responsible for long‐life cycling and suppression of S‐species passivation at Mg anodes. Without any decoration on the cathode, electrolyte additive, or anode protection, a reversible capacity of more than 200 mAh g^?1 is still preserved for Mg/FeS₂ after 200 cycles.     

半化学法制备钨镁酸铅-钛酸铅陶瓷

采用半化学法制备了纯钙钛矿结构的0.50 Pb(Mg1/2W1/2)O3-0.50 PbTiO3 (0.50 PMW-0.50 PT)陶瓷。以醋酸镁代替传统氧化物混合法中的MgO,提高了MgO的分散性和反应活性,能够有效地促进钙钛矿相0.50 PMW-0.50 PT的形成和抑制钨酸铅的存在。随着预烧温度的提高,0.50 PMW-0.5 0PT粉体的钙钛矿相含量增加,当预烧温度为850℃和保温时间为2 h时其钙钛矿含量达到100%;随着烧结温度的提高,0.50PMW-50PT陶瓷的晶粒尺寸增大,而陶瓷的介电常数先增大后减小,介电损耗先减小后稍微增大。0.50 PMW-0.50 PT陶瓷的最佳烧结条件为1 050℃,2 h,最大相对介电常数为7 606。     

铸态Mg96Zn3Y1合金高温热处理显微结构的电子显微研究

本文应用扫描背散射电子(SEM-BSE)像和透射电子显微(TEM)像观察的方法,研究了铸态Mg96Zn3Y1(at.％)合金经过500℃高温热处理后显微组织结构的变化.结果表明铸态Mg96Zn3Y1(at.％)合金中的初生相为网格状形貌,其中多数为面心立方W(Mg3Zn3Y2)相,少数为二十面体准晶Ⅰ(Mg3Zn6Y)...     

Low-Temperature Midinfrared Absorption in GaSe

We report the measurement of the temperature dependence of the absorption spectra of ε- GaSe over the temperature range 300 K to 5 K. Measurements have been made for both the e-ray (polarized parallel to the crystal’s c-axis) and the o-ray (polarized perpendicular to the c-axis), over the spectral range 4000 to 10 cm^?1. Nine absorption lines at 417, 440, 499, 546, 891, 945, 1015, 1093, 1270 cm^?1 were recorded at 300 K for the e- ray spectra. Some of these lines were identified using the results of a modified single layer, linear chain model of GaSe. The lines at 417, 440 and 499 cm^?1 were assigned to local impurity absorption originating from N, Mg and O, respectively. The weak lines at 945, 1015 and 1093 cm^?1 were assigned to hole transitions from the acceptor levels to the top of the valence band. Two absorption lines at 891 cm^?1 and 1270 cm^?1 were assigned to hole transitions from the quasi-local acceptor levels to the double degenerate valence sub-bands Γ₅ or Γ₆. The origin of lines recorded in the far IR absorption spectra at 20, 37 cm^?1 and 362 cm^?1 were also identified.     

Mg:Er:LiNbO3晶体的激光性能和550nm寿命特性研究

本文采用Czchrzlski技术生长出优质的Mg:Er:LiNbO3[(X=2%, 4%, 6%, 8%, y=% （mol%）)]晶体,测试Mg:Er:LiNbO3晶体的光损伤阈值,红外光谱和紫外—可见吸收光谱,Mg2+浓度增加抗光损伤能力增加,其中Mg(6mol%):Er:LiNbO3和Mg(8mol%):Er:LiNbO3晶体抗光损伤阈值比LiNbO3晶体提高二个数量级以上。它们的红外光谱OH-吸收峰移到3535cm-1附近。Mg:Er:LiNbO3晶体中随着Mg2+浓度增加吸收边紫移程度增大。研究Mg:Er:LiNbO3晶体抗光损伤阈值增强机理,OH-吸收峰移动机理和吸收边移动机理。采用0.523μm激光进行泵浦获得高的利用率。在波长510—580nm范围内得到Mg:Er:LiNbO3晶体稳态发射谱。掺进4mol%的MgO是Mg:Er:LiNbO3晶体寿命最长的晶体。