RbIO_3-HIO_3和CsIO_3-HIO_3两个赝二元系的研究

用X射线衍射及差热分析法研究了两系统的相平衡。确定了RbH_2(IO_3)_3的结构(三斜晶系,点阵常数:a=8.338,b=8.244,c=8.254,α=60.66°,β=85.58°,γ=66.01°,z=2)。密度D_m=4.61g/cm~3。CsIO_3-HIO_3系中有两个化合物:CsH(IO_3)_2(为质子导体)和3CsIO_3·17HIO_2。     

Phase transition and chemical decomposition of liquid carbon dioxide and nitrogen mixture under extreme conditions

Thermodynamic and chemical properties of liquid carbon dioxide and nitrogen(CO_(2~–)N_2) mixture under the conditions of extremely high densities and temperatures are studied by using quantum molecular dynamic(QMD) simulations based on density functional theory including dispersion corrections(DFT-D). We present equilibrium properties of liquid mixture for 112 separate density and temperature points, by selecting densities ranging from ρ = 1.80 g/cm~3 to 3.40 g/cm~3 and temperatures from T = 500 K to 8000 K. In the range of our study, the liquid CO_(2~–)N_2 mixture undergoes a continuous transition from molecular to atomic fluid state and liquid polymerization inferred from pair correlation functions(PCFs)and the distribution of various molecular components. The insulator–metal transition is demonstrated by means of the electronic density of states(DOS).     

O_2/CO_2气氛下不同密度煤粉燃烧特性研究

本文将大同烟煤分为低(1.4 g/cm~3)、中(1.4～2.0 g/cm~3)、高(2.0 g/cm~3)3个密度段,进行不同密度原煤的工业和元素分析,利用热重分析仪研究了O_2/N_2、O_2/CO_2气氛(不同氧气浓度下)各样品的燃烧特性,并开展了反应动力学分析。结果显示在O_2/CO_2气氛下,随煤粉密度增加,煤粉最大失重速率减小,最大放热速率减小,燃尽温度升高;提高氧气浓度可降低燃尽温度。与O_2/N_2气氛相比,在氧气浓度相同的条件下,各样品在O_2/CO_2气氛下的着火温度、燃尽温度、表观活化能均升高。     

利用类铜离子谱线诊断银等离子体电子密度

测量了激光加热块状银靶产生的等离子体XUV光谱.计算了T_e分别为65eV,86eV和130eV时,AgXIX4s-4P,4P-4d,4d-4f7条谱线在不同电子密度时的强度.根据AgXIX4d~2D_(s/2~-)4f~2F_(r/2)和4P~2P_(3/2)-4d~2D_(s/2)两条谱线的强度比,推导了激光银等离子体电子密度.当入射激光功率密度W为6×10~(12)W/cm~2时,银等离子体电子密度N_e=1×10~(20)/cm~3. 关键词：     

Mechanical,elastic, anisotropy,and electronic properties of monoclinic phase of m-Si_xGe_(3-x)N_4

The structural,mechanical,elastic anisotropic,and electronic properties of the monoclinic phase of m-Si_3N_4,mSi_2GeN_4,m-SiGe_2N_4,and m-Ge_3N_4are systematically investigated in this work.The calculated results of lattice parameters,elastic constants and elastic moduli of m-Si_3N_4and m-Ge_3N_4are in good agreement with previous theoretical results.Using the Voigt–Reuss–Hill method,elastic properties such as bulk modulus B and shear modulus G are investigated.The calculated ratio of B/G and Poisson’s ratio v show that only m-SiGe_2N_4should belong to a ductile material in nature.In addition,m-SiGe_2N_4possesses the largest anisotropic shear modulus,Young’s modulus,Poisson’s ratio,and percentage of elastic anisotropies for bulk modulus ABand shear modulus AG,and universal anisotropic index AUamong m-Si_xGe_(3-x)N_4(x=0,1,2,3.)The results of electronic band gap reveal that m-Si_3N_4,m-Si_2GeN_4,m-SiGe_2N_4,and m-Ge_3N_4 are all direct and wide band gap semiconducting materials.     

XeCl激光触发气体开关的实验研究

通过实验研究了在自流工作状态下,XeCl准分子激光(λ=308nm,FWHM=21ns)对N_2和SF_6两种气体开关的触发特性。实验结果表明:(1)在p=0.1MPa,开关工作电压90％V_(SB)(V_(SB)为开关的自击穿电压)时,XeCl激光对N_2和SF_6两种气体开关的触发阈值约为10~8W/cm~2。(2)开关的触发延时和抖动随着激光能量和开关欠压比的增大而减小,当激光能量为33.8mJ,开关工作电压90％V_(SB)(V(SB)=36.5kV)时,充N_2开关的延时和抖动分别为85.5ns和400ps。相同欠压比下,SF_6气体开关(V_(SB)=52kV)的最小抖动度为2ns。(3)SF_6气体开关的触发延时与用T.H.Martin公式计算的结果一致。     

该测哪些牛顿环

由牛顿环测透镜曲率半径R的公式是 R=(D_m~2-D_n~2)/(4(m-n)λ) (1) 式中m、n是环的表观序数,m>n,D_m、D_n是环径,λ是光源的波长。测牛顿环时该测哪些环呢?国内教材的一些说法是:有人研究过从哪一级环开始测量比较合理的问题,得出的结论是“要根据仪器条件决定”。一般认为,牛顿环中心附近的环宽度变化很大,不易测准。现在从误差分析来解决这个问题,以便使结论更科学、更合理。由(1)式 |ΔR|≤(D_m|ΔD_m|+D_n|ΔD_n|)/(2(m-n)λ)≤2r_m|△r_m|+2r_n|△r_n|/(m-n)λ即 |ΔR|≤(2(r_m|Δr_m|+r_n|Δr_n|))/((m-n)λ) (2) 牛顿环的光强度分布为 I=4I_0sin~2((πr~2)/(Rλ)) (3) 式中I_0为入射光的强度,r为牛顿环半径。I=0的r为暗环半径。取(3)中的I=0可得 r_k=(kRλ)~(1/2) k=0,1,2,3,…(4)     

Dependence of surface-enhanced Raman scattering from Calf thymus DNA on anions

Dependence of surface-enhanced Raman scattering (SERS) from Calf thymus DNA on anions is inves- tigated.With the silver colloid,the bands at 732,960 and 1333 cm~(-1) for adenine (A),1466 cm~(-1) for deoxyribose,and 1652 cm~(-1) for the C=O group of thymine (T) are observably enhanced.With the pres- ence of the C1 or SO~-anions,the bands at 732 and 1326/1329 cm-1 for the symmetric stretching and skeletal vibrational modes of adenine (A) are dramatically enhanced,and the enhancement effect with the SO_4~(2-) ion is more than that with the Cl~-ion.The experimental results show that the DNA molecule can be adsorbed on the silver colloid particles through the C_6N and N_7 of adenine (A),the C=O of thymine (T) and deoxyribose.Moreover,the formed hydrogen bonding of the Cl~-or SO_4~(2-) ions to the C_6NH_2 group of adenine (A) can induce larger C_6N electronegativity,which is favor for the C_6N/N_7 cooperative adsorption on the (Ag)_n~ colloid particles.     

N_2(B~3Ⅱ_g)高振动态在Xe原子中的碰撞激发和弛豫

在用双光子激发产生的Xe(5p~56p)原子与N_2分子碰撞过程中,有效地生成了N_2(B~3П_g,v=9～14)振动激发态.观察到相应的Δv=4的N_2(B~3П_g-A~3∑_u~+)辐射跃迁萤光,测量了Xe(6p)原子在N_2中的淬灭速率常数,对碰撞弛豫过程进行了讨论.     

Phase Transformation and Enhancing Electron Field Emission Properties in Microcrystalline Diamond Films Induced by Cu Ion Implantation and Rapid Annealing

Cu ion implantation and subsequent rapid annealing at 500℃in N_2 result in low surface resistivity of 1.611 ohm/sq with high mobility of 290 cm~2 V~(-1)S~(-1)for microcrystalline diamond(MCD)films.Its electrical field emission behavior can be turned on at E_0=2.6 V/μm,attaining a current density of 19.5μA/cm~2 at an applied field of 3.5 V/μm.Field emission scanning electron microscopy combined with Raman and x-ray photoelectron microscopy reveal that the formation of Cu nanoparticles in MCD films can catalytically convert the less conducting disorder/a-C phases into graphitic phases and can provoke the formation of nanographite in the films,forming conduction channels for electron transportation.     

PbBi_2Nb_2O_9的晶体结构

PbBi_2Nb_2O_9晶体属正交晶系,空间群为D_(2h)~(23)-Fmmm。晶胞参数为a=5.4806(7)A,b=5.4791(7)A,c=25.416(3)A,α=β=γ=90.0(0)°,V=763.2(2)A~3。单位晶胞内化学式数z=4,D_(obs)=7.91g/cm~3,D_x=8.26g/cm~3,μ(Mo,K_α)=678.38cm~(-1),F(000)=1608。用直接法(Multan-78程序)及Fourier方法测定了结构,对结构的原子位置参数、各向同性及各向异性热参数进行了块对角矩阵最小二乘方修正,R=0.107。Nb-O八面体为O_h→C_(4v)型畸变,处于八面体内的Nb原子沿4次轴方向与中心位置偏离0.225A,Nb-O八面体的畸变及Nb原子的这种偏离可能是PbBi_2Nb_2O_9晶体具有铁电性能的主要结构原因。     

5.33μm处磁旋转吸收光谱NO分子探测研究（英文）

本文基于直流磁场的磁旋转吸收光谱技术探测研究一氧化氮分子的痕量.使用5.33μm连续波量子级联激光器作为探测光源,结合C hernin型光学多通池,在1875.81 cm~(-1)(~2Π_(3/2)(3/2),v=1←0)波长处进行探测.108 m吸收光程下,实现了1.15 ppbv的探测极限(1s,1σ).当采样时间延长到15 s,探测极限可提高至0.43 ppbv.     

Compression behavior and phase transition of β-Si_3N_4 under high pressure

The compressibility and pressure-induced phase transition of β-Si_3N_4 were investigated by using an angle dispersive x-ray diffraction technique in a diamond anvil cell at room temperature. Rietveld refinements of the x-ray powder diffraction data verified that the hexagonal structure(with space group P63/m, Z = 2 formulas per unit cell) β-Si_3N_4 remained stable under high pressure up to 37 GPa. Upon increasing pressure, β-Si3 N4 transformed to δ-Si_3N_4 at about 41 GPa. The initial β-Si_3N_4 was recovered as the pressure was released to ambient pressure, implying that the observed pressureinduced phase transformation was reversible. The pressure–volume data of β-Si_3N_4 was fitted by the third-order Birch–Murnaghan equation of state, which yielded a bulk modulus K_0= 273(2) GPa with its pressure derivative K_0= 4(fixed)and K0= 278(2) GPa with K 0= 5. Furthermore, the compressibility of the unit cell axes(a and c-axes) for the β-Si_3N_4 demonstrated an anisotropic property with increasing pressure.     

理疗超声空化及其自由基的ESR检测

本文利用5,5-dimethy1-1-purrolinel-oxide(DMPO)自旋捕集剂及电子自旋共振(ESR)技术研究证明,理疗级超声辐照可在自然空气饱和的水溶液中导致OH及H自由基的形成。认为这是超声瞬态空化过程产生局部高温高压的结果。当超声辐照时间取3min时,发现超声阈值空化强度在0.537W/cm~2—0.632W/cm~2间。随着辐照声强的增加,OH自由基产量在声强为1W/cm~2—2W/cm~2间迅速增长,大约在3W/cm~2以上,产量将不再增加。OH产量D与辐照声强τ的关系可近似用拟合方程D=8.1I(1/2)1/2I(1/2)来描述。取声强一定时,OH产量随辐照时间呈单调增长趋势。     

改性的Pb(Mg1/3Nb2/3)O3-PbTiO3-PbZrO3陶瓷及其在超声实时显像线阵的应用

Ph(Mg_(1/3)Nb_(2/3)_(0.380)Ti_(0.360)Zr_(0.260)O_3中的Pb为6％mol的Ba所置换的晶片,比置换量为5％mol的Ba,有更优良的压电性和均匀性,其K_t=0.503,K_p=0.658,N_t=2050KC·mm,tgδ=2.5×10~(-3),ρ=7.8g/cm~3,ε_(33)~T/ε_0=3188,用3％molBa和3％molSr复合置换Pb(Mg_(1/3)Nb_(2/3))_0.380Ti_(0.360)Zr_(0.260)O_3的Pb时仍保持纯Ba置换的良好均匀性和压电性,其K_t=0.504,K_p=0.660,N_t=2060KC·mm,thδ=2.5×10~(-3),ρ=7.8g/cm~3,ε_(33)~T/ε_0=3356.它们良好的压电性和均匀性合乎制作超声实时显像线阵晶片的要求.在线阵晶片中重现这些优良性能的工艺条件是现实的,因而得到实际应用.     

氖原子奇宇称里德堡能级的理论计算

本文依据最弱受约束电子势模型理论,计算了氖原子1s22s22p5(2Po3/2)ns 2[3/2]o1,2(n=3-50) 和 1s22s22p5(2Po3/2)nd 2[1/2]o0,1(n=3-50)里德堡系列能级和量子亏损。计算结果与已有的51个实验数据符合得很好,并预言了141个能级的位置。     

氖原子奇宇称里德堡能级的理论计算

本文依据最弱受约束电子势模型理论,计算了氖原子1s22s22p5(2Po3/2)ns 2[3/2]o1,2(n=3～50) 和 1s22s22p5(2Po3/2)nd 2[1/2]o0,1(n=3～50)里德堡系列能级和量子亏损.计算结果与已有的51个实验数据符合得很好,并预言了141个能级的位置.     

二甲亚砜对关节软骨渗透性研究

玻璃化被认为是低温保存关节软骨的一种有效方法,但需要考虑低温保护剂渗入软骨的速率以及低温保护剂毒性的制约。本文选用二甲亚砜(DMSO)作为低温保护剂,对其在1℃,22℃和37℃时对绵羊关节软骨的渗透特性进行了研究,得到相应的扩散系数为1.9×10~(-6) cm~2/s,3.3×10~(-6) cm~2/s和5.7×10~(-6)cm~2/s,活化能为22.84 kJ/mol。认识低温保护剂对关节软骨的渗透特性有助于建立低温保护剂加入/取出过程的数学模型,从而优化关节软骨的玻璃化保存方案。     

Therapeutic ultrasound cavitation and its free radical ESR determination

The formation of free radicals (?)OH and (?)H in a naturallyair-saturated aqueous solution exposed to therapeutic CW ultrasound at afrequency of 820 kHz has been confirmed by using spin trapping 5,5-dimethyl-1-pyrroline-1-oxide(DMPO)and electron spin resonance(ESR)technique.It is suggested that these radicals are formed due tothe high temperature and pressure produced by the ultrasonic transientcavitation.The transient cavitation threshold is found at 0.537-0.632W/cm~2 under a sonication time of 3 minutes.With increasing soundintensity the yield of free radicals (?)OH raises rapidly at the intensityranging from 1—2W/cm~2,and no longer increase is observed at above3W/cm~2.The sound intensity (I) dependence of the yield of (?)OH (D)can be approximately described by a regression equation:D=8.1(I~(1/2) -(I_c)~(1/2))~(1/2), where I_c=0.667W/cm~2 .Under a fixing soundintensity the yield of OH increases monotonously with the sonicationtime.     

Theoretical study of the optical gain characteristics of a Ge1-xSnx alloy for a short-wave infrared laser

Optical gain characteristics of Ge_(1_x)Snμx are simulated systematically.With an injection carrier concentration of 5×10~(18)/cm~3 at room temperature,the maximal optical gain of Ge_(0.922)Sn_(0.078) alloy(with n-type doping concentration being 5×10~(18)/cm~3) reaches 500 cm~(-1).Moreover,considering the free-carrier absorption effect,we find that there is an optimal injection carrier density to achieve a maximal net optical gain.A double heterostructure Ge_(0.554)Si_(0.289)Sn_(0.157)/Ge_(0.922)Sn_(0.078)/Ge_(0.554)Si_(0.289)Sn_(0.157) short-wave infrared laser diode is designed to achieve a high injection efficiency and low threshold current density.The simulation values of the device threshold current density J_(th)are 6.47 kA/cm~2(temperature:200 K,and λ=2050 nm),10.75 kA/cm~2(temperature:200 K,and λ=2000 nm),and23.12 kA/cm~2(temperature:300 K,and λ=2100 nm),respectively.The results indicate the possibility to obtain a Si-based short-wave infrared Ge_(1-x)Sn_x laser.