中低能区He2++He碰撞反应转移电离机制研究

反应显微成像谱仪能够对离子-原子碰撞反应中的末态产物进行运动学完 全测量。本论文基于反应显微成像谱仪对70-400keV He 2+ -He 碰撞中转移电离机 制进行了实验研究。 通过对不同出射角度电子的能谱研究表明， ECC电子和速度分布在0和入射 炮弹速度之间的“分子化”特征电子是出射电子能谱的主要贡献，前者是动力学 两步过程的作用，后者可由“准分子”激发模型给予定性解释，“鞍点电子”仅 是后者的一部分。通过对不同平面内出射电子的速度分布研究发现出射电子主要 集中在散射平面内，而且其速度分布介于0与炮弹速度之间且前向出射，同时在 炮弹与靶核核间轴处有一极小值；在入射离子能量较低时，出射电子空间分布较 为对称，随着入射离子能量的增加，出射电子逐渐靠近炮弹或靶核；与此同时， 由于 态电子与 态电子相互干涉，出射电子在散射平面内的分布还与碰撞参数 相关，在大碰撞参数下， 态电子的作用更加明显，而在小碰撞参数下 态电子 的作用更加显著。实验结果表明准分子激发和动力学两步过程是中低能He2+ -He 转移电离过程的两种主要机制。

尖晶石中He离子辐照缺陷的演化及其对重金属原子的俘获效应研究

本项工作利用多种分析手段（FTIR、TDS、RBS/C、AFM、SEM），对100keV He离子不同剂量（0.5，2.0，8.0×1016cm-2）注入的尖晶石中缺陷的形成及其对重金属原子的俘获效应进行了研究。在FTIR谱上观察到了Al-O键的共振吸收峰随剂量增加向小波数方向移动和随退火温度升高向大波数方向回复；随退火温度增加这三组样品的晶格损伤均经历先增大后减小的过程，但随剂量不同晶格损伤开始增加的温度不同；注入剂量为2.0×1016 cm-2样品在退火过程中其表面发生了形变，随剂量增加样品表面发现起皮现象。上述差异被认为是样品中不同缺陷的形成所引起的。随后，尝试了利用He离子注入形成的空位型缺陷俘获重金属原子的方法在尖晶石中合成金属纳米颗粒。吸收光谱上SPR吸收峰的出现，证实了金属纳米颗粒的形成

碳化硅中氦离子辐照缺陷演化及SiCOI薄膜合成的研究

碳化硅是一种宽带隙半导体材料,具有禁带宽度大、击穿电压高、热导率高、电子饱和漂移速度大、介电常数小、抗辐射能力强、化学稳定性好等优良特性,使其在越来越多的领域如航空航天、太空探测、人造卫星、地热勘探、核能仪器、雷达通讯等, 所需要高温、高速、高频、大功率的微电子器件方面倍受青睐,并和氮化镓、金刚石一起被誉为发展前景十分广阔的第三代半导体材料。本论文采用He+离子注入,在SiC衬底一定深度引入纳米气泡/空腔的方法,来增强对氧原子的俘获以增加O原子在RP处局域浓度,使得更利于O与Si的反应,从而促进氧化埋层的形成,以达到降低注入O的剂量而形成优良的氧化物电绝缘层的目的。由于高剂量的O注入会引起表层SiC材料的损伤，该方法有望缓解目前SIMOX技术中O离子高剂量注入引起表层材料的损伤问题，以期获得低成本、低缺陷密度的SiCOI材料。论文主要开展了如下研究：（1）对He+离子高温（600 K）注入6H-SiC中产生的辐照缺陷,以及缺陷在阶梯温度退火的演化行为的特征进行了分析。实验采用100 keV的He+,辐照剂量范围为3.0×1015～3.0×1016 He+/cm2。利用拉曼光谱、室温光致发光谱、红外吸收光谱、沟道卢瑟福背散射谱的特征进行了分析。实验结果表明,离子注入所产生晶格损伤的程度与He+离子注入剂量有关；高温退火使得损伤得到恢复,不同注入剂量造成的晶格损伤需要不同的退火温度才可恢复。高剂量注入的样品在阶梯温度退火条件下呈现出了点缺陷的复合、氦-空位团的产生、氦泡的形核、长大等特性。与室温注入相比,高温注入引入的自退火作用使大部分简单缺陷发生复合,限制了损伤的积累,从而在材料中产生相对较小的损伤。在一定剂量范围内是避免注入层非晶化的一个重要方法,为后续利用氦离子注入空腔掩埋层吸杂或者制备低成本、低缺陷密度的绝缘层上碳化硅(SiCOI)材料提供了可能。 （2）对He的预注入引入的辐照缺陷与随后注入的氧原子的相互作用机理进行了初步分析。实验采用先He后O注入的方法，采用的离子能量为30 keV (He+)，100 keV (O+)；剂量分别为3.0×1016 (He+)、1.0×1017 (O+) ions/cm2。拉曼散射谱结果表明,空腔对氧的吸收主要是通过捕获简单缺陷释放出来的间隙氧原子实现的,进而促进了对氧的吸附,形成硅氧化合物,有利于氧化埋层的形成。紫外-可见吸收谱中的干涉带表明在材料表面下大概198 nm处是损伤层与晶体层的分界面，接近于SRIM2006估算得到的30 keV He+和100 keV O+辐照损伤的深度（He+辐照损伤的深度为195 nm；O+辐照损伤的深度为165 nm）。沟道卢瑟福背散射谱表明，在特定深度（约150 nm）处,样品中形成了接近非晶的埋层。He离子预注入的碳化硅基体由于含有较多的空位,注入的氧在退火过程中从简单缺陷中释放,向空腔层扩散并捕获在空腔层内,使得He离子预先注入形成的空腔层限制了随后O离子注入造成的损伤层的厚度

非全裸氟离子与氦原子和氖原子碰撞中的多电子过程研究

本工作采用反冲离子飞行时间技术和散射离子位置灵敏探测技术测量了F~(2+)、F~(3+)离子与He原子和Ne原子碰撞中转移电离截面与单电子俘获截面比和入射离子损失一个电子情况下靶原子多重电离与单重电离的截面比。研究了这些截面比随作用强度κ的变化规律，并对不同的碰撞体系进行了比较，总结了强相互作用区(1.4 < κ < 4.4) F~(2+)、F~(3+)离子与He和Ne原子碰撞中的转移电离过程和入射离子电子损失过程的规律。实验发现：（1）对本工作中所有的碰撞体系，转移电离截面与单电子俘获截面比随作用强度κ的增大而减小；（2）对He原子靶，入射离子损失一个电子时He原子二重电离与单重电离的截面比随作用强度κ的增大而减小；（3）对于Ne原子靶，入射离子损失一个电子时Ne原子四重电离、三重电离、二重电离截面与单重电离截面比随作用强度κ有不同的变化规律。本工作对于上述实验现象进行了定性分析和讨论。在本实验能区，转移电离现象可视作一个电子被俘获、另一个电子被电离的两步过程；当入射离子损失一个电子时，He原子二重电离的主要机制为Two-Step机制，而Ne原子的多重电离则为Two-Step机制和随后的电子重组过程的共同作用的结果。深入研究强相互作用区离子一原子碰撞过程，还需要积更多的实验数据和发展有效的理论模型。

二维无关联振子系统的量子化及能谱中长程关联的理论分析

量子经典对应是人们一直关心的基本问题．早期的WKB量子论及其推广EBK理论分别给出了一维及多维可积系统周期轨道的作用量量子化条件，但是，这些理论都没有明确的给出周期轨道与量子能级之间的对应关系．另一方面，近年来，人们在数值计算中发现量子能谱中存在着与周期轨道有紧密联系的长程关联，但是目前对长程关联的研究大多局限于数值计算，其背后的动力学原因有待进一步的探讨。应用二维无关联振子系统具有的标度不变性，对量子态密度进行Fourier变换，得到二维无关联振子系统的回归函数．另一方面，在有理环面上积分Hamiltonian运动方程，数值计算给出二维无关联四次振子系统的半经典回归谱。对二维无关联四次振子系统的量子回归谱和经典回归谱进行比较，量子和经典回归谱中的峰(显示了能级之间存在着长程关联)的位置大致一定验证了Berry-Tabor求迹公式的有效性。从可积系统的Be：rry-Tabor公式出发，导出了二维可积系统周期轨道作用量量子化条件，考虑有理环面上周期轨道必须满足的周期性条件，找到了量子能级与经典周期轨道之间的对应关系．这一对应关系表明，二维无关联振子系统的一组能级与一组周期轨道之间存在着一一对应关系。这组能级对应的周期轨道具有相同的拓扑，但每条周期轨道对应的系统能量等于它所对应的量子能级。进一步的，我们用二维无关联振子系统的量子经典对应关系去分析量子能谱中的长程关联。分析表明，当二维无关联振子系统回归函数中的作用量取某一系统能量下某一周期轨道的作用量的值时，那些与这一周期轨道拓扑相同的周期轨道对应的量子能级对回归函数的贡献相干。这些具有相同拓扑的周期轨道对应的量子能级间存在着长程关联。

多电荷态硫离子与氦原子和氢分子碰撞中的多电子转移过程研究

本工作采用反冲离子飞行时间技术和散射离子位置灵敏探测技术，实验研究了Sq+离子与He、H2碰撞中的多电子转移过程和分子离子的碎裂现象。研究了转移电离截面与单电子俘获截面比值和入射离子损失一个电子和两个电子的情况下，靶原子双重电离与单重电离的截面比值随入射离子能量和入射离子电荷态的变化规律，并对不同的碰撞体系的结果进行了比较。研究发现：在本工作研究的入射离子能区，对于HZ分子靶，双电子俘获自电离反应道：S2+H2→S(q-l)+2H++e-。是转移电离过程的主要贡献，而直接转移电离的贡献可以忽略；随着入射离子电荷态的增加，双电子俘获自电离的贡献增加，直接转移电离的贡献逐渐减小，但双电子俘获自电离的贡献的增加比理论预言的要慢。建立了蒙特卡罗程序模拟离子与分子碰撞中产生的具有不同的初始动能的离子碎片的飞行时间谱，深入分析和研究了Sq＋与H2分子碰撞中产生的H2+的解离过程和库仑爆炸过程，以及H＋碎片的能量分布。模拟结果与实验测量到的TOF谱的分析比较说明：在Sq＋与H2分子碰撞实验中，库仑爆炸是产生H+的主要反应道，而氢分子离子H2+发生解离产生H+的反应道相对很弱。

应用IBM-2对混合对称态的一些探讨

本文应用相互作用玻色子模型（IBM-2）的理论对混合对称态作了一些讨论。首先给出IBM-2普遍的和一种简化的Hamiltonian的Casimir算子展开式，通过对几种简化Hamiltonian动力学对称性和F-旋对称性的分析，并且考虑最主要的核子相互作用，选择了一种较理想的简化Hamiltonian。其次，用最小二乘法提取了部分U（5）类核和O（6）类核的玻色子等效电荷，并用此计算了它们的混合对称态的电磁跃迁几率。最后，用数值方法系统地计算和分析了~(150,152,154)Gd核混合对称态的能级和电磁跃迁几率，得到~(150)G和~(152,154)Gd核最低能量的混合对称态分别为2_M~+和I_M~+。另外，还详细讨论了Majorana相互作用参数对能级和电磁跃迁几率的影响

A 2-kW COIL with a square pipe-array JSOG and nitrogen buffer gas

A 2-kW-class chemical oxygen-iodine laser (COIL) using nitrogen buffer gas has been developed and tested since industrial applications of COIL devices will require the use of nitrogen as the buffer gas. The laser, with a gain length of 11.7 cm, is energized by a square pipe-array jet-type singlet oxygen generator (SPJSOG) and employs a nozzle bank with a designed Mach number of 2.5. The SPJSOG has advantages over the traditional plate-type JSOG in that it has less requirements on basic hydrogen peroxide (BHP) pump, and more important, it has much better operational stability. The SPJSOG without a cold trap and a gas-liquid separator could provide reliable operations for a total gas flow rate up to 450 mmol/s and with a low liquid driving pressure of around 0.7 atm or even lower. The nozzle bank was specially designed for a COIL using nitrogen as the buffer gas. The cavity was designed for a Mach number of 2.5, in order to provide a gas speed and static temperature in the cavity similar to that for a traditional COIL with helium buffer gas and a Mach 2 nozzle. An output power of 2.6 kW was obtained for a chlorine flow rate of 140 mmol/s, corresponding to a chemical efficiency of 20.4%. When the chlorine flow rate was reduced to 115 mmol/s, a higher chemical efficiency of 22.7% was attained. Measurements showed that the SPJSOG during normal operation could provide a singlet oxygen yield Y greater than or equal to 55%, a chlorine utilization U greater than or equal to 85%, and a relative water vapor concentration w = [H2O]/([O-2] + [Cl-2]) less than or equal to 0.1.

Gas permeability of a novel cellulose membrane

A novel cellulose membrane was prepared by using amine oxides as the solvent and its mechanical performance was measured. Steady-state permeation rates of carbon dioxide, hydrogen, methane, nitrogen, oxygen, argon and helium in the homogeneous dense cellulose membrane were measured in the temperature range of 298-353 K and under gas pressures up to 1 MPa. The effect of swelling on hydrophilic membrane permeability was studied in some detail on the cellulose membrane. The difference in gas permeability between the "dry" cellulose membrane and the "water-swollen" cellulose membrane was investigated, and the gas permeability between the cellulose membrane and the Cellophane was compared. In this paper, the separation performance Of CO2 over H-2 in a "water-swollen" cellulose membrane is reported for the first time and the separation factor Of CO2/H-2 can be up to 15. (C) 2002 Elsevier Science B.V. All rights reserved.

Syntheses, structures, and magnetic properties of two novel three-dimensional frameworks built from M4O4 cubanes and dicyanamide bridges

Two novel coordination polymers Ni-4(CH3O)(4)(CH3OH)(4)(dca)(4) (1) and Co-4(CH3O)(4)(CH3OH)(4)(dca)(4) (2) have been synthesized by solvethermal reaction. X-ray single-crystal analysis reveals that the two complexes are isostrutural and possess 3D frameworks that are built from the M4O4(M= Ni (1) and Co (2)) cubanelike building blocks linked by dicyanamide (dca) bridges. The temperature dependence of the magnetic susceptibility was measured and the DC experiment data were fitted using the Heisenberg spin Hamiltonian.

Synthesis, crystal structure, and magnetic properties of {[Cu(oxbe)]Mn(H2O)[Cu(oxbe)(DMF)]}(n)center dot nDMF center dot nH(2)O: From dissymmetrical mononuclear entities to a 3D heterometallic supramolecular coordination polymer

Self-assembly of the building block [Cu(oxbe)](-) with Mn(II) led to a novel coordination polymer {[Cu(oxbe)]Mn(H2O)(Cu(oxbe)(DMF)]}(n).nDMF.nH(2)O, where H(3)oxbe is a new dissymmetrical ligand N-benzoato-N'-(2-aminoethyl)-oxamido and DMF = dimethylformamide. The crystal forms in the triclinic system, space group P(1)over-bar, with a = 9.260(4) angstorm, b = 12.833(5) angstrom, c = 15.274(6) angstrom , alpha = 76.18(3)degrees, beta = 82.7(3)degrees, gamma = 82.31(3)degrees, and Z = 2. The crystal structure of the title complex reveals that the two-dimensional bimetallic layers are constructed of (CuMnII)-Mn-II-Cu-II chains linked together by carboxylate bridge and hydrogen bonds help to produce a novel three-dimensional channel-like structure. The magnetic susceptibility measurements (5-300 K) were analyzed by means of the Hamiltonian (H)over-cap = -2J(S)over-cap (Mn)((S)over-cap(Cu1) + (S)over-cap(Cu2)), leading to J = -17.4 cm(-1).

Vibrational spectra and structure of zinc phthalocyanine

Semi-empirical molecular orbital calculations using PM3 Hamiltonian were employed to determine qualitative assignments of the vibrational spectrum of zinc phthalocyanine (ZnPc). The assignments are from the potential energy distribution calculations in the normal coordinate analysis and optimized geometry in the PM3 calculations. The structure of the ZnPc molecule is also deduced. (C) 1999 Elsevier Science B.V. All rights reserved.

Tide-influenced acidic hydrothermal system offshore NE Taiwan

Elemental sulfur and hydrogen sulfide emitted offshore of northeastern Taiwan known to local fishermen for generations, but never studied until recently, are found to have originated from a cluster of shallow (< 30 m depth) hydrothermal vents. Among the mounds is a massive 6 m high chimney with a diameter of 4 m at the base composed of almost pure sulfur and discharging hydrothermal fluid containing sulfur particles. The sulfur in the chimney has a delta(34)S= 1.1 parts per thousand that is isotopically lighter than seawater. A yellow smoker at shallow depths with such characteristics has never been reported on anywhere else in the world. Gas discharges from these vents are dominated by CO2 (> 92%) with small amounts of H2S. Helium isotopic ratios 7.5 times that of air indicate that these gases originate from the mantle. High temperature hydrothermal fluids have measured temperatures of 78-116 degrees C and pH (25 degrees C) values as low as 1.52, likely the lowest to be found in world records. Low temperature vents (30-65 degrees C) have higher pH values. Continuous temperature records from one vent show a close correlation with diumal tides, suggesting rapid circulation of the hydrothermal fluids. (c) 2005 Elsevier B.V. All rights reserved.

He, Ne and Ar isotope compositions of fluid inclusions in hydrothermal sulfides from the TAG hydrothermal field, Mid-Atlantic Ridge

Helium, rieon and argon isotope compositions of fluid inclusions have been measured in hydrothermal sulfide samples from the TAG hydrothermal field at the Mid-Atlantic Ridge. Fluid-inclusion He-3/He-4 ratios are 2.2-13.3 times the air value (Ra), and with a mean of 7.2 Ra. Comparison with the local vent fluids (He-3/He-4=7.5-8.2 Ra) and mid-ocean ridge basalt values (He-3/He-4=6-11 Ra) shows that the variation range of He-3/He-4 ratios from sulfide-hosted fluid inclusions is significantly large. Values for Ne-20/Ne-22 are from 10.2 to 11.4, which are significantly higher than the atmospheric ratio (9.8). And fluid-inclusion Ar-40/Ar-36 ratios range from 287 to 359, which are close to the atmospheric values (295.5). These results indicate that the noble gases of fluid inclusions in hydrothermal sulfides are a mixture of mantle- and seawater-derived noble gases; the partial mantle-derived components of trapped hydrothermal fluids may be from the lower mantle; the helium of fluid inclusions is mainly from upper mantle; and the Ne and Ar components are mainly from seawater.

地震波场模拟及叠前深度偏移的李群方法

The processes of seismic wave propagation in phase space and one way wave extrapolation in frequency-space domain, if without dissipation, are essentially transformation under the action of one parameter Lie groups. Consequently, the numerical calculation methods of the propagation ought to be Lie group transformation too, which is known as Lie group method. After a fruitful study on the fast methods in matrix inversion, some of the Lie group methods in seismic numerical modeling and depth migration are presented here. Firstly the Lie group description and method of seismic wave propagation in phase space is proposed, which is, in other words, symplectic group description and method for seismic wave propagation, since symplectic group is a Lie subgroup and symplectic method is a special Lie group method. Under the frame of Hamiltonian, the propagation of seismic wave is a symplectic group transformation with one parameter and consequently, the numerical calculation methods of the propagation ought to be symplectic method. After discrete the wave field in time and phase space, many explicit, implicit and leap-frog symplectic schemes are deduced for numerical modeling. Compared to symplectic schemes, Finite difference (FD) method is an approximate of symplectic method. Consequently, explicit, implicit and leap-frog symplectic schemes and FD method are applied in the same conditions to get a wave field in constant velocity model, a synthetic model and Marmousi model. The result illustrates the potential power of the symplectic methods. As an application, symplectic method is employed to give synthetic seismic record of Qinghai foothills model. Another application is the development of Ray+symplectic reverse-time migration method. To make a reasonable balance between the computational efficiency and accuracy, we combine the multi-valued wave field & Green function algorithm with symplectic reverse time migration and thus develop a new ray+wave equation prestack depth migration method. Marmousi model data and Qinghai foothills model data are processed here. The result shows that our method is a better alternative to ray migration for complex structure imaging. Similarly, the extrapolation of one way wave in frequency-space domain is a Lie group transformation with one parameter Z and consequently, the numerical calculation methods of the extrapolation ought to be Lie group methods. After discrete the wave field in depth and space, the Lie group transformation has the form of matrix exponential and each approximation of it gives a Lie group algorithm. Though Pade symmetrical series approximation of matrix exponential gives a extrapolation method which is traditionally regarded as implicit FD migration, it benefits the theoretic and applying study of seismic imaging for it represent the depth extrapolation and migration method in a entirely different way. While, the technique of coordinates of second kind for the approximation of the matrix exponential begins a new way to develop migration operator. The inversion of matrix plays a vital role in the numerical migration method given by Pade symmetrical series approximation. The matrix has a Toepelitz structure with a helical boundary condition and is easy to inverse with LU decomposition. A efficient LU decomposition method is spectral factorization. That is, after the minimum phase correlative function of each array of matrix had be given by a spectral factorization method, all of the functions are arranged in a position according to its former location to get a lower triangular matrix. The major merit of LU decomposition with spectral factorization (SF Decomposition) is its efficiency in dealing with a large number of matrixes. After the setup of a table of the spectral factorization results of each array of matrix, the SF decomposition can give the lower triangular matrix by reading the table. However, the relationship among arrays is ignored in this method, which brings errors in decomposition method. Especially for numerical calculation in complex model, the errors is fatal. Direct elimination method can give the exact LU decomposition But even it is simplified in our case, the large number of decomposition cost unendurable computer time. A hybrid method is proposed here, which combines spectral factorization with direct elimination. Its decomposition errors is 10 times little than that of spectral factorization, and its decomposition speed is quite faster than that of direct elimination, especially in dealing with a large number of matrix. With the hybrid method, the 3D implicit migration can be expected to apply on real seismic data. Finally, the impulse response of 3D implicit migration operator is presented.