低能离子注入植物种子的深度分布及生物效应机理研究

采用四种物理测量方法：扫描电子显微镜和能量色散x射线分析，质子激发x荧光分析，双光子激光扫描显微技术和正电子湮没技术测定了能量为200keV V⁺ 注入干花生种 子的深度分布.测量结果表明，注入的低能离子在干种子花生内的深度远比TRIM95的理论计算值为高.对低能离子注入植物种子后的生物效应的机理进行了讨论. 关键词： 低能离子注入 植物种子 深度分布 生物效应机理     

Micro‐Raman depth profiling of silicon amorphization induced by high‐energy ion channeling implantation

In this work, we study the silicon amorphization dependence on the crystal depth induced by 6‐MeV Al²⁺ ions implanted in the <110> and randomly oriented silicon crystal channels, which was not directly experimentally accessible in the previous similar high‐energy ion–crystal implantation cases. Accordingly, the micro‐Raman spectroscopy scanning measurements along the crystal transversal cross section of the ion implanted region were performed. The ion fluence was 10¹⁷ particles/cm². The scanning steps were 0.2 and 0.3 µm, for the channeling and random ion implantations, respectively. The obtained results are compared with the corresponding Rutherford backscattering spectra of 1.2‐MeV protons in the random and channeling orientations measured during the channeling implantation. Additionally, scanning electron microscope picture was taken on the transversal cross section of the implanted region in the channeling implantation case. We show here that the obtained silicon amorphization maxima are in excellent agreement with the corresponding estimated maxima of the aluminum concentration in silicon. This clearly indicates that the used specific micro‐Raman spectroscopy scanning technique can be successfully applied for the depth profiling of the crystal amorphization induced by high‐energy ion implantation. Copyright © 2013 John Wiley & Sons, Ltd.     

Isospin effects of the Skyrme potential and the momentum dependent interaction at intermediate energy heavy ion collisions

We improve the isospin dependent quantum molecular dynamical model by including isospin effects in the Skyrme potential and the momentum dependent interaction to obtain an isospin dependent Skyrme potential and an isospin dependent momentum interaction. We investigate the isospin effects of Skyrme potential and momentum dependent interaction on the isospin fractionation ratio and the dynamical mechanism in intermediate energy heavy ion collisions. It is found that the isospin dependent Skyrme potential and the isospin dependent momentum interaction produce some important isospin effects in the isospin fractionation ratio.     

Electromagnetic energy, momentum, and angular momentum in an inhomogeneous linear dielectric

In a previous work, Optics Communications 284 (2011) 2460-2465, we considered a dielectric medium with an anti-reflection coating and a spatially uniform index of refraction illuminated at normal incidence by a quasimonochromatic field. Using the continuity equations for the electromagnetic energy density and the Gordon momentum density, we constructed a traceless, symmetric energy-momentum tensor for the closed system. In this work, we relax the condition of a uniform index of refraction and consider a dielectric medium with a spatially varying index of refraction that is independent of time, which essentially represents a mechanically rigid dielectric medium due to external constraints. Using continuity equations for energy density and for Gordon momentum density, we construct a symmetric energy-momentum matrix, whose four-divergence is equal to a generalized Helmholtz force density four-vector. Assuming that the energy-momentum matrix has tensor transformation properties under a symmetry group of space-time coordinate transformations, we derive the global conservation laws for the total energy, momentum, and angular momentum.     

反应显微成像谱仪动量及能量分辨因素分析

在对反应显微成像谱仪的工作原理作简要介绍的基础上,全面分析了各种可能影响动量分辨的因素,并结合反应显微成像谱仪的技术参数分别对反冲离子动量分辨以及电子动量与能量分辨进行了详细计算和讨论,确定了反应显微成像谱仪的动量及能量分辨,并为进一步提高分辨提供了重要依据. 关键词： 动量分辨 能量分辨 反应显微成像谱仪 动量成像原理     

Nucleon internal structure: a new set of quark, gluon momentum, angular momentum operators and parton distribution functions

It is unavoidable to deal with the quark and gluon momentum and angular momentum contributions to the nucleon momentum and spin in the study of nucleon internal structure. However we never have the quark and gluon momentum, orbital angular momentum and gluon spin operators which satisfy both the gauge invariance and the canonical momentum and angular momentum commutation relation. The conflicts between the gauge invariance and canonical quantization requirement of these operators are discussed. A new set of quark and gluon momentum, orbital angular momentum and spin operators, which satisfy both the gauge invariance and canonical momentum and angular momentum commutation relation, are proposed. The key point to achieve such a proper decomposition is to separate the gauge field into the pure gauge and the gauge covariant parts. The same conflicts also exist in QED and quantum mechanics and have been solved in the same manner. The impacts of this new decomposition to the nucleon internal structure are discussed.     

Nucleon internal structure: a new set of quark, gluon momentum, angular momentum operators and parton distribution functions

It is unavoidable to deal with the quark and gluon momentum and angular momentum contributions to the nucleon momentum and spin in the study of nucleon internal structure. However we never have the quark and gluon momentum, orbital angular momentum and gluon spin operators which satisfy both the gauge invariance and the canonical momentum and angular momentum commutation relation. The conflicts between the gauge invariance and canonical quantization requirement of these operators are discussed. A new set of quark and gluon momentum, orbital angular momentum and spin operators, which satisfy both the gauge invariance and canonical momentum and angular momentum commutation relation, are proposed. The key point to achieve such a proper decomposition is to separate the gauge field into the pure gauge and the gauge covariant parts. The same conflicts also exist in QED and quantum mechanics and have been solved in the same manner. The impacts of this new decomposition to the nucleon internal structure are discussed.     

反应离子镀光学薄膜的微观结构分析

用反应离子镀方法制备了ＴｉＯ２单层膜及ＴｉＯ２／ＳｉＯ２多层膜，用透射电子显微镜分别观察了由反应离子镀方法及传统蒸镀法二种不同工艺制得的ＴｉＯ２单层膜及ＴｉＯ２／ＳｉＯ２多层膜的断面结构，并对ＴｉＯ２单层膜进行了喇曼分析和卢瑟福背散射分析。     

Three-dimensional range distribution of 400 KeV Nd ions implanted into Si

Abstract

The 400 keV Nd ions were implanted into Si at a variety of tilt angles from 7° to 75°. The range distributions were accurately measured by the TOF-SIMS (Time-of-Flight secondary ion mass spectrometry) method. The results show that the measured range profiles can be represented by Pearson I type distributions which are in the same category as predicted by TRIM (TRansport of Ions in Matter). The first four statistical moments of the Nd-depth distribution, namely range, longitudinal straggling, skewness, and kurtosis, were obtained from the fitted profiles, and compared with the corresponding TRIM calculated values. Results show that the experimentally obtained range profiles are obviously deeper and broader than TRIM'95 (version 95.2) predictions, but very good agreements were obtained between the measured values and TRIM'98 (version 98.10) calculation. The longitudinal and lateral range stragglings for normal incidence were deduced from the angular dependence of the measured range distributions. Based on the range distributions for different angle implantation, the three-dimensional range distribution was reconstructed, and the lateral range straggling was obtained from the three-dimensional distribution and compared with both the predicted TRIM values and the deduced value.     

He,Ne,Ar,Kr和Xe原子电子的动量密度分布研究

对He,Ne,Ar,Kr和Xe原子体系中电子在动量空间的性质进行了系统的理论计算研究.采用自洽场HFR方法计算了坐标空间He,Ne,Kr和Xe原子体系单电子径向波函数,动量空间的单电子波函数由坐标空间原子体系单电子径向波函数通过运用傅立叶变换计算得到.在冲量近似条件下,进一步计算研究了这些原子的单电子动量密度分布和原子体系总的Compton轮廓.计算结果与已有的实验实验值和其他文献的理论计算结果比较表明,本文计算的结果是准确的.     

Canonical momentum,angular momentum,and helicity of circularly polarized Airy beams

We report a study of the momentum, angular momentum, and helicity of circularly polarized Airy beams propagating in free space. By using the vector angular spectrum representation, the explicit analytical expressions for the electric and magnetic field components of circularly polarized Airy beams are derived in detail. To overcome the drawbacks of classical kinematics formulae when applied to structured light beams, a general canonical approach is introduced to describe the momentum, angular momentum and helicity of Airy beams. Numerical simulation results for the spatial distributions of the canonical momentum, spin and orbital angular momentum, as well as the helicity densities are presented and discussed. This study may provide useful insights into the dynamical properties of Airy beams that may be important in several applications, including the optical control, micromanipulation, and information processing.     

Transverse momentum diffusion and broadening of the back-to-back di-hadron correlation function

We extend the Gyulassy–Levai–Vitev reaction operator approach to multiple elastic scattering of fast partons traversing dense nuclear matter to take into account the leading power corrections due to the medium recoil and to derive the change in the partons' longitudinal momentum. We employ a boost-invariant formalism to generalize previous treatments of the problem, which were specific to the target rest frame. We apply the transverse momentum diffusion results in a simple analytic model to evaluate the broadening of the back-to-back di-hadron correlation function in d+Au reactions.     

单晶Si表面离子束溅射沉积Co纳米薄膜的研究

采用离子束溅射沉积法，在单晶Si基片上制备了不同厚度(1—100nm)的Co纳米薄膜.利用原子力显微镜、X射线光电子能谱(XPS)仪和X射线衍射仪对不同厚度的Co纳米薄膜进行了分析和研究.结果表明：当薄膜厚度为1—10nm时，沉积颗粒形态随薄膜厚度增加将由二维生长的细长胞状过渡到多个颗粒聚集成的球状.当膜厚大于10nm时，小颗粒球聚集成大颗粒球，颗粒球呈现三维生长状态.表面粗糙度随膜厚的增加呈现先增加后减小的趋势，在膜厚为3nm时出现极值.XPS全程宽扫描和窄扫描显示：薄膜表面的元素成分为Co，化学态分别 关键词： 离子束沉积 纳米薄膜 X射线光电子能谱 X射线衍射     

Target heating during ion implantation and related problems

We have undertaken a general analysis of wafer heating during implantation and first, we present general considerations of this problem with respect to amorphization doses extracted from Morehead and Crowder theory. Then, radiative properties of silicon wafers are measured: a law of variation of the emissivity with temperature is given; a comparison is made with values found in the literature. Dependence with experimental conditions (heat reflector, conductive losses) is also studied. Three methods for temperature measurement are used: temperature coefficient of a small resistor vacuum deposited on a face, thermocouple measurement and infrared detection. We compare the three kinds of results which are in good agreement and we make some comments about the temperature measurements using infrared detection.     

Effect of intense electron and ion irradiation on optical absorption of boron carbide thin films

ABSTRACT

The energetic characteristics of growth and radiation defects (RDs) in boron carbide films deposited by reactive magnetron sputtering on a steel substrate and irradiated with powerful electron and pulsed ion beams were investigated. The relationship between the characteristics of point RDs, the degree of distortion of the electronic structure and the characteristics of interband and exponential absorption was established. The absorption spectra of the films were due to electronic transitions between the defects energy states localized in the band gap and interband transitions. The stability of characteristics to electron irradiation was due to the high concentration of growth defects, distributed along the boundaries between the structural fragments. Short-pulse implantation of carbon ions stimulates partial annealing of intrinsic RDs and their redistribution and formation of thermally stable complexes from defects. Boron carbide films significantly exceed the radiation resistance of sodium calcium silicate glass, but are slightly inferior to the films of aluminum and silicon nitrides, obtained by magnetron deposition.     

The energy dependence and depth distribution of lattice disorder in ion-implanted silicon

Silicon single crystals were implanted at room temperature with Xe and I ions in the energy range 20 to 150 keV and with 20 to 50 keV P ions. The lattice disorder induced by these implants was measured by a combination of the channeling and Rutherford backscattering techniques. The disorder produced by implanting I and Xe ions exhibited a similar relationship with implantation energy to that previously established for bismuth implants. The P ion implants induced less lattice disorder per incident ion in the energy range studied. Integral depth distributions of the implanted ions and of the lattice disorder were obtained by combining a layer removal technique with radiotracer implants of 110 keV ¹³³Xe and 40 keV ³²P. The depth distributions showed that in both cases the ions penetrate deeper into the crystal than the damage they produce but that the separation is significantly greater for the P implant than for the Xe implant.     

Azimuthal distributions of radial momentum and velocity in relativistic heavy ion collisions

Azimuthal distributions of radial (transverse) momentum, mean radial momentum, and mean radial velocity of final-state particles are suggested for relativistic heavy ion collisions. Using the AMPT transport model with string melting, the distributions of Au+Au collisions at 200 GeV are presented and studied. It is demonstrated that the distribution of total radial momentum is more sensitive to the anisotropic expansion, as the anisotropies of final-state particles and their associated transverse momentums are both counted in the measurement. The mean radial velocity distribution is compared with the radial flow velocity. The thermal motion contributes an isotropic constant to the mean radial velocity.     

On the gravitational angular momentum of rotating sources

The gravitational energy–momentum and angular momentum satisfy the algebra of the Poincaré group in the full phase space of the teleparallel equivalent of general relativity. The expression for the gravitational energy–momentum may be written as a surface integral in the three-dimensional spacelike hypersurface, whereas the definition for the angular momentum is given by a volume integral. It turns out that in practical calculations of the angular momentum of the gravitational field generated by localized sources like rotating neutron stars, the volume integral reduces to a surface integral, and the calculations can be easily carried out. Similar to previous investigations in the literature, we show that the total angular momentum is finite provided a certain asymptotic behaviour is verified. We discuss the dependence of the gravitational angular momentum on the frame, and argue that it is a measure of the dragging of inertial frames.     

铒离子注入绝缘体上Si的射程分布研究

利用离子注入掺杂技术设计、制作半导体集成器件时,了解离子注入半导体材料的射程分布和横向离散规律等是很重要的.用200—500 keV能量的铒(Er)离子注入SOI(silicon-on-insulator,绝缘体上的硅)样品中,利用卢瑟福背散射(RBS)技术研究了剂量为2×1015cm-2的Er离子注入SOI的平均投影射程Rp和射程离散△Rp,把测出的实验值和SRIM软件得到的理论计算值进行了比较,发现平均投影射程Rp的实验值跟理论计算值符合较好,射程离散△Rp的实验值和理论计算值差别大一些.     

Au5+ ion implantation induced structural phase transitions probed through structural,microstructural and phonon properties in BiFeO3 ceramics,using synergistic ion beam energy

Implanted Au⁵⁺-ion-induced modification in structural and phonon properties of phase pure BiFeO₃ (BFO) ceramics prepared by sol–gel method was investigated. These BFO samples were implanted by 15.8?MeV ions of Au⁵⁺ at various ion fluence ranging from 1?×?10¹⁴ to 5?×?10¹⁵?ions/cm². Effect of Au⁵⁺ ions’ implantation is explained in terms of structural phase transition coupled with amorphization/recrystallization due to ion implantation probed through XRD, SEM, EDX and Raman spectroscopy. XRD patterns show broad diffuse contributions due to amorphization in implanted samples. SEM images show grains collapsing and mounds’ formation over the surface due to mass transport. The peaks of the Raman spectra were broadened and also the peak intensities were decreased for the samples irradiated with 15.8?MeV Au⁵⁺ ions at a fluence of 5?×?10¹⁵?ion/cm². The percentage increase/decrease in amorphization and recrystallization has been estimated from Raman and XRD data, which support the synergistic effects being operative due to comparable nuclear and electronic energy losses at 15.8?MeV Au⁵⁺ ion implantation. Effect of thermal treatment on implanted samples is also probed and discussed.