Third-order nonlinear optical response of Cu/Ag nanoclusters by ion implantation under 1064 nm laser excitation

The evolution of nanoclusters in sequentially ion-implanted Cu/Ag into silica glasses has been studied. The doses for implantation (×10¹⁶ ions/cm²) were 5Cu/5Ag, 5Cu/10Ag and 5Cu/15Ag, respectively. The microstructural properties of the nanoclusters are characterized by optical absorption spectra and transmission electron microscopy (TEM). Fast nonlinear optical refraction and nonlinear optical absorption coefficients were measured at 1064 nm of wavelength using Z-scan technique. Results in this project indicate that different optical nonlinearities could be selectively obtained at the near-infrared region of 1064 nm of wavelength by changing the metal ingredient percentage in silica.     

注镧Co-Cr合金表面氧化膜生长规律与微观结构表征

采用热重分析(TGA)方法研究了离子注镧对Co-40Cr合金在1000℃空气中的恒温氧化和循环氧化行为的影响. 用扫描电镜(SEM)和透射电镜(TEM)对表面氧化膜的微观形貌和结构进行了研究. 用二次离子质谱(SIMS)对合金表面元素铬结合能的变化情况以及氧化膜中元素镧的深度分布进行了测试, 并用激光拉曼谱(Raman)对掺杂镧引起的氧化膜内应力改变进行了测量研究.结果表明, 离子注镧后Co-40Cr合金在1000℃空气中的恒温氧化速率显著降低, 表面Cr₂O₃ 关键词： 离子注入 镧 拉曼谱 二次离子质谱     

半圆形容器等离子体源离子注入过程中离子动力学的两维PIC计算机模拟

利用两维particle-in-cell方法研究了半圆形容器表面等离子体源离子注入过程中鞘层的时空演化规律. 详尽考察了鞘层内随时间变化的电势分布和离子密度分布规律,离子在鞘层中的运动轨迹和运动状态,得到了半圆容器内、外表面和边缘平面上各点离子注入剂量分布规律,获得了工件表面各点注入离子的入射角分布规律. 研究结果揭示了半圆容器边缘附近鞘层中离子聚焦现象,以及离子聚焦现象导致工件表面注入剂量分布和注入角度分布存在很大不均匀的基本物理规律. 关键词： 等离子体源离子注入 鞘层 两维particle-in-cell方法 离子运动轨迹     

Paramagnetic defects induced by ion implantation in oxide glasses

Radiation defects induced by ion bombardment of multicomponent oxide glasses of five compositions (phosphates and borosilicates) were investigated by means of electron paramagnetic resonance (EPR). The samples were implanted with N⁺, O⁺, Ar⁺, Mn⁺, Cu⁺ and Pb⁺ ions at energy E=150 keV at three different doses between 3×10¹⁵ and 10¹⁷ ions/cm². The broad anisotropic EPR spectra with principal g-values answering the relationship g_z>g_y>g_x˜g_e (g_e is g-factor of free electron) were observed for the samples of all five compositions. The g-values depend on glass composition. For example, g_z ranges from 2.016 to 2.057. Computer simulation shows that the spectra of many samples are superpositions of two spectra with g-values answering the mentioned relationship. These spectra are attributed to molecular O₂⁻ ions weakly coupled with glass network. In some samples narrow almost symmetric lines with g=2.0025±0.0005 were observed. The possible radiation defects responsible for this signal are discussed.     

Preparation of a Novel COOH Ion Implantation Sensor and Its Application

A novel ion implantation sensor (DNA/COOH/ITO) based on DNA immobilization in COOH/ITO probe was manufactured for the first time. The surface morphologies of the electrodes were characterized by X‐ray photoelectron spectroscopy (XPS), field‐emission‐scanning electron microscopy (FSEM) and electrochemical methods. In a 0.5 mol/L PBS solution, a sensitive oxidation peak of DNA on the COOH/ITO electrode was obtained by voltammetry. The electrochemical behavior of DNA was studied. And the oxidative peak potential of DNA was +0.400 V (vs. Ag/AgCl). Its peak current was proportional to the concentration of DNA over the range of 1.0×10^?8?1.0×10^?6 mol/L with a detection limit of 5.0×10^?9 mol/L (about 0.5 ng/mL). This sensor was applied to the direct detection of DNA samples.     

JRQ and JPA irradiated and annealed reactor pressure vessel steels studied by positron annihilation

The paper is focused on a comprehensive study of JRQ and JPA reactor pressure vessel steels from the positron annihilation lifetime spectroscopy (PALS) point of view. Based on our more than 20 years’ experience with characterization of irradiated reactor steels, we confirmed that defects after irradiation start to grow and/or merge into bigger clusters. Experimental results shown that JPA steel is more sensitive to the creation of irradiation-induced defects than JRQ steel. It is most probably due to high copper content (0.29?wt.% in JPA) and copper precipitation has a major impact on neutron-induced defect creation at the beginning of the irradiation. Based on current PALS results, no large vacancy clusters were formed during irradiation, which could cause dangerous embrittlement concerning operation safety of nuclear power plant. The combined PALS, small angle neutron scattering and atomic probe tomography studies support the model for JRQ and JPA steels describing the structure of irradiation-induced clusters as agglomerations of vacancy clusters (consisting of 2–6 vacancies each) and are separated from each other by a distribution of atoms.     

STUDY OF THE NUCLEAR PHENOMENA IN THE LOW ENERGY (60-360 keV) PROTON BEAM IMPLANTATION ON METALS

A series of studies on the nuclear interaction and its effects in solids during proton implantation were performed in the energy region between 60 and 360keV. Some charged particle products were observed in the implantation experiments on metal samples such as deuterated titanium, titanium alloy, titanium foil on molybdenum substrate, molybdenum and stainless steel, etc.. The energies of the charged particle products are about 3.9, 5.6 and 8.4MeV, respectively. These particles were identified as alpha particles with both detector telescope and absorption measurements. These three kinds of alpha products were found from different proton sub-barrier reactions. The exciting curve of this reaction increases exponentially with the growth of proton energy in the energy region from 90 to 330keV. The radiation damages induced by the nuclear products in the sample have been studied with scanning electron microscopy technique. The possible surface damages induced by them were observed evidently. The origin of the nuclear reactions and their effect on implantation are discussed.     

On the Analysis of Hydrogen in as grown and Ion Implanted GaAs Single Crystals

Hydrogen detection and analysis was carried out on the undoped semi‐insulating (S.I.) gallium arsenide (GaAs) single crystal using conventional elastic recoil detection analysis (ERDA) technique with high energy, heavy ion beam. Presence of hydrogen (nearly 3 x 1020 atoms/cc) has been observed on the as‐grown samples and further high concentration of atomic hydrogen (total concentration of 7 x 1020 atoms/cc) was found at the surface and was found to be decreasing with depth after 100 nm. Further the low energy hydrogen and oxygen ions implanted separately in GaAs at room temperature were also analysed by ERDA technique. From the analysis, the projected range (Rp) of 100 keV hydrogen and oxygen ions in GaAs was determined to be 891 nm (with Δ Rp equal to 320 nm), 170 nm (with Δ Rp equal to 120 nm) respectively. The experimentally determined values of both Rp and Δ Rp are more as compared with the values obtained using the TRIM theoretical program. Low temperature (4K) photoluminescence (PL) measurements of un‐implanted and H⁺ implanted samples show the passivation of intrinsic deep level defect EL2 and shallow acceptor impurity carbon by the low energy implanted hydrogen ions. The low energy hydrogen implantation may be used as a method of hydrogenation for passivation.     

Ion implant-induced change in polyimide films monitored by variable energy positron annihilation spectroscopy

6FDA-pMDA polyimide membranes were implanted with 140 keV N⁺ ions to fluences between 2 × 10¹⁴ and 5 × 10¹⁵ cm⁻². Variable energy positron annihilation spectra were taken and spectral features compared to previously reported changes in gas permeability and permselectivity of these membranes as a function of ion fluence. Positron data corroborate the explanation of these changes in terms of molecular damage caused by the implant: for fluences up to about 1 × 10¹⁵ cm⁻², the concentration of irradiation-induced defects merely increases with implant fluence; while fluences exceeding this threshold value create a second type of positron annihilation site, thereby marking a distinct change in the structure of the polymer, which is responsible for the vast improvement of gas permselectivity data found at the same threshold fluence. PACS codes: 78.70.Bj—positron annihilation; 61.82.Pv—polymers, organic compounds; 61.72.Ww—doping and impurity implantation. © 1998 John Wiley & Sons, Inc. J. Polym. Sci. B Polym. Phys. 36: 2413–2421, 1998     

C+注入a-SiNx：H薄膜的微结构及光发射的研究

常温下对低压化学气相沉积制备的纳米硅镶嵌结构的a-SiN_x:H薄膜进行低能量高剂量的C⁺注入后,在800~1200℃高温进行常规退火处理。X射线光电子能谱(XPS)及X射线光电子衍射(XRD)等实验结果表明,当退火温度由800℃升高到1200℃后,薄膜部分结构由SiC_xN_y转变成SiN_x和SiC的混合结构。低温下利用真空紫外光激发,获得分别来自于SiN_x、SiC_xN_y、SiC的,位于2.95,2.58,2.29 eV的光致发光光谱。随着退火温度的升高,薄膜的结构发生了变化,发光光谱也有相应的改变。