低能离子对氨基酸损伤的红外光谱研究

分别轻注入机和气体常压孤光放电产生的你了子作用于固态和溶液中的氨基酸,研究了样品红外光谱的变化。结果表明,两种方式产生的离子对氨基酸有相同或相似的损伤作用,如分子重排、外来离子沉积等,而且低能离子作用于溶液样品表现出更显著、更丰富的损伤效果。     

Analysis of a hollow-cathode reflex discharge in a hydrocarbon flow

Variation of parameters of a reflex discharge with a hollow cathode operating continuously in propane with a flow rate of 1.3–5.6 (m³ mPa)/s and a discharge current of 0.1–0.4 A is analyzed. It is shown that for a hydrocarbon flow rate of 2.4 (m³ mPa)/s and higher, an increase in the discharge voltage takes place after a time interval depending on the discharge current and gas pressure; this is explained by the formation of coating of the dissociation products of hydrocarbon molecules on the electrodes of the discharge chamber. An increase in the thickness of the carbon coating of the cathodes with time and their charging with ions lead to electric breakdown of coatings and the formation of cathode spots. The oscillograms of the discharge current and voltage indicate a short-term transformation of the glow discharge into the arc discharge. The energy spectra of ions emerging from the discharge are measured, and the effect of the discharge current and the gas flow rate on the energy spread of ions is analyzed. The operation time of the discharge in hydrocarbon after which the cleaning of the discharge chamber is required is determined. The possibility of using an ion source based on the reflex discharge with a hollow cathode for technological purposes is established.     

低能离子对酪氨酸溶液损伤作用的光谱研究初报

利用气体我放电产生低能离子,其在放电间隙的电场加速下撞击水溶液样品。了低能离子作用后酪氨酸溶液的紫外及红外吸收光谱的变化。结果表明,气体放电产生的离子对Ｔｙｒ造成了多种损伤。不仅使化学键断裂,分子解体,而且外来的活性离子会与溶液中的元素形成新的化学基团,妆在受损伤分子碎片上组成新的损伤物质,充分体现了低能离子与物质相互作用的“离子沉积”效应。     

Optical emission spectroscopy of the sputtering process in the triode system

The results of spectroscopic investigation of plane plasma discharge and sputtering processes in the triode system are presented. The forced electric discharge with currents of 1–4 A at an argon pressure of 1 mTorr was studied using the emission spectroscopy method. The spectra of plasma discharge were observed in the 200–1100 nm wavelength range. Two metal targets, gold and silver, were used for sputtering. It was found that a part of sputtered particles is ionized in plasma. The emission spectra of the ionized gold and silver species were observed as a function of target voltage while sputtering. It was shown that the number of ionized metal species depends on the energy of argon ions.     

毛细管放电条件下类氖序列原子参量计算与分析

利用多组态求解相对论性的Hartree-Fock-Roothan方程(HFR)方法计算了类氖离子(Z=13～27)2s^22p^5—2s^22p^53s能级之间跃迁的原子参量,包括类氖氩激光系统的能级,振子强度,自发辐射衰变速率,能级寿命,电子碰撞激发截面及电子碰撞激发速率系数等。以类氖氩离子为例,分析了等离子体内46．9nm激光跃迁的粒子数反转的形成及谱线放大过程,讨论了其它几条谱线产生增益的可能性,分析了激光线振子强度随核电荷数的变化规律。根据获得的原子参量,计算了利用毛细管放电产生类氖氩和类氖氪x射线激光的放电参量,其中类氖氩毛细管放电的初始压强的范围为30~90Pa,放电电流峰值为10～50kA。理论计算结果为类氖氩x光激光实验分析,深入研究等离子体反转动力学,激光增益的估算及理论方案设计等提供了基本数据。     

时间分辨原子发射光谱诊断脉冲放电气体束等离子体

建成了一套脉冲放电气体束和原子发射光谱等离子体诊断实验装置,利用这套实验装置测量了不同放电条件下等离子体的时间分辨发射光谱,并采用玻尔兹曼作图法和Hα谱线斯塔克展宽法研究了等离子体的原子温度、离子温度和自由电子密度等参数的演化。实验结果表明,脉冲放电的总电量对等离子体参数的演化有较大影响;脉冲放电气体束等离子体中的离子温度远高于原子温度,自由电子密度相对较低,等离子体处于非局域热平衡状态。A special designed pulsed discharge nozzle (PDN) ion source and a plasma diagnostics system based on the atomic emission spectroscopy were constructed. The time-resolved emission spectra of Argon atoms and ions in the region of 300-800 nm were observed and analyzed. The plasma temperatures, including atomic and ionic temperatures, were simulated by Boltzmann plot method, and the free electron density was simulated through the Stark broadening of Hα line. The evolution of these plasma parameters were investigated by high-resolution time-resolved emission spectra. The results show that the total energy struck on the pulsed gas beam is the most important factor which determines the plasma properties and its evolution. The plasma in PDN is concluded into non-local thermodynamic equilibrium (non-LTE) during the evaluation because of the low electron density and the big difference between the temperatures of Argon atoms and ions in all discharge conditions.     

短管螺旋波放电中等离子体参数测量和模式转化研究

对长度为45 cm的短放电管螺旋波放电等离子体进行了Langmuir探针、原子发射光谱以及集成电荷耦合检测器(ICCD)检测诊断,研究螺旋波等离子体的放电特性.Langmuir探针数据显示电子密度在射频功率增加过程中出现两次大幅增长,由此确认了放电模式的转换及螺旋波放电模式的出现.发射光谱测量结果与Langmuir探针测量的电子密度数据一致,发现Ar原子和Ar离子的谱线强度与放电模式变化有着密切相关性.而通过对不同放电模式的ICCD测量,获得射频功率吸收因放电模式转变而变化的方式,认为放电模式转换时电子行为和能量传递方式也发生着变化.     

Simple technique for measurement of energy spectra of ions from laser produced plasma

Old absorption technique is revived for measuring the energy spectra of ions arising from laser generated plasma. The technique suggested relies on implantation of produced ions into a light element target situated close to the ion production site. Then the ion energy spectra are reconstructed from the depth profile of the implanted ions measured by some of the common depth profiling techniques such as RBS or SIMS. Theoretical range vs. ion energy relations are used for this purpose. In this study the principles of the method are explained and its capabilities are assessed. The feasibility of the method is demonstrated on the energy spectra of Ta ions arising from the laser generated plasma.     

Ion bombardment of amorphous silicon films during plasma-enhanced chemical vapor deposition in an rf discharge

The characteristics of ion and electron fluxes to the surface of a growing silicon film are investigated in various rf discharge regimes in silane at frequencies of 13.56 MHz and 58 MHz in plasma-enhanced chemical vapor-deposition (PECVD) apparatus. The energy spectra of the ions and electrons bombarding the growing film are measured. The electronic properties of films grown under various degrees of ion bombardment are studied. The correlation of these properties with the ion parameters in the rf discharge plasma during film growth is discussed. Zh. Tekh. Fiz. 68, 52–59 (February 1998)     

氮气射频放电与直流放电PIC/MC模拟的比较

建立氮气容性射频等离子体过程的PIC/MC模型,将模拟结果与直流放电进行比较.结果表明:射频等离子体粒子(e,N₂⁺,N⁺)的平均密度较直流放电约大-个量级,在射频电极附近粒子(e,N₂⁺,N⁺)的平均能量比直流放电阴极附近的能量低3倍左右;密度偏低的原子离子N⁺在两电极附近具较高的能量,能量较低的分子离子N₂⁺在放电空间具较高密度,N₂⁺的密度大约是N⁺的6倍;计算的电子能量几率分布与测量结果-致.     

空气中空心阴极不同放电模式下的发光特性

为了进一步揭示空心阴极放电中放电模式的转换机制,特别是空心阴极放电过程中自脉冲的形成机理,利用柱型空心阴极放电结构,在空气环境下研究了放电处于不同模式时的发光特性。测量得到了不同放电模式下的伏安特性曲线、放电发光图像、自脉冲阶段的脉冲波形等。实验结果表明随着放电电流的增加放电分为汤生放电模式、自脉冲放电模式、正常辉光放电模式和反常辉光放电模式。虽然所用电源为直流电源,但在自脉冲放电阶段电流和电压随时间呈周期性变化。实验结果表明在不同的放电模式下具有不同的发光特性。在由汤生放电转换为自脉冲放电模式和由自脉冲模式转换为正常辉光放电模式过程中,放电腔的径向中心处和轴向孔口附近均存在光强的突变。实验同时在200～700 nm范围内测量得到了不同电流时的发射光谱。结果表明发射光谱主要集中在330～450 nm,主要包括氮分子的第二正带系(C3Π_u→B3Π_g )和氮分子离子的第一负带系（B2Σ+_u→X2Σ+_g）。其中氮分子离子第一负带系具有较强的发射光谱。由于B2Σ+_u激发电位较高,因此该谱带较强发射光谱的存在表明空心阴极放电较其他放电形式更容易获得高激发态粒子和高能量电子。在650～700 nm附近存在一弱的发光谱带,主要为氮分子的第一正带发射谱（B3Π_g→A3Σ+_u）。在此基础上根据双原子光谱发射理论,结合氮分子第二正带系的三组顺序组带：Δν=-1,-2和-3,利用玻尔兹曼斜率法计算得到了不同放电模式下氮气的分子振动温度。结果表明在实验电流范围内分子振动温度在3 300 K左右,随着电流的增加而升高,并且在自脉冲消失时存在一突变迅速增强。由于电子能量、电子密度与分子振动温度密切相关,因此该结果也表明随着放电电流的增加电子平均能量和电子密度不断增加,当脉冲消失时,电子平均能量和电子密度出现跃变升高。最后,对空心阴极放电中自脉冲的形成机理进行了讨论,结果表明自脉冲放电源于放电模式的转换。     

依据光谱研究闪电放电通道的半径及能量传输特性

利用无狭缝摄谱仪获得的云对地闪电回击过程的光谱, 结合同步辐射电场变化资料, 计算了闪电放电通道的温度、线电荷密度、通道的初始半径和扩张后的半径以及回击通道单位长度储存的能量. 结果与文献报道的其他方法得到的结果符合很好. 这些物理量的相关性分析表明: 电弧通道的初始半径主要取决于回击电流的持续时间; 通道温度越高, 半径越大; 通道初始半径、单位长度储存的能量与光谱总强度正相关, 通道单位长度储存的能量与初始半径的平方成正比. 关键词： 闪电放电通道 半径 能量 光谱总强度     

Calculation of LET-spectra of heavy cosmic ray nuclei at various absorber depths

The calculation is based on a factorization of fragmentation cross-sections into a projectile-depending and a target-depending part, which was found at Bavalac for high energy C and O ions. With this the known cross-sections for the fragmentation of heavy ions in collision with protons can be extrapolated to heavier targets. Considering the fragmentation and the energy loss of heavy nuclei the energy spectra of individual elements are calculated for different depths of absorber. This energy spectra can easily be converted to LET (linear energy transfer) spectra. The changes of the isotopic composition with absorber depth and its influence on the shape of the LET-spectra are discussed. The calculated results are compared with experimental data.     

Mechanism and dynamics of the disintegration calcite shock waves

Luminescence spectra associated with calcite disintegration under the action of an electric-discharge-induced shock wave and under friction have been obtained. It has been found that, in these cases, the destruction mechanisms differ. Under the action of the wave, the crystal lattice of calcite decomposes into positively charged calcium, carbon, and oxygen ions. During friction, calcite disintegrates due to microcrack accumulation. The fraction of the volume that decomposes into ions depends on the electrical discharge energy. The percentage of decomposed calcite exceeds 60% when the energy is roughly equal to 80 J and is no higher than several fractions of a percent when the energy equals 0.2 J. In the latter case, disintegration localizes at grain boundaries, as follows from the time-resolved luminescence study (a time resolution of 2 ns).     

Energy spectra of ions sputtered from elements by O+2: A comprehensive study

The results of a comprehensive study of the energy distributions of ions sputtered from 31 pure elements and two compounds by a 5.5 keV O⁺₂ beam are presented. The spectra were determined under three different ambient conditions: residual vacuum or low argon pressure backfill, oxygen backfill, and nitrogen backfill. The energy spectra of polyatomic ions are narrower and peaked at lower energies than the atomic ion spectra and decrease in width and average energy with greater ion complexity. The statistical model of polyatomic ion formation does not correctly describe the shape of the energy distributions. The atomic ion energy spectra reveal that more than one ionization mechanism is responsible for the formation of ions from the various elements and that the dominant mechanism is frequently different in the presence of a reactive gas than in a vacuum. Periodic trends of the parameters describing the energy distributions are dependent on the electronic structure of the ions. The average energies of the distributions correlate with the sublimation energies of the pure elements, but the most probable energies do not. Apparent surface binding energies calculated from the energy distributions are presented.     

气体放电空心阴极鞘层氩离子的蒙特-卡罗模拟研究

建立了气体放电空心圆筒阴极鞘层离子的自洽蒙特-卡罗模拟模型,对鞘层区内离子的输运过程进行了研究。考虑了离子与中性原子的电荷交换碰撞和弹性散射,用到了精确依赖于离子能量的电荷交换和动量输运截面。模拟了氩离子在空心阴极鞘层中的运动,得到了不同放电条件下自洽电场分布,离子的能量分布,角分布以及电子密度分布和离子密度分布。计算结果表明:离子在由鞘层边界向阴极运动过程中,离子能量分布的高能部分逐渐增大,角分布向小角度部分压缩,鞘层中的强电场对离子起加速和聚焦作用;在鞘层内离子密度分布比较均匀,只是在鞘层边界附近变化 关键词：     

Energy distribution of metal and noble gas ions traversing single-crystal copper films

A comparative investigation of the energy distribution of ions that traversed single-crystal cooper films reveals that the energy loss of channeled and nonchanneled particles depends not only on the mass but also on the radius of bombarding ions. It is established that the energy spectra of transmitted ions are highly sensitive to a change in the composition and structure of the films. From the change in these spectra, one can estimate the degree of disordering in thin films under various applied forces.     

Spectral characteristics of a high-current pulsed discharge in xenon

The radiation characteristics of a pulsed discharge xenon lamp are experimentally and theoretically studied. The data on radiation spectra are obtained for various compositions and pressures of working medium, energies and time profiles of excitation pulse, discharge gap configurations, etc. Electron temperature and mean spectroscopic symbol of emitting ions are estimated. It is demonstrated that cw radiation (continuum) results from the photorecombination transitions.     

N2��Ƶ�ŵ��������(e,N2+, N+)��PIC-MCģ��

采用PIC-MC自洽模型,模拟了氮气电容性耦合射频放电的微观等离子体过程及带电粒子(e,N2+,N+)的行为。结果表明,离子(N2+,N+)的运动状态滞后瞬时射频电场的变化;在两极附近,N2+具较高密度,但能量较低,N+具较低的密度但能量较高,两者的密度差6倍左右。两种离子轰击射频电极的能量分布变化规律类似,随放电参数变化,离子(N2+,N+)能量变化显著,其密度变化不明显。模拟的电子能量几率分布与测量结果一致。     

喷气式Z箍缩等离子体装置中离子束能谱的测量

利用新研制的紧凑型汤姆生离子能谱仪（ＴｈｏｍｓｏｎＩｏｎＥｎｅｒｇｙＡｎａｌｙｚｅｒ），对喷气式Ｚ－箍缩等离子体装置中离子能谱进行了测量，在ＣＲ－３９上得到了清晰的Ａｒ＋，Ａｒ２＋，Ａｒ３＋离子抛物线轨迹，通过分析计算结果表明：离子的最大能量在１ＭｅＶ左右，离子能谱分布曲线都随其能量增加而单调下降。