排序方式: 共有47条查询结果,搜索用时 31 毫秒
21.
利用反应显微成像谱仪对70和100keV He2+与He原子碰撞转移电离(TI)过程中不同出射角度的电子能谱进行了测量,观测到出射电子能谱具有如下分布特征:出射电子速度分布介于0和入射离子速度vp之间;在不同出射角度电子能谱分布均有一极大值存在,随着出射角度的增大,能谱分布极大值逐渐减小;当电子出射角度等于45°时,多数电子集中在0eV附近。上述特征可由低能离子-原子碰撞"准分子"模型进行定性解释。在100keV He2+-He转移电离出射电子能谱中有靶电子被俘获至散射离子连续态(electron capture to continuum,简称ECC)电子的贡献,这可看做是动力学两步过程的作用。 相似文献
22.
23.
24.
汶伟强 马新文 张大成 朱小龙 孟令杰 李杰 刘惠萍 赵冬梅 王之帅 毛瑞士 赵铁成 武军霞 马晓明 晏太来 李国宏 杨晓东 刘勇 杨建成 原有进 夏佳文 徐瑚珊 肖国青 赵红卫 《中国物理 C》2013,37(10)
The longitudinal Schottky spectra of a radio-frequency (RF) bunched and electron cooled 22Ne10+ ion beam at 70 MeV/u have been studied by a newly installed resonant Schottky pick-up at the experimental cooler storage ring (CSRe), at IMP. For an RF-bunched ion beam, a longitudinal momentum spread of Δp/p=1.6×10-5 has been reached with less than 107 stored ions. The reduction of momentum spread compared with a coasting ion beam was observed from Schottky noise signal of the bunched ion beam. In order to prepare the future laser cooling experiment at the CSRe, the RF-bunching power was modulated at 25th, 50th and 75th harmonic of the revolution frequency, effective bunching amplitudes were extracted from the Schottky spectrum analysis. Applications of Schottky noise for measuring beam lifetime with ultra-low intensity of ion beams are presented, and it is relevant to upcoming experiments on laser cooling of relativistic heavy ion beams and nuclear physics at the CSRe. 相似文献
25.
Geometric structure of N2Oq+ (q = 5, 6) studied by Ne8+ ion-induced Coulomb explosion imaging 下载免费PDF全文
We report the study on the complete three-body Coulomb explosion (CE) of N2Oq+ (q = 5, 6) induced by 56-keV/u Ne8+ ion collision with N2O gaseous molecule. Six CE channels for N2O5+ and seven for N2O6+ are identified by measuring three ionic fragments and the charge-changed projectile in quadruple coincidence. Correspondingly the kinetic energy release (KER) and momentum correlation angle (MCA) distributions of three ionic fragments for each of the CE channels are also deduced. Numerical computation is presented to reconstruct the geometric structure of N2Oq+ prior to dissociation based on the measured KER and MCA. The N-N and N-O bond lengths and the N-N-O bond angles of N2Oq+ for each of the channels are determined. 相似文献
26.
原子团簇的激发温度可由反应产物(出射电子或碎片)的初始平动能这一可观测量间接获得,为了提高原子团簇激发温度的测量精度,设计并搭建了一套具有高动能分辨的离子速度成像谱仪。本谱仪的高动能分辨性能首先借助Simion8.0软件优化静电透镜和分子束限束装置的几何结构来实现,然后通过理论模拟证明本套谱仪具有预期好的动能分辨能力。设备搭建完成后,研究了C60分子束在纳秒激光场中发生的延迟电离过程,获得了C60+离子随延迟时间增加而逐渐变窄的二维时间切片图像。分析表明,激光脉冲产生的多个C60+离子间的库仑耦合作用将会扩展二维切片图像的横向分布,提取库仑耦合作用对C60+离子初始平动能的影响,并通过分析C60+离子间的库仑耦合随延迟时间增加而逐渐变弱的定量依赖关系,证实了本套谱仪具有了设计预期的高动能分辨能力。这一工作为下一步基于离子速度成像技术细致研究分子热力学的相关课题提供技术参考。Excitation temperature of fragmenting atomic clusters can been extracted from the initial kinetic energies of ionic products. To improve the accuracy of the temperature measurements, we have designed an ionic velocity map imaging spectrometer with high kinetic energy resolution. Firstly, based on the simulations using Simion8.0 software, the high resolution is obtained by adjusting the structure of the electrostatic lenses and collimation of molecular beam. According to theoretical analysis, it is proved that the spectrometer has a well defined kinetic energy resolution. Then, we have studied the delay ionization processes of C60 induced by nanosecond laser. A series of narrowed two-dimensional time-sliced velocity images of the C60+ with increasing the delayed time were recorded. Analysis revealed that Coulomb force between C60+ clusters in same laser shots will broadening the transverse distribution of 2D image. Considering the influence of Coulomb force on initial kinetic energy of C60+ clusters, the high resolution has been proved by analysing the negative relationship between Coulomb force and delayed time. It indicates that the establishment of the spectrometer builds up a good basis for next experiments on the studies for molecular thermodynamics in atomic clusters. 相似文献
27.
三角代数上的广义Jordan导子 总被引:1,自引:0,他引:1
主要研究了三角代数上的广义Jordan导子.利用三角代数上广义Jordan导子和广义内导子的联系.证明了作用在一个含单位元的可交换环上的三角代数到其自身上的环线性广义Jordan导子是一个广义导子. 相似文献
28.
基于纳秒Nd∶YAG激光器与卡塞格林式望远镜系统建立了一套25m远距离激光诱导击穿光谱测量装置,实现了对金属靶材的远距离测量.在此基础上,利用铝合金标样开展了金属中微量元素远程定量分析,研究了不同距离下铝合金中Pb、Fe、Ni三种元素的定量分析标定曲线与探测极限.实验结果表明,在5m至20m三种测量距离下,Pb、Fe、Ni三种元素定标曲线的相关性系数均高于0.97;尽管激光诱导击穿光谱的光谱信号随测量距离增加快速下降,但是检测限随测量距离增加并无显著改变,均在50ppm以下. 相似文献
29.
利用反应显微成像谱仪开展了56 keV/u的Ne~(4+)离子与羰基硫(OCS)气体的交叉碰撞实验,研究了Ne~(4+)离子诱导的OCS~(3+)的碎裂动力学.通过符合探测三个末态离子,重构了OCS~(3+)离子三体碎裂对应的牛顿图和Dalitz图,并明确区分了直接解离和次序解离两种碎裂过程.重构了OCS~(3+)离子解离过程的动能释放(KER)分布,发现其峰值在25 eV处,同时在18 eV处有肩膀结构的存在,其中25 eV左右的峰来源于直接解离过程,18 eV处的肩膀结构来源于次序解离和非次序解离两种过程.通过分析不同能量和不同电荷态下重离子碰撞实验所得到的KER谱,发现微扰强度不是影响态布居的主要因素.OCS~(3+)次序解离中的第二步KER的峰值在6.2 eV处.结合以往的实验结果,我们得出结论:多电离态的分子发生次序碎裂的根源在于二价离子碎片存在亚稳态,而重构得到的第二步KER可以反映亚稳态离子的电子态信息. 相似文献
30.
利用冷靶反冲离子动量谱仪装置系统研究了20-40 keV He2+-He碰撞体系的态选择单电子俘获过程,实验获得了单电子俘获过程的态选择截面以及角微分截面.在所研究的能区范围,电子俘获到L壳层的截面最大,为主要的反应道,这与分子库仑过垒模型的反应窗理论的预测一致.实验测量的态选择截面与原子轨道紧耦合的计算结果很好地符合,与光谱方法的测量结果存在一定的差别,主要原因是光谱方法不能测量完整的反应通道信息.实验结果表明,总角微分截面在小角度范围主要来源于电子俘获到基态的贡献,在大角度范围主要来自电子俘获到激发态的贡献;电子俘获到基态的和激发态的角微分截面均出现振荡结构,这种振荡来源于电子俘获反应中分子轨道之间的相干效应.实验测量的角微分截面与其他实验和紧耦合方法的计算结果进行了比较和分析. 相似文献