Differential cross section measurements at 10 eV region for one-electron caputure processes concerning multiply-charged ion collisions.

在测量电荷转移反应产生的散射离子角分布时，交叉光束仪的性能得到了很大的提高。它由一个小型电子束-离子源、一个双静电半球形能量选择器和一个离子探测器组成。为了获得良好的能量和角分辨率，采用超音速喷管束制备靶。碰撞能量测定的精度优于0.1 eV，角度读数的精度约为0.5度。离子以2 kV的萃取电位从源中提取，然后减速到250 x q eV （q表示离子的电荷态），然后通过维恩滤波器进行质量选择。将大量选择的离子减速到选择器的传输能量约为30 xq eV，然后使用两组三元透镜再次减速到所需的碰撞能量。主光束的角散度约为*0.5度，在FWHM下的能量扩散估计为0.3 x q eV。在10 eV时，光束强度为pA数量级。对于产物离子的能量分析，使用了一个90度的静电圆柱形偏转板，并在其上附加了一个位置敏感探测器系统。在研究过程中，我们注意到最重要的一点是对噪声的抑制。因此，分析系统位于井屏蔽盒内。在实验室框架下，测量了0^<2+> + He碰撞中0^<2+>离子在Ecm = 10 eV， 0 ~ 5度范围内的单电子捕获过程中产生的动能。在能谱上只观察到一个单峰。这个峰对应于反应，0^<2+>(^3P) + He—> 0^+(^2P) + H^e + 5.6 eV；这与先前报道的结果一致，证明了该仪器的性能足以在未开发的能量区域进行测量。

The performance of the crossed-beam apparatus to measure the angular distribution of the scattered ions created by charge-transfer reactions was improved much. It consists of a small Electron-Beam-Ion-Source, a double electrostatic hemispherical energy-selector, and an ion detector. To obtain good energy- and angular-resolution, a supersonic nozzle-beam is used to prepare the target. The accuracy of the collision-energy detennination was found to be better than 0.1 eV, and that of angular -reading was about 0.5 degree. The ions were extracted from the source by the extraction potential of 2 kV, then decelerated to 250 x q eV, where q denote the charge-state of the ions, then mass-selected by a Wien-filter. The mass-selected ions were decelerated to the transmission energy of the selector, about 30 xq eV, then again decelerated to the desired collision energy using two sets of three-element lens.The angular divergence of the primary beam was about*0.5 degree , and the energy spread was estimated to be 0.3 x q eV, at FWHM.The intensity of the beam was in the order of pA at 10 eV.For the energy analysis of the product ions, a 90 degree electrostatic cylindrical deflector was used, and a position-sensitive detector system is attached to that. During the course of this study, it is noticed that the most important point is the noise redaction. Therefore, the analyzer system is located inside well shielded-box.The kinetic energy of 0^<2+> ions produced in one-electron capture process in 0^<2+> + He collisions were measured at Ecm = 10 eV, from 0 to 5 degree in the laboratory frame. Only a single peak was observed on the energy spectrum. This peak corresponds to the reaction, 0^<2+>(^3P) + He ---> 0^+(^2P) + H^e + 5.6 eV ; this agrees well with that reported previously, and proved that the performance of the apparatus is good enough to do measurement in an unexplored energy region.