SPECTROSCOPIC DETERMINATION OF THE BRANCHING RATIOS OF DISSOCIATIVE RECOMBINATION REACTIONS

该装置由离子源、离子光学、质谱仪、离子-电子碰撞室、低温气体基质和红外傅里叶变换光谱仪组成。在本项目的两年时间里，与红外光谱仪一起实施了开放式质谱仪和矩阵形成装置，并对系统的整体性能进行了检查。电晕放电超音速膨胀喷嘴和离子选择速度过滤器被安装在定制的燃烧室中。整个系统现已接近完成。然而，低能电子束发生器的制造和测试有些延迟，目前它的设计已经敲定。为了确定离子与电子之间解离复合反应的支化比，必须测量产物中性分子的浓度。我们的第一个目标是HCNH的解离复合，主要的中性体是HCN和HNC，但目前还不知道HNC的跃迁偶极矩。我们用傅里叶变换红外光谱仪记录了HNC的v_1和v_3带，发现Herman-Wallis效应足以确定v_1带的跃迁偶极矩，并得到了跃迁偶极矩的初步值。综上所述，尽管光谱测定解离复合分支率对于理解星际化学和物理过程极其重要，但它仍然是一个相当未被开发的领域。我们肯定会继续完善实验设置，并将向我们的社会提供必要的信息。

The apparatus consists of an ion source, ion optics, a mass spectrometer, an ion-electron collision chamber, a low-temperature gas matrix, and an infrared Fourier transform spectrometer. During the two-year period of this project, open-type mass spectrometer and a matrix formation apparatus were implemented together with the IR spectrometer, and checked the overall performance of the system. A corona discharge supersonic expansion nozzle, and an ion selection velocity filter have been installed in a custom made chamber. The whole system is now at near completion. Manufacturing and testing a low-energy electron beam generator, however, is somewhat delayd, and at the present stage, its design has been finalized. In order to determine the branching ratio of dissociative recombination reactions between ions and electrons, it is imperative to measure the concentration of the product neutral molecules. Our first target is the dissociative recombination of HCNH^+ and the primary neutrals are HCN and HNC.However, currently the transition dipole moments of HNC are not known. We recorded the v_1 and v_3 bands of HNC using a Fourier transform IR spectrometer and found that the Herman-Wallis effect is large enough to determine the transition dipole monent for the v_1 band, and a preliminary vale for the transition dipole moment has been obtained. In summary, this field of spectroscopic determination of dissociative recombination branching ratio has been quite uncultivated despite its extreme importance for understanding interstellar chemical and physical processes. We certainly continue perfecting the experimental setups and will provide essential information to our community.