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、低温气体基体和红外傅里叶变换光谱仪组成。在本项目为期两年的时间里，与红外光谱仪一起实施了开放式质谱仪和矩阵形成仪，并对系统的整体性能进行了检查。在定制的实验室内安装了电晕放电超音速膨胀喷嘴和离子选择速度过滤器。整个系统现在已接近完成。制造和测试低能量电子束发生器，然而，有点延迟，在目前阶段，它的设计已经完成。为了确定离子与电子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^+的解离重组，主要的中性物质是HCN和HNC。然而，目前尚不清楚HNC的跃迁偶极矩。利用傅里叶变换红外光谱仪记录了HNC的v_1和v_3波段，发现Herman-Wallis效应大到足以确定v_1波段的跃迁偶极矩，并得到了初步的跃迁偶极矩值。总之，尽管光谱测定解离重组分支比对理解星际化学和物理过程具有极其重要的意义，但这一领域仍未得到充分开发。我们当然会继续完善实验设置，并将向我们的社区提供必要的信息。

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.