Electron Attachment to van der Waals Molecules

电子附着在货车范德瓦耳斯分子上不仅在气相中的基本反应过程中而且在电离气体中的各种现象中具有重要意义。最近，我们小组在气相中获得了电子附着过程中的一些特殊现象，这些现象已被解释为与货车der Walls分子的附着过程。本工作的目的是阐明电子附着在货车范德华分子上这一特殊现象的基本机理，并提取各种反应动力学过程的一般规律。首先，电子附着在O_2、N_2O、NO、NO_2、SO_2、C_3O_2、用微波电导技术结合脉冲辐解方法对卤代烷烃和卤代烷烃进行了详细的研究。得到了吸附过程速率常数的绝对值，阐明了吸附过程的机理。为了用更直接的方法推广上述研究，我们自制了一套用于超声膨胀产生的货车分子的低能电子能量损失谱的装置。我们已经用常规喷管获得了孤立原子和分子的电子能量损失谱及其与散射角的关系，证实了在超音速喷管膨胀中货车德瓦耳斯分子和货车德瓦耳斯团簇的有效产生。

Electron attachment to van der Waals molecules is of great importance not only in a fundamental reaction process in gas phase but also in various phenomena in ionized gas. Very recently, our group has obtained some peculiar phenomena in electron attachment process in gas phase, which has been interpreted in terms of an attachment process to van der Walls moleules. The objectives of the present project are to elucidate a fundamental mechnizm of the peculiar phenomena in the electron attachment to van der Waals molecules and to extract general rules which governs the process in various reaction kinetics.In this work, first, electron attachment to isolated moleules of O_2, N_2O, NO, NO_2, SO_2, C_3O_2, and some alkyl halides has been studied in detail using a microwave conductivity technique combined with a pulse radiolysis 1method. The absolute values of rate constants of the attachment process to the molecules have been obtained elucidating the mechanizm of the attachment process. Furthermore, pressure dependence and temperature dependence of the rate constants have been obtained, in which electron attachement to van der Waals molecules are clearly observed.In order to extend the study described above by means of a more direct method, we have constracted an apparatus of a low energy electron energy loss spectroscopy from van der Waals molecules produced in a supersonic expansion. We have already obtained electron energy loss spectra and scattering angular dependence of the spectra for isolated atoms and molecules using a convensional effusive nozzle, and confirmed efficient production of van der Waals moleules and van der Waals clusters in supersonic nozzle expansion.