A Study of the Chemical Evolution by the Molecular-beam Epitaxy Method

为了模拟有机分子在空间中的化学演化，研究矿物表面的催化作用，我们构建了以下装置：一种玻璃制成的分子束装置。在高真空条件下，将高频放电产生的等离子体混合气体注入到矿物衬底上。结果表明，蒙脱土可以吸收水解生成的氨基酸分子。一种分子束外延装置。实验条件可以用质谱仪监测。衬底温度可控制在液氮温度~ 150℃之间，采用了高频放电、热电离、高温催化反应等多种方法对混合气体进行活化，其中磁铁矿活化是最有效的。微波放电技术目前正在规划中。一种微波化学气相沉积装置。模拟了泰坦大气中氨基酸的形成。当放置磁铁矿时，氨基酸的形成似乎通过释放自由基反应和费托催化反应两种方式发生。对上述实验产生的矿物表面薄膜，部分采用水解后的液相色谱法，部分采用未成功的电子衍射法，部分采用红外反射光谱法进行分析。现在正在计划对有机宇宙尘埃形成过程的模拟。

We constructed the following apparatus in order to simulate the chemical evolution of organic molecules in space and to study the catalytic effect of the surface of minerals.1. A glass-made molecular beam apparatus. The plasmic gas mixture produced by high-frequency discharge was injected on a mineral substrate under high vacuum. Montmorillonite was found to absorb the resulting molecules which yielded amino-acids by hydrolyzation.2. A molecular-beam epitaxy apparatus. The experimental condition can be monitored by a mass-spectrometer. The substrate temperature can be controled between the liquid-nitrogen temperature and 150 C. Various kinds of techniques to activate the gas mixture were used, such as the high-frequency discharge, thermal ionization, catalytic reaction at a high temperature, among which the last one by the use of magnetite was found to be the most effective. The microwave discharge technique is now planned.3. A microwave chemical vapor deposition apparatus. Amino-acid formation in the Titan atmosphere was simulated. When magnetite was placed, the formation of amino acids seemed to occur both by the radical reaction by the discharge and by the catalytic reactin of the Fischer-Tropsch type.The thin films on the mineral surface produced by the above-mentioned experiments were analyzed partly by the liquid chromatography after hydrolyzation, partly by the electron diffraction analysis which was unsuccessful, and partly by the infra-red reflection spectroscopy. The simulation of organic,cosmic dust formation is now planned.