An experimental investigation on gas-solid reactions using nebular gas and planetary atmospheres.

我们研究了星际尘埃蒸发/凝结的反应动力学，以及行星表面的化学侵蚀率作为温度、压力和化学成分的函数，通过实验室实验使用星云和/或行星大气模拟物。我们设计了一种新的系统，使三种最基本的元素H、O、c按规定的比例混合，以产生模拟的星云气体，用精密的自动流量计控制H_2、CO_2和CO的流量，并将其引入高真空室的混合容器中。四极杆质谱仪已连接到该系统，以允许气体分析。为了在规定的温度下达到容器内的热力学平衡，颗粒状Pt催化剂被掺杂在PtRh反应细胞内。设计了一种氧化铝保护管，以防止PtRh在真空高温度下过度蒸发。该气体控制系统与真空炉内的混合容器相连，并在高达1600℃的高温下进行了实用性测试。我们已经开发了一个计算机程序来计算各种自由基包括氧在各种T， P和组成条件下的分压。有了这个程序，我们就能预测实际实验中各种自由基的浓度与反应速率之间的关系。作为对星云真实情况的一阶近似，我们对星际尘埃物质在蒸发/凝结过程中的反应速率进行了研究。我们发现反应速率与原子氢的浓度成正比，我们还发现反应速率的温度依赖性反映了金属元素与氧之间化学键断裂所需的活化能。再缩聚速率与氢原子压力成反比的事实表明OH自由基参与了反应。我们还发现了温度对缩合的影响，这种影响随着温度的升高而增强，其原因正在调查中。少

We have investigated the reaction kinetics of evaporation/condensation of interstellar dust and also the chemical erosion rates of planetary surface as functions of temperature, pressure, and chemical compositions, by means of laboratory experiments using nebular and/or planetary atmosphere analogue. We have devised a new system that allowed a mixing in desired ratios of the three most fundamental elements, H, O, and C.In order to generate the analogue nebular gas, H_2, CO_2, and CO were controlled for their flow rates with precision automatic flowmeters, and introduced into the mixing vessel inside a high vacuum chamber. A quadrupole mass spectrometer has been attached to this system to allow gas analyses.To achieve a thermodynamic equilibrium inside the vessel at a prescribed temperature, granular Pt catalyses were doped inside the PtRh reaction cell. An alumina protection tube was devised to prevent PtRh from excessive evaporation at high T in vacuo. The gas controlling system was c … More onnected to the mixing vessel inside the vacuum furnace, and is being tested for its utility at high temperatures up to 1600℃. We have developed a computer program that calculates partial pressures of various radicals including oxygen under various T, P, and composition conditions. With this program we are able to predict the relationships between the concentration of various radicals and the reaction rate that occurs in actual experiments.As a first-order approximation to the real situation in the nebula, we have carried out investigation on the reaction rate of interstellar dust materials during evaporation/condensation processes. We have found that the reaction rate was proportional to the concentration of atomic hydrogen, we also found that the temperature dependence of the reaction rate was reflecting the activation energy required for breaking a chemical bond between metallic element and oxygen. The fact that the recondensation rate was inversely proportional to the atomic hydrogen pressure have indicated an involvement of OH radical in the reaction. We have also found a temperature effect on recondensation, that enhanced with temperature, its cause is under investigation. Less