Experimental study of the formation and destruction of carbonates in circumstellar and interstellar environments and their impact on the oxygen depletion in the interstellar medium

星周和星际环境中碳酸盐的形成和破坏及其对星际介质耗氧影响的实验研究

• 批准号: 451244650
• 负责人: Dr. Cornelia Jäger
• 金额: --
• 依托单位: Laboratory Astrophysics and Cluster Physics Group
• 依托单位国家: 德国
• 项目类别: Research Grants
• 财政年份: 2020
• 资助国家: 德国
• 起止时间: 2019-12-31 至 2022-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/451244650?language=en
• 关键词: Experimental; study; formation; destruction; carbonates

Carbonates are found in various astrophysical environments including circumstellar envelopes around evolved stars, protoplanetary disks, solar and extrasolar planets, and comets. Their formation and destruction in astrophysical environments is a complex interplay between different refractory and nonrefractory solids, gaseous components, and irradiation with energetic photons. Carbonates can be formed from silicates and carbonaceous material. A considerable amount of carbon and in particular of oxygen can be sequestered in such inorganic and organic carbonates, which provides a possible solution to the oxygen depletion problem in the interstellar medium. In the course of the project, we are going to simulate the formation and destruction of carbonates in the laboratory at conditions prevailing in various astrophysical environments. Inorganic and organic carbonates will be produced from carbonaceous and silicate dust analogues produced in our laboratory. The carbonation of silicates will be realized by gas phase condensation in CO2/H2O-containing atmospheres, gas-surface reactions between CO, CO2, and H2O molecules and cosmic silicate analogues, reactions of cold silicates or silicate/carbon mixtures with molecular ice composed of CO, CO2, and H2O. In addition, the effect of simultaneous ultraviolet irradiation on the carbonate formation produced from silicates either in the gas phase or at the interface grains/ice will be investigated. The exposure of carbon grains to a bombardment of oxygen atoms and a flow of CO and CO2 molecules will be used to synthesize organic carbonates. Their formation is expected to occur in two reaction steps including the formation of epoxide functional groups and their reaction into cyclic carbonates. IR spectroscopy will be used to monitor the formation of inorganic and organic carbonates in situ. The formation rates will be determined as a function of temperature covering a range between 10 K and ~400 K. IR spectroscopy, electron microscopy, and organic analyses will be used to explain the chemical and structural modifications of the silicate and carbon grains. Besides the formation rate of carbonates, their photon-induced destruction by VUV irradiation plays an important role and has to be analyzed. The results of our studies will provide us significant information on the spectral properties of cosmic carbonates and their potential role in astrochemical and astrophysical processes such as the depletion of oxygen and the formation of complex organic molecules in the interstellar medium, as well as the formation of planets.

在各种天体物理环境中发现了碳酸盐，包括周围的恒星周围的折叠信封，原球盘，太阳能和极性行星以及彗星。它们在天体物理环境中的形成和破坏是不同难治性和非耐磨固体，气态成分以及用能量光子照射的复杂相互作用。碳酸盐可以由硅酸盐和碳质物质形成。可以在这种无机和有机碳酸盐中隔离大量的碳，尤其是氧气，这为星际培养基中的氧耗尽问题提供了一种解决方案。在项目的过程中，我们将在各种天体物理环境中占据普遍的条件下模拟实验室中碳酸盐的形成和破坏。无机和有机碳酸盐将是由我们实验室生产的碳质和硅酸盐类似物产生的。硅酸盐的碳化将通过气相凝结在含CO2/H2O的大气中，CO，CO2和H2O分子之间的气体表面反应以及COSMIC硅酸盐类似物，冷硅酸盐或硅酸盐/碳混合物与CO，CO2，CO2和H2O的分子冰的反应来实现。此外，将研究同时紫外线照射对气相或界面晶粒/冰中硅酸盐产生的碳酸盐形成的影响。将碳颗粒暴露于氧气原子的轰击以及CO和CO2分子的流动将用于合成有机碳酸盐。预计它们的形成将以两个反应步骤发生，包括形成环氧官能团和它们在环状碳酸盐中的反应。红外光谱法将用于监测原位的无机和有机碳酸盐的形成。形成速率将确定为覆盖10 K至〜400 K之间的温度的函数。红外光谱，电子显微镜和有机分析将用于解释硅酸盐和碳晶粒的化学和结构修饰。除了碳酸盐的形成速率外，其光子诱导的VUV辐射诱导的破坏起着重要作用，必须分析。我们的研究结果将为我们提供有关宇宙碳酸盐的光谱特性及其在天体化和天体物理过程中的潜在作用的重要信息，例如氧的消耗以及星际介质中复杂有机分子的形成，以及星球的形成。