Laboratory Simulation Studies of EUV-VUV Photolysis of Cosmic Ice Analogs

冰冷的太阳系天体表面主要是水冰，还有少量的甲烷、一氧化碳、二氧化碳、氮和氨。除了热循环外，外表面还不断受到光子照射和粒子轰击、太阳风、宇宙射线和表面化学反应的影响。在这个项目中，合作团队将在NSF的支持下继续进行他们的实验室实验，研究宇宙冰类似物的极紫外(EUV)-真空紫外（VUV）光解物理。他们计划同时研究含有水和其他相关物质的冰类似物中光子诱导的化学反应和光解吸。​该团队将确定冰样本中形成的分子类型，以及那些从冰表面脱落的分子，量化它们的产量，了解它们的生产机制，母冰分子的破坏产量（寿命或稳定性），并确定它们在天文环境中的意义。这项工作所需要的许多复杂的设备和先进的实验技术都是由该团队在国家科学基金的资助下开发的。这些结果对于了解巨行星、彗星、星际介质、分子云和原恒星区域的富含水的冰卫星尤其重要。研究成果也将被纳入高等本科和研究生课程的教材。该项目将培训一名博士后和一名研究生，重点是在同步辐射设备上工作。

The surfaces of icy Solar System bodies are predominantly water ice, with small amounts of methane, carbon monoxide, carbon dioxide, nitrogen, and ammonia. The outer surfaces are constantly subject to photon irradiation and particle bombardment, the solar wind, cosmic rays, and chemical reactions on surfaces, in addition to thermal cycling. In this project, the collaborating team will continue, with renewed NSF support, their laboratory experiments on the physics of extreme ultraviolet (EUV)-vacuum ultraviolet (VUV) photolysis of cosmic ice analogs. They plan simultaneous investigations of photon-induced chemical reactions and photodesorption in ice analogs containing water and other relevant species. A tunable intense synchrotron radiation light source available at the National Synchrotron Radiation Research Center (NSRRC), Taiwan, will provide the required EUV-VUV photons. The team will identify the type of molecules that form in the ice samples, and those that come off the ice surfaces, quantify their production yields, understand their production mechanisms, the destruction yields (lifetimes or stabilities) of the parent ice molecule(s), and ascertain their significance in astronomical environments. Much of the sophisticated equipment and advanced experimental techniques required for the proposed work have been developed by the team with prior NSF funding. The results will be particularly relevant to understanding of the water-rich icy satellites of the giant planets, comets, the interstellar medium, molecular clouds, and protostellar regions. The research results will also be incorporated into teaching materials for advanced undergraduate and graduate courses. The project will train a postdoctoral associate and a graduate student, with an emphasis on working with a synchrotron radiation facility.