Diffusion of atoms and molecules on interstellar dust grain and ice analogs

星际空间，或恒星之间的空间，包含极冷和稀薄的气体云，其中播撒着微小的尘埃颗粒。在最密集的星际云中，尘埃颗粒覆盖着冰，为简单原子和分子的化学反应提供了场所。尘埃颗粒和冰上的反应会产生越来越复杂的分子，其中一些是生命的基石。这项研究项目将使用来自各种科学领域的先进实验和理论工具，研究原子和分子在类似于太空的恶劣条件下如何与尘埃颗粒和冰发生反应。这项研究的结果将帮助天文学家了解尘埃颗粒和冰上的过程如何导致太空中丰富的化学物质。该项目还将培训处于天体物理研究前沿的跨学科领域的学生。该项目将把成熟的实验技术(原子束和分子束、四极杆质谱仪和红外光谱)与新技术(时间分辨反应散射)相结合，以获得关于星际气体中常见的原子和分子的吸附、扩散、反应和解吸的定量信息。新开发的理论方法将被用来从实验数据中推导出原子和分子的吸附(粘)系数和扩散系数。这些数据和导出的参数将用于星际环境的模拟。PI和他的团队将：(1)测量原子和分子在尘埃颗粒类似物和冰表面的扩散系数；(2)测量原子和分子在各种颗粒类似物表面的粘着系数；(3)对实验数据进行理论分析；(4)在化学模型中使用新的扩散系数，以帮助解释对星际云的观测；以及(5)以可供天文学家研究星际气体化学演化的格式提供数据。该项目还将支持雪城大学的一名本科生、一名研究生和一名博士后学者。

Interstellar space, or the space between the stars, contains extremely cold and tenuous clouds of gas seeded with tiny dust grains. Within the densest interstellar clouds, dust grains are coated with ice, providing sites for chemical reactions of simple atoms and molecules. Reactions on dust grains and ices can produce increasingly complex molecules, some of which are the building blocks of life. This research project will use advanced experimental and theoretical tools from a variety of scientific fields to study how atoms and molecules react on dust grains and ices under harsh conditions similar to those in space. Results from the study will help astronomers understand how processes on dust grains and ices can lead to the rich chemistry of space. The project will also train students in an interdisciplinary field at the forefront of astrophysical research. This project will combine proven experimental techniques (atomic and molecular beams, quadrupole mass spectrometry, and infrared spectroscopy) with new techniques (time-resolved reactive scattering) to obtain quantitative information on adsorption, diffusion, reaction, and desorption of atoms and molecules that are commonly found in the interstellar gas. Newly developed theoretical methods will be used to derive adsorption (sticking) and diffusion coefficients of the atoms and molecules from the experimental data. The data and derived parameters will be used in simulations of interstellar environments. The PI and his team will: (1) measure diffusion coefficients of atoms and molecules on surfaces of dust grain analogs and ices; (2) measure sticking coefficients of atoms and molecules on surfaces of various grain analogs; (3) perform theoretical analyses of the experimental data; (4) use the new diffusion coefficients in chemical models that will help interpret observations of interstellar clouds; and (5) provide the data in a format that can be used by astronomers studying the chemical evolution of the interstellar gas. The project will also support an undergraduate student, a graduate student, and a postdoctoral scholar at Syracuse University.