NSF-BSF: A Coordinated Study of the Isotope effect in the Vacuum Ultraviolet Photodissociation of Astronomically Important Molecules: Implications for the Early Solar System

了解陨石和行星大气的同位素组成对于了解太阳星云的早期演化阶段和深入了解行星的形成和演化非常重要。 该研究项目是一项协调一致的实验和理论研究，研究分子氮及其含有重原子氮-15的同位素取代形式被紫外光解离如何影响空间化合物中的氮-15含量。 这项研究的结果将使天文学家能够准确地解释太阳系行星体和陨石表面大气中含氮分子同位素组成的观测范围。 该项目由美国国家科学基金会（NSF）和美国-以色列两国科学基金会（BSF）共同支持，将促进美国实验研究小组和以色列计算研究小组之间的合作，培养学生和博士后研究人员，并在圣地亚哥地区对不同人群进行科学推广。美国小组将进行氮分子及其氮-15同位素的真空紫外光解离实验。 以色列小组的高级理论计算将指导实验，并将根据实验结果进行改进。 调查将显示分子氮如何经历作为波长的函数的光解离，并建立被纳入分子的氮-15的分数。 该项目的数据将立即适用于各种天文环境的物理化学模型。对真空紫外光解离驱动的同位素分馏的基本机理的理解也将为其他天文学重要分子的类似研究提供信息。该奖项反映了NSF的法定使命，并被认为值得通过使用基金会的知识价值和更广泛的影响审查标准进行评估来支持。

Understanding the isotopic composition of meteorites and planetary atmospheres is important to understanding the early evolutionary stages of the Solar Nebula and gaining insight into planet formation and evolution. This research project is a coordinated experimental and theoretical study of how the dissociation of molecular nitrogen and its isotopically substituted forms containing the heavy atom nitrogen-15 by ultraviolet (UV) light influences the nitrogen-15 content of compounds in space. Results from the study will allow astronomers to accurately interpret the observed range in isotopic composition of nitrogen-bearing molecules in the atmospheres of planetary bodies and surfaces of meteorites in the Solar System. Supported jointly by the National Science Foundation (NSF) and the US-Israel Binational Science Foundation (BSF), this project will foster a collaboration between an experimental research group in the US and a computational research group in Israel, train students and postdoctoral researchers, and conduct science outreach to a diverse population in the San Diego area.Using the Advanced Light Source of the Lawrence Berkeley National Laboratory, the US group will perform experiments on the vacuum-UV photodissociation of molecular nitrogen and its nitrogen-15 isotopologues. High-level theoretical calculations from the Israeli group will guide the experiments and will be refined by the experimental results. The investigations will show how molecular nitrogen undergoes photodissociation as a function of wavelength and establish the fraction of nitrogen-15 that is incorporated into molecules. Data from this project will be of immediate applicability to physico-chemical models of a variety of astronomical environments. A fundamental mechanistic understanding of isotopic fractionation driven by vacuum-UV photodissociation will also inform similar studies of other astronomically important molecules.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.