RUI: Condensed Phase Radiolysis vs. Photolysis

化学系的化学结构、动力学和机制A(CSDM-A)项目获得这一奖项，资助韦尔斯利学院的Christopher Arumainayagam教授研究由低能电子和光(光子)驱动的凝聚相(而不是气相)化学反应之间的异同。主要目标是为宏观效应提供详细的化学解释(在分子相互作用机制一级)，例如光子和电子诱导的冰化学如何促成(1)南极上空的臭氧层空洞和(2)外层空间甘氨酸等益生生物(生命的前身)分子的形成。除了为自然界中冰的能量加工提供洞察外，Arumainayagam教授的研究还可能有助于更好地控制工业化学反应，以形成特定的产品，而不会产生不需要的副产品。例如，光子和电子在极端紫外线光刻(EUVL)中都扮演着关键角色，这是一种对更好的智能手机至关重要的下一代半导体芯片制造技术。除了科学对冰化学、大气化学、天体生物学和工业化学知识的广泛影响外，这一本科院校研究奖对女本科生的教育也有重大影响，包括促进少数族裔和经济困难学生的参与，该奖项还包括进一步促进STEM劳动力队伍多样性的计划。参加该奖项研究的学生除了在研究实验室中进行批判性思维、故障排除和解决问题等技能外，还可以获得先进的实验技术的经验。在超高真空(UHV)条件下，利用辐照后程序升温解吸(TPD)、辐照后红外光谱和等温电子/光子刺激解吸(ESD/PSD)技术，研究凝聚相NH3、H2O和CH3OH的辐射分解和光解。采用亚电离能(10 EV)的电子/光子来避免阳离子和低能二次电子的产生，确保可以探测到电子和光子之间的根本差异。这些实验涉及最近商业化的高强度激光驱动的低能量(7.4 eV)宽带光子源。当与用该合同的资金购买的单色仪相结合时，这种高强度光子源将允许进行以前在同步加速器设施中完成的与波长相关的凝聚相光化学研究。使用相同的实验方案在单个UHV室中研究凝聚态辐射分解和光解对于探索凝聚态电子和光子诱导反应动力学之间的根本差异至关重要。该奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

With this award, the Chemical Structure, Dynamics, and Mechanisms A (CSDM-A) program of the Division of Chemistry is funding Professor Christopher Arumainayagam of Wellesley College to study the differences and similarities between condensed-phase (as opposed to gas-phase) chemical reactions driven by low-energy electrons and light (photons). The main goal is to provide detailed chemical explanations (at the level of the mechanisms of molecular interactions) for macroscopic effects such as how photon- and electron-induced ice chemistry contribute to the (1) ozone hole over the Antarctic and (2) formation of prebiotic (precursors to life) molecules such as glycine in outer space. As well as providing insight into the energetic processing of ices in nature, Professor Arumainayagam’s studies may help to better control industrial chemical reactions to form specific products without unwanted side products. For example, both photons and electrons play a critical role in extreme ultraviolet lithography (EUVL), which is a next-generation manufacturing technique of semiconductor chips critical for better smartphones. In addition to scientific broader impacts to knowledge of ice chemistry, atmospheric chemistry, astrobiology, and industrial chemistry, this Research at Undergraduate Institutions award has a significant impact on education of female undergraduate students, including promoting participation by minority and economically disadvantaged students, and the award includes plans to further promote diversity within the STEM workforce. Students participating in research under this award gain experience with advanced experimental techniques, in addition to skills such as critical thinking, troubleshooting, and problem solving in the research lab.Radiolysis and photolysis of condensed phase NH3, H2O, and CH3OH are being investigated under ultrahigh vacuum (UHV) conditions by using post-irradiation temperature-programmed desorption (TPD), post-irradiation infrared spectroscopy, and isothermal electron/photon-stimulated desorption (ESD/PSD) techniques. Electrons/photons with sub-ionization energies (10 eV) are employed to avoid the production of cations and low-energy secondary electrons, ensuring that fundamental differences between electrons and photons can be probed. The experiments involve a recently-commercialized high-intensity laser-driven low-energy (7.4 eV) broadband photon source. When coupled to a monochromator, purchased with funds from this award, this high-intensity photon source will allow for wavelength-dependent condensed phase photochemistry studies that have previously been done at synchrotron facilities. Studying condensed-phase radiolysis and photolysis in a single UHV chamber using the same experimental protocol is critical in exploring fundamental differences between the dynamics of condensed phase electron- and photon-induced reactions.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.