Photodissociation Dynamics of Transient Species: Hydrogen-Bonded Dimers and Trimers

在该项目中，Reisler教授将在化学部门的结构、动力学和机制项目的支持下，对氢键配合物在气相中的预解离动力学进行详细的研究。尽管氢键的结合很弱，但在从活细胞到太阳系冰体的各种环境中，氢键都至关重要。为了深入了解预解离机制，将利用光碎片离子成像的状态分辨率和检测灵敏度来获得激光激发水、酸和碱的氢键二聚体或三聚体的一个亚基后碎片的成对相关分布。循环三聚体将作为振动能量耗散的原型在更大的氢键网络。导致键断裂的特定状态的能量流模式将从碎片中的量子态分布中推断出来，并以光谱精度获得键解离能。振动预解离动力学和机制将通过与涉及水、氨或氯化氢的基准配合物的高级计算进行比较来阐明。最终目标是了解导致键断裂的振动能量流中尚未解释的精致状态特异性，这在很大程度上取决于特定的配合物和激发的振动模式。参与本研究的学生观察光谱学和动力学课程中所学概念的实验表现，将实验结果与理论进行比较，并构建强调物理洞察力的动力学模型。所选择的分子系统与影响气候变化的大气过程相关，增强学生对社会影响的认识。结果将与科学界广泛共享，并且先前开发的图像重建方法，基集展开法（BASEX）继续流行。学生将学习应用于广泛科学技术领域的解决问题的技巧，为他们加入高科技劳动力做好准备。该项目的首席研究员开发并领导一系列旨在鼓励科学和工程领域的女性从事研究事业的活动。她还参与了一些指导项目，这些项目旨在促进弱势群体成员的职业准备和发展。

In this project, supported by the Structure, Dynamics and Mechanisms Program of the Chemistry Division, Professor Reisler will undertake a detailed study of the predissociation dynamics of hydrogen-bonded complexes in the gas phase. Despite their weak bonding, hydrogen bonds are crucially important in environments ranging from living cells to icy bodies in the solar system. To gain insight into the predissociation mechanisms, the state resolution and detection sensitivity of photofragment ion imaging will be exploited to obtain pair-correlated distributions of fragments following laser excitation of one subunit of hydrogen-bonded dimers or trimers of water, acids and bases. Cyclic trimers will serve as prototypes of vibrational energy dissipation in larger hydrogen-bonded networks. State-specific energy flow patterns that lead to bond breaking will be inferred from quantum state distributions in the fragments, and bond dissociation energies will be obtained with spectroscopic accuracy. Vibrational predissociation dynamics and mechanisms will be elucidated by comparisons with high-level calculations of benchmark complexes involving water, ammonia, or hydrogen chloride. The ultimate goal is to understand the yet unexplained exquisite state specificity in vibrational energy flow that leads to bond breaking, which depends strongly on the specific complex and the excited vibrational mode.Students participating in this research observe experimental manifestations of concepts learned in courses on spectroscopy and dynamics, compare their experimental results to theory, and construct dynamical models that emphasize physical insight. The chosen molecular systems are relevant to atmospheric processes that affect climate change, enhancing student awareness of societal impacts. Results will be shared broadly with the scientific community, and the previously developed image reconstruction method, Basis Set Expansion Method (BASEX), continues to be popular. Students learn problem-solving techniques applied to broad areas of science and technology, preparing them to join the high technology workforce. The principal investigator in this project develops and leads a range of activities aimed at encouraging women in science and engineering to pursue research careers. She also participates in mentoring programs that promote career preparation and advancement of members of underrepresented groups.