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

瞬态物质的光解动力学：氢键二聚体和三聚体

• 批准号: 0951976
• 负责人: Hanna Reisler
• 金额: $ 56.4万
• 依托单位: University of Southern California
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2010
• 资助国家: 美国
• 起止时间: 2010-06-01 至 2013-05-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0951976&HistoricalAwards=false
• 关键词: Photodissociation; Dynamics; Transient; Species; Hydrogen

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.

在这个项目中，由化学系的结构，动力学和机制计划的支持下，Reisler教授将进行详细的研究在气相中的氢键复合物的预解离动力学。尽管它们的键合很弱，但氢键在太阳系中从活细胞到冰冷物体的环境中至关重要。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氢键二聚体或水，酸和碱的三聚体的一个亚基后的碎片的配对相关分布。环状三聚体将作为较大氢键网络中振动能量耗散的原型。 状态特定的能量流模式，导致键断裂将推断从碎片中的量子态分布，和键离解能将获得光谱精度。振动predissociation动力学和机制将阐明与高层次的基准计算复杂的水，氨，氯化氢。最终目的是理解导致键断裂的振动能量流中尚未解释的精细状态特异性，这在很大程度上取决于特定的复合物和激发的振动模式。参加本研究的学生观察光谱学和动力学课程中学习的概念的实验表现，将实验结果与理论进行比较，构建强调物理洞察力的动力学模型。 所选的分子系统与影响气候变化的大气过程有关，提高了学生对社会影响的认识。结果将与科学界广泛分享，先前开发的图像重建方法，基集扩展方法（BASEX），继续受到欢迎。 学生学习应用于科学和技术的广泛领域的解决问题的技术，准备他们加入高科技劳动力。该项目的首席研究员制定并领导了一系列旨在鼓励科学和工程领域的妇女从事研究事业的活动。她还参加辅导计划，促进职业准备和代表性不足的群体成员的进步。