Time resolved and size selective infrared-spectroscopic studies on the structure and dynamics of neutral (water) clusters generated in supersonic expansions

对超音速膨胀中产生的中性（水）团簇的结构和动力学的时间分辨和尺寸选择性红外光谱研究

• 批准号: 400183980
• 负责人: Professor Dr. Thomas Zeuch
• 金额: --
• 依托单位: Institut für Physikalische Chemie
• 依托单位国家: 德国
• 项目类别: Research Grants
• 财政年份: 2018
• 资助国家: 德国
• 起止时间: 2017-12-31 至 2021-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/400183980?language=en
• 关键词: Time; resolved; size; selective; infrared

The isomerism and the dynamics of water clusters reflect on the microscopic scale the special properties of macroscopic water that enable the existence of life as we know it. In this project an infrared-spectroscopy approach is pursued for characterizing size-selectively neutral water clusters exploiting the nanosecond cluster dynamics after IR excitation for isomer discrimination. For larger clusters a similar isomer selectivity has been so far only achieved for ionic clusters. The method utilizes the supersonic expansion technique and relies on the special, temperature dependent interaction of sodium atoms with water clusters enabling their soft single photon ionization. The spectroscopic data accumulated in the this project will provide references for benchmarking and improving water model potentials in size ranges so far difficult to access. Central goals are the determination of the critical lower size for the emergence of a crystalline core in water clusters, the detection of (H2O)n isomers of high stability in the size range n=20-60 and the exploration of the presence of temperature range in which liquid and crystalline water clusters can coexist, a so far only theoretically predicted water cluster property.

水团的同分异构和动力学在微观尺度上反映了宏观水的特殊性质，这些性质使我们所知道的生命得以存在。在这个项目中，红外光谱方法被用于表征大小选择性中性水簇，利用红外激发后的纳秒簇动力学来辨别异构体。对于较大的簇，到目前为止，只有离子簇具有类似的同分异构体选择性。该方法利用超音速膨胀技术，并依赖于钠原子与水团簇的特殊，温度依赖的相互作用，使其软单光子电离。本项目积累的光谱数据将为目前难以获得的尺度范围内的水模型电位的基准化和改进提供参考。中心目标是确定在水团簇中出现结晶核心的临界低尺寸，在尺寸范围n=20-60的高稳定性（H2O）n异构体的检测，以及探索液态水和结晶水团簇可以共存的温度范围的存在，迄今为止仅在理论上预测了水团簇的性质。