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

的异构性和动态的水集群反映在微观尺度上的宏观水，使生命的存在，因为我们知道it. In这个项目的红外光谱的方法是追求特征的大小选择性中性水集群利用纳秒集群动力学后，红外激发异构体歧视的特殊属性。对于较大的簇，类似的异构体选择性迄今为止仅实现了离子簇。该方法利用超声膨胀技术，并依赖于钠原子与水簇之间的特殊的、依赖于温度的相互作用，使它们能够进行软单光子电离。本项目所积累的光谱数据将为迄今为止难以获得的尺度范围内的水模型潜力的基准测试和改进提供参考。中心目标是确定的临界较低的尺寸出现的结晶核心的水簇，（H2O）n异构体的检测的高稳定性的尺寸范围n=20-60和探索的存在下的温度范围内，液体和结晶水簇可以共存，到目前为止只有理论预测的水簇的属性。

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.