Angle-resolved photoelectron spectroscopy of size-selected clusters using synchrotron radiation

在第一个资助期间，已经开发了一种用于大规模选择团簇和纳米颗粒的光电子能谱的新方法，现在将用于测量。在实验之前，需要选择簇的大小，为此，粒子必须带电。通常，离子束中的低目标密度由激光的高强度来补偿。商用激光器提供的最大光子能量为7.9 eV，限制了这类实验仅限于研究最上层已占据轨道。相比之下，用同步辐射可以研究大小选择团簇的完整价带甚至核心能级。问题是同步辐射的强度很低。在第一个资助期间，我们证明了用同步辐射记录大小选择的簇离子的价带光电子能谱是可能的。在第一次成功之后，我们进一步改进和改进了这台机器。在10**13光子/秒的光强下，现在可以在10-30分钟内记录角度分辨光电子能谱。现在，这项新技术将用于研究O2、CO和N2在金属团簇上的化学吸附。

During the first funding period a new method for photoelectron spectroscopy of mass-selected clusters and nanoparticles has been developed and will now be used for measurements. Clusters need to be size-selected prior to an experiment and for this the particles must be charged. Usually, the low target density in an ion beam is compensated by the high intensity of a laser. The maximum photon energy provided by commercial lasers is 7.9 eV restricting this type of experiments to the study of the uppermost occupied orbitals. In contrast, with synchrotron radiation the complete valence bands und even core levels of size-selected clusters could be studied. The problem is the low intensity of synchrotron radiation. During the first funding period, we demonstrated that it is possible to record valence band photoelectron spectra of size selected cluster ions with synchrotron radiation. After this first success, we modified and improved the machine further. At a light intensity of 10**13 photon/s it is now possible to record angle-resolved photoelectron spectra within 10-30 min. Now, the new technique will be used to study the chemisorption of O2, CO and N2 on metal clusters.