Studies of Size-Selected Semiconductor Clusters Using Negative Ion Photodetachment

小行星9521805 这项研究的目的是了解半导体团簇的性质如何在大尺寸范围内演变，跨越分子极限（10个原子或更少）到纳米晶制度（1000个原子或更多）。拟议的实验是专门针对探测这些集群的电子和振动光谱作为其大小的函数。实验将使用两种负离子光剥离技术进行：光电子能谱，用于中等分辨率（10 meV）的调查工作，和阴离子零电子动能（ZEKE）光谱更高的分辨率研究（0.2-0.3 meV）。这些技术结合了联合收割机的大小选择性与合理的光谱分辨率，因此是理想的光谱研究团簇在一个很宽的尺寸范围。 光谱学的大小选择集群提供了一个前所未有的机会，了解如何从分子的性质演变到批量限制。从基础化学和物理学的角度来看，这种类型的工作很有吸引力，因为我们可以了解小分子的分子轨道和振动频率如何演变成扩展晶体结构中的电子带和声子。从更应用的观点来看，小的团簇已经涉及到半导体的等离子体处理中出现的问题，并且较大的半导体团簇开始显示出用于电子设备的前景。 因此，非常需要进一步表征这些应用中所涉及的物质的能量学和结构。该提案的目的是绘制出半导体团簇的电子和振动光谱，其尺寸范围很宽，从小于10个原子到超过1000个原子。为了进行这项工作，需要将联合收割机尺寸选择性与合理的光谱分辨率相结合的实验。这将使用两种负离子光电子能谱技术来完成：光电子能谱，对于更高分辨率的工作，阴离子零电子动能谱。

9521805 Neumark The aim of this research is to learn about how the properties of semiconductor clusters evolve over a large size range, spanning the molecular limit (10 atoms or less) up to the nanocrystalline regime (1000 atoms or more). The proposed experiments are specifically aimed at probing the electronic and vibrational spectroscopy of these clusters as a function of their size. The experiments will be conducted using two negative ion photodetachment techniques: photoelectron spectroscopy, for medium resolution (10 meV) survey work, and anion zero electron kinetic energy (ZEKE) spectroscopy for much higher resolution studies (0.2-0.3 meV). These techniques combine size-selectivity with reasonable spectral resolution and hence are ideal for spectroscopic studies of clusters over a wide size range. %%% The spectroscopy of size-selected clusters offers an unprecedented opportunity to understand how the properties of matter evolve from the molecular to the bulk limits. This type of work is appealing from the perspective of fundamental chemistry and physics, since we can learn how the molecular orbitals and vibrational frequencies of small molecules evolve into the electronic bands and phonons in extended crystalline structures. From a more applied point-of-view, small clusters have been implicated in the problems that arise in the plasma processing of semiconductors, and larger semiconductor clusters are beginning to show promise for use in electronic devices. Further characterization of the energetics and structure of the species involved in these applications is therefore highly desirable. This proposal is specifically aimed at mapping out the electronic and vibrational spectroscopy of semiconductor clusters over a wide size range, from less than 10 to more than 1000 atoms. To conduct this work, one requires experiments which combine size-selectivity with reasonable spectral resolution. This will be accomplished using two negative ion photodetachmen t techniques: photoelectron spectroscopy and, for higher resolution work, anion zero electron kinetic energy spectroscopy.