NANOESCA - ELECTRON SPECTROSCOPY FOR CHEMICAL ANALYSIS IMAGED AT THE NANOSCALE.

NanoESCA是一种超高真空（UHV）光电发射光谱系统，具有亚微米空间分辨率，可从几微米的平坦材料表面进行实空间和k空间（倒易空间）映射，并具有在纳米尺度上进行定量化学状态映射的能力。该系统设计用于安装在同步加速器束流线端站或纳米科学实验室。该系统有多种操作模式。紫外光子源用于紫外光发射光谱（UPS）、角度分辨UPS和光发射电子显微镜（PEEM），软x射线用于x射线光发射光谱（XPS）。UPS给出了实空间中的弱束缚态、价带结构和k空间中的表面电子带结构的能量滤波信息。XPS用于探测核能级光谱，以获得表面化学成分的定量信息。与高分辨率扫描电子显微镜相比，PEEM直接对表面发射光电子进行实时成像，而无需扫描。通过能量滤波PEEM图像，可以得到表面功函数的定量映射。视野范围从毫米到微米可调，允许小至30纳米（UPS模式）和480纳米（XPS模式）的高分辨率成像。所要求的NanoESCA机器代表了成像和光谱PEEM的下一代。它利用已建立的平行成像技术的扩展，同时成像和过滤光电子，通过使用双半球（像差校正）电子分析仪与高光子通量VUV和x射线源相结合，实现在实际空间和k空间的纳米级成像和光谱；后一种模式允许将材料的电子能带结构信息可视化，并直接与理论模型进行比较。独特的是，这种使用x射线或VUV源获得纳米级光谱的能力是通过通过同样的PEEM“柱”平行成像获得的，该柱也充当成像光谱仪的入口透镜。

The NanoESCA is an Ultra High Vacuum (UHV) photoemission spectroscopy system with sub-micron spatial resolution for real-space and k-space (reciprocal space) mapping from areas of a few microns of flat material surfaces, and the capability to perform quantitative chemical state mapping at the nanoscale. The system is designed for installation on a synchrotron beam line end-station or in a Nano Science Laboratory.The system has various modes of operation. UV photon sources are used for Ultra-violet Photoemission Spectroscopy (UPS), Angle Resolved UPS, and Photo Emission Electron Microscopy (PEEM), soft X-rays are used for X-ray Photoemission Spectroscopy (XPS). UPS gives energy filtered information on weakly bound states and the valence band structure in real space and the surface electronic band structure in k-space. XPS is used to probe core level spectra to obtain quantitative information on the chemical composition of a surface. In contrast to the high resolution Scanning Electron Microscope, PEEM directly images surface areas emitting photoelectrons in real time without scanning. By energy filtering PEEM images it is possible to obtain quantitative maps of surface work function. The field of view is adjustable from millimetres to microns allowing high resolution imaging of features as small as 30nm (UPS modes) and 480nm (XPS mode).The NanoESCA machine being requested represents the next generation in imaging and spectroscopic PEEM. It uses an extension of the established parallel imaging technique, to simultaneously image and filter photoelectrons, by using a double hemispherical (aberration corrected) electron analyser in combination with high photon flux VUV and X-ray sources, to realise nano scale imaging and spectroscopy in real space and in k-space; the latter mode allows information on the electronic band structure of materials to be visualised and compared directly with theoretical models. Uniquely, this capability to obtain nanoscale spectroscopy using either X-ray or VUV sources is obtained by parallel imaging through the same PEEM 'column' which also acts as the entrance lens of the imaging spectrometer.