Soft x-ray optics for spectromicroscopy at the Advanced Light Source

摘要

A variety of systems for performing spectromicroscopy, spatially resolved spectroscopy, are in operation or under construction at the Advanced Light Source (ALS). For example, part of the program is centered around the surface analysis problems of local semiconductor industries, and this has required the construction of a microscope with wafer handling, fiducialization, optical microscopy, coordinated ion beam etching, and X-ray Photoelectron Spectroscopy (XPS) integrated in this case with Kirkpatrick-Baez (K-B) grazing incidence micro-focusing optics. The microscope is to be used in conjunction with a highly efficient entrance slitless Spherical Grating Monochromator (SGM). The design and expected performance of this instrument will be described, with emphasis on the production of the elliptically curved surfaces of the K-B mirrors by elastic bending of flat mirror substrates. For higher resolution, zone-plate (Z-P) focusing optics are used and one instrument, a Scanning Transmission X-ray Microscope (STXM) is in routine operation on undulator beamline 7.0. A second Z-P based system is being commissioned on the same beamline, and differs from the STXM in that it will operate at Ultra-High Vacuum (UHV) and will be able to perform XPS at 0.1 (micro)m spatial resolution. Spatially resolved X-ray Absorption Spectroscopy (XAS) can be performed by imaging electrons photoemitted from a material with a Photo-Emission Electron Microscope (PEEM). The optical requirements of a beamline designed for PEEM are very different to those of micro-focus systems and they give examples of bending magnet and undulator based instruments.