XM-1, the high-rsolution soft x-ray microscope at the Advanced Light Source

摘要

The XM-1 soft x-ray microscope utilizes bending-magnet radiation from the Advanced Light Source (ALS) in Berkeley, CA. This radiation is collected by a "large" (9 mm diameter) fresnel condesner zone plate (CZP) which projects light through a pinhole and illuminates the sample. The radiation transmitted through the sample is then focused and magnified by a high-precision objective micro zone plate and recorded by a soft x-ray CCD camera. Our condensor zone plate and pinhole combination serves as our adjustable monochromator for selecting the desired photon energy, giving us a lambda/triangle openlambda of 700. This moderate spectral resolution allows for spectroscopic imaging with XM-1, including samples of magnetic materials with contrast provided by magnetic circular dichroism. Our user-friendly software programs allow for frequent utilization of complex image processing techniques. When a single field of view (10 mum diameter) is too small, we use an automated process for combining overlapping individual images into a larger, coherent montage image. In addition, our colleagues use a labeling technique for localizing specific proteins within cellular structure. Natural antibodies are utilized to attach dense silver and gold particles to the protein of interest. A computerized process is used after the imaging to locate the sharp increases in intensity to identify the regions of labeling.