Development and application of soft X-ray spectrometer for electron microscopes

Koike, Masato

Electron microscope and has a nearly 90-year history, has a lot of contributions to the observation and analysis of the micro-region. Therefore elemental analysis, structural analysis, energy dispersive spectrometer for the purpose of state analysis (EDS), wavelength dispersive spectrometer (WDS) and many of the spectrometer have been developed. However, a practical electron microscope spectrometer in the soft X-ray region required for the analysis of light elements such as lithium was present. To overcome this problem, the group of Tohoku University, JEOL Ltd., Shimadzu Corporation, and Japan Atomic Energy Agency have developed a soft X-ray spectrometer for electron microscopy to achieve high energy resolution by combining varied-line-spacing aberration-corrected diffraction gratings and a high sensitivity X-ray CCD camera. This instrument allows us parallel detection like EDS, and it is possible to perform high energy resolution analysis, e.g., 0.3 eV (Fermi edge Al-L), in a wide energy region of 50 eV 4 keV. By spectroscopic system design of the new development, spectra including various energies can be measured simultaneously without moving diffraction grating and detector. Moreover, taking advantage of a high energy resolution, it is possible to collect the state analysis map. We describe the development of flat-field varied-line-spacing holographic laminar type diffraction grating, which is the heart of this device, and give an overview of the spectrometer system as well as an summary of measured data including mapping.