A cathodoluminescence (CL) spectroscopy system equipped into a High Voltage Electron Microscope of Kyushu University (maximum acceleration voltage of 1250 kV) is introduced. This equipment allows us to acquire CL spectra in situ under high-energy electron irradiation, or under the production of Frenkel defects in specimens. Monitoring the accumulation process and charge states of point defects, which would not be available from conventional image analysis, is expected during electron irradiation. In this paper, recent results by the authors, that is, the accumulation of F centers and electron energy dependence of CL spectra in α-Al2O3 and cubic stabilized zirconia doped with 9.5, 18 mol% yttria (ZrO2: Y, or YSZ) during electron irradiation are described.
Study on irradiation defects in metals is strongly initiating by utilizing the large space around the pole piece, the superior electron penetrating capability compared to the conventional TEM and collision damage by high energy electrons of high voltage electron microscope (HVEM). Because effects of transmutation elements on defect formation and growth were not unclear for a long time, superposition effects of high energy electron irradiation with simultaneous ion irradiation have been studied by using HVEM with ion accelerators. We have successfully developed multi quantum-beam high voltage electron microscope (MQB-HVEM) with adding laser irradiation equipment. MQB-HVEM could reveal superposition effects of high-energy electrons, ions and laser by in-situ observation. In this paper, MQB-HVEM will be briefly introduced. Moreover, application of MQB-HVEM and expected research fields in near future are discussed.
High voltage electron microscopy (HVEM) has been the unique and indispensable irradiation facility equipped with simultaneous observation function. One of the current expected applications of HVEM is for developing structural component materials for nuclear fusion reactors in which severe irradiation with neutrons is expected. Reduced activation ferritic/martensitic steels (F82H) and oxide dispersion strengthened steels (ODS) were subjected to electron irradiations at elevated temperatures. Through in-situ microscopic observations, the instability of the strengthened factors, such as MX, M23C6 and Y-Ti oxide were investigated, and effects of displacements in matrix and irradiation-enhanced diffusion are deduced.
Energetic particles produce extensive defects in a target material, and finally structural changes are induced by damage accumulation. The damage processes under radiation environments are roughly classified into the “knock-on effects” and “electron excitation effects”. The former and the latter become more prominent under electron beam irradiation with higher and lower acceleration voltage, respectively. These effects degrade the quality of structural analysis, and therefore they should be avoided during electron microscopy observations. On the other hand, radiation effects are useful to realize atomic configurations far from an equilibrium state, which is difficult to be realized by conventional heat treatments. In this article, we demonstrate the synthesis of polycrystalline GeSn using the recrystallization of amorphous by low-energy electron-beam irradiation.
Single-particle electron cryo-microscopy (cryo-EM), which unlike x-ray crystallography and electron crystallography does not need a crystallization step, is expected to be useful for drug discovery. Therefore, the Japan Agency for Medical Research and Development (AMED) has implemented a program of cryo-EM-especially single-particle cryo-EM-to support drug discovery. Single-particle cryo-EM provides an alternative method of structural analysis that might allow us to build atomic models of target molecules when crystallographic analysis cannot be applied. Moreover, the structural data obtained should be useful in structure-based drug design. Although atomic models obtained for important biological molecules by using single-particle cryo-EM continue to be reported in top journals, expectations still precede concrete results in the field of drug development. This paper explains the problems of single-particle cryo-EM in drug discovery, and it uses real examples to describe why drug development needs this structural information.
Basic configuration and functions of a focused ion beam (FIB) system will be introduced. Basic preparation techniques for transmission electron microscopy (TEM) specimens using FIB systems will be explained. In addition, some TEM images of specimens prepared by such the FIB technique are presented. I hope that this paper will be useful for engineers and researchers who will use FIB systems in near future.
We have visualized distribution and concentration of elements comprising the calcified tissues using analytical scanning electron microscopy (Scanning electron microscopy with energy dispersive X-ray spectroscopy: SEM-EDX) to investigate propagation and maturation of calcification during development and healing of teeth and bones. The elements of calcium (Ca), phosphorus (P) and carbon (C) were analyzed in developing enamel and dentin of rat incisors. Developing bones in embryonic and postnatal rat mandibles and calvaria as well as healing bones in the standard defects in rat parietal bone were likely examined. The concentrations of Ca and P increased as enamel and dentin developed and bone developed and healed. In contrast, that of C decreased in developing teeth and bones and healing bones. SEM-EDX demonstrated that the calcium phosphate minerals increase and mature while organic components decrease during development and healing of the calcified tissues.
The thickness dependence of electron transmittance, observed as mass-thickness contrast in transmission electron microscopy images, was precisely measured. Based on the result, it was found that a function containing three parameters well expressed the nonlinear transmission attenuation with increasing thickness. The application of the result to quantitative-density tomography is also described.