The division of Microbeam Analysis (MBA) was established in May 2020. This division conducts various activities such as regular research meetings, training seminars, international symposia, and so on. This special issue introduces recent research topics on atomic-resolution holography, electron microscopy, Secondary Ion Mass Spectroscopy, and multimodal data analysis. The database for Auger and secondary electron spectra that is available online is also introduced.
Atomic-resolution holography microscope is proposed, and has been composed by combining a small SEM and a new two-dimensional display-type analyzer CoDELMA. CoDELMA can display an angular distribution of emitted electrons from the sample up to ±50° with high energy-resolution at once. The electron beam size can be down to 20 nm, which ensures the spatial resolution of several tens nm. A holographic reconstruction from the angular distribution of Auger or energy-loss electrons emitted from selected atomic species reveals the three-dimensional atomic arrangement around the atom. Hence this system works as an atomic-resolution holography microscope, which can reveal the three-dimensional atomic arrangement around the selected atomic species in nm region for the first time.
Overview of SIMS technique is reported in conjunction with novel primary ion beams and advanced mass spectrometers. Many applications of SIMS, from organic semiconductors to cells and tissues, have been demonstrated over the past 10 years. One of the biggest problems was the “static limit” in the analysis of organic molecules, which are very fragile in ion bombardment. However, this problem was overcome after the development of large cluster ion beams.
This opens up new possibilities for SIMS to analyze organic materials. Future prospects of MS/MS technique and “Ambient SIMS” with MeV ion beam are discussed.
In this article, the development of a new nano/atomic-scale imaging method based on electron diffraction intensity is introduced. The method is based on the technique called diffractive imaging, in which the sample structure is reconstructed from its diffraction intensity through iterative calculations. As a result of the developments of specific experimental setups and reconstruction algorithms suitable for transmission electron microscopes (TEM), the phase imaging across the field of view of 100 nm and the atomic-resolution imaging superior to the aberration-corrected TEM imaging have been achieved.
Multimodal data analysis provides useful information that is not generally obtained from one of the analysis methods. In this study, time-course images of hydrogen distribution on a steel sample measured using electron stimulated desorption (ESD), scanning electron microscopy (SEM) images and electron backscatter diffraction (EBSD) images were fused to create a multimodal image data set. The fused multimodal images were analyzed by principal component analysis, least absolute shrinkage and selection operator (LASSO) and autoencoder. Each method is one of the most popular methods in each field, multivariate analysis, sparse modeling, and unsupervised learning based on artificial neural networks, respectively. The results of PCA, LASSO and autoencoder were consistent, and each method provides different aspects of the sample data information.
The Division of Microbeam Analysis, the Japan Society of Vacuum and Surface Science, publishes the Database for Auger and Secondary Electron Spectra online (https://www.jvss.jp/division/mba/sedb/). These spectral data were measured with an SI traceable cylindrical mirror analyzer developed by Keisuke Goto (absolute measurement system). The database body stores measurement data and spectra of 56 materials and 47 materials as an appendix. This paper reports the concept and characteristics of the absolute measurement system and introduces the electron spectra database.