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Nanomaterial, Surface analysis, Background signal, Secondary electron
Dr Bo Da has been engaged in developing novel measurement-analysis methods to extract more information from measured spectra by surface analysis techniques. For instance, he developed the reverse Monte Carlo method to extract optical constant of bulk material from measured surface electron spectra, and the extended Mermin method to determine low energy electron mean free path of bulk material. Most recently, Da’s research focus has been largely related to development of new measurement-analysis method for nanomaterial samples. The virtual substrate method developed by him represents a benchmark for surface analysis to provide “free-standing” information about supported nanomaterials, and brought him President’s Prize awarded by NIMS. He has had ten first-author papers related to these new methods published in various journals, including Nature Communications, Physical Review Letters and Journal of Applied Physics, among others.
Characterization techniques available for bulk or thin-film solid-state materials have been extended to substrate-supported nanomaterials, but generally non-quantitatively. This is because the nanomaterial signals are inevitably buried in the signals from the underlying substrate in common reflection-configuration techniques. Here, we propose a virtual substrate method, inspired by the four-point probe technique for resistance measurement as well as the chop-nod method in infrared astronomy, to characterize nanomaterials without the influence of underlying substrate signals from four interrelated measurements. This method in secondary electron (SE) microscopy, a SE spectrum (white electrons) associated with the reflectivity difference between two different substrates can be tracked and controlled. The SE spectrum is used to quantitatively investigate the covering nanomaterial based on subtle changes in the transmission of the nanomaterial with high efficiency rivaling that of conventional core-level electrons. The virtual substrate method represents a benchmark for surface analysis to provide “free-standing” information about supported nanomaterials.
- Bo Da, Jiangwei Liu, Mahito Yamamoto, Yoshihiro Ueda, Kazuyuki Watanabe, Nguyen Thanh Cuong, Songlin Li, Kazuhito Tsukagoshi, Hideki Yoshikawa, Hideo Iwai, Shigeo Tanuma, Hongxuan Guo, Zhaoshun Gao, Xia Sun, Zejun Ding. Virtual substrate method for nanomaterials characterization. Nature Communications. 8 (2017) 15629 10.1038/ncomms15629
- H. Xu, B. Da, J. Tóth, K. Tőkési, Z. J. Ding. Absolute determination of optical constants by reflection electron energy loss spectroscopy. Physical Review B. 95  (2017) 10.1103/physrevb.95.195417
- B. Da, H. Shinotsuka, H. Yoshikawa, Z. J. Ding, S. Tanuma. Extended Mermin Method for Calculating the Electron Inelastic Mean Free Path. Physical Review Letters. 113  (2014) 10.1103/physrevlett.113.063201
- DA, Bo, YOSHIKAWA, Hideki, TANUMA, Shigeo. Electron transport properties of monolayer graphene measured from secondary electron microscopy according to the substrate variational method. EMAS Workshop / IUMAS Meeting. 2017
- DA, Bo, YOSHIKAWA, Hideki, TANUMA, Shigeo. Extracting pure nanomaterial information by surface analysis using the chop-nod method. the 20th International Vacuum Congress. 2016
- DA, Bo, YOSHIKAWA, Hideki, TANUMA, Shigeo, IWAI, Hideo. Low Energy Electron-Electron Interaction Information of Graphene Measured from Secondary Electron Microscopy. 7th International Symposium on Practical Surface Analysis. 2016
- Best Poster Award, by the Executive Committee of Joint Symposium on Materials Integration and Advanced Materials Characterization, Japan (Tsukuba). (2018)
- President’s Prize for Advances in Science and Technology for Young Scientists, by National Institute for Materials Science, Japan (Tsukuba). (2017)
- Best Poster Award, by the Executive Committee of Joint Symposium on Intercommunity and Measurement, Japan (Tsukuba). (2016)
- Best Poster Award, by the Executive Committee of Joint Symposium on Intercommunity and Measurement, Japan (Tsukuba). (2014)
- President’s Prize for Advances in Science and Technology for Young Scientists (2011)
- Student Award, by The 141st Committee on Microbeam Analysis of Japan Society for the Promotion of Science, Korea (Seoul). (2011)