Senior Staff Researcher

Team Leader

Nano-Optics Research Team

Center for Applied Near-Field Optics

National Institutes of Advanced Industrial Science & Technology

I am a senior research scientist here at AIST (National Institutes for Advanced Industrial Science & Technology). I am a staff member of the Center for Applied Near-Field Optics Research (CAN-FOR). I am also an affiliated staff member at SPring-8, the world's largest synchrotron. As of 2007, I became group leader of the 近接場基礎研究チーム。I would roughly translate this as the Near-Field Fundamental Research Team, but I guess Nano-Optics is shorter.

I graduated from the University of Illinois where I took my Ph.D. There a took a sort of hybrid path involving the growth of metastable III-IV-V semiconductor alloys, experimental characterization of them (XPS and XRD), and modeling of them (kinetic Monte-Carlo growth models and Lancos recursion methods for electronic structure simulation). After a two year stint in the Institute of Applied Physics Department at the University of Tsukuba, I moved to the Electrotechnical Laboratory (now part of AIST) and became a permanent staff member there in 1993. After a lot of molecular beam epitaxy experience, I spent a lot of time learning analytical technqiues such as transmission electron microscopy, photoluminescence, and high-resolution x-ray diffraction to name a few. Following up on the desire to be able to characterize point defects, I started using x-ray absorption spectroscopy (XAFS).

XAFS allows probing of local order about a selected atom type up to a characteristic distance of <0.8 nm. As such it provides a method for measuring atomic ordering on a length scale inaccessible to diffraction (which typically probes lengths from tens of nanometers up to the coherence length of the probe beam). XAFS is actually quantum mechanical interference of a photoelectron with itself. As short range order exists even in amorphous structures, XAFS is an idea tool for investigating transformations from the amorphous to the crystalline state.

I am also a heavy user of the Photon Factory located about 20 minutes from AIST. The Photon Factory is a 2.5 GeV electron storage ring with a storage current of 450 mA and an emittance of 27 nm*rad. The beam lifetime is also over 50 hours resulting in people often referring to it as a-second-and-a-half generation synchrotron. In addition to the wavelength tunability (from the IR to the hard x-ray), a very large advantage from my point of view is that it is about 20 minutes by car from the laboratory. In addition to the very large increase in brilliance, the tunability of the synchrotron allows for elementally selective determination of local structure about atoms in a material via X-ray Absorption Spectroscopy (XAFS). At CAN-FOR, I am now a heavy user of SPring-8, the world's highest energy (largest) light source. It is only about an eight hour trip from my house by Shinkansen (so much for close!). The higher energy and larger source brightness allow for use of higher energy excitation (heavier elements) as well as smaller focus spot size.