Applied Chemistry
At the laboratories…

Development of innovative radiation
sensors having the best quality in the world
Applied Chemistry

Quantum Physical Chemistry（Asai Laboratory）

W chemistry from the viewpoint of ultrafast
e are exploring a new frontier in materials

dynamics, peculiar electronic excitation generated byionizing radiations, and nanostructures. At the moment,
we are mainly focusing on the development of novel
scintillation materials, which can be used to
manufacture radiation sensors. Our aim is to develop
excellent scintillation materials in order tomanufacture a novel high-quality detector that canvery accurately determine the arrival time of ionizing
radiation, i.e., a detector with a very high time
resolution. We have already developed a detector thatexhibits a time resolution of less than 100 ps (= 10billionth of a second), which in the best time resolution

Schematic structure of novel scintillation material:organic-inorganic perovskite-type compounds

reported so far. Our unique approach allow the production of novel high-quality scintillation materials.
Controlling the electronic states is very important in the development of scintillation materials,
because the scintillation process is dependent on the nature of the electronic states. We havebeen employing nanotechnology to achieve this control. One example is the development ofProfessor of Applied Chemistry atthe Graduate School of Engineering
Doctor of Engineering

Keisuke Asai
Graduated from Asahigaoka High School(Aichi Prefecture) in 1981. Graduated in1986 from the Department of Applied
Physics, Faculty of Engineering,
University of Tokyo, majoring in physics
engineering, before joining Sony.
Completed a master's course at theUniversity of Tokyo Graduate School ofEngineering in 1991 and was appointed
as an assistant at the University of TokyoGraduate School of Engineering thatyear. Served as a lecturer before being
appointed assistant professor at theUniversity of Tokyo Graduate School ofEngineering in 1999. Assumed current
position in 2003.
"I was fascinated by things like stars,
rocks and insects from an early age,particularly fossils, which inspired in me
a sense of the drama of ancient history."
The slogan of the Asai Laboratory is:
Don't be too serious, but do be diligent.

organic-inorganic perovskite-type compounds, in which a two-dimensional structure (quantum well)is naturally formed. We have succeeded in developing novel high-quality scintillation materials, andthese materials have attracted much attention from researchers and potential users. This was thefirst successful development of scintillation materials by utilizing the quantum confinement effect.
At present, by using various fabrication methods, we are developing novel materials of higher
quality for practical use. These high-quality materials will greatly contribute to advances in basic
science and industrial applications.
We are investing considerable efforts to develop materials having the best quality in the world. In
the course of our daily research activities, we often encounter unprecedented results. This is amajor source of inspiration that motivates us to conduct further studies and has helped us carryout pioneering research in this unexplored field of science. The vast universe of science canbenefit from our diligence and enthusiasm.

Main research themes● Fabrication of ultrafast scintillation materials (light-emitting radiation sensors) byusing nanotechnology● Development of novel radiation sensors using correlated electron system● Structural analysis of minute space within materials using elementary particles―from atomic vacancies to pores at nanometer scale● S ynthesis of self-organized semiconductor nanostructure to achieve novel
optical and magneto-optical properties