Tokyo Institute of Technology, Japan
Mitsumasa Iwamoto completed his PHD at Tokyo Institute of Technology in 1981, and now a professor of the same university. He is a fellow of JSAP (Japan Society of Applied Physics), and also a fellow of IEICE (The Institute of Electronics, Information and Communication Engineers). He is a council member of Association of Asia Pacific Physical Societies (AAPPS). He has published many papers in reputed journals, such as Nature, Nature photonics, Physical Review Letters, etc., and he wrote and edited many books, such as “The physical Properties of Organic Monolayers” (World Scientific, Singapore, 2001) and “Nanoscale-interface for organic electronics”.
Optical second harmonic generation (SHG) measurement has been widely used to characterize the structure of organic thin films, including Langmuir films on the water surface, where non-linear optical susceptibilities of organic films which originates from arrangement of molecules and nonlinear molecular susceptibility are well probed. However once we focus on the electric field coming out from electron motion and rotational dipolar motion, which are governed by the Gauss law, we can directly probe electron motion in organic thin films as well as rotational dipolar motion in monolayer. The technique we use here is a novel optical second harmonic generation technique based on electric field induced optical second harmonic generation (EFISHG) measurement. Using EFISHG, we visualize carrier motions in organic thin films, which are introduced in organic devices. In this presentation, we first discuss basic principle of EFISHG for probing dynamical carrier motion in organic films, and then visualize carrier motion. Similarly we show rotational dipolar motion in organic monolayer is directly probed by using Maxwell-displacement current. Finally as the extension of SHG measurement, we show the advanced conventional optical second harmonic generation measurement coupled with the Brewster Angle Microscope (BAM), which is capable of visualizing polarization structure of Langmuir-monolayers. We then demonstrate that the domain shapes of mixed lipid layers which are visualized by SHG and BAM are the same, but we can see textures originated from induced dipoles, different from macroscopic domain patters. Finally we show rotational dipolar motion in organic layer is directly probed by using Maxwell-displacement current.