Motoki Imamura

Determination of the complex dielectric constant of an epithelial cell monolayer in the terahertz region

We present a method to determine the complex dielectric constant of a cell monolayer using terahertz time-domain attenuated total reflection spectroscopy combined with a two-interface model. The imaginary part of the dielectric constant of the cell monolayer shows a lower absorption of slow relaxation mode than that of the liquid medium. This result allows us to estimate the intracellular water dynamics on a picosecond time scale, and the existence of weakly hydrated water molecules inside the cell monolayer was indicated. This method will provide a perspective to investigate the intracellular water dynamics in detail.

3D Imaging and analysis system using terahertz waves

We have developed the “3D Imaging Analysis System” that uses terahertz waves, the worlds first such system for practical applications. This system has an unprecedented capability for nondestructive three-dimensional spectroscopic analysis of the spatial distribution of constituents.

3D Spectroscopic computed tomography imaging using terahertz waves

We have developed a three-dimensional spectroscopic imaging system that uses terahertz waves and is based on transmission computed tomography. Using this system, we demonstrate transmission three-dimensional computed tomography imaging of high refractive index objects, with identification of chemical components, by analyzing spectroscopic information.

Pore-size dependent THz absorption of nano-confined water.

We performed a THz absorption spectroscopy study on liquid water confined in mesoporous silica materials, MCM-41-S-18 and MCM-41-S-21, of two different pore sizes at room temperatures. We found that stronger confinement with a smaller pore size causes reduced THz absorption, indicating reduced water mobility due to confinement. Combined with recent theoretical studies showing that the microscopic structure of water inside the nanopores can be separated into a core water region and an interfacial water region, our spectroscopy analysis further reveals a bulk-water-like THz absorption behavior in the core water region and a solid-like THz absorption behavior in the interfacial water region.

Failure analysis of LSI interconnection by terahertz time-domain reflectometry

It is getting significant to identify the fault location in advanced IC packaging technology. However, challenges have been posed to precisely determine the fault location in the failure analysis process, which is difficult to be handled by the conventional electronic based time domain reflectometry. In this work, we developed a time-domain reflectometry technology with extremely small distance-to-fault measurement error less than 50 μm, which includes X-ray length measuring error, by introducing pulsed terahertz probing signal to Quad Flat Package.