Search

The complex dielectric constant of human cultured cell, HeLa, is determined in the terahertz region. Since they are sensitive to picosecond motions, intracellular water dynamics mediated by hydrogen bonds are discussed. As a result, it is suggested that about 25 % of water molecules are slightly perturbed and hydrogen bonds are more “unstructured” in the cellular milieu, indicating 6 % of total intracellular water molecules are isolated from hydrogen bond network of water.

To confirm the feasibility of applying THz time domain spectroscopy (TDS) technique to nondestructive evaluation (NDE) of wood, the relation of relative permittivity to density for specimens of 12 wood species was investigated using THz-TDS transmission measurement system. The dielectric anisotropy, the difference in the relative permittivity in the fiber and transverse direction of wood, was also examined. The relative permittivity increased with wood density. The relation between the anisotropy and density was concave downward. These findings indicate that THz-TDS technique can be applied to NDE of wood density and grain direction.