Waveguide terahertz time-domain spectroscopy of nanometer water layers

Waveguide terahertz time-domain spectroscopy is demonstrated to have the sensitivity to characterize nanometer-thick water layers on the surfaces of a parallel-plate metal waveguide. The measured far-infrared absorption and index of refraction of the 20-nm water layers are in reasonable self-consistent agreement with those of bulk water. (C) 2004 Optical Society of America.