Characteristics of Gadolinium Oxide Nanoparticles as Contrast Agents for Terahertz Imaging

For the application of gadolinium oxide (Gd₂O₃) nanoparticles as terahertz contrast agents, their optical properties in a solvent were studied using terahertz time-domain spectroscopy. The power absorption and refractive index of the samples were measured with various concentrations of nanoparticles. The power absorption was extremely large, as much as three orders of magnitude higher than that of water, so that a few ppms of Gd₂O₃ nanoparticles were distinguished in terms of their power absorption capacity. The results show that the interaction between the terahertz electromagnetic waves and the Gd₂O₃ nanoparticles is strong enough to allow their exploitation as contrast agents for terahertz medical imaging.