Abstract-New terahertz dielectric spectroscopy for the study of aqueous solutions

Deepu K. George¹, Ali Charkhesht¹ and N. Q. Vinh^1,a)
1 Department of Physics, Virginia Tech, Blacksburg, Virginia 24061, USA
a) Electronic mail: Vinh@vt.edu
Rev. Sci. Instrum. 86, 123105 (2015); http://dx.doi.org/10.1063/1.4936986

http://scitation.aip.org/content/aip/journal/rsi/86/12/10.1063/1.4936986


We present the development of a high precision, tunable far-infrared (terahertz) frequency-domain dielectricspectrometer for studying the dynamics of biomolecules in aqueous solutions in the gigahertz-to-terahertz frequency. As an important benchmark system, we report on the measurements of the absorption and refractive index for liquid water in the frequency range from 5 GHz to 1.12 THz (0.17–37.36 cm⁻¹ or 0.268–60 mm). The system provides a coherent radiation source with power up to 20 mW in the gigahertz-to-terahertz region. The dynamicrange of our instrument reaches 10¹² and the system achieves a spectral resolution of less than 100 Hz. The temperature of samples can be controlled precisely with error bars of ±0.02 °C from 0 °C to 90 °C. Given these attributes, our spectrometer provides unique capabilities for the accurate measurement of even very strongly absorbing materials such as aqueous solutions.