Dielectric constants of H sub(2)O and D sub(2)O ice in the terahertz frequency regime over a wide temperature range

We measured the real and imaginary dielectric constants, [varepsilon]' and [varepsilon]", of H sub(2)O and D sub(2)O ice over the frequency range of 0.2-1.4 THz and temperature range of 20-240 K using terahertz-time domain spectroscopy and a gas-cooled cryostat. The constant [varepsilon]' increased with frequency; numerical calculations indicated a local maximum in [varepsilon]' at a few terahertz. The polarizability alpha obtained from [varepsilon]' exhibited a linear increase with respect to the temperature squared (T super(2)). The constant [varepsilon]", which is mainly influenced by infrared phonon absorption, increased with the frequency and temperature over the entire range considered in this study. A mathematical model was created to describe the frequency and temperature dependence of [varepsilon]".