I have measured temperature-dependent α-hydroquinone and CH₄, CH₃(OH), CO₂ loaded β-hydroquinone clathrates up to 3THz using the THz Time-Domain Spectroscopy. Absorption spectrum is compared with the magnitude and the phase of THz pulse through the sample and the reference THz pulses at low temperature(158K) and room temperature(298K), respectively. α-hydroquinone has 9 resonances and 11 resonances at room temperature(298K) and low temperature(158K) respectively, whereas CH₄, CH₃(OH) loaded β-hydroquinone clathrates have only one resonance. At low temperature, the observed absorption resonances of hydroquinone have narrower peak and shift towards higher frequency compare with that of room temperature. Also, there are two and three new resonances that coming out at low temperature measurement in the α-hydorquinone and CH₄ loaded β-hydroquinone clathrate, respectively.
The CO₂ loaded β-hydroquinone clathrate shows resonance variation during 46 days at room temperature.
The observed THz resonances seem to represent the intermolecular and lattice vibrations of the hydroquinone frameworks and insensitive to the encaged guest species. Also, indices of refraction are measured to be 1.6 for α-hydroquinone and methane-loaded β-hydroquinone clathrate and 1.7 for methanol-loaded β-hydroquinone clathrate.