Terahertz Signatures of the Methane Replacement Reaction in Hydroquinone Clathrates.

We report a comprehensive experimental and computational study into low-frequency vibrational dynamics of hydroquinone clathrate during gas loading, in order to monitor replacement of carbon dioxide with methane in its atomic-level pores. We used terahertz time-domain spectroscopy, because terahertz modes are highly sensitive to the identity and structure of enclathrated guest molecules. Through simulations, we determined that the replacement reaction is not completed.