Knowledge Bank

The guest molecules in a clathrate hydrate are isolated in well-defined cages. Such systems were difficult to study spectroscopically prior to the demonstration that crystaline films of the clathrate hydrates of polar molecules can be readily deposited from the vapor $phase1,2$. Recently, as part of a study of the mechanism of the growth of ice-like crystals at low temperatures, infrared spectra of several caged molecules have been measured. The spectra are marked by evidence of dynamical coupling between neighbour guest molecules, Evans holes (i.e., Fano antiresonances) caused by the interaction of guest and host vibrational states, and sharp variations with temperature that reflect the orientational dynamics of the engaged molecules.