High resolution infrared studies of dynamics in low temperature matrics: Vibrational dephasing for SeF6 in noble gas solids

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Abstract
High resolution infrared absorption spectra for the y3 mode of SeF6 in low temperature noble gas matrices have been observed. A remarkable amount of structure is observed leading to the conclusion that multiple trapping sites as well as site symmetry splittings, similar to those observed previously for SF6, are common. Temperature dependent studies give a rich display of dynamics arising from host–guest interactions. These give evidence for dynamic exchange among equivalent low symmetry sites within a given trapping cage. This exchange is evidence for a dephasing of the components of y3 by a local site phonon mode in resonance with part of the phonon bath. Unexpected matrix shifts and intensity changes with temperature have been observed. Accurate isotope shifts, especially in a neon matrix, are shown to be useful for calculation of potential constants. A discussion of host–guest interactions, dephasing, and dynamic site exchange in these matrices is given.