IR und XRD studies on the interactions between cryogenic matrices and isolated molecules

Cryogenic matrices have widely been used in order to spectroscopically characterize molecular species in an inert environment and at reduced thermal motion. In fact, even the unpolar, chemically inert nobelgas matrices have influences on the spectra of isolated molecules due to interactions between matrices and isolated molecules. In this work the complicated interactions between the isolated molecule and its matrix cage are studied by combination FT-IR spectroscopy with X-ray powder diffraction. The influences of cage structure on the dynamic of the isolated molecules were characterized by FT-IR spectroscopy. In how far these effects are related to type and extent of long-range order in the matrix was detected by XRD measurements. The influences of the parameters such as size, form and dipol moment of the probe molecules as well of the matrix molecules on the interactions between matrix and isolated molecules were systematic studied by variation on one hand the probe molecules (e.g. CH4, CH3CN and HCN), on the other hand the matrix materials (e.g. CF4, SF6, CH4, Ar and Kr). (author)