High-pressure 129Xe NMR study of supercritical xenon interacting with polymers

High-pressure 129Xe NMR experiments have been performed by using a newly designed probe. 129Xe NMR spectrum for the mixture of Xe and a polymer, either bisphenol-A polycarbonate or polytetrafluoroethylene, consists of two lines in a pressure range of 0.3–10 MPa. 129Xe NMR chemical shift (δ) for the free Xe is mainly governed by the Xe–Xe interactions. δ for Xe confined in the micropore of polymers is strongly affected by the Xe-wall interactions. It is found that δ of the confined Xe is mainly determined by a sort of `virtual pressureʹ and is not influenced by a drastic change of the free Xe density in the critical region.