Nuclear magnetic resonance study of xenon adsorbed on metal-NaY: zeolites

The NMR spectrum of 129Xe adsorbed on a sample of platinum supported on NaY zeolite, at 25°C, consists usually of a single component whose chemical shift is : δ (Xe) = λ . δPt + μ . δs + δ(Xe–Xe). PXe where δPt, δS and δ(Xe–Xe) are the chemical shifts of Xe atoms colliding with the platinum particles, the wall S of the supercages or another Xe atom, respectively. pXe is the adsorbate density ; λ and μ are the Xe-Pt and Xe-S collision frequencies. We have shown that it is possible to calculate the shift δPt from the dependence of δ (Xe) on pXe. δPt varies with the number of Pt atoms per particle, x and with the coverage of the metal surface by prechemisorbed hydrogen. The high value of δPt is attributed to charge transfer from xenon to the metal (Pt–, Xe+)