129Xe contact shift in oxygen gas

Abstract
We have determined the temperature dependence of σ1 of 129Xe in oxygen gas. These results were obtained by measurement of the resonance frequency of 129Xe in gas samples of known densities in Xe and O2. The shift of the resonance frequency due to Xe-Xe interactions has been measured in pure Xe gas samples with improved precision. This allows the determination of σ1(Xe-O2) by subtracting out the known effect of Xe-Xe interactions in mixed Xe-O2 samples. σ1(Xe-O2) values are reported here for the temperature range 220 to 440 K. The values of σ1(Xe-O2) are adequately described by the polynomial function in p.p.m. amagat-1 σ1(Xe-O2) = - 1·061 + 3·64 × 10-3τ - 2·19 × 10-5τ2 + 9·58 × 10-8τ3 - 2·08 × 10-10τ4, where τ = (T - 300 K). It is found that the temperature dependence of σ1(Xe-O2) can be interpreted in terms of a contact interaction between Xe and the paramagnetic O2 molecule.