Temperature and density dependence of 129Xe chemical shift in xenon gas

Studies of density dependence of 129Xe chemical shift in xenon gas at room temperature have shown that while the chemical shielding does have quadratic and cubic dependence on density over densities up to 250 amagat, σ(ρ, T) = σ0 + σ1(T)ρ + σ2(T)ρ2 + σ3(T)ρ3, the curve is essentially linear up to about 100 amagat. We have now obtained σ1(T), the linear density coefficient of chemical shielding, for pure xenon over the temperature range 240–440 °K. The experimental values of σ1(T) can be fitted by a fourth degree polynomial: σ1(τ) = 0.536 − 0.135 × 10−2τ + 0.132 × 10−4 τ2 − 0.598 × 10−7τ3 + 0.663 × 10−10τ4 (ppm/amagat), where τ = T − 300 °K. Comparison is made with σ1(T) for other nuclei and with σ1(T) predicted by various theoretical models.