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

Abstract

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.