Diffusivity of 3He, 4He, H2, D2, Ne, CH4, Ar, Kr, and CF4 in (C4F9)3N

An earlier paper from this laboratory reported that diffusion coefficients of gases in CCl₄ multiplied by their molecular cross sections are the same for gases heavier than Ne, but that they increase linearly from D₂ to ⁴He with the square of the de Boer quantum parameter A^*. The present study of gases in (C₄F₉)₃N includes ³He. For relative cross sections we use, instead of uncertain values of σ², the $\frac{2}{3}$ power of the critical volumes, V_c, accurately known from critical densities. Measured values conform to the equation ${10}^2{\mathrm{DV}}_c^{\text{2/3}}{\text{= 70(1+1.94Λ}}^{\text{*2}})$ . Diffusion coefficients in CCl₄, multiplied by $V_c^{\text{2/3}}$ yield ${10}^2{\mathrm{DV}}_c^{\text{2/3}}{\text{= 70(1+3.00Λ}}^{\text{*2}})$ . The relative steepness of the two quantum lines is $\text{3.00 ÷ 1.94 = 1.60}$ , exactly the same as the ratio of the internal pressures of the two liquids, 3350/2160.