Refractive Index Variations for Argon, Nitrogen, and Carbon Dioxide at λ = 632.8 nm (He−Ne Laser Light) in the Range 288.15 K ≤ T ≤ 323.15 K, 0 < p < 110 kPa

Direct measurements of the refractive index n of three gases (Ar, N 2, and CO 2 ) near ambient temperature and pressure states have been made by interferometry at the wavelength of the He−Ne laser light. Comparison with data obtained by interpolation of previous data shows good agreement (Δ( n − 1)/( n − 1) < 0.6%), the present data being always slightly higher than those obtained indirectly. Partial derivatives ∂ n /∂ T, useful in interferogram interpretation, have also been obtained for the three gases.