Helium: the curated data

Every direct helium dataset (a refractivity, polarizability or molar refractivity) turned into the refractivity of the real gas at 0 °C and 1 atm, with the published formulas (solid), the recorded luna_physdata formulas (dashed) and refractiveindex.info’s entries (dotted), each over the range its source supports. The lower panel shows the deviations from Mansfield & Peck’s two-pole fit to their own theoretical values (Eq. 8, corrected), which is smooth down to the first resonance.

from _helpers import data_overview

fig = data_overview("He", "mansfield_peck_1969/eq8", xlim=(4e-08, 2e-05))