Refractivity and dispersion of hydrogen in the visible and near infrared

The refractivity of natural hydrogen gas has been measured at eighteen wavelengths from 0.4047 to 1.6945 μm by means of a corner-reflector interferometer. The resulting refractivity at 0.5462252 μm, and at standard conditions, is 139.304 × 10−6. Sixteen points of our data are well fitted by the dispersion formula 106(n − 1) = 21.113 + 12723.2/(111 − σ2), where σ is wave number in reciprocal micrometers. The combination of our data with recent measurements in the ultraviolet by Smith, Huber, and Parkinson is fitted by the formula 106(n − 1) = [14895.6/(180.7 − σ2)] + [4903.7/(92 − σ2)]. Comparisons are made with the literature in respect to refractivity, dispersion, dielectric constant, molecular polarizability, Rayleigh scattering cross section, and Verdet constant.