Dispersion formulæ and the polarisation of scattered light: vith application to hydrogen

Since Lord Rayleigh’s experimental study of the polarisation of light scattered by gases, the subject has been examined theoretically from various points of view; in particular by the late Lord Rayleigh, M. Born, Sir J. J. Thomson, and R. Gans. The object of the following paper is to connect the polarisation of light scattered by a simple homogeneous medium with the constants of the dispersion formula for that medium. The result of the calculation gives the ratio of the intensities of the two polarised components for all wave-lengths for which the dispersion formula is valid. Although the expressions can be generalised, they, are given in the first instance in their simplest form. Assuming the medium to be a gas whose approximate dispersion formula contains only one natural frequency in the ultra-violet, this is generalised by supposing the molecules to be anisotropic; the single natural frequency is then replaced by a triplet, or by a doublet for molecules with axial symmetry. In the latter case the dispersion formula is, in the usual notationn 2 - 1 = ⅓ C {(p 1 2 -p 2 )-1 + 2 (p 2 2 -p 2 )-1 }.