The Scattering of X-Rays by Polyatomic Gases

Recently Jauncey has shown that the factor $F$ in Compton's formula for the scattering of x-rays by an atom should be the average atomic structure factor $F^{\prime }$ instead of the true atomic structure factor. Taking this into account, the general expression for the intensity of total scattering of x-rays by polyatomic gases previously deduced by the writer is modified replacing $F$ by $F^{\prime }$. The theory is applied to the scattering of x-rays by diatomic gases and the theoretical scattered intensity is actually compared with the absolute measurements made by Wollan on the scattering of Mo $K\alpha$ rays by ${\mathrm{H}}_2$, ${\mathrm{N}}_2$ and ${\mathrm{O}}_2$. The values of $F$ and $F^{\prime }$ are calculated from the Hartree field. On the whole Wollan's results support the new formula, though the old one represents in each case the general feature of the scattering curve. It is pointed out that, for the scattering by a diatomic gas of like atoms, Jauncey's theory of the scattering of x-rays by polyatomic molecules consisting of atoms of one kind gives results practically identical with those of the present theory, provided the change of wave-length due to the Compton effect is corrected for.