Dispersion relations appropriate to the scattering of electrons by hydrogen atoms are deduced, and applied to actual measurements in the 0-10 ev energy range. Two such experiments exist, yielding quite different results. Dispersion relations indicate that only certain angular distributions at low energy are consistent with these low-energy total cross-section measurements; this suggests experiments which could be used as checks on the accuracy of the existing measurements.

• Received 17 December 1959

DOI:https://doi.org/10.1103/PhysRev.119.705