Published online by Cambridge University Press: 24 October 2008
1. The formulae usually given for the scattering of electrons by atoms are calculated without taking into account the radiative forces. It has been suggested by the author in a former paper that in the case of the large-angle scattering of electrons with velocity comparable with that of light (for which case the scattering is entirely nuclear), these forces might influence the scattering by an appreciable amount, which would explain the divergence between the theoretical formula and the results of Chadwick and Mercier, which are some 40 per cent. greater. In this paper we shall show that for electrons–of any velocity the influence of these forces cannot be greater than 2 or 3 per cent., and so cannot be invoked to explain discrepancies between theory and experiment.
* Proc. Roy. Soc. Vol. 124 (1929), p. 425.Google Scholar
† Loc. cit., equation (25).
‡ I.e. such that one electron crosses unit area per unit time.
§ Throughout this paper, 2πh is used for Planck's constant.
* Kramers, , Phil. Mag. Vol. 46 (1923), p. 836.CrossRefGoogle Scholar The formula is deduced by means of classical electrodynamics and the correspondence principle, and is qualitatively in agreement with experiment.
† Dirac, , Proc. Roy. Soc. Vol. 114 (1927), p. 243.CrossRefGoogle Scholar
* Dirac, loc. cit. equation (30).
* For the case of a Coulomb field we can use a shielded potential.
* Mott, loc. cit. p. 431.
* Gordon, , Zeits. für Physik, Vol. 48 (1928), p. 180.CrossRefGoogle Scholar
* The validity of approximations used in obtaining this formula is discussed at the end of section 5. For α particles, twice this must be taken.
† Gaunt, , Phil. Trans. Roy. Soc. Vol. 229 (1930), p. 163.CrossRefGoogle Scholar
* N.B. Planck's constant is 2πh.