Ionisation of highly excited atoms by electric fields. II. Classical theory of the Stark effect

Abstract

For pt.I see ibid., vol.11, no.1, p.37 (1978). The classical adiabatic theory of the Stark ionisation threshold for hydrogenic ions (paper I) is extended to obtain the Stark shifts for all values of the electric field. Exact classical values are calculated and used to find an approximate expression for the energy for all values of the nuclear charge, the parabolic-action integrals and the electric field. Simple quantisation rules are used to obtain a quasiclassical expression for the energy, which is valid for highly excited hydrogenic ions in strong slowly varying electric fields. Comparisons of individual levels with the quantal calculations of Damburg (1976) suggest that the energy expression is accurate to within about 0.2% for all values of the nuclear charge, quantum numbers and electric field, in the absence of relativistic and level-crossing effects.