The electron momentum spectroscopy of lead

Abstract

Results of electron momentum spectroscopy measurements on lead vapour at a total energy of 1000 eV are presented in conjunction with a theoretical analysis using relativistic structure calculations. The 6p-1 transition is seen to be split, resulting in transitions to the 6p1 and 6p3/2 ion states. The measured branching ratio for these transitions is reproduced when a multiconfiguration Dirac-Fock wavefunction is used for the target ground state. The transition involving ejection of an electron from the 6s subshell is also seen to undergo significant splitting. The splitting in this case is mainly due to final-state configuration interaction, although a multiconfiguration target state must again be used to obtain detailed agreement with experiment. The measured momentum probability distributions for the 6p and 6s electrons agree with the orbital momentum distributions given by relativistic Dirac-Fock wavefunctions, although distortion effects are evident at high momenta for the 6s-1 transitions. The corresponding non-relativistic Hartree-Fock momentum distributions are in poorer agreement with the data. An inner valence 5d-1 transition is also seen, but the cross section is too small for detailed comparison with theory.