Spin Blocking in the Correlated Double-Electron Capture from Metal Surfaces

Abstract

The resonant capture of electrons from a metallic surface into the outer shell of a helium ion creates doubly excited states in a spin singlet (↑↓) or triplet (↑↑) configuration. Here it is shown that the capture of one or two electrons can be described in a simple quantitative model, and the capture of two electrons by He(++) proceeds in a single step. The double capture of electrons from the Fermi energy of the metal is dominated by the spin dependent electron correlation that blocks the occupation of triplet states in the ion, but creates a singlet two-hole final state at the surface, related to the concept of the exchange-correlation hole.

Imaging Momentum–Space Two‐Particle Correlations at Surfaces

“…This view is further corroborated by a recent work in which the electron capture for He 2þ ions into excited states proceeds in a single step. [40] Extending this picture of a correlated double-electron capture, we observe here a single step of an electron pair from the metal into the ground state of the He atom.…”

“…[37,38] A modified sputter ion gun allowed the excitation of the surface with low-energy He þ and He 2þ ions. [39][40][41] Studies on Auger decay were conducted at the synchrotron light source BESSY II of the Helmholtz-Zentrum Berlin (HZB). We comment briefly on a new DPE setup which uses a light source based on high harmonics generation in combination with a pair of time-of-flight spectrometers.…”