Electron Correlation Leading to Double-K-Shell Vacancy Production in Li-Like Ions Colliding with Helium

摘要

Single and double K-shell vacancies in Be~+, B~(2+), C~(3+), and O~(5+) Li-like ions colliding with neutral helium at intermediate-to-high velocities have been investigated. Specific excited states were observed using high-resolution Auger-electron spectroscopy. The velocity dependence of the measured cross sections for the formation of doubly vacant K-shell states was used to determine the mechanisms responsible for producing these so-called "hollow states". Electron correlation effects were inferred from the spectral features and the velocity dependence of the observed hollow states. The variation of the correlation strength was investigated as a function of the atomic number of the Li-like ion.